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make malloc(0) return unique pointers rather than NULL

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this change is made with some reluctance, but i think it's for the
best. correct programs must handle either behavior, so there is little
advantage to having malloc(0) return NULL. and i managed to actually
make the malloc code slightly smaller with this change.
This commit is contained in:
Rich Felker 2011-02-20 16:16:33 -05:00
parent 598a0147cd
commit 26031da0f8
2 changed files with 10 additions and 6 deletions
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2
src/malloc/__simple_malloc.c
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@ -15,7 +15,7 @@ void *__simple_malloc(size_t n)
static int lock;
size_t align=1;
if (!n) return 0;
if (!n) n++;
if (n > SIZE_MAX/2) goto toobig;
while (align<n && align<ALIGN)

14
src/malloc/malloc.c
View File

@ -216,9 +216,14 @@ static int init_malloc()
static int adjust_size(size_t *n)
{
/* Result of pointer difference must fit in ptrdiff_t. */
if (*n > PTRDIFF_MAX - SIZE_ALIGN - PAGE_SIZE) {
errno = ENOMEM;
return -1;
if (*n-1 > PTRDIFF_MAX - SIZE_ALIGN - PAGE_SIZE) {
if (*n) {
errno = ENOMEM;
return -1;
} else {
*n = SIZE_ALIGN;
return 0;
}
}
*n = (*n + OVERHEAD + SIZE_ALIGN - 1) & SIZE_MASK;
return 0;
@ -325,7 +330,7 @@ void *malloc(size_t n)
struct chunk *c;
int i, j;
if (!n || adjust_size(&n) < 0) return 0;
if (adjust_size(&n) < 0) return 0;
if (n > MMAP_THRESHOLD) {
size_t len = n + PAGE_SIZE - 1 & -PAGE_SIZE;
@ -377,7 +382,6 @@ void *realloc(void *p, size_t n)
void *new;
if (!p) return malloc(n);
else if (!n) return free(p), (void *)0;
if (adjust_size(&n) < 0) return 0;