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/*
* Replacement for a missing reallocarray.
*
* Provides the same functionality as the OpenBSD library function
* reallocarray for those systems that don't have it. This function is the
* same as realloc, but takes the size arguments in the same form as calloc
* and checks for overflow so that the caller doesn't need to.
*
* The canonical version of this file is maintained in the rra-c-util package,
* which can be found at <http://www.eyrie.org/~eagle/software/rra-c-util/>.
*
* Written by Russ Allbery <eagle@eyrie.org>
*
* The authors hereby relinquish any claim to any copyright that they may have
* in this work, whether granted under contract or by operation of law or
* international treaty, and hereby commit to the public, at large, that they
* shall not, at any time in the future, seek to enforce any copyright in this
* work against any person or entity, or prevent any person or entity from
* copying, publishing, distributing or creating derivative works of this
* work.
*/
#include <config.h>
#include <portable/system.h>
#include <errno.h>
/*
* If we're running the test suite, rename reallocarray to avoid conflicts
* with the system version. #undef it first because some systems may define
* it to another name.
*/
#if TESTING
# undef reallocarray
# define reallocarray test_reallocarray
void *test_reallocarray(void *, size_t, size_t);
#endif
/*
* nmemb * size cannot overflow if both are smaller than sqrt(SIZE_MAX). We
* can calculate that value statically by using 2^(sizeof(size_t) * 8) as the
* value of SIZE_MAX and then taking the square root, which gives
* 2^(sizeof(size_t) * 4). Compute the exponentiation with shift.
*/
#define CHECK_THRESHOLD (1UL << (sizeof(size_t) * 4))
void *
reallocarray(void *ptr, size_t nmemb, size_t size)
{
if (nmemb >= CHECK_THRESHOLD || size >= CHECK_THRESHOLD)
if (nmemb > 0 && SIZE_MAX / nmemb <= size) {
errno = ENOMEM;
return NULL;
}
return realloc(ptr, nmemb * size);
}
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