Fixes a stack overflow in the h5dump test generator (#1903)

* Fixes a stack overflow in the h5dump test generator

The opaque type size was declared to be the size of the "buffer of two
opaque elements", causing a memcpy call in H5Dwrite to read outside
the buffer, dumping garbage into the file.

Note that this only affected the test generator and not h5dump itself.

* Committing clang-format changes

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

3 files changed, 31 insertions, 30 deletions

diff --git a/tools/test/h5dump/h5dumpgentest.c b/tools/test/h5dump/h5dumpgentest.c
index 949aa43..caacc2c 100644
--- a/tools/test/h5dump/h5dumpgentest.c
+++ b/tools/test/h5dump/h5dumpgentest.c
@@ -2570,41 +2570,42 @@ gent_nestcomp(void)
 static void
 gent_opaque(void)
 {
-    hid_t   file, type, dataset, space;
-    char    test[100][2];
-    int     x;
-    hsize_t dim = 2;
+    hid_t file    = H5I_INVALID_HID;
+    hid_t type    = H5I_INVALID_HID;
+    hid_t dataset = H5I_INVALID_HID;
+    hid_t space   = H5I_INVALID_HID;
 
-    for (x = 0; x < 100; x++) {
-        test[x][0] = (char)x;
-        test[x][1] = (char)(99 - x);
-    }
+    const uint8_t OPAQUE_NBYTES = 100;
+    const int     N_ELEMENTS    = 2;
 
-    /*
-     * Create the data space.
-     */
-    space = H5Screate_simple(1, &dim, NULL);
+    /* The dataset contains N_ELEMENTS elements of OPAQUE_NBYTES bytes */
+    uint8_t data[OPAQUE_NBYTES][N_ELEMENTS];
+    hsize_t dim = N_ELEMENTS;
 
-    /*
-     * Create the file.
-     */
     file = H5Fcreate(FILE19, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT);
 
-    /*
-     * Create the memory datatype.
-     */
-    type = H5Tcreate(H5T_OPAQUE, sizeof(char) * 100 * 2);
+    /* The opaque datatype is OPAQUE_NBYTES bytes in size */
+    type = H5Tcreate(H5T_OPAQUE, sizeof(uint8_t) * OPAQUE_NBYTES);
     H5Tset_tag(type, "test opaque type");
 
-    /*
-     * Create the dataset.
-     */
+    space   = H5Screate_simple(1, &dim, NULL);
     dataset = H5Dcreate2(file, "opaque test", type, space, H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
 
-    /*
-     * Write data to the dataset;
+    /* Given the data fill algorithm, make sure that the number of bytes
+     * in the opaque type isn't so big that i or (OPAQUE_NBYTES - 1) - i
+     * don't fit in a uint8_t value..
      */
-    H5Dwrite(dataset, type, H5S_ALL, H5S_ALL, H5P_DEFAULT, test);
+    HDcompile_assert(OPAQUE_NBYTES < UINT8_MAX);
+
+    /* Write out two opaque data elements with predictable data to
+     * the file.
+     */
+    for (uint8_t i = 0; i < OPAQUE_NBYTES; i++) {
+        data[i][0] = i;
+        data[i][1] = (OPAQUE_NBYTES - 1) - i;
+    }
+
+    H5Dwrite(dataset, type, H5S_ALL, H5S_ALL, H5P_DEFAULT, data);
 
