1/* vi: set sw=4 ts=4: */ 2/* 3 * openvt.c - open a vt to run a command. 4 * 5 * busyboxed by Quy Tonthat <quy@signal3.com> 6 * hacked by Tito <farmatito@tiscali.it> 7 * 8 * Licensed under GPLv2 or later, see file LICENSE in this source tree. 9 */ 10//config:config OPENVT 11//config: bool "openvt (7.2 kb)" 12//config: default y 13//config: help 14//config: This program is used to start a command on an unused 15//config: virtual terminal. 16 17//applet:IF_OPENVT(APPLET(openvt, BB_DIR_USR_BIN, BB_SUID_DROP)) 18 19//kbuild:lib-$(CONFIG_OPENVT) += openvt.o 20 21//usage:#define openvt_trivial_usage 22//usage: "[-c N] [-sw] [PROG ARGS]" 23//usage:#define openvt_full_usage "\n\n" 24//usage: "Start PROG on a new virtual terminal\n" 25//usage: "\n -c N Use specified VT" 26//usage: "\n -s Switch to the VT" 27/* //usage: "\n -l Run PROG as login shell (by prepending '-')" */ 28//usage: "\n -w Wait for PROG to exit" 29//usage: 30//usage:#define openvt_example_usage 31//usage: "openvt 2 /bin/ash\n" 32 33#include <linux/vt.h> 34#include "libbb.h" 35 36/* "Standard" openvt's man page (we do not support all of this): 37 38openvt [-c NUM] [-fsulv] [--] [command [args]] 39 40Find the first available VT, and run command on it. Stdio is directed 41to that VT. If no command is specified then $SHELL is used. 42 43-c NUM 44 Use the given VT number, not the first free one. 45-f 46 Force opening a VT: don't try to check if VT is already in use. 47-s 48 Switch to the new VT when starting the command. 49 The VT of the new command will be made the new current VT. 50-u 51 Figure out the owner of the current VT, and run login as that user. 52 Suitable to be called by init. Shouldn't be used with -c or -l. 53-l 54 Make the command a login shell: a "-" is prepended to the argv[0] 55 when command is executed. 56-v 57 Verbose. 58-w 59 Wait for command to complete. If -w and -s are used together, 60 switch back to the controlling terminal when the command completes. 61 62bbox: 63-u: not implemented 64-f: always in effect 65-l: not implemented, ignored 66-v: ignored 67-ws: does NOT switch back 68*/ 69 70/* Helper: does this fd understand VT_xxx? */ 71static int not_vt_fd(int fd) 72{ 73 struct vt_stat vtstat; 74 return ioctl(fd, VT_GETSTATE, &vtstat); /* !0: error, it's not VT fd */ 75} 76 77/* Helper: get a fd suitable for VT_xxx */ 78static int get_vt_fd(void) 79{ 80 int fd; 81 82 /* Do we, by chance, already have it? */ 83 for (fd = 0; fd < 3; fd++) 84 if (!not_vt_fd(fd)) 85 return fd; 86 fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK); 87 if (fd >= 0 && !not_vt_fd(fd)) 88 return fd; 89 bb_simple_error_msg_and_die("can't find open VT"); 90} 91 92static int find_free_vtno(void) 93{ 94 int vtno; 95 int fd = get_vt_fd(); 96 97 errno = 0; 98 /*xfunc_error_retval = 3; - do we need compat? */ 99 if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0) 100 bb_simple_perror_msg_and_die("can't find open VT"); 101// Not really needed, grep for DAEMON_CLOSE_EXTRA_FDS 102// if (fd > 2) 103// close(fd); 104 return vtno; 105} 106 107/* vfork scares gcc, it generates bigger code. 108 * Keep it away from main program. 109 * TODO: move to libbb; or adapt existing libbb's spawn(). 110 */ 111static NOINLINE void vfork_child(char **argv) 112{ 113 if (vfork() == 0) { 114 /* CHILD */ 115 /* Try to make this VT our controlling tty */ 116 setsid(); /* lose old ctty */ 117 ioctl(STDIN_FILENO, TIOCSCTTY, 0 /* 0: don't forcibly steal */); 118 //bb_error_msg("our sid %d", getsid(0)); 119 //bb_error_msg("our pgrp %d", getpgrp()); 120 //bb_error_msg("VT's sid %d", tcgetsid(0)); 121 //bb_error_msg("VT's pgrp %d", tcgetpgrp(0)); 122 BB_EXECVP_or_die(argv); 123 } 124} 125 126int openvt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 127int openvt_main(int argc UNUSED_PARAM, char **argv) 128{ 129 char vtname[sizeof(VC_FORMAT) + sizeof(int)*3]; 130 struct vt_stat vtstat; 131 char *str_c; 132 int vtno; 133 int flags; 134 enum { 135 OPT_c = (1 << 0), 136 OPT_w = (1 << 1), 137 OPT_s = (1 << 2), 138 OPT_l = (1 << 3), 139 OPT_f = (1 << 4), 140 OPT_v = (1 << 5), 141 }; 142 143 /* "+" - stop on first non-option */ 144 flags = getopt32(argv, "+c:wslfv", &str_c); 145 argv += optind; 146 147 if (flags & OPT_c) { 148 /* Check for illegal vt number: < 1 or > 63 */ 149 vtno = xatou_range(str_c, 1, 63); 150 } else { 151 vtno = find_free_vtno(); 152 } 153 154 /* Grab new VT */ 155 sprintf(vtname, VC_FORMAT, vtno); 156 /* (Try to) clean up stray open fds above fd 2 */ 157 bb_daemon_helper(DAEMON_CLOSE_EXTRA_FDS); 158 close(STDIN_FILENO); 159 /*setsid(); - BAD IDEA: after we exit, child is SIGHUPed... */ 160 xopen(vtname, O_RDWR); 161 xioctl(STDIN_FILENO, VT_GETSTATE, &vtstat); 162 163 if (flags & OPT_s) { 164 console_make_active(STDIN_FILENO, vtno); 165 } 166 167 if (!argv[0]) { 168 argv--; 169 argv[0] = (char *) get_shell_name(); 170 /*argv[1] = NULL; - already is */ 171 } 172 173 xdup2(STDIN_FILENO, STDOUT_FILENO); 174 xdup2(STDIN_FILENO, STDERR_FILENO); 175 176#ifdef BLOAT 177 { 178 /* Handle -l (login shell) option */ 179 const char *prog = argv[0]; 180 if (flags & OPT_l) 181 argv[0] = xasprintf("-%s", argv[0]); 182 } 183#endif 184 185 vfork_child(argv); 186 if (flags & OPT_w) { 187 /* We have only one child, wait for it */ 188 safe_waitpid(-1, NULL, 0); /* loops on EINTR */ 189 if (flags & OPT_s) { 190 console_make_active(STDIN_FILENO, vtstat.v_active); 191 // Compat: even with -c N (try to) disallocate: 192 // # /usr/app/kbd-1.12/bin/openvt -f -c 9 -ws sleep 5 193 // openvt: could not deallocate console 9 194 xioctl(STDIN_FILENO, VT_DISALLOCATE, (void*)(ptrdiff_t)vtno); 195 } 196 } 197 return EXIT_SUCCESS; 198} 199