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: select PLATFORM_LINUX 14//config: help 15//config: This program is used to start a command on an unused 16//config: virtual terminal. 17 18//applet:IF_OPENVT(APPLET(openvt, BB_DIR_USR_BIN, BB_SUID_DROP)) 19 20//kbuild:lib-$(CONFIG_OPENVT) += openvt.o 21 22//usage:#define openvt_trivial_usage 23//usage: "[-c N] [-sw] [PROG ARGS]" 24//usage:#define openvt_full_usage "\n\n" 25//usage: "Start PROG on a new virtual terminal\n" 26//usage: "\n -c N Use specified VT" 27//usage: "\n -s Switch to the VT" 28/* //usage: "\n -l Run PROG as login shell (by prepending '-')" */ 29//usage: "\n -w Wait for PROG to exit" 30//usage: 31//usage:#define openvt_example_usage 32//usage: "openvt 2 /bin/ash\n" 33 34#include <linux/vt.h> 35#include "libbb.h" 36 37/* "Standard" openvt's man page (we do not support all of this): 38 39openvt [-c NUM] [-fsulv] [--] [command [args]] 40 41Find the first available VT, and run command on it. Stdio is directed 42to that VT. If no command is specified then $SHELL is used. 43 44-c NUM 45 Use the given VT number, not the first free one. 46-f 47 Force opening a VT: don't try to check if VT is already in use. 48-s 49 Switch to the new VT when starting the command. 50 The VT of the new command will be made the new current VT. 51-u 52 Figure out the owner of the current VT, and run login as that user. 53 Suitable to be called by init. Shouldn't be used with -c or -l. 54-l 55 Make the command a login shell: a "-" is prepended to the argv[0] 56 when command is executed. 57-v 58 Verbose. 59-w 60 Wait for command to complete. If -w and -s are used together, 61 switch back to the controlling terminal when the command completes. 62 63bbox: 64-u: not implemented 65-f: always in effect 66-l: not implemented, ignored 67-v: ignored 68-ws: does NOT switch back 69*/ 70 71/* Helper: does this fd understand VT_xxx? */ 72static int not_vt_fd(int fd) 73{ 74 struct vt_stat vtstat; 75 return ioctl(fd, VT_GETSTATE, &vtstat); /* !0: error, it's not VT fd */ 76} 77 78/* Helper: get a fd suitable for VT_xxx */ 79static int get_vt_fd(void) 80{ 81 int fd; 82 83 /* Do we, by chance, already have it? */ 84 for (fd = 0; fd < 3; fd++) 85 if (!not_vt_fd(fd)) 86 return fd; 87 fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK); 88 if (fd >= 0 && !not_vt_fd(fd)) 89 return fd; 90 bb_error_msg_and_die("can't find open VT"); 91} 92 93static int find_free_vtno(void) 94{ 95 int vtno; 96 int fd = get_vt_fd(); 97 98 errno = 0; 99 /*xfunc_error_retval = 3; - do we need compat? */ 100 if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0) 101 bb_perror_msg_and_die("can't find open VT"); 102// Not really needed, grep for DAEMON_CLOSE_EXTRA_FDS 103// if (fd > 2) 104// close(fd); 105 return vtno; 106} 107 108/* vfork scares gcc, it generates bigger code. 109 * Keep it away from main program. 110 * TODO: move to libbb; or adapt existing libbb's spawn(). 111 */ 112static NOINLINE void vfork_child(char **argv) 113{ 114 if (vfork() == 0) { 115 /* CHILD */ 116 /* Try to make this VT our controlling tty */ 117 setsid(); /* lose old ctty */ 118 ioctl(STDIN_FILENO, TIOCSCTTY, 0 /* 0: don't forcibly steal */); 119 //bb_error_msg("our sid %d", getsid(0)); 120 //bb_error_msg("our pgrp %d", getpgrp()); 121 //bb_error_msg("VT's sid %d", tcgetsid(0)); 122 //bb_error_msg("VT's pgrp %d", tcgetpgrp(0)); 123 BB_EXECVP_or_die(argv); 124 } 125} 126 127int openvt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 128int openvt_main(int argc UNUSED_PARAM, char **argv) 129{ 130 char vtname[sizeof(VC_FORMAT) + sizeof(int)*3]; 131 struct vt_stat vtstat; 132 char *str_c; 133 int vtno; 134 int flags; 135 enum { 136 OPT_c = (1 << 0), 137 OPT_w = (1 << 1), 138 OPT_s = (1 << 2), 139 OPT_l = (1 << 3), 140 OPT_f = (1 << 4), 141 OPT_v = (1 << 5), 142 }; 143 144 /* "+" - stop on first non-option */ 145 flags = getopt32(argv, "+c:wslfv", &str_c); 146 argv += optind; 147 148 if (flags & OPT_c) { 149 /* Check for illegal vt number: < 1 or > 63 */ 150 vtno = xatou_range(str_c, 1, 63); 151 } else { 152 vtno = find_free_vtno(); 153 } 154 155 /* Grab new VT */ 156 sprintf(vtname, VC_FORMAT, vtno); 157 /* (Try to) clean up stray open fds above fd 2 */ 158 bb_daemon_helper(DAEMON_CLOSE_EXTRA_FDS); 159 close(STDIN_FILENO); 160 /*setsid(); - BAD IDEA: after we exit, child is SIGHUPed... */ 161 xopen(vtname, O_RDWR); 162 xioctl(STDIN_FILENO, VT_GETSTATE, &vtstat); 163 164 if (flags & OPT_s) { 165 console_make_active(STDIN_FILENO, vtno); 166 } 167 168 if (!argv[0]) { 169 argv--; 170 argv[0] = (char *) get_shell_name(); 171 /*argv[1] = NULL; - already is */ 172 } 173 174 xdup2(STDIN_FILENO, STDOUT_FILENO); 175 xdup2(STDIN_FILENO, STDERR_FILENO); 176 177#ifdef BLOAT 178 { 179 /* Handle -l (login shell) option */ 180 const char *prog = argv[0]; 181 if (flags & OPT_l) 182 argv[0] = xasprintf("-%s", argv[0]); 183 } 184#endif 185 186 vfork_child(argv); 187 if (flags & OPT_w) { 188 /* We have only one child, wait for it */ 189 safe_waitpid(-1, NULL, 0); /* loops on EINTR */ 190 if (flags & OPT_s) { 191 console_make_active(STDIN_FILENO, vtstat.v_active); 192 // Compat: even with -c N (try to) disallocate: 193 // # /usr/app/kbd-1.12/bin/openvt -f -c 9 -ws sleep 5 194 // openvt: could not deallocate console 9 195 xioctl(STDIN_FILENO, VT_DISALLOCATE, (void*)(ptrdiff_t)vtno); 196 } 197 } 198 return EXIT_SUCCESS; 199} 200