Cleanup usage of malloc_usable_size. (#8554)

* Add better control of malloc_usable_size() usage.
* Use malloc_usable_size on alpine libc daily job.
* Add no-malloc-usable-size daily jobs.
* Fix zmalloc(0) when HAVE_MALLOC_SIZE is undefined.

In order to align with the jemalloc behavior, this should never return
NULL or OOM panic.

1 files changed, 8 insertions, 2 deletions

diff --git a/src/zmalloc.c b/src/zmalloc.c
index fbac09616..1dc662e57 100644
--- a/src/zmalloc.c
+++ b/src/zmalloc.c
@@ -60,6 +60,11 @@ void zlibc_free(void *ptr) {
 #define ASSERT_NO_SIZE_OVERFLOW(sz) assert((sz) + PREFIX_SIZE > (sz))
 #endif
 
+/* When using the libc allocator, use a minimum allocation size to match the
+ * jemalloc behavior that doesn't return NULL in this case.
+ */
+#define MALLOC_MIN_SIZE(x) ((x) > 0 ? (x) : sizeof(long))
+
 /* Explicitly override malloc/free etc when using tcmalloc. */
 #if defined(USE_TCMALLOC)
 #define malloc(size) tc_malloc(size)
@@ -93,7 +98,7 @@ static void (*zmalloc_oom_handler)(size_t) = zmalloc_default_oom;
  * '*usable' is set to the usable size if non NULL. */
 void *ztrymalloc_usable(size_t size, size_t *usable) {
     ASSERT_NO_SIZE_OVERFLOW(size);
-    void *ptr = malloc(size+PREFIX_SIZE);
+    void *ptr = malloc(MALLOC_MIN_SIZE(size)+PREFIX_SIZE);
 
     if (!ptr) return NULL;
 #ifdef HAVE_MALLOC_SIZE
@@ -153,7 +158,7 @@ void zfree_no_tcache(void *ptr) {
  * '*usable' is set to the usable size if non NULL. */
 void *ztrycalloc_usable(size_t size, size_t *usable) {
     ASSERT_NO_SIZE_OVERFLOW(size);
-    void *ptr = calloc(1, size+PREFIX_SIZE);
+    void *ptr = calloc(1, MALLOC_MIN_SIZE(size)+PREFIX_SIZE);
     if (ptr == NULL) return NULL;
 
 #ifdef HAVE_MALLOC_SIZE
@@ -675,6 +680,7 @@ int zmalloc_test(int argc, char **argv) {
 
     UNUSED(argc);
     UNUSED(argv);
+    printf("Malloc prefix size: %d\n", (int) PREFIX_SIZE);
     printf("Initial used memory: %zu\n", zmalloc_used_memory());
     ptr = zmalloc(123);
     printf("Allocated 123 bytes; used: %zu\n", zmalloc_used_memory());