malloc.3: realloc() return value
One might be tempted to think that realloc() always requests a new
allocation before moving the contents over (at least in the case
where the new size is bigger than the original). This is not the
case; for example, on my system the following program:
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
void *x = malloc(15);
void *y = malloc(32);
printf("x = %p\n", x);
printf("y = %p\n", y);
printf("usable_size(x) = %lu\n", malloc_usable_size(x));
void *z = realloc(x, 24);
printf("z = %p\n", z);
return 0;
}
prints:
x = 0x1b3a010
y = 0x1b3a030
usable_size(x) = 24
z = 0x1b3a010
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
1 file changed
