Clean up off_t usage (#4095)

* Add comments to C++ and Fortran API calls that use off_t
* Remove noise casts for small integers

26 files changed, 70 insertions, 63 deletions

diff --git a/HDF5Examples/FORTRAN/H5D/h5ex_d_extern.F90 b/HDF5Examples/FORTRAN/H5D/h5ex_d_extern.F90
index faef397..e44fdf0 100644
--- a/HDF5Examples/FORTRAN/H5D/h5ex_d_extern.F90
+++ b/HDF5Examples/FORTRAN/H5D/h5ex_d_extern.F90
@@ -40,7 +40,7 @@ PROGRAM main
   INTEGER :: i, j
   ! This change was introduced in the 1.8.12 release
 #if H5_VERSION_GE(1,8,12)
-  INTEGER(OFF_T) :: offset = 0 ! Offset, in bytes, from thebeginning of the file to the 
+  INTEGER(OFF_T) :: offset = 0 ! Offset, in bytes, from the beginning of the file to the 
                                ! location in the file where the data starts.
 #else
   INTEGER :: offset = 0
diff --git a/c++/src/H5DcreatProp.cpp b/c++/src/H5DcreatProp.cpp
index 8f4ee7e..f45b54e 100644
--- a/c++/src/H5DcreatProp.cpp
+++ b/c++/src/H5DcreatProp.cpp
@@ -645,6 +645,8 @@ DSetCreatPropList::setFletcher32() const
 ///             the total size is larger than the size of a dataset then the
 ///             dataset can be extended (provided the data space also allows
 ///             the extending).
+///\note        On Windows, off_t is typically a 32-bit signed long value, which
+///             limits the valid offset that can be set to 2 GiB.
 //--------------------------------------------------------------------------
 void
 DSetCreatPropList::setExternal(const char *name, off_t offset, hsize_t size) const
@@ -693,6 +695,8 @@ DSetCreatPropList::getExternalCount() const
 ///             external file name will not be returned.  If \a offset or
 ///             \a size are null pointers then the corresponding information
 ///             will not be returned.
+///\note        On Windows, off_t is typically a 32-bit signed long value, which
+///             limits the valid offset that can be returned to 2 GiB.
 //--------------------------------------------------------------------------
 void
 DSetCreatPropList::getExternal(unsigned idx, size_t name_size, char *name, off_t &offset, hsize_t &size) const
diff --git a/fortran/src/H5Pff.F90 b/fortran/src/H5Pff.F90
index 516c34b..ab6765a 100644
--- a/fortran/src/H5Pff.F90
+++ b/fortran/src/H5Pff.F90
@@ -1615,6 +1615,9 @@ CONTAINS
 !! \param bytes  Size of the external file data.
 !! \param hdferr \fortran_error
 !!
+!! \note On Windows, off_t is typically a 32-bit signed long value, which
+!!       limits the valid offset that can be set to 2 GiB.
+!!
 !! See C API: @ref H5Pset_external()
 !!
   SUBROUTINE h5pset_external_f(prp_id, name, offset, bytes, hdferr)
@@ -1686,9 +1689,12 @@ CONTAINS
 !! \param bytes     Size of the external file data.
 !! \param hdferr    \fortran_error
 !!
+!! \note On Windows, off_t is typically a 32-bit signed long value, which
+!!       limits the valid offset that can be returned to 2 GiB.
+!!
 !! See C API: @ref H5Pget_external()
 !!
-  SUBROUTINE h5pget_external_f(prp_id, idx, name_size, name, offset,bytes, hdferr)
+  SUBROUTINE h5pget_external_f(prp_id, idx, name_size, name, offset, bytes, hdferr)
     IMPLICIT NONE
     INTEGER(HID_T), INTENT(IN) :: prp_id
     INTEGER, INTENT(IN) :: idx
diff --git a/src/H5FDcore.c b/src/H5FDcore.c
index 3767420..7c48469 100644
--- a/src/H5FDcore.c
+++ b/src/H5FDcore.c
@@ -393,7 +393,7 @@ H5FD__core_write_to_bstore(H5FD_core_t *file, haddr_t addr, size_t size)
             int    myerrno = errno;
             time_t mytime  = HDtime(NULL);
 
