release/src/router/busybox/miscutils/wall.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * wall - write a message to all logged-in users
   4  * Copyright (c) 2009 Bernhard Reutner-Fischer
   5  *
   6  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   7  */
   8
   9 //config:config WALL
  10 //config:       bool "wall"
  11 //config:       default y
  12 //config:       depends on FEATURE_UTMP
  13 //config:       help
  14 //config:         Write a message to all users that are logged in.
  15
  16 /* Needs to be run by root or be suid root - needs to write to /dev/TTY: */
  17 //applet:IF_WALL(APPLET(wall, BB_DIR_USR_BIN, BB_SUID_REQUIRE))
  18
  19 //kbuild:lib-$(CONFIG_WALL) += wall.o
  20
  21 //usage:#define wall_trivial_usage
  22 //usage:        "[FILE]"
  23 //usage:#define wall_full_usage "\n\n"
  24 //usage:        "Write content of FILE or stdin to all logged-in users"
  25 //usage:
  26 //usage:#define wall_sample_usage
  27 //usage:        "echo foo | wall\n"
  28 //usage:        "wall ./mymessage"
  29
  30 #include "libbb.h"
  31
  32 int wall_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  33 int wall_main(int argc UNUSED_PARAM, char **argv)
  34 {
  35         struct utmpx *ut;
  36         char *msg;
  37         int fd;
  38
  39         fd = STDIN_FILENO;
  40         if (argv[1]) {
  41                 /* The applet is setuid.
  42                  * Access to the file must be under user's uid/gid.
  43                  */
  44                 fd = xopen_as_uid_gid(argv[1], O_RDONLY, getuid(), getgid());
  45         }
  46         msg = xmalloc_read(fd, NULL);
  47         if (ENABLE_FEATURE_CLEAN_UP && argv[1])
  48                 close(fd);
  49         setutxent();
  50         while ((ut = getutxent()) != NULL) {
  51                 char *line;
  52                 if (ut->ut_type != USER_PROCESS)
  53                         continue;
  54                 line = concat_path_file("/dev", ut->ut_line);
  55                 xopen_xwrite_close(line, msg);
  56                 free(line);
  57         }
  58         if (ENABLE_FEATURE_CLEAN_UP) {
  59                 endutxent();
  60                 free(msg);
  61         }
  62         return EXIT_SUCCESS;
  63 }