From: Sami Kerola <kerolasa@iki.fi>
Date: Thu, 3 May 2018 21:57:57 +0000 (+0100)
Subject: lib/canonicalize: fix truncation warning
X-Git-Tag: v2.33-rc1~280
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bf99940f649959fcc73590c043d28b1ab0d83e1c;p=thirdparty%2Futil-linux.git

lib/canonicalize: fix truncation warning

lib/canonicalize.c: In function ‘canonicalize_dm_name’:
lib/canonicalize.c:42:45: warning: ‘%s’ directive output may be truncated
writing up to 255 bytes into a region of size 244 [-Wformat-truncation=]
   snprintf(path, sizeof(path), "/dev/mapper/%s", name);

Notice that this warnign fix does not improve code enormously.  The earlier
snprintf() truncation will not happen a bit earlier when fgets() is called.
In that sense this change merely makes one easy to silence warning to
disappear, and therefore improve change of noticing useful messaging as such
crops up.

[kzak@redhat.com: - use macro rather than hardcoded string for mapper path]

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/include/pathnames.h b/include/pathnames.h
index 59cc667362..abf0cdee98 100644
--- a/include/pathnames.h
+++ b/include/pathnames.h
@@ -131,6 +131,8 @@
 # define _PATH_DEV		"/dev/"
 #endif
 
+#define _PATH_DEV_MAPPER	"/dev/mapper"
+
 #define _PATH_DEV_MEM		"/dev/mem"
 
 #define _PATH_DEV_LOOP		"/dev/loop"
diff --git a/lib/canonicalize.c b/lib/canonicalize.c
index b600248c71..ef3342b12b 100644
--- a/lib/canonicalize.c
+++ b/lib/canonicalize.c
@@ -16,6 +16,7 @@
 #include <sys/stat.h>
 
 #include "canonicalize.h"
+#include "pathnames.h"
 
 /*
  * Converts private "dm-N" names to "/dev/mapper/<name>"
@@ -27,7 +28,7 @@ char *canonicalize_dm_name(const char *ptname)
 {
 	FILE	*f;
 	size_t	sz;
-	char	path[256], name[256], *res = NULL;
+	char	path[256], name[sizeof(path) - sizeof(_PATH_DEV_MAPPER)], *res = NULL;
 
 	if (!ptname || !*ptname)
 		return NULL;
@@ -39,7 +40,7 @@ char *canonicalize_dm_name(const char *ptname)
 	/* read "<name>\n" from sysfs */
 	if (fgets(name, sizeof(name), f) && (sz = strlen(name)) > 1) {
 		name[sz - 1] = '\0';
-		snprintf(path, sizeof(path), "/dev/mapper/%s", name);
+		snprintf(path, sizeof(path), _PATH_DEV_MAPPER "/%s", name);
 
 		if (access(path, F_OK) == 0)
 			res = strdup(path);