-            offset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
+            offset = HDlseek(file->fd, 0, SEEK_CUR);
 
             HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
                         "write to backing store failed: time = %s, filename = '%s', file descriptor = %d, "
@@ -871,8 +871,8 @@ H5FD__core_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr
                  * partial results, and the end of the file.
                  */
 
-                uint8_t *mem    = file->mem;  /* memory pointer for writes */
-                HDoff_t  offset = (HDoff_t)0; /* offset for reading */
+                uint8_t *mem    = file->mem; /* memory pointer for writes */
+                HDoff_t  offset = 0;         /* offset for reading */
 
                 while (size > 0) {
                     h5_posix_io_t     bytes_in   = 0;  /* # of bytes to read       */
@@ -900,7 +900,7 @@ H5FD__core_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr
                         int    myerrno = errno;
                         time_t mytime  = HDtime(NULL);
 
-                        offset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
+                        offset = HDlseek(file->fd, 0, SEEK_CUR);
 
                         HGOTO_ERROR(
                             H5E_IO, H5E_READERROR, NULL,
diff --git a/src/H5FDdirect.c b/src/H5FDdirect.c
index 08c4a83..49f80d4 100644
--- a/src/H5FDdirect.c
+++ b/src/H5FDdirect.c
@@ -541,7 +541,7 @@ H5FD__direct_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxad
         }
         else {
             file->fa.must_align = false;
-            if (-1 == HDftruncate(file->fd, (HDoff_t)0))
+            if (-1 == HDftruncate(file->fd, 0))
                 HSYS_GOTO_ERROR(H5E_IO, H5E_SEEKERROR, NULL, "unable to truncate file")
         }
     }
@@ -554,7 +554,7 @@ H5FD__direct_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxad
         }
         else {
             if (o_flags & O_RDWR) {
-                if (HDlseek(file->fd, (HDoff_t)0, SEEK_SET) < 0)
+                if (HDlseek(file->fd, 0, SEEK_SET) < 0)
                     HSYS_GOTO_ERROR(H5E_IO, H5E_SEEKERROR, NULL, "unable to seek to proper position")
                 if (HDwrite(file->fd, buf1, sizeof(int)) < 0)
                     file->fa.must_align = true;
diff --git a/src/H5FDlog.c b/src/H5FDlog.c
index e35a6a6..64d3662 100644
--- a/src/H5FDlog.c
+++ b/src/H5FDlog.c
@@ -1229,7 +1229,7 @@ H5FD__log_read(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id, had
             int    myerrno = errno;
             time_t mytime  = HDtime(NULL);
 
-            offset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
+            offset = HDlseek(file->fd, 0, SEEK_CUR);
 
             if (file->fa.flags & H5FD_LOG_LOC_READ)
                 fprintf(file->logfp, "Error! Reading: %10" PRIuHADDR "-%10" PRIuHADDR " (%10zu bytes)\n",
@@ -1448,7 +1448,7 @@ H5FD__log_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id, ha
             int    myerrno = errno;
             time_t mytime  = HDtime(NULL);
 
-            offset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
+            offset = HDlseek(file->fd, 0, SEEK_CUR);
 
             if (file->fa.flags & H5FD_LOG_LOC_WRITE)
                 fprintf(file->logfp, "Error! Writing: %10" PRIuHADDR "-%10" PRIuHADDR " (%10zu bytes)\n",
diff --git a/src/H5FDsec2.c b/src/H5FDsec2.c
index 15accf7..c4bfbff 100644
--- a/src/H5FDsec2.c
+++ b/src/H5FDsec2.c
@@ -697,7 +697,7 @@ H5FD__sec2_read(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type, hid_t H5_ATTR_UNU
             int    myerrno = errno;
             time_t mytime  = HDtime(NULL);
 
