X-Git-Url: https://ruderich.org/simon/gitweb/?a=blobdiff_plain;f=src%2Fwall-notify.c;h=0e77e97ecce2d8638fd91ec27cc83a88d6cec8ba;hb=702d46155ea3f168dea38e513748b15f256d8b2e;hp=292b71a1d9d026208db979be56cc5c03bdffb4d0;hpb=3553a29a54f7755debfa189db830c4b8de51826f;p=wall-notify%2Fwall-notify.git

diff --git a/src/wall-notify.c b/src/wall-notify.c
index 292b71a..0e77e97 100644
--- a/src/wall-notify.c
+++ b/src/wall-notify.c
@@ -1,7 +1,7 @@
 /*
  * Receive wall messages and pass them to a notification program via stdin.
  *
- * Copyright (C) 2014  Simon Ruderich
+ * Copyright (C) 2014-2015  Simon Ruderich
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -48,8 +48,13 @@
 #endif
 
 
+static sig_atomic_t signaled = 0;
+
+
 static void sig_handler(int signal) {
     (void)signal;
+
+    signaled = 1;
 }
 static void setup_signals(void) {
     struct sigaction action;
@@ -67,7 +72,18 @@ static void setup_signals(void) {
     sigaction(SIGUSR2, &action, NULL);
 }
 
-static int open_tty(void) {
+static int set_cloexec(int fd) {
+    int flags = fcntl(fd, F_GETFD);
+    if (flags == -1) {
+        return 0;
+    }
+    if (fcntl(fd, F_SETFD, flags | FD_CLOEXEC) == -1) {
+        return 0;
+    }
+    return 1;
+}
+
+static int open_tty(int public) {
     int ptm;
     const char *name;
 
@@ -78,15 +94,20 @@ static int open_tty(void) {
     if (grantpt(ptm) != 0) {
         return -1;
     }
+    if (!set_cloexec(ptm)) {
+        return -1;
+    }
 
     /* Prevent write access for other users so they can't use wall to send
      * messages to this program. */
-    name = ptsname(ptm);
-    if (!name) {
-        return -1;
-    }
-    if (chmod(name, S_IRUSR | S_IWUSR) != 0) {
-        return -1;
+    if (!public) {
+        name = ptsname(ptm);
+        if (!name) {
+            return -1;
+        }
+        if (chmod(name, S_IRUSR | S_IWUSR) != 0) {
+            return -1;
+        }
     }
 
     if (unlockpt(ptm) != 0) {
@@ -212,14 +233,14 @@ static void drop_privileges(void) {
     gid = getgid();
 
     /* Drop all privileges. */
-    if (setresuid(uid, uid, uid) != 0) {
-        perror("setresuid");
-        exit(EXIT_FAILURE);
-    }
     if (setresgid(gid, gid, gid) != 0) {
         perror("setresgid");
         exit(EXIT_FAILURE);
     }
+    if (setresuid(uid, uid, uid) != 0) {
+        perror("setresuid");
+        exit(EXIT_FAILURE);
+    }
 
     /* Verify all privileges were dropped. */
     if (getresuid(&ruid, &euid, &suid) != 0) {
@@ -316,7 +337,7 @@ static void handle_wall(int fd, char **argv) {
     ssize_t r;
 
     assert(SSIZE_MAX <= SIZE_MAX);
-    while ((r = read(fd, buffer, sizeof(buffer))) > 0) {
+    while (!signaled && (r = read(fd, buffer, sizeof(buffer))) > 0) {
         size_t space;
         ssize_t r2;
 
@@ -359,25 +380,74 @@ static void *x11_event_loop_thread(void *unused) {
 #endif
 
 static void usage(const char *argv0) {
-    fprintf(stderr, "usage: %s <cmd args..>\n", argv0);
+    fprintf(stderr, "usage: %s [-X] [-m] [-v] <cmd args..>\n", argv0);
+    fprintf(stderr, "Pass wall messages to <cmd args..>.\n");
+    fprintf(stderr, "\n");
+    fprintf(stderr, "-X quit when the current X session terminates\n");
+    fprintf(stderr, "-m allow messages from normal users (like `mesg y`)\n");
+    fprintf(stderr, "-v display version\n");
+#ifdef DONT_USE_X11
+    fprintf(stderr, "\n");
+    fprintf(stderr, "compiled without X11 support, -X disabled\n");
+#endif
     exit(EXIT_FAILURE);
 }
 
 
 int main(int argc, char **argv) {
+    int option, enable_x11, mesg_yes;
+    const char *argv0;
     int ptm, pts;
     char *name;
-    const char *argv0;
+
+    /* Don't display error messages for unknown options. */
+    opterr = 0;
+
+    enable_x11 = 0;
+    mesg_yes = 0;
 
     argv0 = argv[0];
-    /* Don't pass our argv[0] to the notification program. */
-    argv++;
 
-    if (argc < 2) {
+    /*
+     * Glibc violates POSIX by default and skips over non-option arguments and
+     * parses later arguments which look like options as well. But we want to
+     * pass everything except the options unmodified to execvp(). Prefixing
+     * the optstring with "+" fixes this behaver. This is not POSIX
+     * compatible, but the option should be ignored on other systems.
+     */
+    while ((option = getopt(argc, argv, "+Xmhv")) != -1) {
+        switch (option) {
+            case 'X':
+                enable_x11 = 1;
+                break;
+            case 'm':
+                mesg_yes = 1;
+                break;
+            case 'h':
+                usage(argv0);
+                break;
+            case 'v':
+                printf("%s%s\n",
+                       PACKAGE_STRING,
+                       strlen(GIT_VERSION) ? " (Git " GIT_VERSION ")" : "");
+                exit(EXIT_SUCCESS);
+                break;
+            default:
+                fprintf(stderr, "%s: unknown option '%s'!\n\n",
+                                argv0, argv[optind - 1]);
+                usage(argv0);
+                break;
+        }
+    }
+
+    /* No arguments remaining, abort. */
+    if (!argv[optind]) {
         usage(argv0);
     }
+    /* Arguments for notification program. */
+    argv += optind;
 
-    ptm = open_tty();
+    ptm = open_tty(mesg_yes);
     if (ptm < 0) {
         perror("open_tty");
         exit(EXIT_FAILURE);
@@ -394,24 +464,27 @@ int main(int argc, char **argv) {
 
     /* We need to open the slave or reading from the master yields EOF after
      * the first wall write to it. */
-    pts = open(name, O_RDWR);
+    pts = open(name, O_RDWR | O_CLOEXEC);
     if (pts < 0) {
         perror(name);
         exit(EXIT_FAILURE);
     }
 
-#ifndef DONT_USE_X11
     /* Start a thread which connects to X11. This way we die if the user logs
      * out of its X11 session. */
-    {
+    if (enable_x11) {
+#ifdef DONT_USE_X11
+        fprintf(stderr, "%s: option -X is disabled!\n\n", argv0);
+        usage(argv0);
+#else
         pthread_t tid;
 
         if (pthread_create(&tid, NULL, x11_event_loop_thread, NULL) != 0) {
             perror("pthread_create");
             exit(EXIT_FAILURE);
         }
-    }
 #endif
+    }
 
     /* Cleanup on signals. Necessary before login(). */
     setup_signals();