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Limit number of mem allocs and copies

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If we have good enough glibc to return number of needed chars, do not
loop try to reach good size, but use this size directly for allocation,
saving also last strdup.

Since now we start with 16 bytes - skip buffer realloc for shorter string.
This commit is contained in:
Zdenek Kabelac 2012-02-23 18:05:12 +00:00
parent b6c5ea358e
commit f72b184e3e
2 changed files with 19 additions and 14 deletions
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1
WHATS_NEW_DM
View File

@ -1,5 +1,6 @@
Version 1.02.72 - Version 1.02.72 -
==================================== ====================================
Avoid memory reallocation for dm_asprintf.
Version 1.02.71 - 20th February 2012 Version 1.02.71 - 20th February 2012
==================================== ====================================

32
libdm/libdm-string.c
View File

@ -1,5 +1,5 @@
/* /*
* Copyright (C) 2006-2007 Red Hat, Inc. All rights reserved. * Copyright (C) 2006-2012 Red Hat, Inc. All rights reserved.
* *
* This file is part of the device-mapper userspace tools. * This file is part of the device-mapper userspace tools.
* *
@ -131,7 +131,7 @@ const char *dm_basename(const char *path)
int dm_asprintf(char **result, const char *format, ...) int dm_asprintf(char **result, const char *format, ...)
{ {
int n, ok = 0, size = 32; int i, n, size = 16;
va_list ap; va_list ap;
char *buf = dm_malloc(size); char *buf = dm_malloc(size);
@ -140,26 +140,30 @@ int dm_asprintf(char **result, const char *format, ...)
if (!buf) if (!buf)
return -1; return -1;
while (!ok) { for (i = 0;; i++) {
va_start(ap, format); va_start(ap, format);
n = vsnprintf(buf, size, format, ap); n = vsnprintf(buf, size, format, ap);
va_end(ap); va_end(ap);
if (0 <= n && n < size) if (0 <= n && n < size)
ok = 1; break;
else {
dm_free(buf); dm_free(buf);
size *= 2; /* Up to glibc 2.0.6 returns -1 */
buf = dm_malloc(size); size = (n < 0) ? size * 2 : n + 1;
if (!buf) if (!(buf = dm_malloc(size)))
return -1; return -1;
}
} }
if (!(*result = dm_strdup(buf))) if (i > 1) {
n = -2; /* return -1 */ /* Reallocating more then once? */
if (!(*result = dm_strdup(buf))) {
dm_free(buf);
return -1;
}
} else
*result = buf;
dm_free(buf);
return n + 1; return n + 1;
} }