-            offset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
+            offset = HDlseek(file->fd, 0, SEEK_CUR);
 
             HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL,
                         "file read failed: time = %s, filename = '%s', file descriptor = %d, errno = %d, "
@@ -803,7 +803,7 @@ H5FD__sec2_write(H5FD_t *_file, H5FD_mem_t H5_ATTR_UNUSED type, hid_t H5_ATTR_UN
             int    myerrno = errno;
             time_t mytime  = HDtime(NULL);
 
-            offset = HDlseek(file->fd, (HDoff_t)0, SEEK_CUR);
+            offset = HDlseek(file->fd, 0, SEEK_CUR);
 
             HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL,
                         "file write failed: time = %s, filename = '%s', file descriptor = %d, errno = %d, "
diff --git a/test/big.c b/test/big.c
index 428da0a..ed38251 100644
--- a/test/big.c
+++ b/test/big.c
@@ -143,7 +143,7 @@ is_sparse(void)
 
     if ((fd = HDopen("x.h5", O_RDWR | O_TRUNC | O_CREAT, H5_POSIX_CREATE_MODE_RW)) < 0)
         return 0;
-    if (HDlseek(fd, (HDoff_t)(1024 * 1024), SEEK_SET) != 1024 * 1024)
+    if (HDlseek(fd, (1024 * 1024), SEEK_SET) != 1024 * 1024)
         return 0;
     if (5 != HDwrite(fd, "hello", (size_t)5))
         return 0;
diff --git a/test/enc_dec_plist.c b/test/enc_dec_plist.c
index e643b1b..878fe86 100644
--- a/test/enc_dec_plist.c
+++ b/test/enc_dec_plist.c
@@ -220,13 +220,13 @@ main(void)
                 FAIL_STACK_ERROR;
 
             max_size[0] = 100;
-            if ((H5Pset_external(dcpl, "ext1.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+            if ((H5Pset_external(dcpl, "ext1.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
                 FAIL_STACK_ERROR;
-            if ((H5Pset_external(dcpl, "ext2.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+            if ((H5Pset_external(dcpl, "ext2.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
                 FAIL_STACK_ERROR;
-            if ((H5Pset_external(dcpl, "ext3.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+            if ((H5Pset_external(dcpl, "ext3.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
                 FAIL_STACK_ERROR;
-            if ((H5Pset_external(dcpl, "ext4.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+            if ((H5Pset_external(dcpl, "ext4.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
                 FAIL_STACK_ERROR;
 
             /* Test encoding & decoding property list */
diff --git a/test/enc_dec_plist_cross_platform.c b/test/enc_dec_plist_cross_platform.c
index a368214..d2d6810 100644
--- a/test/enc_dec_plist_cross_platform.c
+++ b/test/enc_dec_plist_cross_platform.c
@@ -178,8 +178,8 @@ test_plists(const char *filename_prefix)
             testfile = H5_get_srcdir_filename(filename);
             if ((fd_1 = HDopen(testfile, O_RDONLY)) < 0)
                 TEST_ERROR;
-            size_1 = (size_t)HDlseek(fd_1, (HDoff_t)0, SEEK_END);
-            HDlseek(fd_1, (HDoff_t)0, SEEK_SET);
+            size_1 = (size_t)HDlseek(fd_1, 0, SEEK_END);
+            HDlseek(fd_1, 0, SEEK_SET);
             buf_1 = (void *)malloc(size_1);
             if (HDread(fd_1, buf_1, size_1) < 0)
                 TEST_ERROR;
@@ -194,8 +194,8 @@ test_plists(const char *filename_prefix)
             testfile = H5_get_srcdir_filename(filename);
             if ((fd_2 = HDopen(testfile, O_RDONLY)) < 0)
                 TEST_ERROR;
-            size_2 = (size_t)HDlseek(fd_2, (HDoff_t)0, SEEK_END);
-            HDlseek(fd_2, (HDoff_t)0, SEEK_SET);
+            size_2 = (size_t)HDlseek(fd_2, 0, SEEK_END);
+            HDlseek(fd_2, 0, SEEK_SET);
             buf_2 = (void *)malloc(size_2);
             if (HDread(fd_2, buf_2, size_2) < 0)
                 TEST_ERROR;
diff --git a/test/external.c b/test/external.c
index bf3c5bd..efd24fa 100644
--- a/test/external.c
+++ b/test/external.c
@@ -106,7 +106,7 @@ test_non_extendible(hid_t file)
     /* Create the dataset and close */
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl, "ext1.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int))) < 0)
+    if (H5Pset_external(dcpl, "ext1.data", 0, (hsize_t)(max_size[0] * sizeof(int))) < 0)
         FAIL_STACK_ERROR;
     if ((space = H5Screate_simple(1, cur_size, max_size)) < 0)
         FAIL_STACK_ERROR;
@@ -203,8 +203,7 @@ test_too_small(hid_t file)
 
