blob: facb1ffbbd174f0d0945e7b3887c73591194e9b0 [file] [log] [blame]
/*
* consoles.c Routines to detect the system consoles
*
* Copyright (c) 2011 SuSE LINUX Products GmbH, All rights reserved.
* Copyright (C) 2012 Karel Zak <kzak@redhat.com>
* Copyright (C) 2012 Werner Fink <werner@suse.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING); if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
* MA 02110-1301, USA.
*
* Author: Werner Fink <werner@suse.de>
*/
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#ifdef __linux__
# include <sys/vt.h>
# include <sys/kd.h>
# include <linux/serial.h>
# include <linux/major.h>
#endif
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#ifdef USE_SULOGIN_EMERGENCY_MOUNT
# include <sys/mount.h>
# include <linux/fs.h>
# include <linux/magic.h>
# ifndef MNT_DETACH
# define MNT_DETACH 2
# endif
#endif
#include "c.h"
#include "canonicalize.h"
#include "sulogin-consoles.h"
#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
# ifndef typeof
# define typeof __typeof__
# endif
# ifndef restrict
# define restrict __restrict__
# endif
#endif
#define alignof(type) ((sizeof(type)+(sizeof(void*)-1)) & ~(sizeof(void*)-1))
#define strsize(string) (strlen((string))+1)
static int consoles_debug;
#define DBG(x) do { \
if (consoles_debug) { \
fputs("consoles debug: ", stderr); \
x; \
} \
} while (0)
static inline void __attribute__ ((__format__ (__printf__, 1, 2)))
dbgprint(const char * const mesg, ...)
{
va_list ap;
va_start(ap, mesg);
vfprintf(stderr, mesg, ap);
va_end(ap);
fputc('\n', stderr);
}
#ifdef USE_SULOGIN_EMERGENCY_MOUNT
/*
* Make C library standard calls such like ttyname(3) work
* even if the system does not show any of the standard
* directories.
*/
static uint32_t emergency_flags;
# define MNT_PROCFS 0x0001
# define MNT_DEVTMPFS 0x0002
void emergency_do_umounts(void)
{
if (emergency_flags & MNT_DEVTMPFS)
umount2("/dev", MNT_DETACH);
if (emergency_flags & MNT_PROCFS)
umount2("/proc", MNT_DETACH);
}
void emergency_do_mounts(void)
{
struct stat rt, xt;
if (emergency_flags) {
emergency_flags = 0;
return;
}
if (stat("/", &rt) != 0) {
warn("cannot get file status of root file system\n");
return;
}
if (stat("/proc", &xt) == 0
&& rt.st_dev == xt.st_dev
&& mount("proc", "/proc", "proc", MS_RELATIME, NULL) == 0)
emergency_flags |= MNT_PROCFS;
if (stat("/dev", &xt) == 0
&& rt.st_dev == xt.st_dev
&& mount("devtmpfs", "/dev", "devtmpfs",
MS_RELATIME, "mode=0755,nr_inodes=0") == 0) {
emergency_flags |= MNT_DEVTMPFS;
mknod("/dev/console", S_IFCHR|S_IRUSR|S_IWUSR,
makedev(TTYAUX_MAJOR, 1));
if (symlink("/proc/self/fd", "/dev/fd") == 0) {
ignore_result( symlink("fd/0", "/dev/stdin") );
ignore_result( symlink("fd/1", "/dev/stdout") );
ignore_result( symlink("fd/2", "/dev/stderr") );
}
}
}
#else /* !USE_SULOGIN_EMERGENCY_MOUNT */
void emergency_do_umounts(void) { }
void emergency_do_mounts(void) { }
#endif /* USE_SULOGIN_EMERGENCY_MOUNT */
/*
* Read and allocate one line from file,
* the caller has to free the result
*/
static __attribute__((__nonnull__))
char *oneline(const char * const file)
{
FILE *fp;
char *ret = NULL;
size_t dummy = 0;
ssize_t len;
DBG(dbgprint("reading %s", file));
if (!(fp = fopen(file, "r" UL_CLOEXECSTR)))
return NULL;
len = getline(&ret, &dummy, fp);
if (len >= 0) {
char *nl;
if (len)
ret[len-1] = '\0';
if ((nl = strchr(ret, '\n')))
*nl = '\0';
}
fclose(fp);
return ret;
}
#ifdef __linux__
/*
* Read and determine active attribute for tty below
* /sys/class/tty, the caller has to free the result.
