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author | Lennart Poettering <lennart@poettering.net> | 2019-04-30 10:13:57 +0200 |
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committer | Lennart Poettering <lennart@poettering.net> | 2019-05-02 14:53:40 +0200 |
commit | e59054270c6e37fd08fdd5d0231edd17c7f7495a (patch) | |
tree | a15a01fda8868b75233c977d11c42abe88a35717 | |
parent | 64538af89b4fe72658d7b33e2022d06805badb14 (diff) | |
download | systemd-e59054270c6e37fd08fdd5d0231edd17c7f7495a.tar.gz |
alloc-util: reintroduce malloc_usable_size() into greedy_realloc()
This is another attempt at d4b604baeadbb2498e4f2c3e260260eed210f5d6 and #12438
Instead of blindly using the extra allocated space, let's do so only
after telling libc about it, via a second realloc(). The second
realloc() should be quick, since it never has to copy memory around.
-rw-r--r-- | src/basic/alloc-util.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/src/basic/alloc-util.c b/src/basic/alloc-util.c index f4bd33f4e0..a16db6824f 100644 --- a/src/basic/alloc-util.c +++ b/src/basic/alloc-util.c @@ -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; |