diff options
| -rw-r--r-- | include/malloc.h | 2 | ||||
| -rw-r--r-- | libc/stdlib/malloc-standard/malloc_usable_size.c | 14 |
2 files changed, 16 insertions, 0 deletions
diff --git a/include/malloc.h b/include/malloc.h index b16a1105a..e52792381 100644 --- a/include/malloc.h +++ b/include/malloc.h @@ -162,6 +162,8 @@ extern int malloc_trim(size_t pad); /* Prints brief summary statistics on the stderr. */ extern void malloc_stats(void); +extern size_t malloc_usable_size(void *); + /* SVID2/XPG mallopt options */ #ifndef M_MXFAST # define M_MXFAST 1 /* UNUSED in this malloc */ diff --git a/libc/stdlib/malloc-standard/malloc_usable_size.c b/libc/stdlib/malloc-standard/malloc_usable_size.c new file mode 100644 index 000000000..c78c6a867 --- /dev/null +++ b/libc/stdlib/malloc-standard/malloc_usable_size.c @@ -0,0 +1,14 @@ +/* + malloc_usable_size - fully inspired by musl implementation +*/ + +#include "malloc.h" + +/* for malloc_usable_size */ +#define OVERHEAD (2*sizeof(size_t)) +#define CHUNK_SIZE(c) ((c)->size & -2) +#define MEM_TO_CHUNK(p) (struct malloc_chunk *)((char *)(p) - OVERHEAD) + +size_t malloc_usable_size(void *p) { + return p ? CHUNK_SIZE(MEM_TO_CHUNK(p)) - OVERHEAD : 0; +} |