Add Splitter VFD to library.

* "Simultaneous and equivalent" Read-Write and Write-Only channels for
  file I/O.
* Only supports drivers with the H5FD_FEAT_DEFAULT_VFD_COMPATIBLE flag for
  now, preventing issues with multi-file drivers.

Add Mirror VFD to library.

* Write-only operations over a network.
* Uses TCP/IP sockets.
* Server and auxiliary server-shutdown programs provided in a new directory,
  `utils/mirror_vfd`.
* Automated testing via loopback ("remote" of localhost).

1 files changed, 2736 insertions, 0 deletions

diff --git a/test/mirror_vfd.c b/test/mirror_vfd.c
new file mode 100644
index 0000000..00902dd
--- /dev/null
+++ b/test/mirror_vfd.c
@@ -0,0 +1,2736 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by The HDF Group.                                               *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the COPYING file, which can be found at the root of the source code       *
+ * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
+ * If you do not have access to either file, you may request a copy from     *
+ * help@hdfgroup.org.                                                        *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Purpose: Test the Mirror VFD functionality.
+ */
+
+/* WARNING: The use of realpath() is probably system-dependent, as are
+ * other things here such as the socket calls.
+ * Notable to realpath() in particular is the use of "PATH_MAX", which
+ * apparently has some major potential issues if paths are abused.
+ * http://insanecoding.blogspot.com/2007/11/pathmax-simply-isnt.html
+ * so BE CAREFUL about the paths we throw around?
+ */
+
+#include "h5test.h"
+#include "cache_common.h"
+#include "genall5.h"
+
+#ifdef H5_HAVE_MIRROR_VFD
+
+/* For future consideration, IP address and port number might be
+ * environment variables?
+ */
+#define SERVER_IP_ADDRESS "127.0.0.1"
+
+/* Primary listening port on server. */
+#define SERVER_HANDSHAKE_PORT 3000
+
+#define DATABUFFER_SIZE 128
+#define DSET_NAME_LEN   16
+
+/* Parameters for the "large chunked dataset" writing */
+#define MAX_DSET_COUNT 255
+#define DSET_DIM        32
+#define CHUNK_DIM        8
+
+#define CONCURRENT_COUNT 3 /* Number of files in concurrent test */
+
+/* Macro: LOGPRINT()
+ * Prints logging and debugging messages to the output stream based
+ * on the level of verbosity.
+ *     0 : no logging
+ *     1 : errors only
+ *     2 : details
+ *     3 : all
+ */
+#define DEFAULT_VERBOSITY 1
+static unsigned int g_verbosity = DEFAULT_VERBOSITY;
+
+/* Macro for selective debug printing / logging */
+#define LOGPRINT(lvl, ...)                  \
+do {                                        \
+    if ((lvl) <= g_verbosity) {             \
+        fprintf(g_log_stream, __VA_ARGS__); \
+        fflush(g_log_stream);               \
+    }                                       \
+} while (0)
+
+#define MIRROR_RW_DIR "mirror_rw/"
+#define MIRROR_WO_DIR "mirror_wo/"
+
+/* String buffer for error messages */
+#define MIRR_MESG_SIZE 128
+static char mesg[MIRR_MESG_SIZE + 1];
+
+/* Convenience structure for passing file names via helper functions.
+ */
+struct mirrortest_filenames {
+    char rw[H5FD_SPLITTER_PATH_MAX+1];
+    char wo[H5FD_SPLITTER_PATH_MAX+1];
+    char log[H5FD_SPLITTER_PATH_MAX+1];
+};
+
+static FILE *g_log_stream = NULL; /* initialized at runtime */
+
+static herr_t _verify_datasets(unsigned min_dset, unsigned max_dset,
+        hid_t *filespace_id, hid_t *dataset_id, hid_t memspace_id);
+
+static herr_t _create_chunking_ids(hid_t file_id, unsigned min_dset,
+        unsigned max_dset, hsize_t *chunk_dims, hsize_t *dset_dims,
+        hid_t *dataspace_ids, hid_t *filespace_ids, hid_t *dataset_ids,
+        hid_t *memspace_id);
+
+static herr_t _close_chunking_ids(unsigned min_dset, unsigned max_dset,
+        hid_t *dataspace_ids, hid_t *filespace_ids, hid_t *dataset_ids,
+        hid_t *memspace_id);
+
+static herr_t _populate_filepath(const char *dirname, const char *_basename,
+        hid_t fapl_id, char *path_out, hbool_t h5suffix);
+
+static hid_t create_mirroring_split_fapl(const char *_basename,
+        struct mirrortest_filenames *names);
+
+
+/* ----------------------------------------------------------------------------
+ * Function:   _populate_filepath
+ *
+ * Purpose:    Given a directory name and a base name, concatenate the two and
+ *             run h5fixname() to get the "actual" path to the intented target.
+ *             `h5suffix' should be FALSE to keep the base name unaltered;
+ *             TRUE will append the '.h5' h5suffix to the basename...
+ *             FALSE -> h5fixname_no_suffix(), TRUE -> h5fixname()
+ *             <h5fixname_prefix> / <dirname> / <_basename> <h5prefix?>
+ *
+ * Programmer: Jacob Smith
+ *             2019-08-16
+ * ----------------------------------------------------------------------------
+ */
+static herr_t
+_populate_filepath(const char *dirname, const char *_basename, hid_t fapl_id,
+                   char *path_out, hbool_t h5suffix)
+{
+    char _path[H5FD_SPLITTER_PATH_MAX];
+
+    if ((_basename == NULL) ||
+        (*_basename == 0)   ||
+        (dirname == NULL)   ||
+        (*dirname == 0)     ||
+        (path_out == NULL))
+    {
+        TEST_ERROR;
+    }
+
+    if (HDsnprintf(_path, H5FD_SPLITTER_PATH_MAX, "%s%s%s", dirname,
+            (dirname[strlen(dirname)] == '/') ? "" : "/", /* slash iff needed */
+            _basename)
+        > H5FD_SPLITTER_PATH_MAX)
+    {
+        TEST_ERROR;
+    }
+
+    if (h5suffix == TRUE) {
+        if (h5_fixname(_path, fapl_id, path_out,
+                H5FD_SPLITTER_PATH_MAX)
+            == NULL)
+        {
+            TEST_ERROR;
+        }
+    }
+    else {
+        if (h5_fixname_no_suffix(_path, fapl_id, path_out,
+                H5FD_SPLITTER_PATH_MAX)
+            == NULL)
+        {
+            TEST_ERROR;
+        }
+    }
+
+    return SUCCEED;
+
+error:
+    return FAIL;
+} /* end _populate_filepath() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    build_paths
+ *
+ * Purpose:     Convenience function to create the three file paths used in
+ *              most mirror tests.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jacob Smith
+ *              2019-08-16
+ * ---------------------------------------------------------------------------
+ */
+static herr_t
+build_paths(
+        const char                  *_basename,
+        H5FD_splitter_vfd_config_t  *splitter_config,
+        struct mirrortest_filenames *names)
+{
+    char baselogname[H5FD_SPLITTER_PATH_MAX];
+
+    if (_populate_filepath(MIRROR_RW_DIR, _basename,
+            splitter_config->rw_fapl_id, names->rw, TRUE)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    if (_populate_filepath(MIRROR_WO_DIR, _basename,
+            splitter_config->wo_fapl_id, names->wo, TRUE)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    if (_basename == NULL || *_basename == 0)
+        return FAIL;
+    if (HDsnprintf(baselogname, H5FD_SPLITTER_PATH_MAX, "%s_err.log",
+            _basename)
+        > H5FD_SPLITTER_PATH_MAX)
+    {
+        TEST_ERROR;
+    }
+
+    if (_populate_filepath(MIRROR_WO_DIR, baselogname,
+            splitter_config->wo_fapl_id, names->log, FALSE)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    return SUCCEED;
+
+error:
+    return FAIL;
+} /* end build_paths() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_fapl_configuration
+ *
+ * Purpose:     Test FAPL configuration and examination.
+ *
+ * Return:      Success: 0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2019-03-12
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_fapl_configuration(void)
+{
+    hid_t fapl_id;
+    H5FD_mirror_fapl_t mirror_conf = {
+        H5FD_MIRROR_FAPL_MAGIC,          /* magic */
+        H5FD_MIRROR_CURR_FAPL_T_VERSION, /* version */
+        SERVER_HANDSHAKE_PORT,           /* handhake_port */
+        SERVER_IP_ADDRESS,               /* remote_ip "IP address" */
+    };
+    H5FD_mirror_fapl_t fa_out = {0, 0, 0, ""};
+
+    TESTING("Mirror fapl configuration (set/get)");
+
+    fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+    if (H5I_INVALID_HID == fapl_id) {
+        TEST_ERROR;
+    }
+
+    if (H5Pset_fapl_mirror(fapl_id, &mirror_conf) == FAIL) {
+        TEST_ERROR;
+    }
+
+    if (H5Pget_fapl_mirror(fapl_id, &fa_out) == FAIL) {
+        TEST_ERROR;
+    }
+    if (H5FD_MIRROR_FAPL_MAGIC != fa_out.magic) {
+        TEST_ERROR;
+    }
+    if (H5FD_MIRROR_CURR_FAPL_T_VERSION != fa_out.version) {
+        TEST_ERROR;
+    }
+    if (SERVER_HANDSHAKE_PORT != fa_out.handshake_port) {
+        TEST_ERROR;
+    }
+    if (HDstrncmp(SERVER_IP_ADDRESS, (const char *)fa_out.remote_ip,
+            H5FD_MIRROR_MAX_IP_LEN))
+    {
+        TEST_ERROR;
+    }
+
+    if (H5Pclose(fapl_id) == FAIL) {
+        TEST_ERROR;
+    }
+
+    PASSED();
+    return 0;
+
+error:
+    if (H5I_INVALID_HID != fapl_id) {
+        (void)H5Pclose(fapl_id);
+    }
+    return -1;
+} /* end test_fapl_configuration() */
+
+
+
+#define PRINT_BUFFER_DIFF(act, exp, len) do {                                 \
+    size_t _x = 0;                                                            \
+    while ((act)[_x] == (exp)[_x]) {                                          \
+        _x++;                                                                 \
+    }                                                                         \
+    if (_x != (len)) {                                                        \
+        size_t _y = 0;                                                        \
+        HDprintf("First bytes differ at %zu\n", _x);                          \
+        HDprintf("exp  ");                                                    \
+        for (_y = _x; _y < (len); _y++) {                                     \
+            HDprintf("%02X", (unsigned char)(exp)[_y]);                       \
+        }                                                                     \
+        HDprintf("\nact  ");                                                  \
+        for (_y = _x; _y < (len); _y++) {                                     \
+            HDprintf("%02X", (unsigned char)(act)[_y]);                       \
+        }                                                                     \
+        HDprintf("\n");                                                       \
+    }                                                                         \
+} while (0); /* end PRINT_BUFFER_DIFF */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_xmit_encode_decode
+ *
+ * Purpose:     Test byte-encoding operations for network transport.
