Sun Jan 13 06:10:34 2019 UTC ()

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).


(kre)

diff -r1.6 -r1.7 src/lib/libwrap/expandm.c

--- src/lib/libwrap/expandm.c 2019/01/13 01:32:51	1.6
+++ src/lib/libwrap/expandm.c 2019/01/13 06:10:34	1.7

 @@ -1,14 +1,14 @@
-/*	$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.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Christos Zoulas.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
 @@ -19,89 +19,94 @@
  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * 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>
 #include <string.h>
 #include <stdlib.h>
 #include <errno.h>
 #include "expandm.h"
 #ifdef TEST
 #undef INT_MAX
 #define INT_MAX 31
 #endif
 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;
 	for (ptr = fmt, buf = NULL; (m = strstr(ptr, "%m")) != NULL;
 	    ptr = m + 2)
+	{
 		size_t cnt = 0;
 		for (char *p = m; p >= ptr && *p == '%'; p--)
 			cnt++;
                if (__predict_false((m - ptr) >= INT_MAX)) {
                         size_t blen = buf ? strlen(buf) : 0;
                         size_t nlen = (size_t)(m - ptr);
                         nbuf = realloc(buf, blen + nlen + 1);
                         if (nbuf == NULL)
                                 goto out;
                         memcpy(nbuf + blen, ptr, nlen);
                         nbuf[blen + nlen] = '\0';
                         ptr += nlen;
                         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;
 		free(buf);
 		buf = nbuf;
+	}
 	if (asprintf(&nbuf, "%s%s%s", buf ? buf : "", ptr, sf ? sf : "") == -1)
 		goto out;
 	free(buf);
 	if (rbuf)
 		*rbuf = nbuf;
 	errno = err;
 	return nbuf;
 out:
 	free(buf);
 	if (rbuf)
 		*rbuf = NULL;
 	errno = err;
 	return fmt;
+}
 #ifdef TEST
 int
 main(int argc, char *argv[])
+{
 	errno = ERANGE;
 	printf("%s\n", expandm(argc > 1 ? argv[1] : "Message %%m=%m: %%%m%%",
 	    "...", NULL));
 	return 0;
+}
 #endif