syslogd: fix "readpath bug" by using readlink instead

libbb: rename xgetcwd and xreadlink

1 files changed, 24 insertions, 17 deletions

diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 97ddf09b5..53290f1cc 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -24,9 +24,6 @@
 
 #define DEBUG 0
 
-/* Path to the unix socket */
-static const char *dev_log_name;
-
 /* Path for the file where all log messages are written */
 static const char *logFilePath = "/var/log/messages";
 static int logFD = -1;
@@ -446,7 +443,6 @@ static void quit_signal(int sig)
 {
         timestamp_and_log(LOG_SYSLOG | LOG_INFO, (char*)"syslogd exiting", 0);
         puts("syslogd exiting");
-        unlink(dev_log_name);
         if (ENABLE_FEATURE_IPC_SYSLOG)
                 ipcsyslog_cleanup();
         exit(1);
@@ -464,9 +460,9 @@ static void do_syslogd(void) ATTRIBUTE_NORETURN;
 static void do_syslogd(void)
 {
         struct sockaddr_un sunx;
-        socklen_t addr_len;
         int sock_fd;
         fd_set fds;
+        char *dev_log_name;
 
         /* Set up signal handlers */
         signal(SIGINT, quit_signal);
@@ -480,22 +476,33 @@ static void do_syslogd(void)
         signal(SIGALRM, do_mark);
         alarm(markInterval);
 
-        dev_log_name = xmalloc_realpath(_PATH_LOG);
-        if (!dev_log_name)
-                dev_log_name = _PATH_LOG;
-
-        /* Unlink old /dev/log (or object it points to) */
-        unlink(dev_log_name);
-
         memset(&sunx, 0, sizeof(sunx));
         sunx.sun_family = AF_UNIX;
-        strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
+        strcpy(sunx.sun_path, "/dev/log");
+
+        /* Unlink old /dev/log or object it points to. */
+        /* (if it exists, bind will fail) */
+        logmode = LOGMODE_NONE;
+        dev_log_name = xmalloc_readlink_or_warn("/dev/log");
+        logmode = LOGMODE_STDIO;
+        if (dev_log_name) {
+                int fd = xopen(".", O_NONBLOCK);
+                xchdir("/dev");
+                /* we do not check whether this is a link also */
+                unlink(dev_log_name);
+                fchdir(fd);
+                close(fd);
+                safe_strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
+                free(dev_log_name);
+        } else {
+                unlink("/dev/log");
+        }
+
         sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
-        addr_len = sizeof(sunx.sun_family) + strlen(sunx.sun_path);
-        xbind(sock_fd, (struct sockaddr *) &sunx, addr_len);
+        xbind(sock_fd, (struct sockaddr *) &sunx, sizeof(sunx));
 
-        if (chmod(dev_log_name, 0666) < 0) {
-                bb_perror_msg_and_die("cannot set permission on %s", dev_log_name);
+        if (chmod("/dev/log", 0666) < 0) {
+                bb_perror_msg_and_die("cannot set permission on /dev/log");
         }
         if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
                 ipcsyslog_init();