+ *
+ * Return:      Success: 0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2020-02-02
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_xmit_encode_decode(void)
+{
+    H5FD_mirror_xmit_t xmit_mock; /* re-used header in various xmit tests */
+
+    TESTING("Mirror encode/decode of xmit elements");
+
+    /* Set bogus values matching expected; encoding doesn't care
+     * Use sequential values to easily generate the expected buffer with a
+     * for loop.
+     */
+    xmit_mock.magic = 0x00010203;
+    xmit_mock.version = 0x04;
+    xmit_mock.session_token = 0x05060708;
+    xmit_mock.xmit_count = 0x090A0B0C;
+    xmit_mock.op = 0x0D;
+
+    /* Test uint8_t encode/decode
+     */
+    do {
+        unsigned char buf[8];
+        unsigned char expected[8];
+        const uint8_t v = 200;
+        unsigned char out = 0;
+
+        /* Start of buffer uint8_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[0] = 200;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint8(buf, v) != 1) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint8(&out, buf) != 1) {
+            TEST_ERROR;
+        }
+        if (v != out) {
+            TEST_ERROR;
+        }
+
+        /* Middle of buffer uint8_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[3] = v;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint8((buf+3), v) != 1) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint8(&out, (buf+3)) != 1) {
+            TEST_ERROR;
+        }
+        if (v != out) {
+            TEST_ERROR;
+        }
+
+        /* End of buffer uint8_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[7] = v;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint8((buf+7), v) != 1) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint8(&out, (buf+7)) != 1) {
+            TEST_ERROR;
+        }
+        if (v != out) {
+            TEST_ERROR;
+        }
+
+    } while (0); /* end uint8_t en/decode */
+
+    /* Test uint16_t encode/decode
+     */
+    do {
+        unsigned char  buf[8];
+        unsigned char  expected[8];
+        const uint16_t v = 0x8F02;
+        uint16_t out = 0;
+
+        /* Start of buffer uint16_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[0] = 0x8F;
+        expected[1] = 0x02;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint16(buf, v) != 2) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint16(&out, buf) != 2) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+
+        /* Middle of buffer uint16_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[3] = 0x8F;
+        expected[4] = 0x02;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint16((buf+3), v) != 2) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint16(&out, (buf+3)) != 2) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+        /* slice */
+        if (H5FD__mirror_xmit_decode_uint16(&out, (buf+4)) != 2) {
+            TEST_ERROR;
+        }
+        if (out != 0x0200) {
+            TEST_ERROR;
+        }
+
+        /* End of buffer uint16_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[6] = 0x8F;
+        expected[7] = 0x02;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint16((buf+6), v) != 2) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint16(&out, (buf+6)) != 2) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+
+    } while (0); /* end uint16_t en/decode */
+
+    /* Test uint32_t encode/decode
+     */
+    do {
+        unsigned char  buf[8];
+        unsigned char  expected[8];
+        const uint32_t v = 0x8F020048;
+        uint32_t out = 0;
+
+        /* Start of buffer uint32_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[0] = 0x8F;
+        expected[1] = 0x02;
+        expected[2] = 0x00;
+        expected[3] = 0x48;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint32(buf, v) != 4) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint32(&out, buf) != 4) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+
+        /* Middle of buffer uint32_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[3] = 0x8F;
+        expected[4] = 0x02;
+        expected[5] = 0x00;
+        expected[6] = 0x48;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint32((buf+3), v) != 4) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint32(&out, (buf+3)) != 4) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+        /* slice */
+        if (H5FD__mirror_xmit_decode_uint32(&out, (buf+4)) != 4) {
+            TEST_ERROR;
+        }
+        if (out != 0x02004800) {
+            TEST_ERROR;
+        }
+
+        /* End of buffer uint32_t
+         */
+        HDbzero(buf, 8);
+        HDbzero(expected, 8);
+        expected[4] = 0x8F;
+        expected[5] = 0x02;
+        expected[6] = 0x00;
+        expected[7] = 0x48;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint32((buf+4), v) != 4) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 8);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint32(&out, (buf+4)) != 4) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+
+    } while (0); /* end uint32_t en/decode */
+
+    /* Test uint64_t encode/decode
+     */
+    do {
+        unsigned char  buf[16];
+        unsigned char  expected[16];
+        const uint64_t v = 0x90DCBE17939CE4BB;
+        uint64_t out = 0;
+
+        /* Start of buffer uint64_t
+         */
+        HDbzero(buf, 16);
+        HDbzero(expected, 16);
+        expected[0] = 0x90;
+        expected[1] = 0xDC;
+        expected[2] = 0xBE;
+        expected[3] = 0x17;
+        expected[4] = 0x93;
+        expected[5] = 0x9C;
+        expected[6] = 0xE4;
+        expected[7] = 0xBB;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint64(buf, v) != 8) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 16) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 16);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint64(&out, buf) != 8) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+
+        /* Middle of buffer uint64_t
+         */
+        HDbzero(buf, 16);
+        HDbzero(expected, 16);
+        expected[3]  = 0x90;
+        expected[4]  = 0xDC;
+        expected[5]  = 0xBE;
+        expected[6]  = 0x17;
+        expected[7]  = 0x93;
+        expected[8]  = 0x9C;
+        expected[9]  = 0xE4;
+        expected[10] = 0xBB;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint64((buf+3), v) != 8) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 16) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 16);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint64(&out, (buf+3)) != 8) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+        /* slice */
+        if (H5FD__mirror_xmit_decode_uint64(&out, (buf+6)) != 8) {
+            TEST_ERROR;
+        }
+        if (out != 0x17939CE4BB000000) {
+            TEST_ERROR;
+        }
+
+        /* End of buffer uint64_t
+         */
+        HDbzero(buf, 16);
+        HDbzero(expected, 16);
+        expected[8]  = 0x90;
+        expected[9]  = 0xDC;
+        expected[10] = 0xBE;
+        expected[11] = 0x17;
+        expected[12] = 0x93;
+        expected[13] = 0x9C;
+        expected[14] = 0xE4;
+        expected[15] = 0xBB;
+        out = 0;
+        if (H5FD__mirror_xmit_encode_uint64((buf+8), v) != 8) {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, 16) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, 16);
+            TEST_ERROR;
+        }
+        if (H5FD__mirror_xmit_decode_uint64(&out, (buf+8)) != 8) {
+            TEST_ERROR;
+        }
+        if (out != v) {
+            TEST_ERROR;
+        }
+
+    } while (0); /* end uint64_t en/decode */
+
+    /* Test xmit header structure encode/decode
+     * Write bogus but easily verifiable data to inside a buffer, and compare.
+     * Then decode the buffer and compare the structure contents.
+     * Then repeat from a different offset in the buffer and compare.
+     */
+    do {
+        unsigned char buf[H5FD_MIRROR_XMIT_HEADER_SIZE+8];
+        unsigned char expected[H5FD_MIRROR_XMIT_HEADER_SIZE+8];
+        H5FD_mirror_xmit_t xmit_out;
+        size_t i = 0;
+
+        /* sanity check */
+        if (14 != H5FD_MIRROR_XMIT_HEADER_SIZE) {
+            FAIL_PUTS_ERROR("Header size definition does not match test\n");
+        }
+
+        /* Populate the expected buffer; expect end padding of 0xFF
+         */
+        HDmemset(expected, 0xFF, H5FD_MIRROR_XMIT_HEADER_SIZE+8);
+        for (i=0; i < H5FD_MIRROR_XMIT_HEADER_SIZE; i++) {
+            expected[i+2] = (unsigned char)i;
+        }
+
+        /* Encode, and compare buffer contents
+         * Initial buffer is filled with 0xFF to match expected padding
+         */
+        HDmemset(buf, 0xFF, H5FD_MIRROR_XMIT_HEADER_SIZE+8);
+        if (H5FD_mirror_xmit_encode_header((buf+2), &xmit_mock)
+            != H5FD_MIRROR_XMIT_HEADER_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, H5FD_MIRROR_XMIT_HEADER_SIZE+8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, H5FD_MIRROR_XMIT_HEADER_SIZE+8);
+            TEST_ERROR;
+        }
+
+        /* Decode from buffer
+         */
+        if (H5FD_mirror_xmit_decode_header(&xmit_out, (buf+2))
+            != H5FD_MIRROR_XMIT_HEADER_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.magic         != xmit_mock.magic)         TEST_ERROR;
+        if (xmit_out.version       != xmit_mock.version)       TEST_ERROR;
+        if (xmit_out.session_token != xmit_mock.session_token) TEST_ERROR;
+        if (xmit_out.xmit_count    != xmit_mock.xmit_count)    TEST_ERROR;
+        if (xmit_out.op            != xmit_mock.op)            TEST_ERROR;
+
+        /* Decode from different offset in buffer
+         * Observe changes when ingesting the padding
+         */
+        if (H5FD_mirror_xmit_decode_header(&xmit_out, (buf))
+            != H5FD_MIRROR_XMIT_HEADER_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.magic         != 0xFFFF0001) TEST_ERROR;
+        if (xmit_out.version       != 0x02)       TEST_ERROR;
+        if (xmit_out.session_token != 0x03040506) TEST_ERROR;
+        if (xmit_out.xmit_count    != 0x0708090A) TEST_ERROR;
+        if (xmit_out.op            != 0x0B)       TEST_ERROR;
+
+    } while (0); /* end xmit header en/decode */
+
+    /* Test xmit set-eoa structure encode/decode
+     * Write bogus but easily verifiable data to inside a buffer, and compare.
+     * Then decode the buffer and compare the structure contents.
+     * Then repeat from a different offset in the buffer and compare.
