busybox/console-tools/openvt.c

199 lines
5.1 KiB
C
Raw Permalink Normal View History

2002-09-16 08:46:06 +05:30
/* 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.
2002-09-16 08:46:06 +05:30
*/
//config:config OPENVT
//config: bool "openvt (7.2 kb)"
//config: default y
//config: help
//config: This program is used to start a command on an unused
//config: virtual terminal.
//applet:IF_OPENVT(APPLET(openvt, BB_DIR_USR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_OPENVT) += openvt.o
2002-09-16 08:46:06 +05:30
//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"
2002-09-16 08:46:06 +05:30
/* "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))
2008-04-22 05:46:29 +05:30
return fd;
fd = open(DEV_CONSOLE, O_RDONLY | O_NONBLOCK);
if (fd >= 0 && !not_vt_fd(fd))
return fd;
libbb: reduce the overhead of single parameter bb_error_msg() calls Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower overhead call to bb_perror_msg() when only a string was being printed with no parameters. This saves space for some CPU architectures because it avoids the overhead of a call to a variadic function. However there has never been a simple version of bb_error_msg(), and since 2007 many new calls to bb_perror_msg() have been added that only take a single parameter and so could have been using bb_simple_perror_message(). This changeset introduces 'simple' versions of bb_info_msg(), bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and bb_herror_msg_and_die(), and replaces all calls that only take a single parameter, or use something like ("%s", arg), with calls to the corresponding 'simple' version. Since it is likely that single parameter calls to the variadic functions may be accidentally reintroduced in the future a new debugging config option WARN_SIMPLE_MSG has been introduced. This uses some macro magic which will cause any such calls to generate a warning, but this is turned off by default to avoid use of the unpleasant macros in normal circumstances. This is a large changeset due to the number of calls that have been replaced. The only files that contain changes other than simple substitution of function calls are libbb.h, libbb/herror_msg.c, libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c, networking/udhcp/common.h and util-linux/mdev.c additonal macros have been added for logging so that single parameter and multiple parameter logging variants exist. The amount of space saved varies considerably by architecture, and was found to be as follows (for 'defconfig' using GCC 7.4): Arm: -92 bytes MIPS: -52 bytes PPC: -1836 bytes x86_64: -938 bytes Note that for the MIPS architecture only an exception had to be made disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h) because it made these files larger on MIPS. Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-07-02 15:05:03 +05:30
bb_simple_error_msg_and_die("can't find open VT");
}
static int find_free_vtno(void)
{
int vtno;
int fd = get_vt_fd();
2008-04-22 05:46:29 +05:30
errno = 0;
/*xfunc_error_retval = 3; - do we need compat? */
if (ioctl(fd, VT_OPENQRY, &vtno) != 0 || vtno <= 0)
libbb: reduce the overhead of single parameter bb_error_msg() calls Back in 2007, commit 0c97c9d43707 ("'simple' error message functions by Loic Grenie") introduced bb_simple_perror_msg() to allow for a lower overhead call to bb_perror_msg() when only a string was being printed with no parameters. This saves space for some CPU architectures because it avoids the overhead of a call to a variadic function. However there has never been a simple version of bb_error_msg(), and since 2007 many new calls to bb_perror_msg() have been added that only take a single parameter and so could have been using bb_simple_perror_message(). This changeset introduces 'simple' versions of bb_info_msg(), bb_error_msg(), bb_error_msg_and_die(), bb_herror_msg() and bb_herror_msg_and_die(), and replaces all calls that only take a single parameter, or use something like ("%s", arg), with calls to the corresponding 'simple' version. Since it is likely that single parameter calls to the variadic functions may be accidentally reintroduced in the future a new debugging config option WARN_SIMPLE_MSG has been introduced. This uses some macro magic which will cause any such calls to generate a warning, but this is turned off by default to avoid use of the unpleasant macros in normal circumstances. This is a large changeset due to the number of calls that have been replaced. The only files that contain changes other than simple substitution of function calls are libbb.h, libbb/herror_msg.c, libbb/verror_msg.c and libbb/xfuncs_printf.c. In miscutils/devfsd.c, networking/udhcp/common.h and util-linux/mdev.c additonal macros have been added for logging so that single parameter and multiple parameter logging variants exist. The amount of space saved varies considerably by architecture, and was found to be as follows (for 'defconfig' using GCC 7.4): Arm: -92 bytes MIPS: -52 bytes PPC: -1836 bytes x86_64: -938 bytes Note that for the MIPS architecture only an exception had to be made disabling the 'simple' calls for 'udhcp' (in networking/udhcp/common.h) because it made these files larger on MIPS. Signed-off-by: James Byrne <james.byrne@origamienergy.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2019-07-02 15:05:03 +05:30
bb_simple_perror_msg_and_die("can't find open VT");
// Not really needed, grep for DAEMON_CLOSE_EXTRA_FDS
// 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;
2008-07-05 14:48:54 +05:30
int openvt_main(int argc UNUSED_PARAM, char **argv)
2002-09-16 08:46:06 +05:30
{
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();
}
2002-09-16 08:46:06 +05:30
/* Grab new VT */
sprintf(vtname, VC_FORMAT, vtno);
/* (Try to) clean up stray open fds above fd 2 */
bb_daemon_helper(DAEMON_CLOSE_EXTRA_FDS);
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);
2002-09-16 08:46:06 +05:30
#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;
2002-09-16 08:46:06 +05:30
}