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl, "ext1.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) - 1)) <
-        0) /* note -1 */
+    if (H5Pset_external(dcpl, "ext1.data", 0, (hsize_t)(max_size[0] * sizeof(int) - 1)) < 0) /* note -1 */
         FAIL_STACK_ERROR;
     if ((space = H5Screate_simple(1, cur_size, max_size)) < 0)
         FAIL_STACK_ERROR;
@@ -260,7 +259,7 @@ test_large_enough_current_eventual(hid_t file)
 
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl, "ext1.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int))) < 0)
+    if (H5Pset_external(dcpl, "ext1.data", 0, (hsize_t)(max_size[0] * sizeof(int))) < 0)
         FAIL_STACK_ERROR;
     if ((space = H5Screate_simple(1, cur_size, max_size)) < 0)
         FAIL_STACK_ERROR;
@@ -312,8 +311,7 @@ test_large_enough_current_not_eventual(hid_t file)
 
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl, "ext1.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) - 1)) <
-        0) /* note -1 */
+    if (H5Pset_external(dcpl, "ext1.data", 0, (hsize_t)(max_size[0] * sizeof(int) - 1)) < 0) /* note -1 */
         FAIL_STACK_ERROR;
     if ((space = H5Screate_simple(1, cur_size, max_size)) < 0)
         FAIL_STACK_ERROR;
@@ -373,7 +371,7 @@ test_unlimited(hid_t file)
     /* Create dataset */
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl, "ext1.data", (off_t)0, H5F_UNLIMITED) < 0)
+    if (H5Pset_external(dcpl, "ext1.data", 0, H5F_UNLIMITED) < 0)
         FAIL_STACK_ERROR;
     if ((space = H5Screate_simple(1, cur_size, max_size)) < 0)
         FAIL_STACK_ERROR;
@@ -576,12 +574,12 @@ test_add_to_unlimited(void)
 
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl, "ext1.data", (off_t)0, H5F_UNLIMITED) < 0)
+    if (H5Pset_external(dcpl, "ext1.data", 0, H5F_UNLIMITED) < 0)
         FAIL_STACK_ERROR;
 
     H5E_BEGIN_TRY
     {
-        status = H5Pset_external(dcpl, "ext2.data", (off_t)0, (hsize_t)100);
+        status = H5Pset_external(dcpl, "ext2.data", 0, 100);
     }
     H5E_END_TRY
     if (status >= 0)
@@ -627,12 +625,12 @@ test_overflow(void)
 
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl, "ext1.data", (off_t)0, H5F_UNLIMITED - 1) < 0)
+    if (H5Pset_external(dcpl, "ext1.data", 0, H5F_UNLIMITED - 1) < 0)
         FAIL_STACK_ERROR;
 