+     */
+    do {
+        unsigned char buf[H5FD_MIRROR_XMIT_EOA_SIZE+8];
+        unsigned char expected[H5FD_MIRROR_XMIT_EOA_SIZE+8];
+        H5FD_mirror_xmit_eoa_t xmit_in;
+        H5FD_mirror_xmit_eoa_t xmit_out;
+        size_t i = 0;
+
+        /* sanity check */
+        if ((14+9) != H5FD_MIRROR_XMIT_EOA_SIZE) {
+            FAIL_PUTS_ERROR("Header size definition does not match test\n");
+        }
+        if (xmit_mock.op != 0x0D) {
+            FAIL_PUTS_ERROR("shared header structure is not in expected state");
+        }
+
+        /* Populate the expected buffer; expect end padding of 0xFF
+         */
+        HDmemset(expected, 0xFF, H5FD_MIRROR_XMIT_EOA_SIZE+8);
+        for (i=0; i < H5FD_MIRROR_XMIT_EOA_SIZE; i++) {
+            expected[i+2] = (unsigned char)i;
+        }
+
+        /* Set xmit_in
+         */
+        xmit_in.pub = xmit_mock; /* shared/common */
+        xmit_in.type = 0x0E;
+        xmit_in.eoa_addr = 0x0F10111213141516;
+
+        /* Encode, and compare buffer contents
+         * Initial buffer is filled with 0xFF to match expected padding
+         */
+        HDmemset(buf, 0xFF, H5FD_MIRROR_XMIT_EOA_SIZE+8);
+        if (H5FD_mirror_xmit_encode_set_eoa((buf+2), &xmit_in)
+            != H5FD_MIRROR_XMIT_EOA_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, H5FD_MIRROR_XMIT_EOA_SIZE+8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, H5FD_MIRROR_XMIT_EOA_SIZE+8);
+            TEST_ERROR;
+        }
+
+        /* Decode from buffer
+         */
+        if (H5FD_mirror_xmit_decode_set_eoa(&xmit_out, (buf+2))
+            != H5FD_MIRROR_XMIT_EOA_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != xmit_mock.magic)         TEST_ERROR;
+        if (xmit_out.pub.version       != xmit_mock.version)       TEST_ERROR;
+        if (xmit_out.pub.session_token != xmit_mock.session_token) TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != xmit_mock.xmit_count)    TEST_ERROR;
+        if (xmit_out.pub.op            != xmit_mock.op)            TEST_ERROR;
+        if (xmit_out.type              != 0x0E)                    TEST_ERROR;
+        if (xmit_out.eoa_addr          != 0x0F10111213141516)      TEST_ERROR;
+
+        /* Decode from different offset in buffer
+         * Observe changes when ingesting the padding
+         */
+        if (H5FD_mirror_xmit_decode_set_eoa(&xmit_out, (buf))
+            != H5FD_MIRROR_XMIT_EOA_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != 0xFFFF0001)         TEST_ERROR;
+        if (xmit_out.pub.version       != 0x02)               TEST_ERROR;
+        if (xmit_out.pub.session_token != 0x03040506)         TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != 0x0708090A)         TEST_ERROR;
+        if (xmit_out.pub.op            != 0x0B)               TEST_ERROR;
+        if (xmit_out.type              != 0x0C)               TEST_ERROR;
+        if (xmit_out.eoa_addr          != 0x0D0E0F1011121314) TEST_ERROR;
+
+    } while (0); /* end xmit set-eoa en/decode */
+
+    /* Test xmit lock structure encode/decode
+     * Write bogus but easily verifiable data to inside a buffer, and compare.
+     * Then decode the buffer and compare the structure contents.
+     * Then repeat from a different offset in the buffer and compare.
+     */
+    do {
+        unsigned char buf[H5FD_MIRROR_XMIT_LOCK_SIZE+8];
+        unsigned char expected[H5FD_MIRROR_XMIT_LOCK_SIZE+8];
+        H5FD_mirror_xmit_lock_t xmit_in;
+        H5FD_mirror_xmit_lock_t xmit_out;
+        size_t i = 0;
+
+        /* sanity check */
+        if ((14+8) != H5FD_MIRROR_XMIT_LOCK_SIZE) {
+            FAIL_PUTS_ERROR("Header size definition does not match test\n");
+        }
+        if (xmit_mock.op != 0x0D) {
+            FAIL_PUTS_ERROR("shared header structure is not in expected state");
+        }
+
+        /* Populate the expected buffer; expect end padding of 0xFF
+         */
+        HDmemset(expected, 0xFF, H5FD_MIRROR_XMIT_LOCK_SIZE+8);
+        for (i=0; i < H5FD_MIRROR_XMIT_LOCK_SIZE; i++) {
+            expected[i+2] = (unsigned char)i;
+        }
+
+        /* Set xmit_in
+         */
+        xmit_in.pub = xmit_mock; /* shared/common */
+        xmit_in.rw = 0x0E0F101112131415;
+
+        /* Encode, and compare buffer contents
+         * Initial buffer is filled with 0xFF to match expected padding
+         */
+        HDmemset(buf, 0xFF, H5FD_MIRROR_XMIT_LOCK_SIZE+8);
+        if (H5FD_mirror_xmit_encode_lock((buf+2), &xmit_in)
+            != H5FD_MIRROR_XMIT_LOCK_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, H5FD_MIRROR_XMIT_LOCK_SIZE+8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, H5FD_MIRROR_XMIT_LOCK_SIZE+8);
+            TEST_ERROR;
+        }
+
+        /* Decode from buffer
+         */
+        if (H5FD_mirror_xmit_decode_lock(&xmit_out, (buf+2))
+            != H5FD_MIRROR_XMIT_LOCK_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != xmit_mock.magic)         TEST_ERROR;
+        if (xmit_out.pub.version       != xmit_mock.version)       TEST_ERROR;
+        if (xmit_out.pub.session_token != xmit_mock.session_token) TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != xmit_mock.xmit_count)    TEST_ERROR;
+        if (xmit_out.pub.op            != xmit_mock.op)            TEST_ERROR;
+        if (xmit_out.rw                != 0x0E0F101112131415)      TEST_ERROR;
+
+        /* Decode from different offset in buffer
+         * Observe changes when ingesting the padding
+         */
+        if (H5FD_mirror_xmit_decode_lock(&xmit_out, (buf))
+            != H5FD_MIRROR_XMIT_LOCK_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != 0xFFFF0001)         TEST_ERROR;
+        if (xmit_out.pub.version       != 0x02)               TEST_ERROR;
+        if (xmit_out.pub.session_token != 0x03040506)         TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != 0x0708090A)         TEST_ERROR;
+        if (xmit_out.pub.op            != 0x0B)               TEST_ERROR;
+        if (xmit_out.rw                != 0x0C0D0E0F10111213) TEST_ERROR;
+
+    } while (0); /* end xmit lock en/decode */
+
+    /* Test xmit open structure encode/decode
+     * Write bogus but easily verifiable data to inside a buffer, and compare.
+     * Then decode the buffer and compare the structure contents.
+     * Then repeat from a different offset in the buffer and compare.
+     *
+     * Verifies that the first zero character in the filepath will end the
+     * string, with all following bytes in the encoded buffer being zeroed.
+     */
+    do {
+        unsigned char buf[H5FD_MIRROR_XMIT_OPEN_SIZE+8];
+        unsigned char expected[H5FD_MIRROR_XMIT_OPEN_SIZE+8];
+        H5FD_mirror_xmit_open_t xmit_in;
+        H5FD_mirror_xmit_open_t xmit_out;
+        size_t i = 0;
+
+        /* sanity check */
+        if ((14+20+4097) != H5FD_MIRROR_XMIT_OPEN_SIZE) {
+            FAIL_PUTS_ERROR("Header size definition does not match test\n");
+        }
+        if (xmit_mock.op != 0x0D) {
+            FAIL_PUTS_ERROR("shared header structure is not in expected state");
+        }
+
+        /* Populate the expected buffer; expect end padding of 0xFF
+         */
+        HDmemset(expected, 0xFF, H5FD_MIRROR_XMIT_OPEN_SIZE+8);
+        for (i=0; i < H5FD_MIRROR_XMIT_OPEN_SIZE; i++) {
+            /* 0x100 is "zero" in a byte, so encode will treat it as a NULL-
+             * terminator in the filepath string. Expect all zeroes following.
+             */
+            expected[i+2] = (i > 0xFF) ? 0 : (unsigned char)i;
+        }
+
+        /* Set xmit_in
+         */
+        xmit_in.pub = xmit_mock; /* shared/common */
+        xmit_in.flags = 0x0E0F1011;
+        xmit_in.maxaddr = 0x1213141516171819;
+        xmit_in.size_t_blob = 0x1A1B1C1D1E1F2021;
+        for (i=0x22; i < H5FD_MIRROR_XMIT_FILEPATH_MAX+0x22; i++) {
+            /* nonzero values repeat after 0x100, but will not be encoded */
+            xmit_in.filename[i-0x22] = (char)(i % 0x100);
+        }
+        xmit_in.filename[H5FD_MIRROR_XMIT_FILEPATH_MAX-1] = 0;
+
+        /* Encode, and compare buffer contents
+         * Initial buffer is filled with 0xFF to match expected padding
+         */
+        HDmemset(buf, 0xFF, H5FD_MIRROR_XMIT_OPEN_SIZE+8);
+        if (H5FD_mirror_xmit_encode_open((buf+2), &xmit_in)
+            != H5FD_MIRROR_XMIT_OPEN_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, H5FD_MIRROR_XMIT_OPEN_SIZE+8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, H5FD_MIRROR_XMIT_OPEN_SIZE+8);
+            TEST_ERROR;
+        }
+
+        /* Decode from buffer
+         */
+        if (H5FD_mirror_xmit_decode_open(&xmit_out, (buf+2))
+            != H5FD_MIRROR_XMIT_OPEN_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != xmit_mock.magic)         TEST_ERROR;
+        if (xmit_out.pub.version       != xmit_mock.version)       TEST_ERROR;
+        if (xmit_out.pub.session_token != xmit_mock.session_token) TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != xmit_mock.xmit_count)    TEST_ERROR;
+        if (xmit_out.pub.op            != xmit_mock.op)            TEST_ERROR;
+        if (xmit_out.flags             != xmit_in.flags)           TEST_ERROR;
+        if (xmit_out.maxaddr           != xmit_in.maxaddr)         TEST_ERROR;
+        if (xmit_out.size_t_blob       != xmit_in.size_t_blob)     TEST_ERROR;
+        if (HDstrncmp(xmit_out.filename, xmit_in.filename,
+                      H5FD_MIRROR_XMIT_FILEPATH_MAX)
+            != 0)
+        {
+            PRINT_BUFFER_DIFF(xmit_out.filename, xmit_in.filename,
+                    H5FD_MIRROR_XMIT_FILEPATH_MAX);
+            TEST_ERROR;
+        }
+
+        /* Decode from different offset in buffer
+         * Observe changes when ingesting the padding
+         */
+        if (H5FD_mirror_xmit_decode_open(&xmit_out, (buf))
+            != H5FD_MIRROR_XMIT_OPEN_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != 0xFFFF0001)         TEST_ERROR;
+        if (xmit_out.pub.version       != 0x02)               TEST_ERROR;
+        if (xmit_out.pub.session_token != 0x03040506)         TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != 0x0708090A)         TEST_ERROR;
+        if (xmit_out.pub.op            != 0x0B)               TEST_ERROR;
+        if (xmit_out.flags             != 0x0C0D0E0F)         TEST_ERROR;
+        if (xmit_out.maxaddr           != 0x1011121314151617) TEST_ERROR;
+        if (xmit_out.size_t_blob       != 0x18191A1B1C1D1E1F) TEST_ERROR;
+        /* update expected "filepath" in structure */
+        for (i=0x20; i < H5FD_MIRROR_XMIT_FILEPATH_MAX+0x20; i++) {
+            xmit_in.filename[i-0x20] = (i > 0xFF) ? 0 : (char)i;
+        }
+        if (HDstrncmp(xmit_out.filename, xmit_in.filename,
+                      H5FD_MIRROR_XMIT_FILEPATH_MAX)
+            != 0)
+        {
+            PRINT_BUFFER_DIFF(xmit_out.filename, xmit_in.filename,
+                    H5FD_MIRROR_XMIT_FILEPATH_MAX);
+            TEST_ERROR;
+        }
+
+    } while (0); /* end xmit open en/decode */
+
+    /* Test xmit reply structure encode/decode
+     * Write bogus but easily verifiable data to inside a buffer, and compare.
