lib/consoles: /proc/consoles code refactoring

 - move to separate function
 - cleanup code
 - fix fscanf() usage to avoid buffer overflow

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/lib/consoles.c b/lib/consoles.c
index a6a84360b319862db2a50a54cc603b75db79ed74..36325be96a7c21f6d918ad6aca0e9edab36828ab 100644 (file)
--- a/lib/consoles.c
+++ b/lib/consoles.c
@@ -213,6 +213,54 @@ int append_console(struct console **list, char * name)
        return 0;
 }
 
+#ifdef __linux__
+/*
+ * return codes:
+ *     < 0     - fatal error (no mem or so... )
+ *       0     - success
+ *       1     - recoverable error
+ *       2     - detection not available
+ */
+static int detect_consoles_from_proc(struct console **consoles)
+{
+       char fbuf[16 + 1];
+       DIR *dir = NULL;
+       FILE *fc = NULL;
+       int maj, min, rc = 1;
+
+       fc = fopen("/proc/consoles", "re");
+       if (!fc)
+               return 2;
+
+       dir = opendir("/dev");
+       if (!dir)
+               goto done;
+
+       while (fscanf(fc, "%*s %*s (%16[^)]) %d:%d", fbuf, &maj, &min) == 3) {
+               char *name;
+               dev_t comparedev;
+
+               if (!strchr(fbuf, 'E'))
+                       continue;
+               comparedev = makedev(maj, min);
+               name = scandev(dir, comparedev);
+               if (!name)
+                       continue;
+               rc = append_console(consoles, name);
+               if (rc < 0)
+                       goto done;
+       }
+
+       rc = *consoles ? 0 : 1;
+done:
+       if (dir)
+               closedir(dir);
+       if (fc)
+               fclose(fc);
+       return rc;
+}
+#endif /* __linux__ */
+
 /*
  * Try to detect the real device(s) used for the system console
  * /dev/console if but only if /dev/console is used.  On Linux
@@ -228,7 +276,6 @@ int detect_consoles(const char *device, int fallback, struct console **consoles)
        dev_t comparedev = 0;
 #ifdef __linux__
        char *attrib, *cmdline;
-       FILE *fc;
 #endif
        if (!device || !*device)
                fd = dup(fallback);
@@ -309,33 +356,14 @@ console:
         * Detection of devices used for Linux system consolei using
         * the /proc/consoles API with kernel 2.6.38 and higher.
         */
-       if ((fc = fopen("/proc/consoles", "re"))) {
-               char fbuf[16];
-               int maj, min;
-               DIR *dir;
-               dir = opendir("/dev");
-               if (!dir) {
-                       fclose(fc);
-                       goto fallback;
-               }
-               while ((fscanf(fc, "%*s %*s (%[^)]) %d:%d", &fbuf[0], &maj, &min) == 3)) {
-                       char * name;
+       rc = detect_consoles_from_proc(consoles);
+       if (rc == 0)
+               return reconnect;       /* success */
+       if (rc < 0)
+               return rc;              /* fatal error */
+       if (rc == 1)
+               goto fallback;          /* detection error */
 
-                       if (!strchr(fbuf, 'E'))
-                               continue;
-                       comparedev = makedev(maj, min);
-
-                       name = scandev(dir, comparedev);
-                       if (!name)
-                               continue;
-                       rc = append_console(consoles, name);
-                       if (rc < 0)
-                               return rc;
-               }
-               closedir(dir);
-               fclose(fc);
-               return reconnect;
-       }
        /*
         * Detection of devices used for Linux system console using
         * the sysfs /sys/class/tty/ API with kernel 2.6.37 and higher.