From: Xavi Hernandez <xhernandez@gmail.com>
Date: Tue, 13 Jan 2026 11:57:33 +0000 (+0100)
Subject: libcephfs_proxy: add helper function for robust snprintf()
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=ac744e208289b31fb56a41f3136d26af9185fed8;p=ceph.git

libcephfs_proxy: add helper function for robust snprintf()

Signed-off-by: Xavi Hernandez <xhernandez@gmail.com>
---

diff --git a/src/libcephfs_proxy/CMakeLists.txt b/src/libcephfs_proxy/CMakeLists.txt
index 83de8bdf9fc..43c9ae29136 100644
--- a/src/libcephfs_proxy/CMakeLists.txt
+++ b/src/libcephfs_proxy/CMakeLists.txt
@@ -1,5 +1,5 @@
-set(proxy_common_srcs proxy_link.c proxy_async.c proxy_log.c)
-set(libcephfsd_srcs libcephfsd.c proxy_manager.c proxy_mount.c proxy_helpers.c ${proxy_common_srcs})
+set(proxy_common_srcs proxy_helpers.c proxy_link.c proxy_async.c proxy_log.c)
+set(libcephfsd_srcs libcephfsd.c proxy_manager.c proxy_mount.c ${proxy_common_srcs})
 set(libcephfs_proxy_srcs libcephfs_proxy.c ${proxy_common_srcs})
 
 add_executable(libcephfsd ${libcephfsd_srcs})
diff --git a/src/libcephfs_proxy/proxy_helpers.c b/src/libcephfs_proxy/proxy_helpers.c
index 149d84d34bb..7df163ada2b 100644
--- a/src/libcephfs_proxy/proxy_helpers.c
+++ b/src/libcephfs_proxy/proxy_helpers.c
@@ -79,3 +79,24 @@ int32_t proxy_hash_hex(char *digest, size_t size,
 
 	return 0;
 }
+
+int32_t proxy_snprintf(char *buffer, int32_t size, const char *fmt, ...)
+{
+	va_list args;
+	int32_t len;
+
+	va_start(args, fmt);
+	len = vsnprintf(buffer, size, fmt, args);
+	va_end(args);
+
+	if (len < 0) {
+		return proxy_log(LOG_ERR, errno, "vsnprintf() failed");
+	}
+
+	if (len >= size) {
+		return proxy_log(LOG_ERR, ENOBUFS,
+				 "vsnprintf() truncated a string");
+	}
+
+	return len;
+}
diff --git a/src/libcephfs_proxy/proxy_helpers.h b/src/libcephfs_proxy/proxy_helpers.h
index ec7a1ad90ed..9177bb52800 100644
--- a/src/libcephfs_proxy/proxy_helpers.h
+++ b/src/libcephfs_proxy/proxy_helpers.h
@@ -371,4 +371,6 @@ int32_t proxy_hash(uint8_t *hash, size_t size,
 int32_t proxy_hash_hex(char *digest, size_t size,
 		       int32_t (*feed)(void **, void *, int32_t), void *data);
 
+int32_t proxy_snprintf(char *buffer, int32_t size, const char *fmt, ...);
+
 #endif
diff --git a/src/libcephfs_proxy/proxy_link.c b/src/libcephfs_proxy/proxy_link.c
index 7582822268e..1fc3f65967b 100644
--- a/src/libcephfs_proxy/proxy_link.c
+++ b/src/libcephfs_proxy/proxy_link.c
@@ -50,14 +50,10 @@ static int32_t proxy_link_prepare(struct sockaddr_un *addr, const char *path)
 
 	memset(addr, 0, sizeof(*addr));
 	addr->sun_family = AF_UNIX;
-	len = snprintf(addr->sun_path, sizeof(addr->sun_path), "%s", path);
+	len = proxy_snprintf(addr->sun_path, sizeof(addr->sun_path), "%s",
+			     path);
 	if (len < 0) {
-		return proxy_log(LOG_ERR, EINVAL,
-				 "Failed to copy Unix socket path");
-	}
-	if (len >= sizeof(addr->sun_path)) {
-		return proxy_log(LOG_ERR, ENAMETOOLONG,
-				 "Unix socket path too long");
+		return len;
 	}
 
 	sd = socket(AF_UNIX, SOCK_STREAM, 0);
diff --git a/src/libcephfs_proxy/proxy_mount.c b/src/libcephfs_proxy/proxy_mount.c
index a29d2a1fdda..33cc0e62c31 100644
--- a/src/libcephfs_proxy/proxy_mount.c
+++ b/src/libcephfs_proxy/proxy_mount.c
@@ -590,6 +590,7 @@ static int32_t proxy_config_destination_write(int32_t fd, void *data,
 static int32_t proxy_config_destination_commit(int32_t fd, const char *name)
 {
 	char path[32];
+	int32_t len;
 
 	if (fsync(fd) < 0) {
 		return proxy_log(LOG_ERR, errno, "fsync() failed");
@@ -605,7 +606,11 @@ static int32_t proxy_config_destination_commit(int32_t fd, const char *name)
 		 * filesystem. */
 	}
 
-	snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
+	len = proxy_snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
+	if (len < 0) {
+		return len;
+	}
+
 	if (linkat(AT_FDCWD, path, AT_FDCWD, name, AT_SYMLINK_FOLLOW) < 0) {
 		if (errno != EEXIST) {
 			return proxy_log(LOG_ERR, errno, "linkat() failed");
@@ -678,14 +683,8 @@ static int32_t proxy_config_prepare(const char *config, char *path,
 		goto done_dst;
 	}
 
-	err = snprintf(path, size, "ceph-%s.conf", hash);
+	err = proxy_snprintf(path, size, "ceph-%s.conf", hash);
 	if (err < 0) {
-		err = proxy_log(LOG_ERR, errno, "snprintf() failed");
-		goto done_dst;
-	}
-	if (err >= size) {
-		err = proxy_log(LOG_ERR, ENOBUFS,
-				"Insufficient space to store the name");
 		goto done_dst;
 	}