[dm-devel] [PATCH v3 45/72] libmultipath: fix -Wsign-compare warnings with snprintf()
Martin Wilck
Martin.Wilck at suse.com
Thu Nov 7 09:27:41 UTC 2019
From: Martin Wilck <mwilck at suse.com>
snprintf() returns int, but the size argument "n" is size_t.
Use safe_snprintf() to avoid -Wsign-compare warnings. At the same
time, improve these macros to check for errors in snprintf(), too.
Note: there are more uses of snprintf() in our code that may
need review, too. For now, I'm fixing only those that were causing
warnings.
Signed-off-by: Martin Wilck <mwilck at suse.com>
---
kpartx/devmapper.c | 3 ++-
kpartx/kpartx.h | 11 ++++++++++-
libmultipath/foreign/nvme.c | 6 ++----
libmultipath/sysfs.c | 7 +++----
libmultipath/util.c | 3 +--
libmultipath/util.h | 11 +++++++++--
libmultipath/wwids.c | 3 +--
multipath/main.c | 3 +--
8 files changed, 29 insertions(+), 18 deletions(-)
diff --git a/kpartx/devmapper.c b/kpartx/devmapper.c
index 3aa4988d..b100b5ef 100644
--- a/kpartx/devmapper.c
+++ b/kpartx/devmapper.c
@@ -10,6 +10,7 @@
#include <errno.h>
#include <sys/sysmacros.h>
#include "devmapper.h"
+#include "kpartx.h"
#define _UUID_PREFIX "part"
#define UUID_PREFIX _UUID_PREFIX "%d-"
@@ -107,7 +108,7 @@ strip_slash (char * device)
static int format_partname(char *buf, size_t bufsiz,
const char *mapname, const char *delim, int part)
{
- if (snprintf(buf, bufsiz, "%s%s%d", mapname, delim, part) >= bufsiz)
+ if (safe_snprintf(buf, bufsiz, "%s%s%d", mapname, delim, part))
return 0;
strip_slash(buf);
return 1;
diff --git a/kpartx/kpartx.h b/kpartx/kpartx.h
index 52920e43..8a2db046 100644
--- a/kpartx/kpartx.h
+++ b/kpartx/kpartx.h
@@ -16,8 +16,17 @@
#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)
+#define safe_snprintf(var, size, format, args...) \
+ ({ \
+ size_t __size = size; \
+ int __ret; \
+ \
+ __ret = snprintf(var, __size, format, ##args); \
+ __ret < 0 || (size_t)__ret >= __size; \
+ })
+
#define safe_sprintf(var, format, args...) \
- snprintf(var, sizeof(var), format, ##args) >= sizeof(var)
+ safe_snprintf(var, sizeof(var), format, ##args)
#ifndef BLKSSZGET
#define BLKSSZGET _IO(0x12,104) /* get block device sector size */
diff --git a/libmultipath/foreign/nvme.c b/libmultipath/foreign/nvme.c
index e8ca516c..09cdddf0 100644
--- a/libmultipath/foreign/nvme.c
+++ b/libmultipath/foreign/nvme.c
@@ -591,8 +591,7 @@ static void test_ana_support(struct nvme_map *map, struct udev_device *ctl)
return;
dev_t = udev_device_get_sysattr_value(ctl, "dev");
- if (snprintf(sys_path, sizeof(sys_path), "/dev/char/%s", dev_t)
- >= sizeof(sys_path))
+ if (safe_sprintf(sys_path, "/dev/char/%s", dev_t))
return;
fd = open(sys_path, O_RDONLY);
@@ -663,8 +662,7 @@ static void _find_controllers(struct context *ctx, struct nvme_map *map)
char *fn = di[i]->d_name;
struct udev_device *ctrl, *udev;
- if (snprintf(pathbuf + n, sizeof(pathbuf) - n, "/%s", fn)
- >= sizeof(pathbuf) - n)
+ if (safe_snprintf(pathbuf + n, sizeof(pathbuf) - n, "/%s", fn))
continue;
if (realpath(pathbuf, realbuf) == NULL) {
