/* vi: set sw=4 ts=4: */ /* * openvt.c - open a vt to run a command. * * busyboxed by Quy Tonthat <quy@signal3.com> * hacked by Tito <farmatito@tiscali.it> * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ //usage:#define openvt_trivial_usage //usage: "[-c N] [-sw] [PROG ARGS]" //usage:#define openvt_full_usage "\n\n" //usage: "Start PROG on a new virtual terminal\n" //usage: "\n -c N Use specified VT" //usage: "\n -s Switch to the VT" /* //usage: "\n -l Run PROG as login shell (by prepending '-')" */ //usage: "\n -w Wait for PROG to exit" //usage: //usage:#define openvt_example_usage //usage: "openvt 2 /bin/ash\n" #include <linux/vt.h> #include "libbb.h" /* "Standard" openvt's man page (we do not support all of this): openvt [-c NUM] [-fsulv] [--] [command [args]] Find the first available VT, and run command on it. Stdio is directed to that VT. If no command is specified then $SHELL is used. -c NUM Use the given VT number, not the first free one. -f Force opening a VT: don't try to check if VT is already in use. -s Switch to the new VT when starting the command. The VT of the new command will be made the new current VT. -u Figure out the owner of the current VT, and run login as that user. Suitable to be called by init. Shouldn't be used with -c or -l. -l Make the command a login shell: a "-" is prepended to the argv[0] when command is executed. -v Verbose. -w Wait for command to complete. If -w and -s are used together, switch back to the controlling terminal when the command completes. bbox: -u: not implemented -f: always in effect -l: not implemented, ignored -v: ignored -ws: does NOT switch back */ /* Helper: does this fd understand VT_xxx? */ static int not_vt_fd(int fd) { struct vt_stat vtstat; return ioctl(fd, VT_GETSTATE, &vtstat); /* !0: error, it's not VT fd */ } /* Helper: get a fd suitable for VT_xxx */ static int get_vt_fd(void) { int fd; /* Do we, by chance, already have it? */ for (fd = 0; fd < 3; fd++) if (!not_vt_fd(fd)) return fd; fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK); if (fd >= 0 && !not_vt_fd(fd)) return fd; bb_error_msg_and_die("can't find open VT"); } static int find_free_vtno(void) { int vtno; int fd = get_vt_fd(); errno = 0; /*xfunc_error_retval = 3; - do we need compat? */ if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0) bb_perror_msg_and_die("can't find open VT"); // Not really needed, grep for DAEMON_ONLY_SANITIZE // if (fd > 2) // close(fd); return vtno; } /* vfork scares gcc, it generates bigger code. * Keep it away from main program. * TODO: move to libbb; or adapt existing libbb's spawn(). */ static NOINLINE void vfork_child(char **argv) { if (vfork() == 0) { /* CHILD */ /* Try to make this VT our controlling tty */ setsid(); /* lose old ctty */ ioctl(STDIN_FILENO, TIOCSCTTY, 0 /* 0: don't forcibly steal */); //bb_error_msg("our sid %d", getsid(0)); //bb_error_msg("our pgrp %d", getpgrp()); //bb_error_msg("VT's sid %d", tcgetsid(0)); //bb_error_msg("VT's pgrp %d", tcgetpgrp(0)); BB_EXECVP_or_die(argv); } } int openvt_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int openvt_main(int argc UNUSED_PARAM, char **argv) { char vtname[sizeof(VC_FORMAT) + sizeof(int)*3]; struct vt_stat vtstat; char *str_c; int vtno; int flags; enum { OPT_c = (1 << 0), OPT_w = (1 << 1), OPT_s = (1 << 2), OPT_l = (1 << 3), OPT_f = (1 << 4), OPT_v = (1 << 5), }; /* "+" - stop on first non-option */ flags = getopt32(argv, "+c:wslfv", &str_c); argv += optind; if (flags & OPT_c) { /* Check for illegal vt number: < 1 or > 63 */ vtno = xatou_range(str_c, 1, 63); } else { vtno = find_free_vtno(); } /* Grab new VT */ sprintf(vtname, VC_FORMAT, vtno); /* (Try to) clean up stray open fds above fd 2 */ bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS | DAEMON_ONLY_SANITIZE, NULL); close(STDIN_FILENO); /*setsid(); - BAD IDEA: after we exit, child is SIGHUPed... */ xopen(vtname, O_RDWR); xioctl(STDIN_FILENO, VT_GETSTATE, &vtstat); if (flags & OPT_s) { console_make_active(STDIN_FILENO, vtno); } if (!argv[0]) { argv--; argv[0] = (char *) get_shell_name(); /*argv[1] = NULL; - already is */ } xdup2(STDIN_FILENO, STDOUT_FILENO); xdup2(STDIN_FILENO, STDERR_FILENO); #ifdef BLOAT { /* Handle -l (login shell) option */ const char *prog = argv[0]; if (flags & OPT_l) argv[0] = xasprintf("-%s", argv[0]); } #endif vfork_child(argv); if (flags & OPT_w) { /* We have only one child, wait for it */ safe_waitpid(-1, NULL, 0); /* loops on EINTR */ if (flags & OPT_s) { console_make_active(STDIN_FILENO, vtstat.v_active); // Compat: even with -c N (try to) disallocate: // # /usr/app/kbd-1.12/bin/openvt -f -c 9 -ws sleep 5 // openvt: could not deallocate console 9 xioctl(STDIN_FILENO, VT_DISALLOCATE, (void*)(ptrdiff_t)vtno); } } return EXIT_SUCCESS; }