lib: Improve error reporting from broken config files

cleans up a few items with error reporting at startup:

 - Line numbers are now reported alongside error text
 - All errors now go to stderr instead of some stderr and some stdout
 - The vty buffer is flushed so that errors now come out in the right order

3 files changed, 20 insertions, 9 deletions

diff --git a/lib/command.c b/lib/command.c
index e79d462e..ce7a989f 100644
--- a/lib/command.c
+++ b/lib/command.c
@@ -2264,13 +2264,15 @@ cmd_execute_command_strict (vector vline, struct vty *vty,
 
 /* Configration make from file. */
 int
-config_from_file (struct vty *vty, FILE *fp)
+config_from_file (struct vty *vty, FILE *fp, unsigned int *line_num)
 {
   int ret;
+  *line_num = 0;
   vector vline;
 
   while (fgets (vty->buf, VTY_BUFSIZ, fp))
     {
+      ++(*line_num);
       vline = cmd_make_strvec (vty->buf);
 
       /* In case of comment line */
diff --git a/lib/command.h b/lib/command.h
index 1275efee..541b259a 100644
--- a/lib/command.h
+++ b/lib/command.h
@@ -341,7 +341,7 @@ extern void cmd_free_strvec (vector);
 extern vector cmd_describe_command (vector, struct vty *, int *status);
 extern char **cmd_complete_command (vector, struct vty *, int *status);
 extern const char *cmd_prompt (enum node_type);
-extern int config_from_file (struct vty *, FILE *);
+extern int config_from_file (struct vty *, FILE *, unsigned int *line_num);
 extern enum node_type node_parent (enum node_type);
 extern int cmd_execute_command (vector, struct vty *, struct cmd_element **, int);
 extern int cmd_execute_command_strict (vector, struct vty *, struct cmd_element **);
diff --git a/lib/vty.c b/lib/vty.c
index e4818eb6..b82add84 100644
--- a/lib/vty.c
+++ b/lib/vty.c
@@ -2229,28 +2229,37 @@ vty_read_file (FILE *confp)
 {
   int ret;
   struct vty *vty;
+  unsigned int line_num = 15;
 
   vty = vty_new ();
-  vty->fd = 0;			/* stdout */
-  vty->type = VTY_TERM;
+  vty->fd = dup(STDERR_FILENO); /* vty_close() will close this */
+  if (vty->fd < 0)
+  {
+    /* Fine, we couldn't make a new fd. vty_close doesn't close stdout. */
+    vty->fd = STDOUT_FILENO;
+  }
+  vty->type = VTY_FILE;
   vty->node = CONFIG_NODE;
   
   /* Execute configuration file */
-  ret = config_from_file (vty, confp);
+  ret = config_from_file (vty, confp, &line_num);
+
+  /* Flush any previous errors before printing messages below */
+  buffer_flush_all (vty->obuf, vty->fd);
 
   if ( !((ret == CMD_SUCCESS) || (ret == CMD_ERR_NOTHING_TODO)) ) 
     {
       switch (ret)
        {
          case CMD_ERR_AMBIGUOUS:
-           fprintf (stderr, "Ambiguous command.\n");
+           fprintf (stderr, "*** Error reading config: Ambiguous command.\n");
            break;
          case CMD_ERR_NO_MATCH:
-           fprintf (stderr, "There is no such command.\n");
+           fprintf (stderr, "*** Error reading config: There is no such command.\n");
            break;
        }
-      fprintf (stderr, "Error occured during reading below line.\n%s\n", 
-	       vty->buf);
+      fprintf (stderr, "*** Error occured processing line %u, below:\n%s\n",
+		       line_num, vty->buf);
       vty_close (vty);
       exit (1);
     }