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Remove H5_NO_ALIGNMENT_RESTRICTIONS (#1426)
* Do not conditionally compile code that uses a pointer dereference and assignment to copy a potentially unaligned variable to aligned automatic storage, or vice versa. Instead, always use naked `memcpy(3)`s. Disassembling the generated code reveals that the `memcpy(3)`s optimize (`-O3`) to a single `mov` instruction for x86_64, which is not strict about alignment. This change reduces the size of code and scripts by 143 lines, eases our way to cross-compilation, and avoids invoking undefined behavior. * Committing clang-format changes * Per discussion, use HD and add comments. Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>
This commit is contained in:
David Young
GitHub
parent
463ef39bc7
commit
a80897ee49
@ -416,7 +416,3 @@ H5ConversionTests (${HDF_PREFIX}_LLONG_TO_LDOUBLE_CORRECT "Checking IF correctly
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# some long double values
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#-----------------------------------------------------------------------------
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H5ConversionTests (${HDF_PREFIX}_DISABLE_SOME_LDOUBLE_CONV "Checking IF the cpu is power9 and cannot correctly converting long double values")
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# ----------------------------------------------------------------------
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# Check if pointer alignments are enforced
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#-----------------------------------------------------------------------------
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H5ConversionTests (${HDF_PREFIX}_NO_ALIGNMENT_RESTRICTIONS "Checking IF alignment restrictions are strictly enforced")
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@ -234,59 +234,6 @@ done:
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}
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#endif
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS_TEST
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#include <stdlib.h>
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#include <string.h>
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typedef struct {
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size_t len;
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void *p;
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} hvl_t;
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#ifdef FC_DUMMY_MAIN
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#ifndef FC_DUMMY_MAIN_EQ_F77
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# ifdef __cplusplus
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extern "C"
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# endif
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int FC_DUMMY_MAIN()
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{ return 1;}
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#endif
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#endif
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int HDF_NO_UBSAN
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main ()
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{
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char *chp = "beefs";
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char **chpp = malloc (2 * sizeof (char *));
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char **chpp2;
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hvl_t vl = { 12345, (void *) chp };
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hvl_t *vlp;
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hvl_t *vlp2;
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memcpy ((void *) ((char *) chpp + 1), &chp, sizeof (char *));
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chpp2 = (char **) ((char *) chpp + 1);
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if (strcmp (*chpp2, chp)) {
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free (chpp);
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return 1;
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}
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free (chpp);
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vlp = malloc (2 * sizeof (hvl_t));
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memcpy ((void *) ((char *) vlp + 1), &vl, sizeof (hvl_t));
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vlp2 = (hvl_t *) ((char *) vlp + 1);
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if (vlp2->len != vl.len || vlp2->p != vl.p) {
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free (vlp);
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return 1;
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}
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free (vlp);
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;
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return 0;
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}
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#endif
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#ifdef H5_DISABLE_SOME_LDOUBLE_CONV_TEST
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#include <stdio.h>
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@ -434,9 +434,6 @@
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/* Define to enable internal memory allocation sanity checking. */
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#cmakedefine H5_MEMORY_ALLOC_SANITY_CHECK @H5_MEMORY_ALLOC_SANITY_CHECK@
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/* Define if we can violate pointer alignment restrictions */
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#cmakedefine H5_NO_ALIGNMENT_RESTRICTIONS @H5_NO_ALIGNMENT_RESTRICTIONS@
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/* Define if deprecated public API symbols are disabled */
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#cmakedefine H5_NO_DEPRECATED_SYMBOLS @H5_NO_DEPRECATED_SYMBOLS@
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19
configure.ac
19
configure.ac
@ -3989,25 +3989,6 @@ AC_ARG_ENABLE([embedded-libinfo],
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fi
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## ----------------------------------------------------------------------
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## Check if pointer alignments are enforced
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##
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AC_MSG_CHECKING([if alignment restrictions are strictly enforced])
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TEST_SRC="`(echo \"#define H5_NO_ALIGNMENT_RESTRICTIONS_TEST 1\"; cat $srcdir/config/cmake/ConversionTests.c)`"
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AC_RUN_IFELSE([
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AC_LANG_SOURCE([$TEST_SRC])
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], [
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AC_DEFINE([NO_ALIGNMENT_RESTRICTIONS], [1], [Define if we can violate pointer alignment restrictions])
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AC_MSG_RESULT([no])
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], [
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AC_MSG_RESULT([yes])
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], [
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AC_MSG_RESULT([unknown, assuming yes])
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])
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## ----------------------------------------------------------------------
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## Restore user's CFLAGS.