     H5E_BEGIN_TRY
     {
-        status = H5Pset_external(dcpl, "ext2.data", (off_t)0, (hsize_t)100);
+        status = H5Pset_external(dcpl, "ext2.data", 0, 100);
     }
     H5E_END_TRY
     if (status >= 0)
@@ -1286,7 +1284,7 @@ test_h5d_get_access_plist(hid_t fapl_id)
     /* Create the dcpl and set external storage */
     if ((dcpl_id = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
-    if (H5Pset_external(dcpl_id, "extern_1r.raw", (off_t)0, (hsize_t)0) < 0)
+    if (H5Pset_external(dcpl_id, "extern_1r.raw", 0, 0) < 0)
         FAIL_STACK_ERROR;
 
     /* Create the dapl and set the prefix */
diff --git a/test/file_image.c b/test/file_image.c
index 81b49d6..66881c4 100644
--- a/test/file_image.c
+++ b/test/file_image.c
@@ -871,7 +871,7 @@ test_get_file_image(const char *test_banner, const int file_name_num, hid_t fapl
             HDoff_t off;
 
             /* Position at userblock */
-            off = HDlseek(fd, (HDoff_t)USERBLOCK_SIZE, SEEK_SET);
+            off = HDlseek(fd, USERBLOCK_SIZE, SEEK_SET);
             VERIFY(off >= 0, "HDlseek() failed.");
         }
 
diff --git a/test/fillval.c b/test/fillval.c
index 2e8cb47..c8f4638 100644
--- a/test/fillval.c
+++ b/test/fillval.c
@@ -2098,7 +2098,7 @@ test_extend(hid_t fapl, const char *base_name, H5D_layout_t layout)
         if ((fd = HDopen(FILE_NAME_RAW, O_RDWR | O_CREAT | O_TRUNC, H5_POSIX_CREATE_MODE_RW)) < 0 ||
             HDclose(fd) < 0)
             goto error;
-        if (H5Pset_external(dcpl, FILE_NAME_RAW, (off_t)0, (hsize_t)nelmts * sizeof(int)) < 0)
+        if (H5Pset_external(dcpl, FILE_NAME_RAW, 0, (hsize_t)nelmts * sizeof(int)) < 0)
             goto error;
     }
 #endif
diff --git a/test/gen_bad_offset.c b/test/gen_bad_offset.c
index 4f7b959..9c52195 100644
--- a/test/gen_bad_offset.c
+++ b/test/gen_bad_offset.c
@@ -31,11 +31,11 @@
  *              (A) Open the file:
  *                  fd = HDopen(TESTFILE, O_RDWR, 0663);
  *              (B) Position the file at:
- *                  (1) HDlseek(fd, (HDoff_t)880, SEEK_SET);
+ *                  (1) HDlseek(fd, 880, SEEK_SET);
  *                      "/group1/group2": replace heap offset "8" by bad offset
- *                  (2) HDlseek(fd, (HDoff_t)1512, SEEK_SET);
+ *                  (2) HDlseek(fd, 1512, SEEK_SET);
  *                      "/dsetA": replace name offset into private heap "72" by bad offset
- *                  (3) HDlseek(fd, (HDoff_t)1616, SEEK_SET);
+ *                  (3) HDlseek(fd, 1616, SEEK_SET);
  *                      /soft_one: replace link value offset in the scratch pad "32" by bad offset
  *              (C) Write the bad offset value to the file for (1), (2) and (3):
  *                  write(fd, &val, sizeof(val));
@@ -104,21 +104,21 @@ main(void)
         FAIL_STACK_ERROR;
 
     /* Position the file for /group1/group2: replace heap offset "8" by bad offset */
-    if (HDlseek(fd, (HDoff_t)880, SEEK_SET) < 0)
+    if (HDlseek(fd, 880, SEEK_SET) < 0)
         FAIL_STACK_ERROR;
     /* Write the bad offset value to the file */
     if (HDwrite(fd, &val, sizeof(val)) < 0)
         FAIL_STACK_ERROR;
 