     H5Tclose(type);
     H5Sclose(space);
diff --git a/tools/testfiles/topaque.h5 b/tools/testfiles/topaque.h5
index d56b594..d0b29c6 100644
--- a/tools/testfiles/topaque.h5
+++ b/tools/testfiles/topaque.h5
diff --git a/tools/testfiles/topaque.h5.xml b/tools/testfiles/topaque.h5.xml
index 25dbcdb..c0699f0 100644
--- a/tools/testfiles/topaque.h5.xml
+++ b/tools/testfiles/topaque.h5.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <hdf5:HDF5-File xmlns:hdf5="http://hdfgroup.org/HDF5/XML/schema/HDF5-File.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://hdfgroup.org/HDF5/XML/schema/HDF5-File http://www.hdfgroup.org/HDF5/XML/schema/HDF5-File.xsd">
-<hdf5:RootGroup OBJ-XID="xid_696" H5Path="/">
-   <hdf5:Dataset Name="opaque test" OBJ-XID="xid_744" H5Path= "/opaque test" Parents="xid_696" H5ParentPaths="/">
+<hdf5:RootGroup OBJ-XID="xid_96" H5Path="/">
+   <hdf5:Dataset Name="opaque test" OBJ-XID="xid_800" H5Path= "/opaque test" Parents="xid_96" H5ParentPaths="/">
       <hdf5:StorageLayout>
          <hdf5:ContiguousLayout/>
       </hdf5:StorageLayout>
@@ -17,13 +17,13 @@
       </hdf5:Dataspace>
       <hdf5:DataType>
          <hdf5:AtomicType>
-            <hdf5:OpaqueType Tag="test opaque type" Size="200"/>
+            <hdf5:OpaqueType Tag="test opaque type" Size="100"/>
          </hdf5:AtomicType>
       </hdf5:DataType>
       <hdf5:Data>
          <hdf5:DataFromFile>
-         00:63:01:62:02:61:03:60:04:5f:05:5e:06:5d:07:5c:08:5b:09:5a:0a:59:0b:58:0c:57:0d:56:0e:55:0f:54:10:53:11:52:12:51:13:50:14:4f:15:4e:16:4d:17:4c:18:4b:19:4a:1a:49:1b:48:1c:47:1d:46:1e:45:1f:44:20:43:21:42:22:41:23:40:24:3f:25:3e:26:3d:27:3c:28:3b:29:3a:2a:39:2b:38:2c:37:2d:36:2e:35:2f:34:30:33:31:32:32:31:33:30:34:2f:35:2e:36:2d:37:2c:38:2b:39:2a:3a:29:3b:28:3c:27:3d:26:3e:25:3f:24:40:23:41:22:42:21:43:20:44:1f:45:1e:46:1d:47:1c:48:1b:49:1a:4a:19:4b:18:4c:17:4d:16:4e:15:4f:14:50:13:51:12:52:11:53:10:54:0f:55:0e:56:0d:57:0c:58:0b:59:0a:5a:09:5b:08:5c:07:5d:06:5e:05:5f:04:60:03:61:02:62:01:63:00
-         38:00:00:2c:3c:00:00:27:34:00:01:ea:04:00:00:12:00:00:00:00:00:08:a4:64:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:ef:7e:c9:c0:00:00:00:01:ef:ff:fa:84:ef:ff:fa:8c:00:03:fc:00:00:00:00:00:00:00:00:00:ef:ff:fa:20:00:01:2e:84:ef:ff:fa:20:00:01:2e:58:00:00:00:03:ef:ff:fa:84:00:00:00:04:ef:ff:fa:8c:00:00:00:05:ef:ff:fa:f0:00:00:00:00:00:00:00:00:00:00:00:01:ef:ff:fa:84:ef:ff:fa:8c:00:03:fc:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
+         00:63:01:62:02:61:03:60:04:5f:05:5e:06:5d:07:5c:08:5b:09:5a:0a:59:0b:58:0c:57:0d:56:0e:55:0f:54:10:53:11:52:12:51:13:50:14:4f:15:4e:16:4d:17:4c:18:4b:19:4a:1a:49:1b:48:1c:47:1d:46:1e:45:1f:44:20:43:21:42:22:41:23:40:24:3f:25:3e:26:3d:27:3c:28:3b:29:3a:2a:39:2b:38:2c:37:2d:36:2e:35:2f:34:30:33:31:32
+         32:31:33:30:34:2f:35:2e:36:2d:37:2c:38:2b:39:2a:3a:29:3b:28:3c:27:3d:26:3e:25:3f:24:40:23:41:22:42:21:43:20:44:1f:45:1e:46:1d:47:1c:48:1b:49:1a:4a:19:4b:18:4c:17:4d:16:4e:15:4f:14:50:13:51:12:52:11:53:10:54:0f:55:0e:56:0d:57:0c:58:0b:59:0a:5a:09:5b:08:5c:07:5d:06:5e:05:5f:04:60:03:61:02:62:01:63:00
          </hdf5:DataFromFile>
       </hdf5:Data>
    </hdf5:Dataset>