*/
static __attribute__((__malloc__))
char *actattr(const char * const tty)
{
char *ret, *path;
if (!tty || !*tty)
return NULL;
if (asprintf(&path, "/sys/class/tty/%s/active", tty) < 0)
return NULL;
ret = oneline(path);
free(path);
return ret;
}
/*
* Read and determine device attribute for tty below
* /sys/class/tty.
*/
static
dev_t devattr(const char * const tty)
{
dev_t dev = 0;
char *path, *value;
if (!tty || !*tty)
return 0;
if (asprintf(&path, "/sys/class/tty/%s/dev", tty) < 0)
return 0;
value = oneline(path);
if (value) {
unsigned int maj, min;
if (sscanf(value, "%u:%u", &maj, &min) == 2)
dev = makedev(maj, min);
free(value);
}
free(path);
return dev;
}
#endif /* __linux__ */
/*
* Search below /dev for the character device in `dev_t comparedev' variable.
* Note that realpath(3) is used here to avoid not existent devices due the
* strdup(3) used in our canonicalize_path()!
*/
static
#ifdef __GNUC__
__attribute__((__nonnull__,__malloc__,__hot__))
#endif
char* scandev(DIR *dir, const dev_t comparedev)
{
char path[PATH_MAX];
char *name = NULL;
const struct dirent *dent;
int len, fd;
DBG(dbgprint("scanning /dev for %u:%u", major(comparedev), minor(comparedev)));
/*
* Try udev links on character devices first.
*/
if ((len = snprintf(path, sizeof(path),
"/dev/char/%u:%u", major(comparedev), minor(comparedev))) > 0 &&
(size_t)len < sizeof(path)) {
name = realpath(path, NULL);
if (name)
goto out;
}
fd = dirfd(dir);
rewinddir(dir);
while ((dent = readdir(dir))) {
struct stat st;
#ifdef _DIRENT_HAVE_D_TYPE
if (dent->d_type != DT_UNKNOWN && dent->d_type != DT_CHR)
continue;
#endif
if (fstatat(fd, dent->d_name, &st, 0) < 0)
continue;
if (!S_ISCHR(st.st_mode))
continue;
if (comparedev != st.st_rdev)
continue;
if ((len = snprintf(path, sizeof(path), "/dev/%s", dent->d_name)) < 0 ||
(size_t)len >= sizeof(path))
continue;
name = realpath(path, NULL);
if (name)
goto out;
}
#ifdef USE_SULOGIN_EMERGENCY_MOUNT
/*
* There was no /dev mounted hence and no device was found hence we create our own.
*/
if (!name && (emergency_flags & MNT_DEVTMPFS)) {
if ((len = snprintf(path, sizeof(path),
"/dev/tmp-%u:%u", major(comparedev), minor(comparedev))) < 0 ||
(size_t)len >= sizeof(path))
goto out;
if (mknod(path, S_IFCHR|S_IRUSR|S_IWUSR, comparedev) < 0 && errno != EEXIST)
goto out;
name = realpath(path, NULL);
}
#endif
out:
return name;
}
/*
* Default control characters for an unknown terminal line.
*/
/*
* Allocate an aligned `struct console' memory area,
* initialize its default values, and append it to
* the global linked list.
*/
static
#ifdef __GNUC__
__attribute__((__hot__))
#endif
int append_console(struct list_head *consoles, const char * const name)
{
struct console *restrict tail;
const struct console *last = NULL;
DBG(dbgprint("appending %s", name));
if (!list_empty(consoles))
last = list_last_entry(consoles, struct console, entry);
if (posix_memalign((void *) &tail, sizeof(void *),
alignof(struct console) + strsize(name)) != 0)
return -ENOMEM;
INIT_LIST_HEAD(&tail->entry);
INIT_CHARDATA(&tail->cp);
list_add_tail(&tail->entry, consoles);
tail->tty = ((char *) tail) + alignof(struct console);
strcpy(tail->tty, name);
tail->file = (FILE*)0;
tail->flags = 0;
tail->fd = -1;
tail->id = last ? last->id + 1 : 0;
tail->pid = -1;
memset(&tail->tio, 0, sizeof(tail->tio));
return 0;
}
#ifdef __linux__
/*
* return codes:
* < 0 - fatal error (no mem or so... )
* 0 - success
* 1 - recoverable error
* 2 - detection not available
*/
static int detect_consoles_from_proc(struct list_head *consoles)
{
char fbuf[16 + 1];
DIR *dir = NULL;
FILE *fc = NULL;
