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Merge pull request #12440 from poettering/realloc-again

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another shot at the malloc_usable_size() thing
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2019-05-06 17:17:22 +02:00 committed by GitHub
commit 3759c0bdd3
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2 changed files with 45 additions and 6 deletions
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24
src/basic/alloc-util.c
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@ -1,5 +1,6 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#include <malloc.h>
#include <stdint.h>
#include <string.h>
@ -63,6 +64,29 @@ void* greedy_realloc(void **p, size_t *allocated, size_t need, size_t size) {
if (!q)
return NULL;
if (size > 0) {
size_t bn;
/* Adjust for the 64 byte minimum */
newalloc = a / size;
bn = malloc_usable_size(q) / size;
if (bn > newalloc) {
void *qq;
/* The actual size allocated is larger than what we asked for. Let's call realloc() again to
* take possession of the extra space. This should be cheap, since libc doesn't have to move
* the memory for this. */
qq = realloc(q, bn * size);
if (_likely_(qq)) {
*p = qq;
*allocated = bn;
return qq;
}
}
}
*p = q;
*allocated = newalloc;
return q;

27
src/test/test-alloc-util.c
View File

@ -1,5 +1,6 @@
/* SPDX-License-Identifier: LGPL-2.1+ */
#include <malloc.h>
#include <stdint.h>
#include "alloc-util.h"
@ -21,21 +22,35 @@ static void test_alloca(void) {
static void test_GREEDY_REALLOC(void) {
_cleanup_free_ int *a = NULL, *b = NULL;
size_t n_allocated = 0, i;
size_t n_allocated = 0, i, j;
/* Give valgrind a chance to verify our realloc operations */
/* Give valgrind a chance to verify our realloc() operations */
for (i = 0; i < 2048; i++) {
for (i = 0; i < 20480; i++) {
assert_se(GREEDY_REALLOC(a, n_allocated, i + 1));
a[i] = i;
assert_se(n_allocated >= i + 1);
assert_se(malloc_usable_size(a) >= (i + 1) * sizeof(int));
a[i] = (int) i;
assert_se(GREEDY_REALLOC(a, n_allocated, i / 2));
assert_se(n_allocated >= i / 2);
assert_se(malloc_usable_size(a) >= (i / 2) * sizeof(int));
}
for (i = 30, n_allocated = 0; i < 2048; i+=7) {
for (j = 0; j < i / 2; j++)
assert_se(a[j] == (int) j);
for (i = 30, n_allocated = 0; i < 20480; i += 7) {
assert_se(GREEDY_REALLOC(b, n_allocated, i + 1));
b[i] = i;
assert_se(n_allocated >= i + 1);
assert_se(malloc_usable_size(b) >= (i + 1) * sizeof(int));
b[i] = (int) i;
assert_se(GREEDY_REALLOC(b, n_allocated, i / 2));
assert_se(n_allocated >= i / 2);
assert_se(malloc_usable_size(b) >= (i / 2) * sizeof(int));
}
for (j = 30; j < i / 2; j += 7)
assert_se(b[j] == (int) j);
}
static void test_memdup_multiply_and_greedy_realloc(void) {