condlog(3, "%s: %s: realpath: %s", __func__, THIS,
diff --git a/libmultipath/sysfs.c b/libmultipath/sysfs.c
index 923b529b..62ec2ed7 100644
--- a/libmultipath/sysfs.c
+++ b/libmultipath/sysfs.c
@@ -306,7 +306,7 @@ bool sysfs_is_multipathed(const struct path *pp)
n = snprintf(pathbuf, sizeof(pathbuf), "/sys/block/%s/holders",
pp->dev);
- if (n >= sizeof(pathbuf)) {
+ if (n < 0 || (size_t)n >= sizeof(pathbuf)) {
condlog(1, "%s: pathname overflow", __func__);
return false;
}
@@ -327,9 +327,8 @@ bool sysfs_is_multipathed(const struct path *pp)
int nr;
char uuid[6];
- if (snprintf(pathbuf + n, sizeof(pathbuf) - n,
- "/%s/dm/uuid", di[i]->d_name)
- >= sizeof(pathbuf) - n)
+ if (safe_snprintf(pathbuf + n, sizeof(pathbuf) - n,
+ "/%s/dm/uuid", di[i]->d_name))
continue;
fd = open(pathbuf, O_RDONLY);
diff --git a/libmultipath/util.c b/libmultipath/util.c
index ccc0de29..51c38c87 100644
--- a/libmultipath/util.c
+++ b/libmultipath/util.c
@@ -212,8 +212,7 @@ int devt2devname(char *devname, int devname_len, char *devt)
continue;
if ((major == tmpmaj) && (minor == tmpmin)) {
- if (snprintf(block_path, sizeof(block_path),
- "/sys/block/%s", dev) >= sizeof(block_path)) {
+ if (safe_sprintf(block_path, "/sys/block/%s", dev)) {
condlog(0, "device name %s is too long", dev);
fclose(fd);
return 1;
diff --git a/libmultipath/util.h b/libmultipath/util.h
index 913ab7c2..56bd78c7 100644
--- a/libmultipath/util.h
+++ b/libmultipath/util.h
@@ -29,9 +29,16 @@ void set_max_fds(rlim_t max_fds);
#define ARRAY_SIZE(x) (sizeof(x)/sizeof((x)[0]))
#define safe_sprintf(var, format, args...) \
- snprintf(var, sizeof(var), format, ##args) >= sizeof(var)
+ safe_snprintf(var, sizeof(var), format, ##args)
+
#define safe_snprintf(var, size, format, args...) \
- snprintf(var, size, format, ##args) >= size
+ ({ \
+ size_t __size = size; \
+ int __ret; \
+ \
+ __ret = snprintf(var, __size, format, ##args); \
+ __ret < 0 || (size_t)__ret >= __size; \
+ })
#define pthread_cleanup_push_cast(f, arg) \
pthread_cleanup_push(((void (*)(void *))&f), (arg))
diff --git a/libmultipath/wwids.c b/libmultipath/wwids.c
index 291db8f5..28a2150d 100644
--- a/libmultipath/wwids.c
+++ b/libmultipath/wwids.c
@@ -393,8 +393,7 @@ static int _failed_wwid_op(const char *wwid, bool rw,
long lockfd;
int r = -1;
- if (snprintf(path, sizeof(path), "%s/%s", shm_dir, wwid)
- >= sizeof(path)) {
+ if (safe_sprintf(path, "%s/%s", shm_dir, wwid)) {
condlog(1, "%s: path name overflow", __func__);
return -1;
}
diff --git a/multipath/main.c b/multipath/main.c
index c2ef8c7b..c553437b 100644
--- a/multipath/main.c
+++ b/multipath/main.c
@@ -423,8 +423,7 @@ static int find_multipaths_check_timeout(const struct path *pp, long tmo,
clock_gettime(CLOCK_REALTIME, &now);
- if (snprintf(path, sizeof(path), "%s/%s", shm_find_mp_dir, pp->dev_t)
- >= sizeof(path)) {
+ if (safe_sprintf(path, "%s/%s", shm_find_mp_dir, pp->dev_t)) {
condlog(1, "%s: path name overflow", __func__);
return FIND_MULTIPATHS_ERROR;
}
--
2.23.0
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