Submitted by: Damon Harper <address@hidden>
Date: 2006-08-28
Summary: Run comsatd exec actions even if user is not logged in

Currently, comsatd's child process simply exits if it cannot find a
tty where the user to be notified is logged in.  This is fine for the
default action, or echo and beep actions; however, this also prevents
exec actions from running unless the user is actively logged in at the
time of notification.

This should not be the desired behaviour.  A user might use exec to
perform an action that should fire off even if that user is not logged
in to a tty.  In the comsatd documentation, an example is given of an
exec command that will run xmessage to show a message in x-windows.
With the current behaviour, that example will only work if the user is
also logged in to a tty (perhaps via xterm) at the time of the
message.

This patch changes the semantics of find_user, so that the tty is set
to the device name if a usable tty is found, but is otherwise set to
NULL.  The return value of find_user is still provided but is now
ignored.  run_user_action, open_rc, and action_* functions are now
reworked to assume that tty could be NULL.  action_beep and
action_echo both return immediately if this is the case, but
action_exec simply continues with all output directed to /dev/null.

This patch also fixes all functions to use the cr string instead of
hard-coded \r\n when writing to the tty.

diff -urN mailutils-1.0.orig/comsat/action.c mailutils-1.0/comsat/action.c
--- mailutils-1.0.orig/comsat/action.c	2005-08-29 03:21:54.000000000 -0700
+++ mailutils-1.0/comsat/action.c	2006-08-27 15:37:06.000000000 -0700
@@ -233,6 +233,8 @@
 static void
 action_beep (FILE *tty)
 {
+  if (tty == NULL)
+    return;
   fprintf (tty, "\a\a");
 }
 
@@ -241,6 +243,8 @@
 {
   if (!str)
     return;
+  if (tty == NULL)
+    return;
   for (; *str; str++)
     {
       if (*str == '\n')
@@ -290,11 +294,14 @@
   pid = fork ();
   if (pid == 0)
     {
-      close (1);
-      close (2);
-      dup2 (fileno (tty), 1);
-      dup2 (fileno (tty), 2);
-      fclose (tty);
+      if (tty != NULL)
+        {
+          close (1);
+          close (2);
+          dup2 (fileno (tty), 1);
+          dup2 (fileno (tty), 2);
+          fclose (tty);
+        }
       execv (argv[0], argv);
       syslog (LOG_ERR, _("Cannot execute %s: %s"), argv[0], strerror (errno));
       exit (0);
@@ -302,7 +309,7 @@
 }
 
 static FILE *
-open_rc (const char *filename, FILE *tty)
+open_rc (const char *filename, FILE *tty, char *cr)
 {
   struct stat stb;
   struct passwd *pw = getpwnam (username);
@@ -320,8 +327,9 @@
 	}
       if ((stb.st_mode & 0777) != 0600)
 	{
-	  fprintf (tty, "%s\r\n",
-		   _("Warning: your .biffrc has wrong permissions"));
+          if (tty != NULL)
+            fprintf (tty, "%s%s",
+                     _("Warning: your .biffrc has wrong permissions"), cr);
 	  syslog (LOG_NOTICE, _("%s's %s has wrong permissions"),
 		  username, filename);
 	  return NULL;
@@ -338,7 +346,7 @@
   char *stmt = NULL;
   size_t size = 0;
 
-  fp = open_rc (BIFF_RC, tty);
+  fp = open_rc (BIFF_RC, tty, cr);
   if (fp)
     {
       int line = 0;
@@ -379,8 +387,11 @@
 	    }
 	  else
 	    {
-	      fprintf (tty, _(".biffrc:%d: unknown keyword"), line);
-	      fprintf (tty, "\r\n");
+              if (tty != NULL)
+                {
+                  fprintf (tty, _(".biffrc:%d: unknown keyword"), line);
+                  fprintf (tty, "%s", cr);
+                }
 	      syslog (LOG_ERR, _("%s:.biffrc:%d: unknown keyword %s"),
 		      username, line, argv[0]);
 	      break;
diff -urN mailutils-1.0.orig/comsat/comsat.c mailutils-1.0/comsat/comsat.c
--- mailutils-1.0.orig/comsat/comsat.c	2005-09-30 03:41:07.000000000 -0700
+++ mailutils-1.0/comsat/comsat.c	2006-08-27 15:37:37.000000000 -0700
@@ -103,8 +103,8 @@
 static void comsat_daemon_init (void);
 static void comsat_daemon (int _port);
 static int comsat_main (int fd);
-static void notify_user (const char *user, const char *device, const char *path, off_t offset);
-static int find_user (const char *name, char *tty);
+static void notify_user (const char *user, const char *path, off_t offset);
+static int find_user (const char *name, char **tty);
 static char *mailbox_path (const char *user);
 static void change_user (const char *user);
 