+     * Then decode the buffer and compare the structure contents.
+     * Then repeat from a different offset in the buffer and compare.
+     *
+     * Verifies that the first zero character in the filepath will end the
+     * string, with all following bytes in the encoded buffer being zeroed.
+     */
+    do {
+        unsigned char buf[H5FD_MIRROR_XMIT_REPLY_SIZE+8];
+        unsigned char expected[H5FD_MIRROR_XMIT_REPLY_SIZE+8];
+        H5FD_mirror_xmit_reply_t xmit_in;
+        H5FD_mirror_xmit_reply_t xmit_out;
+        size_t i = 0;
+
+        /* sanity check */
+        if ((14+4+256) != H5FD_MIRROR_XMIT_REPLY_SIZE) {
+            FAIL_PUTS_ERROR("Header size definition does not match test\n");
+        }
+        if (xmit_mock.op != 0x0D) {
+            FAIL_PUTS_ERROR("shared header structure is not in expected state");
+        }
+
+        /* Populate the expected buffer; expect end padding of 0xFF
+         */
+        HDmemset(expected, 0xFF, H5FD_MIRROR_XMIT_REPLY_SIZE+8);
+        for (i=0; i < H5FD_MIRROR_XMIT_REPLY_SIZE; i++) {
+            /* 0x100 is "zero" in a byte, so encode will treat it as a NULL-
+             * terminator in the filepath string. Expect all zeroes following.
+             */
+            expected[i+2] = (i > 0xFF) ? 0 : (unsigned char)i;
+        }
+
+        /* Set xmit_in
+         */
+        xmit_in.pub = xmit_mock; /* shared/common */
+        xmit_in.status = 0x0E0F1011;
+        for (i=0x12; i < H5FD_MIRROR_STATUS_MESSAGE_MAX+0x12; i++) {
+            /* nonzero values repeat after 0x100, but will not be encoded */
+            xmit_in.message[i-0x12] = (char)(i % 0x100);
+        }
+        xmit_in.message[H5FD_MIRROR_STATUS_MESSAGE_MAX-1] = 0;
+
+        /* Encode, and compare buffer contents
+         * Initial buffer is filled with 0xFF to match expected padding
+         */
+        HDmemset(buf, 0xFF, H5FD_MIRROR_XMIT_REPLY_SIZE+8);
+        if (H5FD_mirror_xmit_encode_reply((buf+2), &xmit_in)
+            != H5FD_MIRROR_XMIT_REPLY_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, H5FD_MIRROR_XMIT_REPLY_SIZE+8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, H5FD_MIRROR_XMIT_REPLY_SIZE+8);
+            TEST_ERROR;
+        }
+
+        /* Decode from buffer
+         */
+        if (H5FD_mirror_xmit_decode_reply(&xmit_out, (buf+2))
+            != H5FD_MIRROR_XMIT_REPLY_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != xmit_mock.magic)         TEST_ERROR;
+        if (xmit_out.pub.version       != xmit_mock.version)       TEST_ERROR;
+        if (xmit_out.pub.session_token != xmit_mock.session_token) TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != xmit_mock.xmit_count)    TEST_ERROR;
+        if (xmit_out.pub.op            != xmit_mock.op)            TEST_ERROR;
+        if (xmit_out.status            != xmit_in.status)          TEST_ERROR;
+        if (HDstrncmp(xmit_out.message, xmit_in.message,
+                      H5FD_MIRROR_STATUS_MESSAGE_MAX)
+            != 0)
+        {
+            PRINT_BUFFER_DIFF(xmit_out.message, xmit_in.message,
+                    H5FD_MIRROR_STATUS_MESSAGE_MAX);
+            TEST_ERROR;
+        }
+
+        /* Decode from different offset in buffer
+         * Observe changes when ingesting the padding
+         */
+        if (H5FD_mirror_xmit_decode_reply(&xmit_out, (buf))
+            != H5FD_MIRROR_XMIT_REPLY_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != 0xFFFF0001)         TEST_ERROR;
+        if (xmit_out.pub.version       != 0x02)               TEST_ERROR;
+        if (xmit_out.pub.session_token != 0x03040506)         TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != 0x0708090A)         TEST_ERROR;
+        if (xmit_out.pub.op            != 0x0B)               TEST_ERROR;
+        if (xmit_out.status            != 0x0C0D0E0F)         TEST_ERROR;
+        /* update expected "message" in structure */
+        for (i=0x10; i < H5FD_MIRROR_STATUS_MESSAGE_MAX+0x10; i++) {
+            xmit_in.message[i-0x10] = (i > 0xFF) ? 0 : (char)i;
+        }
+        if (HDstrncmp(xmit_out.message, xmit_in.message,
+                      H5FD_MIRROR_STATUS_MESSAGE_MAX)
+            != 0)
+        {
+            PRINT_BUFFER_DIFF(xmit_out.message, xmit_in.message,
+                    H5FD_MIRROR_STATUS_MESSAGE_MAX);
+            TEST_ERROR;
+        }
+
+    } while (0); /* end xmit reply en/decode */
+
+    /* Test xmit write structure encode/decode
+     * Write bogus but easily verifiable data to inside a buffer, and compare.
+     * Then decode the buffer and compare the structure contents.
+     * Then repeat from a different offset in the buffer and compare.
+     */
+    do {
+        unsigned char buf[H5FD_MIRROR_XMIT_WRITE_SIZE+8];
+        unsigned char expected[H5FD_MIRROR_XMIT_WRITE_SIZE+8];
+        H5FD_mirror_xmit_write_t xmit_in;
+        H5FD_mirror_xmit_write_t xmit_out;
+        size_t i = 0;
+
+        /* sanity check */
+        if ((14+17) != H5FD_MIRROR_XMIT_WRITE_SIZE) {
+            FAIL_PUTS_ERROR("Header size definition does not match test\n");
+        }
+        if (xmit_mock.op != 0x0D) {
+            FAIL_PUTS_ERROR("shared header structure is not in expected state");
+        }
+
+        /* Populate the expected buffer; expect end padding of 0xFF
+         */
+        HDmemset(expected, 0xFF, H5FD_MIRROR_XMIT_WRITE_SIZE+8);
+        for (i=0; i < H5FD_MIRROR_XMIT_WRITE_SIZE; i++) {
+            expected[i+2] = (unsigned char)i;
+        }
+
+        /* Set xmit_in
+         */
+        xmit_in.pub    = xmit_mock; /* shared/common */
+        xmit_in.type   = 0x0E;
+        xmit_in.offset = 0x0F10111213141516;
+        xmit_in.size   = 0x1718191A1B1C1D1E;
+
+        /* Encode, and compare buffer contents
+         * Initial buffer is filled with 0xFF to match expected padding
+         */
+        HDmemset(buf, 0xFF, H5FD_MIRROR_XMIT_WRITE_SIZE+8);
+        if (H5FD_mirror_xmit_encode_write((buf+2), &xmit_in)
+            != H5FD_MIRROR_XMIT_WRITE_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (HDmemcmp(buf, expected, H5FD_MIRROR_XMIT_WRITE_SIZE+8) != 0) {
+            PRINT_BUFFER_DIFF(buf, expected, H5FD_MIRROR_XMIT_WRITE_SIZE+8);
+            TEST_ERROR;
+        }
+
+        /* Decode from buffer
+         */
+        if (H5FD_mirror_xmit_decode_write(&xmit_out, (buf+2))
+            != H5FD_MIRROR_XMIT_WRITE_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != xmit_mock.magic)         TEST_ERROR;
+        if (xmit_out.pub.version       != xmit_mock.version)       TEST_ERROR;
+        if (xmit_out.pub.session_token != xmit_mock.session_token) TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != xmit_mock.xmit_count)    TEST_ERROR;
+        if (xmit_out.pub.op            != xmit_mock.op)            TEST_ERROR;
+        if (xmit_out.type              != 0x0E)                    TEST_ERROR;
+        if (xmit_out.offset            != 0x0F10111213141516)      TEST_ERROR;
+        if (xmit_out.size              != 0x1718191A1B1C1D1E)      TEST_ERROR;
+
+        /* Decode from different offset in buffer
+         * Observe changes when ingesting the padding
+         */
+        if (H5FD_mirror_xmit_decode_write(&xmit_out, (buf))
+            != H5FD_MIRROR_XMIT_WRITE_SIZE)
+        {
+            TEST_ERROR;
+        }
+        if (xmit_out.pub.magic         != 0xFFFF0001)         TEST_ERROR;
+        if (xmit_out.pub.version       != 0x02)               TEST_ERROR;
+        if (xmit_out.pub.session_token != 0x03040506)         TEST_ERROR;
+        if (xmit_out.pub.xmit_count    != 0x0708090A)         TEST_ERROR;
+        if (xmit_out.pub.op            != 0x0B)               TEST_ERROR;
+        if (xmit_out.type              != 0x0C)               TEST_ERROR;
+        if (xmit_out.offset            != 0x0D0E0F1011121314) TEST_ERROR;
+        if (xmit_out.size              != 0x15161718191A1B1C) TEST_ERROR;
+
+    } while (0); /* end xmit write en/decode */
+
+    PASSED();
+    return 0;
+
+error:
+    return -1;
+} /* end test_xmit_encode_decode */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    create_mirroring_split_fapl
+ *
+ * Purpose:     Create and populate a mirroring FAPL ID.
+ *              Creates target files with the given base name -- ideally the
+ *              test name -- and creates mirroring/split FAPL set to use the
+ *              global mirroring info and a sec2 R/W channel driver.
+ *
+ *              TODO: receive target IP from caller?
+ *
+ * Return:      Success: HID of the top-level (splitter) FAPL, a non-negative
+ *                       value.
+ *              Failure: H5I_INVALID_HID, a negative value.