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CFLAGS="$saved_user_CFLAGS"
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@ -369,11 +369,7 @@ done:
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static herr_t
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H5T__vlen_mem_seq_getlen(H5VL_object_t H5_ATTR_UNUSED *file, const void *_vl, size_t *len)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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const hvl_t *vl = (const hvl_t *)_vl; /* Pointer to the user's hvl_t information */
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#else
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hvl_t vl; /* User's hvl_t information */
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#endif
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FUNC_ENTER_PACKAGE_NOERR
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@ -381,13 +377,12 @@ H5T__vlen_mem_seq_getlen(H5VL_object_t H5_ATTR_UNUSED *file, const void *_vl, si
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HDassert(_vl);
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HDassert(len);
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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*len = vl->len;
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#else
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H5MM_memcpy(&vl, _vl, sizeof(hvl_t));
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/* Copy to ensure correct alignment. memcpy is best here because
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* it optimizes to fast code.
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*/
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HDmemcpy(&vl, _vl, sizeof(hvl_t));
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*len = vl.len;
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#endif
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FUNC_LEAVE_NOAPI(SUCCEED)
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} /* end H5T__vlen_mem_seq_getlen() */
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@ -407,25 +402,16 @@ H5T__vlen_mem_seq_getlen(H5VL_object_t H5_ATTR_UNUSED *file, const void *_vl, si
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static void *
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H5T__vlen_mem_seq_getptr(void *_vl)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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const hvl_t *vl = (const hvl_t *)_vl; /* Pointer to the user's hvl_t information */
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#else
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hvl_t vl; /* User's hvl_t information */
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#endif
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FUNC_ENTER_PACKAGE_NOERR
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/* check parameters, return result */
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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HDassert(vl);
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FUNC_LEAVE_NOAPI(vl->p)
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#else
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HDassert(_vl);
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H5MM_memcpy(&vl, _vl, sizeof(hvl_t));
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/* Copy to ensure correct alignment. */
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HDmemcpy(&vl, _vl, sizeof(hvl_t));
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FUNC_LEAVE_NOAPI(vl.p)
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#endif
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} /* end H5T__vlen_mem_seq_getptr() */
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/*-------------------------------------------------------------------------
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@ -443,24 +429,17 @@ H5T__vlen_mem_seq_getptr(void *_vl)
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static herr_t
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H5T__vlen_mem_seq_isnull(const H5VL_object_t H5_ATTR_UNUSED *file, void *_vl, hbool_t *isnull)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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const hvl_t *vl = (const hvl_t *)_vl; /* Pointer to the user's hvl_t information */
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#else
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hvl_t vl; /* User's hvl_t information */
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#endif
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FUNC_ENTER_PACKAGE_NOERR
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/* Check parameters */
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HDassert(_vl);
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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*isnull = ((vl->len == 0 || vl->p == NULL) ? TRUE : FALSE);
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#else
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H5MM_memcpy(&vl, _vl, sizeof(hvl_t));
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/* Copy to ensure correct alignment. */
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HDmemcpy(&vl, _vl, sizeof(hvl_t));
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*isnull = ((vl.len == 0 || vl.p == NULL) ? TRUE : FALSE);
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#endif
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FUNC_LEAVE_NOAPI(SUCCEED)
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} /* end H5T__vlen_mem_seq_isnull() */
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@ -512,27 +491,18 @@ H5T__vlen_mem_seq_setnull(H5VL_object_t H5_ATTR_UNUSED *file, void *_vl, void H5
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static herr_t
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H5T__vlen_mem_seq_read(H5VL_object_t H5_ATTR_UNUSED *file, void *_vl, void *buf, size_t len)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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const hvl_t *vl = (const hvl_t *)_vl; /* Pointer to the user's hvl_t information */
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#else
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hvl_t vl; /* User's hvl_t information */
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#endif
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FUNC_ENTER_PACKAGE_NOERR
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/* check parameters, copy data */
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HDassert(buf);
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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HDassert(vl && vl->p);
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H5MM_memcpy(buf, vl->p, len);
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#else
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HDassert(_vl);
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H5MM_memcpy(&vl, _vl, sizeof(hvl_t));