     /* Position the file for /dsetA: replace name offset into private heap "72" by bad offset */
-    if (HDlseek(fd, (HDoff_t)1512, SEEK_SET) < 0)
+    if (HDlseek(fd, 1512, SEEK_SET) < 0)
         FAIL_STACK_ERROR;
     /* Write the bad offset value to the file */
     if (HDwrite(fd, &val, sizeof(val)) < 0)
         FAIL_STACK_ERROR;
 
     /* Position the file for /soft_one: replace link value offset in the scratch pad "32" by bad offset */
-    if (HDlseek(fd, (HDoff_t)1616, SEEK_SET) < 0)
+    if (HDlseek(fd, 1616, SEEK_SET) < 0)
         FAIL_STACK_ERROR;
     /* Write the bad offset value to the file */
     if (HDwrite(fd, &val, sizeof(val)) < 0)
diff --git a/test/gen_plist.c b/test/gen_plist.c
index 6d40ae7..1400b40 100644
--- a/test/gen_plist.c
+++ b/test/gen_plist.c
@@ -123,13 +123,13 @@ main(void)
         assert(ret > 0);
 
     max_size[0] = 100;
-    if ((ret = H5Pset_external(dcpl1, "ext1.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+    if ((ret = H5Pset_external(dcpl1, "ext1.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
         assert(ret > 0);
-    if ((ret = H5Pset_external(dcpl1, "ext2.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+    if ((ret = H5Pset_external(dcpl1, "ext2.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
         assert(ret > 0);
-    if ((ret = H5Pset_external(dcpl1, "ext3.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+    if ((ret = H5Pset_external(dcpl1, "ext3.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
         assert(ret > 0);
-    if ((ret = H5Pset_external(dcpl1, "ext4.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
+    if ((ret = H5Pset_external(dcpl1, "ext4.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4))) < 0)
         assert(ret > 0);
 
     if ((ret = encode_plist(dcpl1, little_endian, word_length, "plist_files/dcpl_")) < 0)
diff --git a/test/istore.c b/test/istore.c
index 33032d1..8da9961 100644
--- a/test/istore.c
+++ b/test/istore.c
@@ -62,7 +62,7 @@ is_sparse(void)
 
     if ((fd = HDopen("x.h5", O_RDWR | O_TRUNC | O_CREAT, H5_POSIX_CREATE_MODE_RW)) < 0)
         return 0;
-    if (HDlseek(fd, (HDoff_t)(1024 * 1024), SEEK_SET) != 1024 * 1024)
+    if (HDlseek(fd, (1024 * 1024), SEEK_SET) != 1024 * 1024)
         return 0;
     if (5 != HDwrite(fd, "hello", (size_t)5))
         return 0;
diff --git a/test/objcopy.c b/test/objcopy.c
index d604c54..08e7b07 100644
--- a/test/objcopy.c
+++ b/test/objcopy.c
@@ -5200,7 +5200,7 @@ test_copy_dataset_external(hid_t fcpl_src, hid_t fcpl_dst, hid_t src_fapl, hid_t
     size = DIM_SIZE_1 * sizeof(int);
     if ((pid = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         TEST_ERROR;
-    if (H5Pset_external(pid, FILE_EXT, (off_t)0, size) < 0)
+    if (H5Pset_external(pid, FILE_EXT, 0, size) < 0)
         TEST_ERROR;
 
     /* create dataset at SRC file */
diff --git a/test/set_extent.c b/test/set_extent.c
index d418f2e..6e2b7c5 100644
--- a/test/set_extent.c
+++ b/test/set_extent.c
@@ -1831,10 +1831,10 @@ test_external(hid_t fapl, bool use_select_io)
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         FAIL_STACK_ERROR;
 
-    if (H5Pset_external(dcpl, EXT_FILE_NAME1, (off_t)0, size) < 0)
+    if (H5Pset_external(dcpl, EXT_FILE_NAME1, 0, size) < 0)
         FAIL_STACK_ERROR;
 