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static hid_t
+create_mirroring_split_fapl(const char                      *_basename,
+                            struct mirrortest_filenames     *names)
+{
+    H5FD_splitter_vfd_config_t  splitter_config;
+    H5FD_mirror_fapl_t          mirror_conf;
+    hid_t                       ret_value = H5I_INVALID_HID;
+
+    if (_basename == NULL || *_basename == '\0') {
+        TEST_ERROR;
+    }
+
+    splitter_config.magic = H5FD_SPLITTER_MAGIC;
+    splitter_config.version = H5FD_CURR_SPLITTER_VFD_CONFIG_VERSION;
+    splitter_config.ignore_wo_errs = FALSE;
+
+    /* Create Splitter R/W channel driver (sec2)
+     */
+    splitter_config.rw_fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+    if (H5I_INVALID_HID == splitter_config.rw_fapl_id) {
+        TEST_ERROR;
+    }
+    if (H5Pset_fapl_sec2(splitter_config.rw_fapl_id) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* Create Splitter W/O channel driver (mirror)
+     */
+    mirror_conf.magic = H5FD_MIRROR_FAPL_MAGIC;
+    mirror_conf.version = H5FD_MIRROR_CURR_FAPL_T_VERSION;
+    mirror_conf.handshake_port = SERVER_HANDSHAKE_PORT;
+    if (HDstrncpy(mirror_conf.remote_ip, SERVER_IP_ADDRESS,
+            H5FD_MIRROR_MAX_IP_LEN)
+        == NULL)
+    {
+        TEST_ERROR;
+    }
+    splitter_config.wo_fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+    if (H5I_INVALID_HID == splitter_config.wo_fapl_id) {
+        TEST_ERROR;
+    }
+    if (H5Pset_fapl_mirror(splitter_config.wo_fapl_id, &mirror_conf) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* Build r/w, w/o, and log file paths
+     */
+    if (build_paths(_basename, &splitter_config, names) < 0) {
+        TEST_ERROR;
+    }
+
+    /* Set file paths for w/o and logfile
+     */
+    if (HDstrncpy(splitter_config.wo_path, (const char *)names->wo,
+            H5FD_SPLITTER_PATH_MAX)
+        == NULL)
+    {
+        TEST_ERROR;
+    }
+    if (HDstrncpy(splitter_config.log_file_path, (const char *)names->log,
+            H5FD_SPLITTER_PATH_MAX)
+        == NULL)
+    {
+        TEST_ERROR;
+    }
+
+    /* Create Splitter FAPL
+     */
+    ret_value = H5Pcreate(H5P_FILE_ACCESS);
+    if (H5I_INVALID_HID == ret_value) {
+        TEST_ERROR;
+    }
+    if (H5Pset_fapl_splitter(ret_value, &splitter_config) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* Close FAPLs created for child channels
+     */
+    if (H5Pclose(splitter_config.rw_fapl_id) < 0) {
+        TEST_ERROR;
+    }
+    splitter_config.rw_fapl_id = H5I_INVALID_HID;
+    if (H5Pclose(splitter_config.wo_fapl_id) < 0) {
+        TEST_ERROR;
+    }
+    splitter_config.wo_fapl_id = H5I_INVALID_HID;
+
+    return ret_value;
+
+error:
+    if (splitter_config.wo_fapl_id >= 0) {
+        (void)H5Pclose(splitter_config.wo_fapl_id);
+    }
+    if (splitter_config.rw_fapl_id >= 0) {
+        (void)H5Pclose(splitter_config.rw_fapl_id);
+    }
+    if (ret_value >= 0) {
+        (void)H5Pclose(ret_value);
+    }
+    return H5I_INVALID_HID;
+} /* end create_mirroring_split_fapl() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_create_and_close
+ *
+ * Purpose:     Test/demonstrate a do-nothing file open and close.
+ *
+ *              Verifying file existence and contents is part of other tests.
+ *
+ *              TODO: receive target IP from caller?
+ *
+ * Return:      Success: 0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2019-12-17
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_create_and_close(void)
+{
+    struct mirrortest_filenames names;
+    hid_t file_id = H5I_INVALID_HID;
+    hid_t fapl_id = H5P_DEFAULT;
+
+    TESTING("File creation and immediate close");
+
+    /* Create FAPL for Splitter[sec2|mirror]
+     */
+    fapl_id = create_mirroring_split_fapl("basic_create", &names);
+    if (H5I_INVALID_HID == fapl_id) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* TEST: Create and Close */
+
+    file_id = H5Fcreate(names.rw, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* Standard cleanup */
+
+    if (H5Fclose(file_id) == FAIL) {
+        TEST_ERROR;
+    }
+    if (fapl_id != H5P_DEFAULT && fapl_id >= 0) {
+        if (H5Pclose(fapl_id) == FAIL) {
+            TEST_ERROR;
+        }
+    }
+
+    PASSED();
+    return 0;
+
+error:
+    H5E_BEGIN_TRY{
+        (void)H5Fclose(file_id);
+        (void)H5Pclose(fapl_id);
+    } H5E_END_TRY;
+    return -1;
+} /* end test_create_and_close() */
+
+
+/* ----------------------------------------------------------------------------
+ * Function:    create_datasets
+ *
+ * Purpose:     Given a file ID and least and greateset dataset indices, create
+ *              populated chunked datasets in the target file from min_dset to
+ *              (and including) max_dset.
+ *              Uses #defined constants to determine chunk and dataset sizes
+ *              and values.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jacob Smith
+ *              2019-08-14
+ * ----------------------------------------------------------------------------
+ */
+static herr_t
+create_datasets(hid_t    file_id,
+                unsigned min_dset,
+                unsigned max_dset)
+{
+    hid_t       dataspace_ids[MAX_DSET_COUNT + 1];
+    hid_t       dataset_ids[MAX_DSET_COUNT + 1];
+    hid_t       filespace_ids[MAX_DSET_COUNT + 1];
+    int         data_chunk[CHUNK_DIM][CHUNK_DIM];
+    unsigned int        i, j, k, l, m;
+    hsize_t     offset[2];
+    hid_t       memspace_id   = H5I_INVALID_HID;
+    hsize_t     a_size[2]     = {CHUNK_DIM, CHUNK_DIM};
+    hsize_t     chunk_dims[2] = {CHUNK_DIM, CHUNK_DIM};
+    hsize_t     dset_dims[2]  = {DSET_DIM, DSET_DIM};
+
+    HDassert(file_id >= 0);
+    HDassert(min_dset <= max_dset);
+    HDassert(max_dset <= MAX_DSET_COUNT);
+
+    LOGPRINT(2, "create_dataset()\n");
+
+    /* ---------------------------------
+     * "Clear" ID arrays
+     */
+
+    for (i = 0; i < MAX_DSET_COUNT; i++) {
+        LOGPRINT(3, "clearing IDs [%d]\n", i);
+        dataspace_ids[i] = H5I_INVALID_HID;
+        dataset_ids[i] = H5I_INVALID_HID;
+        filespace_ids[i] = H5I_INVALID_HID;
+    }
+
+    /* ---------------------------------
+     * Generate dataspace, dataset, and 'filespace' IDs
+     */
+
+    if (_create_chunking_ids(file_id, min_dset, max_dset, chunk_dims,
+            dset_dims, dataspace_ids, filespace_ids, dataset_ids, &memspace_id)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    /* ---------------------------------
+     * Initialize (write) all datasets in a "round robin"...
+     * for a given chunk 'location', write chunk data to each dataset.
+     */
+
+    for (i = 0; i < DSET_DIM; i += CHUNK_DIM)
+    {
+        LOGPRINT(3, "i: %d\n", i);
+        for (j = 0; j < DSET_DIM; j += CHUNK_DIM)
+        {
+            LOGPRINT(3, "  j: %d\n", j);
+            for (m = min_dset; m <= max_dset; m++)
+            {
+                LOGPRINT(3, "    m: %d\n", m);
+                for (k = 0; k < CHUNK_DIM; k++)
+                {
+                    for (l = 0; l < CHUNK_DIM; l++)
+                    {
+                        data_chunk[k][l] = (int)((DSET_DIM * DSET_DIM * m) +
+                                                 (DSET_DIM * (i + k)) + j + l);
+                        LOGPRINT(3, "      data_chunk[%d][%d]: %d\n",
+                                 k, l, data_chunk[k][l]);
+                    }
+                }
+
+                /* select on disk hyperslab */
+                offset[0] = (hsize_t)i;
+                offset[1] = (hsize_t)j;
+                LOGPRINT(3, "    H5Sselect_hyperslab()\n");
+                if (H5Sselect_hyperslab(filespace_ids[m], H5S_SELECT_SET,
+                        offset, NULL, a_size, NULL)
+                    < 0)
+                {
+                    TEST_ERROR;
+                }
+
+                LOGPRINT(3, "    H5Dwrite()\n");
+                if (H5Dwrite(dataset_ids[m], H5T_NATIVE_INT, memspace_id,
+                        filespace_ids[m], H5P_DEFAULT, data_chunk)
+                    < 0)
+                {
+                    TEST_ERROR;
+                }
+
+            }
+        }
+    }
+
+    /* ---------------------------------
+     * Read and verify data from datasets
+     */
+
+    if (_verify_datasets(min_dset, max_dset, filespace_ids, dataset_ids,
+                memspace_id)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    /* ---------------------------------
+     * Cleanup
+     */
+
+    if (_close_chunking_ids(min_dset, max_dset, dataspace_ids, filespace_ids,
+                dataset_ids, &memspace_id)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    return SUCCEED;
+
+error:
+    (void)_close_chunking_ids(min_dset, max_dset, dataspace_ids,
+                filespace_ids, dataset_ids, &memspace_id);
+    LOGPRINT(1, "create_datasets() FAILED\n");
+    return FAIL;
+} /* end create_datasets() */
+
+
+/* ----------------------------------------------------------------------------
+ * Function:   _create_chunking_ids
+ *
+ * Purpose:    Create new IDs to be used with the associated file.