@@ -322,7 +322,6 @@
   struct sockaddr_in sin_from;
   char buffer[216]; /*FIXME: Arbitrary size */
   pid_t pid;
-  char tty[MAX_TTY_SIZE];
   char *p, *endp;
   size_t offset;
   char *path = NULL;
@@ -374,9 +373,6 @@
 	syslog (LOG_ERR, _("Malformed input: address@hidden (near %s)"), buffer, p, endp);
     }
 
-  if (find_user (buffer, tty) != SUCCESS)
-    return 0;
-
   /* All I/O is done by child process. This is to avoid various blocking
      problems. */
 
@@ -399,7 +395,7 @@
     }
 
   /* Child: do actual I/O */
-  notify_user (buffer, tty, path, offset);
+  notify_user (buffer, path, offset);
   exit (0);
 }
 
@@ -422,9 +418,10 @@
 /* NOTE: Do not bother to free allocated memory, as the program exits
    immediately after executing this */
 static void
-notify_user (const char *user, const char *device, const char *path, off_t offset)
+notify_user (const char *user, const char *path, off_t offset)
 {
-  FILE *fp;
+  char *tty;
+  FILE *fp = NULL;
   const char *cr;
   char *blurb;
   mu_mailbox_t mbox = NULL, tmp = NULL;
@@ -435,14 +432,17 @@
   size_t count, n;
 
   change_user (user);
-  if ((fp = fopen (device, "w")) == NULL)
+  find_user (user, &tty);
+  if (tty)
     {
-      syslog (LOG_ERR, _("Cannot open device %s: %m"), device);
-      exit (0);
+      if ((fp = fopen (tty, "w")) == NULL)
+        {
+          syslog (LOG_ERR, _("Cannot open tty device %s: %m"), tty);
+          exit (0);
+        }
+      cr = get_newline_str (fp);
     }
 
-  cr = get_newline_str (fp);
-
   if (!path)
     {
       path = mailbox_path (user);
@@ -502,21 +502,27 @@
   mu_mailbox_get_message (tmp, 1, &msg);
 
   run_user_action (fp, cr, msg);
-  fclose (fp);
+  if (tty)
+    {
+      fclose (fp);
+      free (tty);
+    }
 }
 
 /* Search utmp for the local user */
 static int
-find_user (const char *name, char *tty)
+find_user (const char *name, char **tty)
 {
   UTMP *uptr;
   int status;
   struct stat statb;
-  char ftty[MAX_TTY_SIZE];
+  char trytty[MAX_TTY_SIZE];
+  char *ftty;
   time_t last_time = 0;
 
   status = NOT_HERE;
-  sprintf (ftty, "%s/", PATH_TTY_PFX);
+  *tty = NULL;
+  sprintf (trytty, "%s/", PATH_TTY_PFX);
 
   SETUTENT ();
 
@@ -529,24 +535,24 @@
       if (!strncmp (uptr->ut_name, name, sizeof(uptr->ut_name)))
 	{
 	  /* no particular tty was requested */
-	  strncpy (ftty + sizeof(PATH_DEV),
+	  strncpy (trytty + sizeof(PATH_DEV),
 		   uptr->ut_line,
-		   sizeof (ftty) - sizeof (PATH_DEV) - 2);
-	  ftty[sizeof (ftty) - 1] = 0;
+		   sizeof (trytty) - sizeof (PATH_DEV) - 2);
+	  trytty[sizeof (trytty) - 1] = 0;
 
-	  mu_normalize_path (ftty, "/");
-	  if (strncmp (ftty, PATH_TTY_PFX, strlen (PATH_TTY_PFX)))
+	  mu_normalize_path (trytty, "/");
+	  if (strncmp (trytty, PATH_TTY_PFX, strlen (PATH_TTY_PFX)))
 	    {
 	      /* An attempt to break security... */
-	      syslog (LOG_ALERT, _("Bad line name in utmp record: %s"), ftty);
+	      syslog (LOG_ALERT, _("Bad line name in utmp record: %s"), trytty);
 	      return NOT_HERE;
 	    }
 
-	  if (stat (ftty, &statb) == 0)
+	  if (stat (trytty, &statb) == 0)
 	    {
 	      if (!S_ISCHR (statb.st_mode))
 		{
-		  syslog (LOG_ALERT, _("Not a character device: %s"), ftty);
+		  syslog (LOG_ALERT, _("Not a character device: %s"), trytty);
 		  return NOT_HERE;
 		}
 
@@ -559,8 +565,11 @@
 	      if (statb.st_atime > last_time)
 		{
 		  last_time = statb.st_atime;
-		  strcpy(tty, ftty);
-		  status = SUCCESS;
+                  if ((ftty = malloc (strlen (trytty) + 1)) != NULL)
+                    {
+                      strcpy (ftty, trytty);
+                      status = SUCCESS;
+                    }
 		}
 	      continue;
 	    }
@@ -568,6 +577,8 @@
     }
 
   ENDUTENT ();
+  if (status == SUCCESS)
+    *tty = ftty;
   return status;
 }