-    if (H5Pset_external(dcpl, EXT_FILE_NAME2, (off_t)0, size) < 0)
+    if (H5Pset_external(dcpl, EXT_FILE_NAME2, 0, size) < 0)
         FAIL_STACK_ERROR;
 
     {
diff --git a/test/th5s.c b/test/th5s.c
index f0e4959..4c46c40 100644
--- a/test/th5s.c
+++ b/test/th5s.c
@@ -933,7 +933,7 @@ test_h5s_zero_dim(void)
          * space in the external file is the size of the dataset (zero because one dimension size is zero).
          * There's no need to clean up the external file since the library doesn't create it
          * until the data is written to it. */
-        ret = H5Pset_external(plist_id, EXTFILE_NAME, (off_t)0, (hsize_t)0);
+        ret = H5Pset_external(plist_id, EXTFILE_NAME, 0, (hsize_t)0);
         CHECK(ret, FAIL, "H5Pset_external");
 
         ret = H5Pset_alloc_time(plist_id, alloc_time);
diff --git a/test/twriteorder.c b/test/twriteorder.c
index 9bfe87b..41841b5 100644
--- a/test/twriteorder.c
+++ b/test/twriteorder.c
@@ -283,7 +283,7 @@ write_wo_file(void)
     } /* end for */
 
     /* write the last blkaddr in partition 0 */
-    HDlseek(write_fd_g, (HDoff_t)0, SEEK_SET);
+    HDlseek(write_fd_g, 0, SEEK_SET);
     if ((bytes_wrote = HDwrite(write_fd_g, &blkaddr_old, (size_t)sizeof(blkaddr_old))) !=
         sizeof(blkaddr_old)) {
         printf("blkaddr write failed in partition %d\n", 0);
@@ -310,7 +310,7 @@ read_wo_file(void)
 
     /* keep reading the initial block address until it is non-zero before proceeding. */
     while (blkaddr == 0) {
-        HDlseek(read_fd, (HDoff_t)0, SEEK_SET);
+        HDlseek(read_fd, 0, SEEK_SET);
         if ((bytes_read = HDread(read_fd, &blkaddr, (size_t)sizeof(blkaddr))) != sizeof(blkaddr)) {
             printf("blkaddr read failed in partition %d\n", 0);
             return -1;
diff --git a/testpar/t_2Gio.c b/testpar/t_2Gio.c
index 48abf8e..b6c3988 100644
--- a/testpar/t_2Gio.c
+++ b/testpar/t_2Gio.c
@@ -3906,7 +3906,7 @@ test_no_collective_cause_mode(int selection_mode)
     }
 
     if (selection_mode & TEST_NOT_CONTIGUOUS_OR_CHUNKED_DATASET_EXTERNAL) {
-        ret = H5Pset_external(dcpl, FILE_EXTERNAL, (off_t)0, H5F_UNLIMITED);
+        ret = H5Pset_external(dcpl, FILE_EXTERNAL, 0, H5F_UNLIMITED);
         VRFY((ret >= 0), "set EXTERNAL file layout succeeded");
         is_chunked = 0;
     }
diff --git a/testpar/t_dset.c b/testpar/t_dset.c
index 67d11d2..bf4fcfd 100644
--- a/testpar/t_dset.c
+++ b/testpar/t_dset.c
@@ -3655,7 +3655,7 @@ test_no_collective_cause_mode(int selection_mode)
     }
 