+ *
+ * Return:     SUCCEED/FAIL
+ *
+ * Programer:  Jacob Smith
+ *             2019
+ * ----------------------------------------------------------------------------
+ */
+static herr_t
+_create_chunking_ids(hid_t     file_id,
+                     unsigned  min_dset,
+                     unsigned  max_dset,
+                     hsize_t  *chunk_dims,
+                     hsize_t  *dset_dims,
+                     hid_t    *dataspace_ids,
+                     hid_t    *filespace_ids,
+                     hid_t    *dataset_ids,
+                     hid_t    *memspace_id)
+{
+    char     dset_name[DSET_NAME_LEN + 1];
+    unsigned m         = 0;
+    hid_t    dcpl_id   = H5I_INVALID_HID;
+
+    LOGPRINT(2, "_create_chunking_ids()\n");
+
+    /* --------------------
+     * Create chunking DCPL
+     */
+
+    dcpl_id = H5Pcreate(H5P_DATASET_CREATE);
+    if (dcpl_id < 0) {
+        TEST_ERROR;
+    }
+    if (H5Pset_chunk(dcpl_id, 2, chunk_dims) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* --------------------
+     * Create dataspace IDs
+     */
+
+    for (m = min_dset; m <= max_dset; m++) {
+        dataspace_ids[m] = H5Screate_simple(2, dset_dims, NULL);
+        if (dataspace_ids[m] < 0) {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                    "unable to create dataspace ID %d\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+    }
+
+    /* --------------------
+     * Create dataset IDs
+     */
+
+    for (m = min_dset; m <= max_dset; m++) {
+        if (HDsnprintf(dset_name, DSET_NAME_LEN, "/dset%03d", m)
+            > DSET_NAME_LEN)
+        {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                    "unable to compose dset name %d\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+
+        dataset_ids[m] = H5Dcreate(file_id, dset_name, H5T_STD_I32BE,
+                dataspace_ids[m], H5P_DEFAULT, dcpl_id, H5P_DEFAULT);
+        if (dataset_ids[m] < 0) {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                    "unable to create dset ID %d\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+    }
+
+    /* --------------------
+     * Get file space IDs
+     */
+
+    for (m = min_dset; m <= max_dset; m++) {
+        filespace_ids[m] = H5Dget_space(dataset_ids[m]);
+        if (filespace_ids[m] < 0) {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                    "unable to create filespace ID %d\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+    }
+
+    /* --------------------
+     * Create mem space to be used to read and write chunks
+     */
+
+    *memspace_id = H5Screate_simple(2, chunk_dims, NULL);
+    if (*memspace_id < 0) {
+        TEST_ERROR;
+    }
+
+    /* --------------------
+     * Clean up the DCPL, even if there were errors before
+     */
+
+    if (dcpl_id != H5P_DEFAULT && dcpl_id != H5I_INVALID_HID) {
+        if (H5Pclose(dcpl_id) == FAIL) {
+            TEST_ERROR;
+        }
+    }
+
+    return SUCCEED;
+
+error:
+    if (dcpl_id != H5P_DEFAULT && dcpl_id != H5I_INVALID_HID) {
+        (void)H5Pclose(dcpl_id);
+    }
+    LOGPRINT(1, "_create_chunking_ids() FAILED\n");
+    return FAIL;
+} /* end _create_chunking_ids() */
+
+
+/* ----------------------------------------------------------------------------
+ * Function:    _open_chunking_ids
+ *
+ * Purpose:     Open/access IDs from the given file.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ----------------------------------------------------------------------------
+ */
+static herr_t
+_open_chunking_ids(
+        hid_t     file_id,
+        unsigned  min_dset,
+        unsigned  max_dset,
+        hsize_t  *chunk_dims,
+        hid_t    *filespace_ids,
+        hid_t    *dataset_ids,
+        hid_t    *memspace_id)
+{
+    char     dset_name[DSET_NAME_LEN+1];
+    unsigned m = 0;
+
+    LOGPRINT(2, "_open_chunking_ids()\n");
+
+    /* --------------------
+     * Open dataset IDs
+     */
+
+    for (m = min_dset; m <= max_dset; m++) {
+        if (HDsnprintf(dset_name, DSET_NAME_LEN, "/dset%03d", m)
+            > DSET_NAME_LEN)
+        {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                    "unable to compose dset name %d\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+
+        dataset_ids[m] = H5Dopen2(file_id, dset_name, H5P_DEFAULT);
+        if (dataset_ids[m] < 0) {
+            HDsnprintf(mesg, MIRR_MESG_SIZE, "unable to open dset ID %d\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+    }
+
+    /* --------------------
+     * Open filespace IDs
+     */
+
+    for (m = min_dset; m <= max_dset; m++) {
+        filespace_ids[m] = H5Dget_space(dataset_ids[m]);
+        if (filespace_ids[m] < 0) {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                    "unable to get filespace ID %d\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+    }
+
+    /* --------------------
+     * Create mem space to be used to read and write chunks
+     */
+
+    *memspace_id = H5Screate_simple(2, chunk_dims, NULL);
+    if (*memspace_id < 0) {
+        TEST_ERROR;
+    }
+
+    return SUCCEED;
+
+error:
+    LOGPRINT(1, "_open_chunking_ids() FAILED\n");
+    return FAIL;
+} /* end _open_chunking_ids() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    _close_chunking_ids
+ *
+ * Purpose:     Close IDs that were created or opened.
+ *              Pass NULL into `dataspace_ids` when closing items opened with
+ *              _open_chunking_ids(). (as opposed to created IDs)
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static herr_t
+_close_chunking_ids(unsigned min_dset,
+                    unsigned max_dset,
+                    hid_t *dataspace_ids,
+                    hid_t *filespace_ids,
+                    hid_t *dataset_ids,
+                    hid_t *memspace_id)
+{
+    unsigned m;
+
+    LOGPRINT(2, "_close_chunking_ids()\n");
+
+    for (m = min_dset; m <= max_dset; m++) {
+        LOGPRINT(3, "closing ids[%d]\n", m);
+        if (dataspace_ids) {
+            if (H5Sclose(dataspace_ids[m]) < 0) {
+                HDsnprintf(mesg, MIRR_MESG_SIZE,
+                        "unable to close dataspace_id[%d]\n", m);
+                FAIL_PUTS_ERROR(mesg);
+            }
+        }
+        if (H5Dclose(dataset_ids[m]) < 0) {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                        "unable to close dataset_id[%d]\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+        if (H5Sclose(filespace_ids[m]) < 0) {
+            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                        "unable to close filespace_id[%d]\n", m);
+            FAIL_PUTS_ERROR(mesg);
+        }
+    }
+
+    if ( (*memspace_id != H5I_INVALID_HID) &&
+         (H5Sclose(*memspace_id) < 0) )
+    {
+        TEST_ERROR;
+    }
+
+    return SUCCEED;
+
+error:
+    LOGPRINT(1, "_close_chunking_ids() FAILED\n");
+    return FAIL;
+} /* end _close_chunking_ids() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    _verify_datasets
+ *
+ * Purpose:     Check that each chunk's contents are as expected, as pertaining
+ *              to create_datasets().
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static herr_t
+_verify_datasets(unsigned  min_dset,
+                 unsigned  max_dset,
+                 hid_t    *filespace_ids,
+                 hid_t    *dataset_ids,
+                 hid_t     memspace_id)
+{
+    unsigned i, j, k, l, m;
+    int      data_chunk[CHUNK_DIM][CHUNK_DIM];
+    hsize_t  offset[2];
+    hsize_t  a_size[2] = {CHUNK_DIM, CHUNK_DIM};
+
+    LOGPRINT(2, "_verify_datasets()\n");
+
+    for (i = 0; i < DSET_DIM; i += CHUNK_DIM)
+    {
+        LOGPRINT(3, "i: %d\n", i);
+        for (j = 0; j < DSET_DIM; j += CHUNK_DIM)
+        {
+            LOGPRINT(3, "  j: %d\n", j);
+            for (m = min_dset; m <= max_dset; m++)
+            {
+                LOGPRINT(3, "    m: %d\n", m);
+
+                /* select on disk hyperslab */
+                offset[0] = (hsize_t)i;
+                offset[1] = (hsize_t)j;
+                if (H5Sselect_hyperslab(filespace_ids[m], H5S_SELECT_SET,
+                        offset, NULL, a_size, NULL)
+                    < 0)
+                {
+                    TEST_ERROR;
+                }
+
+                if (H5Dread(dataset_ids[m], H5T_NATIVE_INT, memspace_id,
+                        filespace_ids[m], H5P_DEFAULT, data_chunk)
+                    < 0)
+                {
+                    HDsnprintf(mesg, MIRR_MESG_SIZE,
+                               "      H5Dread() [%d][%d][%d]\n",
+                               i, j, m);
+                    FAIL_PUTS_ERROR(mesg);
+                }
+
+                for (k = 0; k < CHUNK_DIM; k++) {
+                    for (l = 0; l < CHUNK_DIM; l++) {
+                        if ((unsigned)data_chunk[k][l]
+                            !=
+                            ((DSET_DIM * DSET_DIM * m) +
+                             (DSET_DIM * (i + k)) + j + l))
+                        {
+                            HDsnprintf(mesg, MIRR_MESG_SIZE,
+                                    "      MISMATCH [%d][%d][%d][%d][%d]\n",
+                                    i, j, m, k, l);
+                            FAIL_PUTS_ERROR(mesg);
+                        }
+                    }
+                }
+
+            }
+        }
+    }
+
+    return SUCCEED;
+
+error:
+    LOGPRINT(1, "_verify_datasets() FAILED\n");
+    return FAIL;
+} /* end _verify_datasets() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    verify_datasets
+ *
+ * Purpose:     Inspect the datasets in the file created by create_datasets().
+ *              Wrapper for _verify_datasets() -- this function sets up and
+ *              tears down accessor information.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static herr_t
+verify_datasets(hid_t    file_id,
+                unsigned min_dset,
+                unsigned max_dset)
+{
+    hid_t    dataset_ids[MAX_DSET_COUNT + 1];
+    hid_t    filespace_ids[MAX_DSET_COUNT + 1];
+    unsigned i;
+    hid_t    memspace_id   = H5I_INVALID_HID;
+    hsize_t  chunk_dims[2] = {CHUNK_DIM, CHUNK_DIM};
+
+    HDassert(file_id >= 0);
+    HDassert(min_dset <= max_dset);
+    HDassert(max_dset <= MAX_DSET_COUNT);
+
+    LOGPRINT(2, "verify_datasets()\n");
+
+    /* ---------------------------------
+     * "Clear" ID arrays
+     */
+
+    for (i = 0; i < MAX_DSET_COUNT; i++) {
+        LOGPRINT(3, "clearing IDs [%d]\n", i);
+        dataset_ids[i] = H5I_INVALID_HID;
+        filespace_ids[i] = H5I_INVALID_HID;
+    }
+
+    /* ---------------------------------
+     * Generate dataspace, dataset, and 'filespace' IDs
+     */
+
+    if (_open_chunking_ids(file_id, min_dset, max_dset, chunk_dims,
+            filespace_ids, dataset_ids, &memspace_id)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    /* ---------------------------------
+     * Read and verify data from datasets
+     */
+
+    if (_verify_datasets(min_dset, max_dset, filespace_ids, dataset_ids,
+            memspace_id)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    /* ---------------------------------
+     * Cleanup
+     */
+
+    if (_close_chunking_ids(min_dset, max_dset, NULL, filespace_ids,
+                dataset_ids, &memspace_id)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    return SUCCEED;
+
+error:
+    LOGPRINT(1, "verify_datasets() FAILED\n");
+    (void)_close_chunking_ids(min_dset, max_dset, NULL, filespace_ids,
+            dataset_ids, &memspace_id);
+    return FAIL;
+
+} /* end verify_datasets() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_basic_dataset_write
+ *
+ * Purpose:     Create and close files; repoen files and write a dataset,
+ *              close; compare files.
+ *
+ *              TODO: receive target IP from caller?
