rexec: convert to strnprintf()

src/lxc/rexec.c

@@ -98,9 +98,9 @@ static void lxc_rexec_as_memfd(char **argv, char **envp, const char *memfd_name)
 	if (memfd < 0) {
 		char template[PATH_MAX];
 
-		ret = snprintf(template, sizeof(template),
-			       P_tmpdir "/.%s_XXXXXX", memfd_name);
-		if (ret < 0 || (size_t)ret >= sizeof(template))
+		ret = strnprintf(template, sizeof(template),
+				 P_tmpdir "/.%s_XXXXXX", memfd_name);
+		if (ret < 0)
 			return;
 
 		tmpfd = lxc_make_tmpfile(template, true);
@@ -151,8 +151,8 @@ static void lxc_rexec_as_memfd(char **argv, char **envp, const char *memfd_name)
 	} else {
 		char procfd[LXC_PROC_PID_FD_LEN];
 
-		ret = snprintf(procfd, sizeof(procfd), "/proc/self/fd/%d", tmpfd);
-		if (ret < 0 || (size_t)ret >= sizeof(procfd))
+		ret = strnprintf(procfd, sizeof(procfd), "/proc/self/fd/%d", tmpfd);
+		if (ret < 0)
 			return;
 
 		execfd = open(procfd, O_PATH | O_CLOEXEC);