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/* Copy to ensure correct alignment. */
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HDmemcpy(&vl, _vl, sizeof(hvl_t));
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HDassert(vl.p);
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H5MM_memcpy(buf, vl.p, len);
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#endif
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FUNC_LEAVE_NOAPI(SUCCEED)
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} /* end H5T__vlen_mem_seq_read() */
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@ -606,20 +576,15 @@ done:
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static herr_t
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H5T__vlen_mem_str_getlen(H5VL_object_t H5_ATTR_UNUSED *file, const void *_vl, size_t *len)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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const char *s = *(const char *const *)_vl; /* Pointer to the user's string information */
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#else
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const char *s = NULL; /* Pointer to the user's string information */
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#endif
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FUNC_ENTER_PACKAGE_NOERR
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/* check parameters */
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HDassert(_vl);
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#ifndef H5_NO_ALIGNMENT_RESTRICTIONS
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H5MM_memcpy(&s, _vl, sizeof(char *));
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#endif
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/* Copy to ensure correct alignment. */
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HDmemcpy(&s, _vl, sizeof(char *));
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*len = HDstrlen(s);
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@ -641,21 +606,14 @@ H5T__vlen_mem_str_getlen(H5VL_object_t H5_ATTR_UNUSED *file, const void *_vl, si
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static void *
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H5T__vlen_mem_str_getptr(void *_vl)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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char *s = *(char **)_vl; /* Pointer to the user's string information */
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#else
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char * s = NULL; /* Pointer to the user's string information */
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#endif
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char *s = NULL; /* Pointer to the user's string information */
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FUNC_ENTER_PACKAGE_NOERR
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/* check parameters */
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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HDassert(s);
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#else
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HDassert(_vl);
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H5MM_memcpy(&s, _vl, sizeof(char *));
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#endif
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/* Copy to ensure correct alignment. */
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HDmemcpy(&s, _vl, sizeof(char *));
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FUNC_LEAVE_NOAPI(s)
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} /* end H5T__vlen_mem_str_getptr() */
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@ -675,17 +633,12 @@ H5T__vlen_mem_str_getptr(void *_vl)
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static herr_t
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H5T__vlen_mem_str_isnull(const H5VL_object_t H5_ATTR_UNUSED *file, void *_vl, hbool_t *isnull)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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char *s = *(char **)_vl; /* Pointer to the user's string information */
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#else
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char *s = NULL; /* Pointer to the user's string information */
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#endif
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FUNC_ENTER_PACKAGE_NOERR
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#ifndef H5_NO_ALIGNMENT_RESTRICTIONS
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H5MM_memcpy(&s, _vl, sizeof(char *));
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#endif
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/* Copy to ensure correct alignment. */
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HDmemcpy(&s, _vl, sizeof(char *));
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*isnull = (s == NULL ? TRUE : FALSE);
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@ -732,23 +685,16 @@ H5T__vlen_mem_str_setnull(H5VL_object_t H5_ATTR_UNUSED *file, void *_vl, void H5
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static herr_t
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H5T__vlen_mem_str_read(H5VL_object_t H5_ATTR_UNUSED *file, void *_vl, void *buf, size_t len)
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{
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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char *s = *(char **)_vl; /* Pointer to the user's string information */
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#else
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char *s; /* Pointer to the user's string information */
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#endif
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char *s; /* Pointer to the user's string information */
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FUNC_ENTER_PACKAGE_NOERR
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if (len > 0) {
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/* check parameters */
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HDassert(buf);
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#ifdef H5_NO_ALIGNMENT_RESTRICTIONS
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HDassert(s);
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#else
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HDassert(_vl);
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H5MM_memcpy(&s, _vl, sizeof(char *));
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#endif
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/* Copy to ensure correct alignment. */
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HDmemcpy(&s, _vl, sizeof(char *));
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H5MM_memcpy(buf, s, len);
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} /* end if */
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