+ *
+ * Return:      Success: 0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_basic_dataset_write(void)
+{
+    struct mirrortest_filenames names;
+    hid_t       file_id = H5I_INVALID_HID;
+    hid_t       fapl_id = H5P_DEFAULT;
+    hid_t       dset_id = H5I_INVALID_HID;
+    hid_t       dspace_id = H5I_INVALID_HID;
+    hid_t       dtype_id = H5T_NATIVE_INT;
+    hsize_t     dims[2] = { DATABUFFER_SIZE, DATABUFFER_SIZE };
+    int        *buf = NULL;
+    int         i = 0;
+    int         j = 0;
+
+    TESTING("Mirror open and dataset writing");
+
+    /* Create FAPL for Splitter[sec2|mirror]
+     */
+    fapl_id = create_mirroring_split_fapl("basic_write", &names);
+    if (H5I_INVALID_HID == fapl_id) {
+        TEST_ERROR;
+    }
+
+    /* Prepare data to be written
+     */
+    buf = (int *)HDmalloc(DATABUFFER_SIZE * DATABUFFER_SIZE * sizeof(int));
+    if (NULL == buf) {
+        TEST_ERROR;
+    }
+    for (i = 0; i < DATABUFFER_SIZE; i++) {
+        for (j = 0; j < DATABUFFER_SIZE; j++) {
+            int k = i * DATABUFFER_SIZE + j;
+            buf[k] = k;
+        }
+    }
+
+    /* -------------------- */
+    /* TEST: Create and Close */
+
+    file_id = H5Fcreate(names.rw, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+    if (H5Fclose(file_id) == FAIL) {
+        TEST_ERROR;
+    }
+    file_id = H5I_INVALID_HID;
+
+
+    /* -------------------- */
+    /* TEST: Repoen and Write */
+
+    file_id = H5Fopen(names.rw, H5F_ACC_RDWR, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+
+    dspace_id = H5Screate_simple(2, dims, NULL);
+    if (H5I_INVALID_HID == dspace_id) {
+        TEST_ERROR;
+    }
+    dset_id = H5Dcreate2(file_id, "dataset", dtype_id, dspace_id, H5P_DEFAULT,
+            H5P_DEFAULT, H5P_DEFAULT);
+    if (H5I_INVALID_HID == dset_id) {
+        TEST_ERROR;
+    }
+
+    if (H5Dwrite(dset_id, dtype_id, H5S_ALL, H5S_ALL, H5P_DEFAULT, buf)
+        == FAIL)
+    {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* Standard cleanup */
+
+    HDfree(buf);
+    buf = NULL;
+    if (H5Dclose(dset_id) == FAIL) {
+        TEST_ERROR;
+    }
+    if (H5Sclose(dspace_id) == FAIL) {
+        TEST_ERROR;
+    }
+    if (H5Fclose(file_id) == FAIL) {
+        TEST_ERROR;
+    }
+    if (fapl_id != H5P_DEFAULT && fapl_id > 0) {
+        if (H5Pclose(fapl_id) == FAIL) {
+            TEST_ERROR;
+        }
+    }
+
+    /* -------------------- */
+    /* TEST: Verify that the R/W and W/O files are identical */
+
+    if (h5_compare_file_bytes(names.rw, names.wo) < 0) {
+        TEST_ERROR;
+    }
+
+    PASSED();
+    return 0;
+
+error:
+    H5E_BEGIN_TRY{
+        (void)H5Fclose(file_id);
+        if (buf) {
+            HDfree(buf);
+        }
+        (void)H5Dclose(dset_id);
+        (void)H5Sclose(dspace_id);
+        if (fapl_id != H5P_DEFAULT && fapl_id > 0) {
+            (void)H5Pclose(fapl_id);
+        }
+    } H5E_END_TRY;
+    return -1;
+} /* end test_basic_dataset_write() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_chunked_dataset_write
+ *
+ * Purpose:     Create and close files; repoen files and write a dataset,
+ *              close; compare files.
+ *
+ *              TODO: receive target IP from caller?
+ *
+ * Return:      Success: 0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_chunked_dataset_write(void)
+{
+    struct mirrortest_filenames names;
+    hid_t       file_id = H5I_INVALID_HID;
+    hid_t       fapl_id = H5P_DEFAULT;
+
+    TESTING("Mirror open and dataset writing (chunked)");
+
+    /* Create FAPL for Splitter[sec2|mirror]
+     */
+    fapl_id = create_mirroring_split_fapl("chunked_write", &names);
+    if (H5I_INVALID_HID == fapl_id) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* TEST: Create and Close */
+
+    file_id = H5Fcreate(names.rw, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+    if (H5Fclose(file_id) == FAIL) {
+        TEST_ERROR;
+    }
+    file_id = H5I_INVALID_HID;
+
+    /* -------------------- */
+    /* TEST: Reopen and Write */
+
+    file_id = H5Fopen(names.rw, H5F_ACC_RDWR, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+
+    /* Write datasets to file
+     */
+    if (create_datasets(file_id, 0, MAX_DSET_COUNT) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* Close to 'flush to disk', and reopen file
+     */
+    if (H5Fclose(file_id) == FAIL) {
+        TEST_ERROR;
+    }
+    file_id = H5I_INVALID_HID;
+
+    /* Reopen file
+     */
+    file_id = H5Fopen(names.rw, H5F_ACC_RDWR, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+
+    /* Verify written data integrity
+     */
+    if (verify_datasets(file_id, 0, MAX_DSET_COUNT) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* Standard cleanup */
+
+    if (H5Fclose(file_id) == FAIL) {
+        TEST_ERROR;
+    }
+    file_id = H5I_INVALID_HID;
+    if (fapl_id != H5P_DEFAULT && fapl_id > 0) {
+        if (H5Pclose(fapl_id) == FAIL) {
+            TEST_ERROR;
+        }
+        fapl_id = H5I_INVALID_HID;
+    }
+
+    /* -------------------- */
+    /* TEST: Verify that the R/W and W/O files are identical */
+
+    if (h5_compare_file_bytes(names.rw, names.wo) < 0) {
+        TEST_ERROR;
+    }
+
+    PASSED();
+    return 0;
+
+error:
+    H5E_BEGIN_TRY {
+        (void)H5Fclose(file_id);
+        if (fapl_id != H5P_DEFAULT && fapl_id > 0) {
+            (void)H5Pclose(fapl_id);
+        }
+    } H5E_END_TRY;
+    return -1;
+} /* end test_chunked_dataset_write() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_on_disk_zoo
+ *
+ * Purpose:     Verify that the mirror can handle the passing of all the
+ *              various on-disk data structures over the wire, as implemented
+ *              in genall5.c:create_zoo().
+ *
+ *              TODO: receive target IP from caller?
+ *
+ * Return:      Success: 0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_on_disk_zoo(void)
+{
+    const char  grp_name[] = "/only";
+    struct mirrortest_filenames names;
+    hid_t       file_id = H5I_INVALID_HID;
+    hid_t       grp_id  = H5I_INVALID_HID;
+    hid_t       fapl_id = H5P_DEFAULT;
+
+    TESTING("'Zoo' of on-disk structures");
+
+    /* Create FAPL for Splitter[sec2|mirror]
+     */
+    fapl_id = create_mirroring_split_fapl("zoo", &names);
+    if (H5I_INVALID_HID == fapl_id) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* TEST: Create file    */
+    file_id = H5Fcreate(names.rw, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+
+    grp_id = H5Gcreate2(file_id, grp_name, H5P_DEFAULT, H5P_DEFAULT,
+            H5P_DEFAULT);
+    if (grp_id == H5I_INVALID_HID) {
+        TEST_ERROR;
+    }
+
+    /* Create datasets in file, close (flush) and reopen, validate.
+     * Use of ( pass ) a conceit required for using create_ and validate_zoo()
+     * from cache_common and/or genall5.
+     */
+
+    if ( pass ) {
+        create_zoo(file_id, grp_name, 0);
+    }
+    if ( pass ) {
+        if (H5Fclose(file_id) == FAIL) {
+            TEST_ERROR;
+        }
+        file_id = H5Fopen(names.rw, H5F_ACC_RDWR, fapl_id);
+        if (H5I_INVALID_HID == file_id) {
+            TEST_ERROR;
+        }
+    }
+    if ( pass ) {
+        validate_zoo(file_id, grp_name, 0); /* sanity-check */
+    }
+    if ( !pass ) {
+        HDprintf(failure_mssg);
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* Standard cleanup */
+
+    if (fapl_id != H5P_DEFAULT && fapl_id >= 0) {
+        if (H5Pclose(fapl_id) == FAIL) {
+            TEST_ERROR;
+        }
+    }
+    if (H5Gclose(grp_id) == FAIL) {
+        TEST_ERROR;
+    }
+    if (H5Fclose(file_id) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* TEST: Verify that the R/W and W/O files are identical */
+
+    if (h5_compare_file_bytes(names.rw, names.wo) < 0) {
+        TEST_ERROR;
+    }
+
+    PASSED();
+    return 0;
+
+error:
+    H5E_BEGIN_TRY {
+        (void)H5Fclose(file_id);
+        (void)H5Gclose(grp_id);
+        if (fapl_id != H5P_DEFAULT && fapl_id > 0) {
+            (void)H5Pclose(fapl_id);
+        }
+    } H5E_END_TRY;
+    return -1;
+} /* end test_on_disk_zoo() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_vanishing_datasets
+ *
+ * Purpose:     Verify behavior when writing to a file where data is deleted.
+ *
+ *              Each dataset is populated with the value of its suffix
+ *              (dset5 is all fives).
+ *
+ *              Opens 0..15 create one new dataset each, '/dset[i]'.
+ *              Opens 3..18 delete '/dset[1-3]'
+ *
+ *              Should end with no data in file.
