From 3e4f6138b60d8363c377e453d63f875775ec907a Mon Sep 17 00:00:00 2001
From: Dana Robinson <derobins@hdfgroup.org>
Date: Thu, 9 Nov 2017 13:56:58 -0800
Subject: Removed asserts from H5MM calls that conflict with stated behavior
 and added a test to ensure that this doesn't happen in the future.

---
 src/H5MM.c   |  8 +-------
 test/tmisc.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 62 insertions(+), 8 deletions(-)

diff --git a/src/H5MM.c b/src/H5MM.c
index ee3b28f..866dfbe 100644
--- a/src/H5MM.c
+++ b/src/H5MM.c
@@ -268,8 +268,6 @@ H5MM_malloc(size_t size)
 {
     void *ret_value = NULL;
 
-    HDassert(size);
-
     /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
@@ -357,8 +355,6 @@ H5MM_calloc(size_t size)
 {
     void *ret_value = NULL;
 
-    HDassert(size);
-
     /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
@@ -407,8 +403,6 @@ H5MM_realloc(void *mem, size_t size)
     /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
-    HDassert(mem || size);
-
     if(NULL == mem && 0 == size)
         /* Not defined in the standard, return NULL */
         ret_value = NULL;
@@ -454,7 +448,7 @@ H5MM_realloc(void *mem, size_t size)
  *              NULL is an acceptable value for the input string.
  *
  * Return:      Success:    Pointer to a new string (NULL if s is NULL).
- *              Failure:    abort()
+ *              Failure:    NULL
  *
  * Programmer:  Robb Matzke
  *              Jul 10 1997
diff --git a/test/tmisc.c b/test/tmisc.c
index 102325a..6da4589 100644
--- a/test/tmisc.c
+++ b/test/tmisc.c
@@ -30,6 +30,7 @@
 #include "testhdf5.h"
 #include "H5srcdir.h"
 #include "H5Dpkg.h"         /* Datasets                 */
+#include "H5MMprivate.h"    /* Memory                   */
 
 /* Definitions for misc. test #1 */
 #define MISC1_FILE  "tmisc1.h5"
@@ -5526,6 +5527,64 @@ test_misc33(void)
 
 } /* end test_misc33() */
 
+/****************************************************************
+**
+**  test_misc34(): Ensure zero-size memory allocations work
+**
+****************************************************************/
+static void
+test_misc34(void)
+{
+    void *mem = NULL;       /* allocated buffer     */
+    char *dup = NULL;       /* 'duplicated' string  */
+    size_t sz = 0;          /* buffer size          */
+
+    /* Output message about test being performed */
+    MESSAGE(5, ("Testing O and NULL behavior in H5MM API calls"));
+
+    /* H5MM_xfree(): Ensure that passing NULL is allowed and returns NULL */
+    mem = H5MM_xfree(mem);
+    CHECK_PTR_NULL(mem, "H5MM_xfree");
+
+    /* H5MM_malloc(): Ensure that size 0 returns NULL */
+    mem = H5MM_malloc(sz);
+    CHECK_PTR_NULL(mem, "H5MM_malloc");
+    mem = H5MM_xfree(mem);
+
+    /* H5MM_calloc(): Ensure that size 0 returns NULL */
+    mem = H5MM_calloc(sz);
+    CHECK_PTR_NULL(mem, "H5MM_calloc");
+    mem = H5MM_xfree(mem);
+
+    /* H5MM_realloc(): Check behavior:
+     *
+     *  H5MM_realloc(NULL, size)    <==> H5MM_malloc(size)
+     *  H5MM_realloc(ptr, 0)        <==> H5MM_xfree(ptr)
+     *  H5MM_realloc(NULL, 0)       <==> NULL
+     */
+    mem = H5MM_xfree(mem);
+
+    sz = 1024;
+    mem = H5MM_realloc(mem, sz);
+    CHECK_PTR(mem, "H5MM_realloc (case 1)");
+    /* Don't free mem here! */
+
+    sz = 0;
+    mem = H5MM_realloc(mem, sz);
+    CHECK_PTR_NULL(mem, "H5MM_realloc (case 2)");
+    mem = H5MM_xfree(mem);
+
+    mem = H5MM_realloc(mem, sz);
+    CHECK_PTR_NULL(mem, "H5MM_realloc (case 3)");
+    mem = H5MM_xfree(mem);
+
+    /* H5MM_xstrdup(): Ensure NULL returns NULL */
+    dup = H5MM_xstrdup((const char *)mem);
+    CHECK_PTR_NULL(dup, "H5MM_xstrdup");
+    dup = (char *)H5MM_xfree((void *)dup);
+
+} /* end test_misc34() */
+
 
 /****************************************************************
 **
@@ -5575,6 +5634,7 @@ test_misc(void)
     test_misc31();      /* Test Reentering library through deprecated routines after H5close() */
     test_misc32();      /* Test filter memory allocation functions */
     test_misc33();      /* Test to verify that H5HL_offset_into() returns error if offset exceeds heap block */
+    test_misc34();      /* Test behavior of 0 and NULL in H5MM API calls */
 
 } /* test_misc() */
 
@@ -5632,5 +5692,5 @@ cleanup_misc(void)
     HDremove(MISC29_COPY_FILE);
     HDremove(MISC30_FILE);
     HDremove(MISC31_FILE);
-}
+} /* end cleanup_misc() */
 
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