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Always return from expandm() with errno unaltered, so on the 

off chance it failed, there's still the possibility that whatever
processes the result will be able to deal with the %m that would
(presumably) be left in the format string.

And as a frill, don't call strerror() until we know we are
going to use its result (still call it only once, no matter
how many %m's are in the format string).
This commit is contained in:
kre 2019-01-13 06:10:34 +00:00
parent 754a5dbbce
commit 7b39a1eecc
1 changed files with 8 additions and 3 deletions
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11
lib/libwrap/expandm.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: expandm.c,v 1.6 2019/01/13 01:32:51 christos Exp $ */
/* $NetBSD: expandm.c,v 1.7 2019/01/13 06:10:34 kre Exp $ */
/*-
* Copyright (c) 2018 The NetBSD Foundation, Inc.
@ -29,7 +29,7 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: expandm.c,v 1.6 2019/01/13 01:32:51 christos Exp $");
__RCSID("$NetBSD: expandm.c,v 1.7 2019/01/13 06:10:34 kre Exp $");
#include <limits.h>
#include <stdio.h>
@ -48,7 +48,8 @@ __RCSID("$NetBSD: expandm.c,v 1.6 2019/01/13 01:32:51 christos Exp $");
const char * __attribute__((__format_arg__(1)))
expandm(const char *fmt, const char *sf, char **rbuf)
{
const char *e = strerror(errno);
const int err = errno;
const char *e = NULL;
char *buf, *m, *nbuf;
const char *ptr;
@ -74,6 +75,8 @@ expandm(const char *fmt, const char *sf, char **rbuf)
buf = nbuf;
}
if (__predict_true(e == NULL && (cnt & 1) != 0))
e = strerror(err);
if (asprintf(&nbuf, "%s%.*s%s", buf ? buf : "",
(int)(m - ptr), ptr, (cnt & 1) ? e : "%m") == -1)
goto out;
@ -87,11 +90,13 @@ expandm(const char *fmt, const char *sf, char **rbuf)
free(buf);
if (rbuf)
*rbuf = nbuf;
errno = err;
return nbuf;
out:
free(buf);
if (rbuf)
*rbuf = NULL;
errno = err;
return fmt;
}