+ *
+ * Return:      Success:  0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_vanishing_datasets(void)
+{
+    struct mirrortest_filenames names;
+    hid_t       file_id = H5I_INVALID_HID;
+    hid_t       fapl_id = H5I_INVALID_HID;
+    hid_t       dset_id = H5I_INVALID_HID;
+    hid_t       dspace_id = H5I_INVALID_HID;
+    hid_t       mirror_fapl_id = H5I_INVALID_HID;
+    hsize_t     dims[2] = {DATABUFFER_SIZE, DATABUFFER_SIZE};
+    uint32_t    buf[DATABUFFER_SIZE][DATABUFFER_SIZE]; /* consider malloc? */
+    H5G_info_t  group_info;
+    unsigned int        i, j, k;
+    const unsigned int  max_loops = 20;
+    const unsigned int  max_at_one_time = 3;
+
+    TESTING("Vanishing Datasets");
+
+    /* -------------------- */
+    /* Set up recurrent data (FAPL, dataspace) */
+
+    /* Create FAPL for Splitter[sec2|mirror]
+     */
+    fapl_id = create_mirroring_split_fapl("vanishing", &names);
+    if (H5I_INVALID_HID == fapl_id) {
+        TEST_ERROR;
+    }
+
+    dspace_id = H5Screate_simple(2, dims, NULL);
+    if (dspace_id < 0) {
+        TEST_ERROR;
+    }
+
+    /* create file */
+    file_id = H5Fcreate(names.rw, H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+    if (H5I_INVALID_HID == file_id) {
+        TEST_ERROR;
+    }
+
+    for (i=0; i < max_loops; i++) {
+        char namebuf[DSET_NAME_LEN + 1];
+
+        /* deleting datasets */
+        if (i >= max_at_one_time) {
+            if (HDsnprintf(namebuf, DSET_NAME_LEN, "/dset%02d",
+                    (i - max_at_one_time) )
+                > DSET_NAME_LEN)
+            {
+                TEST_ERROR;
+            }
+            if (H5Ldelete(file_id, namebuf, H5P_DEFAULT) < 0) {
+                TEST_ERROR;
+            }
+        } /* end if deleting a dataset */
+
+        /* writing datasets */
+        if (i < (max_loops - max_at_one_time)) {
+            if (HDsnprintf(namebuf, DSET_NAME_LEN, "/dset%02d", i)
+                > DSET_NAME_LEN)
+            {
+                TEST_ERROR;
+            }
+            dset_id = H5Dcreate2(file_id, namebuf, H5T_STD_U32LE, dspace_id,
+                    H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+            if (H5I_INVALID_HID == dset_id) {
+                TEST_ERROR;
+            }
+
+            for (j=0; j < DATABUFFER_SIZE; j++) {
+                for (k=0; k < DATABUFFER_SIZE; k++) {
+                    buf[j][k] = (uint32_t)i;
+                }
+            }
+
+            if (H5Dwrite(dset_id, H5T_STD_U32LE, H5S_ALL, H5S_ALL, H5P_DEFAULT,
+                    buf)
+                < 0)
+            {
+                TEST_ERROR;
+            }
+
+            if (H5Dclose(dset_id) < 0) {
+                TEST_ERROR;
+            }
+            dset_id = H5I_INVALID_HID;
+        } /* end if writing a dataset */
+
+    } /* end for dataset create-destroy cycles */
+
+    if (H5Fclose(file_id) < 0) {
+        TEST_ERROR;
+    }
+    file_id = H5I_INVALID_HID;
+
+    /* verify there are no datasets in file */
+    file_id = H5Fopen(names.rw, H5F_ACC_RDONLY, H5P_DEFAULT);
+    if (file_id < 0) {
+        TEST_ERROR;
+    }
+    if (H5Gget_info(file_id, &group_info) < 0) {
+        TEST_ERROR;
+    }
+    if (group_info.nlinks > 0) {
+        HDfprintf(stderr, "links in rw file: %d\n", group_info.nlinks);
+        HDfflush(stderr);
+        TEST_ERROR;
+    }
+    if (H5Fclose(file_id) < 0) {
+        TEST_ERROR;
+    }
+    file_id = H5Fopen(names.wo, H5F_ACC_RDONLY, H5P_DEFAULT);
+    if (file_id < 0) {
+        TEST_ERROR;
+    }
+    if (H5Gget_info(file_id, &group_info) < 0) {
+        TEST_ERROR;
+    }
+    if (group_info.nlinks > 0) {
+        HDfprintf(stderr, "links in wo file: %d\n", group_info.nlinks);
+        HDfflush(stderr);
+        TEST_ERROR;
+    }
+    if (H5Fclose(file_id) < 0) {
+        TEST_ERROR;
+    }
+    file_id = H5I_INVALID_HID;
+
+    if (h5_compare_file_bytes(names.rw, names.wo) < 0)
+        TEST_ERROR;
+
+    /* -------------------- */
+    /* Teardown */
+
+    if (H5Sclose(dspace_id) < 0) {
+        TEST_ERROR;
+    }
+    if (H5Pclose(fapl_id) < 0) {
+        TEST_ERROR;
+    }
+
+    PASSED();
+    return 0;
+
+error:
+    H5E_BEGIN_TRY {
+        if (mirror_fapl_id != H5I_INVALID_HID) {
+            H5Pclose(mirror_fapl_id);
+        }
+        if (fapl_id != H5I_INVALID_HID) {
+            H5Pclose(fapl_id);
+        }
+        if (file_id != H5I_INVALID_HID) {
+            H5Fclose(file_id);
+        }
+        if (dset_id != H5I_INVALID_HID) {
+            H5Dclose(dset_id);
+        }
+        if (dspace_id != H5I_INVALID_HID) {
+            H5Sclose(dspace_id);
+        }
+    } H5E_END_TRY;
+    return -1;
+} /* test_vanishing_datasets() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    test_concurrent_access
+ *
+ * Purpose:     Verify that more than one file may be opened at a time.
+ *
+ *              TODO: receive target IP from caller?
+ *
+ * Return:      Success: 0
+ *              Failure: -1
+ *
+ * Programmer:  Jacob Smith
+ *              2020-03-09
+ * ---------------------------------------------------------------------------
+ */
+static int
+test_concurrent_access(void)
+{
+    struct file_bundle {
+        struct mirrortest_filenames names;
+        hid_t dset_id;
+        hid_t fapl_id;
+        hid_t file_id;
+    } bundle[CONCURRENT_COUNT];
+    hid_t       dspace_id = H5I_INVALID_HID;
+    hid_t       dtype_id = H5T_NATIVE_INT;
+    hsize_t     dims[2] = { DATABUFFER_SIZE, DATABUFFER_SIZE };
+    int        *buf = NULL;
+    int         i = 0;
+    int         j = 0;
+
+    TESTING("Concurrent opened mirrored files");
+
+    /* blank bundle */
+    for (i = 0; i < CONCURRENT_COUNT; i++) {
+        bundle[i].dset_id = H5I_INVALID_HID;
+        bundle[i].fapl_id = H5I_INVALID_HID;
+        bundle[i].file_id = H5I_INVALID_HID;
+        *bundle[i].names.rw = '\0';
+        *bundle[i].names.wo = '\0';
+        *bundle[i].names.log = '\0';
+    }
+
+    /* Create FAPL for Splitter[sec2|mirror]
+     */
+    for (i = 0; i < CONCURRENT_COUNT; i++) {
+        char _name[16] = "";
+        hid_t _fapl_id = H5I_INVALID_HID;
+        HDsnprintf(_name, 15, "concurrent%d", i);
+        _fapl_id = create_mirroring_split_fapl(_name, &bundle[i].names);
+        if (H5I_INVALID_HID == _fapl_id) {
+            TEST_ERROR;
+        }
+        bundle[i].fapl_id = _fapl_id;
+    }
+
+    /* Prepare data to be written
+     */
+    buf = (int *)HDmalloc(DATABUFFER_SIZE * DATABUFFER_SIZE * sizeof(int));
+    if (NULL == buf) {
+        TEST_ERROR;
+    }
+    for (i = 0; i < DATABUFFER_SIZE; i++) {
+        for (j = 0; j < DATABUFFER_SIZE; j++) {
+            int k = i * DATABUFFER_SIZE + j;
+            buf[k] = k;
+        }
+    }
+
+    /* Prepare generic dataspace
+     */
+    dspace_id = H5Screate_simple(2, dims, NULL);
+    if (H5I_INVALID_HID == dspace_id) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* TEST: Create file and open elements */
+
+    for (i = 0; i < CONCURRENT_COUNT; i++) {
+        hid_t _file_id = H5I_INVALID_HID;
+        hid_t _dset_id = H5I_INVALID_HID;
+
+        _file_id = H5Fcreate(bundle[i].names.rw, H5F_ACC_TRUNC, H5P_DEFAULT,
+                bundle[i].fapl_id);
+        if (H5I_INVALID_HID == _file_id) {
+            TEST_ERROR;
+        }
+
+        bundle[i].file_id  = _file_id;
+
+        _dset_id = H5Dcreate2(_file_id, "dataset", dtype_id, dspace_id,
+                H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+        if (H5I_INVALID_HID == _dset_id) {
+            TEST_ERROR;
+        }
+        bundle[i].dset_id = _dset_id;
+    }
+
+    /* -------------------- */
+    /* TEST: Write to files */
+
+    for (i = 0; i < CONCURRENT_COUNT; i++) {
+        if (H5Dwrite(bundle[i].dset_id, dtype_id, H5S_ALL, H5S_ALL,
+                H5P_DEFAULT, buf)
+            == FAIL)
+        {
+            TEST_ERROR;
+        }
+    }
+
+    /* -------------------- */
+    /* TEST: Close elements  */
+
+    for (i = 0; i < CONCURRENT_COUNT; i++) {
+        if (H5Dclose(bundle[i].dset_id) == FAIL) {
+            TEST_ERROR;
+        }
+        if (H5Fclose(bundle[i].file_id) == FAIL) {
+            TEST_ERROR;
+        }
+        if (H5Pclose(bundle[i].fapl_id) == FAIL) {
+            TEST_ERROR;
+        }
+    }
+
+    /* -------------------- */
+    /* Standard cleanup */
+
+    HDfree(buf);
+    buf = NULL;
+    if (H5Sclose(dspace_id) == FAIL) {
+        TEST_ERROR;
+    }
+
+    /* -------------------- */
+    /* TEST: Verify that the R/W and W/O files are identical */
+
+    for (i = 0; i < CONCURRENT_COUNT; i++) {
+        if (h5_compare_file_bytes(bundle[i].names.rw, bundle[i].names.wo) < 0) {
+            TEST_ERROR;
+        }
+    }
+
+    PASSED();
+    return 0;
+
+error:
+    H5E_BEGIN_TRY{
+        if (buf) {
+            HDfree(buf);
+        }
+        (void)H5Sclose(dspace_id);
+        for (i = 0; i < CONCURRENT_COUNT; i++) {
+            (void)H5Dclose(bundle[i].dset_id);
+            (void)H5Fclose(bundle[i].file_id);
+            (void)H5Pclose(bundle[i].fapl_id);
+        }
+    } H5E_END_TRY;
+    return -1;
+} /* end test_concurrent_access() */
+
+
+/* ---------------------------------------------------------------------------
+ * Function:    main
+ *
+ * Purpose:     Run tests.
+ *
+ * Return:      Success: 0
+ *              Failure: 1
+ *
+ * Programmer:  Jacob Smith
+ *              2019
+ * ---------------------------------------------------------------------------
+ */
+int
+main(void)
+{
+    int nerrors = 0;
+
+    h5_reset();
+
+    g_log_stream = stdout; /* default debug/logging output stream */
+
+    HDprintf("Testing Mirror VFD functionality.\n");
+
+    /* -------------------- */
+    /* SETUP */
+
+    /* Create directories for test-generated .h5 files
+     */
+    if (nerrors == 0) {
+        if ((HDmkdir(MIRROR_RW_DIR, (mode_t)0755) < 0) && (errno != EEXIST)) {
+            nerrors++;
+        }
+    }
+    if (nerrors == 0) {
+        if ((HDmkdir(MIRROR_WO_DIR, (mode_t)0755) < 0) && (errno != EEXIST)) {
+            nerrors++;
+        }
+    }
+
+    /* -------------------- */
+    /* TESTS */
+    /* Tests return negative values; `-=' increments nerrors count */
+
+    if (nerrors == 0) {
+        nerrors -= test_fapl_configuration();
+        nerrors -= test_xmit_encode_decode();
+        nerrors -= test_create_and_close();
+        nerrors -= test_basic_dataset_write();
+        nerrors -= test_chunked_dataset_write();
+        nerrors -= test_on_disk_zoo();
+        nerrors -= test_vanishing_datasets();
+        nerrors -= test_concurrent_access();
+    }
+
+    if (nerrors) {
+        HDprintf("***** %d Mirror VFD TEST%s FAILED! *****\n",
+                nerrors, nerrors > 1 ? "S" : "");
+        return EXIT_FAILURE;
+    }
+
+    HDprintf("All Mirror Virtual File Driver tests passed.\n");
+    return EXIT_SUCCESS;
+} /* end main() */
+
+#else /* H5_HAVE_MIRROR_VFD */
+
+int
+main(void)
+{
+    h5_reset();
+    HDprintf("Testing Mirror VFD functionality.\n");
+    HDprintf("SKIPPED - Mirror VFD not built.\n");
+    return EXIT_SUCCESS;
+}
+
+#endif /* H5_HAVE_MIRROR_VFD */
+
+