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path: root/console-tools/openvt.c (plain)
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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"
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_ONLY_SANITIZE
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_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS | DAEMON_ONLY_SANITIZE, NULL);
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
generated by cgit at 2024-05-15 09:03:36 (GMT)