     if (selection_mode & TEST_NOT_CONTIGUOUS_OR_CHUNKED_DATASET_EXTERNAL) {
-        ret = H5Pset_external(dcpl, FILE_EXTERNAL, (off_t)0, H5F_UNLIMITED);
+        ret = H5Pset_external(dcpl, FILE_EXTERNAL, 0, H5F_UNLIMITED);
         VRFY((ret >= 0), "set EXTERNAL file layout succeeded");
         is_chunked = 0;
     }
diff --git a/testpar/t_prop.c b/testpar/t_prop.c
index 23710d7..af7b9a8 100644
--- a/testpar/t_prop.c
+++ b/testpar/t_prop.c
@@ -172,13 +172,13 @@ test_plist_ed(void)
     VRFY((ret >= 0), "set fill-value succeeded");
 
     max_size[0] = 100;
-    ret         = H5Pset_external(dcpl, "ext1.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4));
+    ret         = H5Pset_external(dcpl, "ext1.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4));
     VRFY((ret >= 0), "set external succeeded");
-    ret = H5Pset_external(dcpl, "ext2.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4));
+    ret = H5Pset_external(dcpl, "ext2.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4));
     VRFY((ret >= 0), "set external succeeded");
-    ret = H5Pset_external(dcpl, "ext3.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4));
+    ret = H5Pset_external(dcpl, "ext3.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4));
     VRFY((ret >= 0), "set external succeeded");
-    ret = H5Pset_external(dcpl, "ext4.data", (off_t)0, (hsize_t)(max_size[0] * sizeof(int) / 4));
+    ret = H5Pset_external(dcpl, "ext4.data", 0, (hsize_t)(max_size[0] * sizeof(int) / 4));
     VRFY((ret >= 0), "set external succeeded");
 
     ret = test_encode_decode(dcpl, mpi_rank, recv_proc);
diff --git a/tools/src/h5import/h5import.c b/tools/src/h5import/h5import.c
index 663f68a..828cb6a 100644
--- a/tools/src/h5import/h5import.c
+++ b/tools/src/h5import/h5import.c
@@ -4702,8 +4702,7 @@ process(struct Options *opt)
                     return (-1);
                 }
                 fclose(extfile);
-                H5Pset_external(proplist, in->externFilename, (off_t)0,
-                                numOfElements * (hsize_t)in->inputSize / 8);
+                H5Pset_external(proplist, in->externFilename, 0, numOfElements * (hsize_t)in->inputSize / 8);
             }
 
             /* create dataspace */
diff --git a/tools/test/h5dump/h5dumpgentest.c b/tools/test/h5dump/h5dumpgentest.c
index e12690c..9c42a0e 100644
--- a/tools/test/h5dump/h5dumpgentest.c
+++ b/tools/test/h5dump/h5dumpgentest.c
@@ -5400,10 +5400,10 @@ make_external(hid_t fid)
     size                      = (max_size[0] * sizeof(int) / 2);
 
     dcpl = H5Pcreate(H5P_DATASET_CREATE);
-    ret  = H5Pset_external(dcpl, "ext1.bin", (off_t)0, size);
+    ret  = H5Pset_external(dcpl, "ext1.bin", 0, size);
     assert(ret >= 0);
 
-    ret = H5Pset_external(dcpl, "ext2.bin", (off_t)0, size);
+    ret = H5Pset_external(dcpl, "ext2.bin", 0, size);
     assert(ret >= 0);
 
     sid = H5Screate_simple(1, cur_size, max_size);
diff --git a/tools/test/h5repack/h5repacktst.c b/tools/test/h5repack/h5repacktst.c
index 98d5362..b414f64 100644
--- a/tools/test/h5repack/h5repacktst.c
+++ b/tools/test/h5repack/h5repacktst.c
@@ -3714,7 +3714,7 @@ make_external(hid_t loc_id)
     /* create */
     if ((dcpl = H5Pcreate(H5P_DATASET_CREATE)) < 0)
         goto out;
-    if (H5Pset_external(dcpl, H5REPACK_EXTFILE, (off_t)0, size) < 0)
+    if (H5Pset_external(dcpl, H5REPACK_EXTFILE, 0, size) < 0)
         goto out;
     if ((sid = H5Screate_simple(1, cur_size, max_size)) < 0)
         goto out;