int maj, min, rc = 1, matches;
DBG(dbgprint("trying /proc"));
fc = fopen("/proc/consoles", "r" UL_CLOEXECSTR);
if (!fc) {
rc = 2;
goto done;
}
dir = opendir("/dev");
if (!dir)
goto done;
while ((matches = fscanf(fc, "%*s %*s (%16[^)]) %d:%d", fbuf, &maj, &min)) >= 1) {
char *name;
dev_t comparedev;
if (matches != 3)
continue;
if (!strchr(fbuf, 'E'))
continue;
comparedev = makedev(maj, min);
name = scandev(dir, comparedev);
if (!name)
continue;
rc = append_console(consoles, name);
free(name);
if (rc < 0)
goto done;
}
rc = list_empty(consoles) ? 1 : 0;
done:
if (dir)
closedir(dir);
if (fc)
fclose(fc);
DBG(dbgprint("[/proc rc=%d]", rc));
return rc;
}
/*
* return codes:
* < 0 - fatal error (no mem or so... )
* 0 - success
* 1 - recoverable error
* 2 - detection not available
*/
static int detect_consoles_from_sysfs(struct list_head *consoles)
{
char *attrib = NULL, *words, *token;
DIR *dir = NULL;
int rc = 1;
DBG(dbgprint("trying /sys"));
attrib = actattr("console");
if (!attrib) {
rc = 2;
goto done;
}
words = attrib;
dir = opendir("/dev");
if (!dir)
goto done;
while ((token = strsep(&words, " \t\r\n"))) {
char *name;
dev_t comparedev;
if (*token == '\0')
continue;
comparedev = devattr(token);
if (comparedev == makedev(TTY_MAJOR, 0)) {
char *tmp = actattr(token);
if (!tmp)
continue;
comparedev = devattr(tmp);
free(tmp);
}
name = scandev(dir, comparedev);
if (!name)
continue;
rc = append_console(consoles, name);
free(name);
if (rc < 0)
goto done;
}
rc = list_empty(consoles) ? 1 : 0;
done:
free(attrib);
if (dir)
closedir(dir);
DBG(dbgprint("[/sys rc=%d]", rc));
return rc;
}
static int detect_consoles_from_cmdline(struct list_head *consoles)
{
char *cmdline, *words, *token;
dev_t comparedev;
DIR *dir = NULL;
int rc = 1, fd;
DBG(dbgprint("trying kernel cmdline"));
cmdline = oneline("/proc/cmdline");
if (!cmdline) {
rc = 2;
goto done;
}
words= cmdline;
dir = opendir("/dev");
if (!dir)
goto done;
while ((token = strsep(&words, " \t\r\n"))) {
#ifdef TIOCGDEV
unsigned int devnum;
#else
struct vt_stat vt;
struct stat st;
#endif
char *colon, *name;
if (*token != 'c')
continue;
if (strncmp(token, "console=", 8) != 0)
continue;
token += 8;
if (strcmp(token, "brl") == 0)
token += 4;
if ((colon = strchr(token, ',')))
*colon = '\0';
if (asprintf(&name, "/dev/%s", token) < 0)
continue;
if ((fd = open(name, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC)) < 0) {
free(name);
continue;
}
free(name);
#ifdef TIOCGDEV
if (ioctl (fd, TIOCGDEV, &devnum) < 0) {
close(fd);
continue;
}
comparedev = (dev_t) devnum;
#else
if (fstat(fd, &st) < 0) {
close(fd);
continue;
}
comparedev = st.st_rdev;
if (comparedev == makedev(TTY_MAJOR, 0)) {
if (ioctl(fd, VT_GETSTATE, &vt) < 0) {
close(fd);
continue;
}
comparedev = makedev(TTY_MAJOR, (int)vt.v_active);
}
#endif
close(fd);
name = scandev(dir, comparedev);
if (!name)
continue;
rc = append_console(consoles, name);
free(name);
if (rc < 0)
goto done;
}
rc = list_empty(consoles) ? 1 : 0;
done:
if (dir)
closedir(dir);
free(cmdline);
DBG(dbgprint("[kernel cmdline rc=%d]", rc));
return rc;
}
#ifdef TIOCGDEV
static int detect_consoles_from_tiocgdev(struct list_head *consoles,
const int fallback,
const char *device)
{
unsigned int devnum;
char *name;
int rc = 1, fd = -1;
dev_t comparedev;
DIR *dir = NULL;
struct console *console;
DBG(dbgprint("trying tiocgdev"));
if (!device || !*device)
fd = dup(fallback);
else
fd = open(device, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
goto done;
if (ioctl (fd, TIOCGDEV, &devnum) < 0)
goto done;
comparedev = (dev_t) devnum;
dir = opendir("/dev");
if (!dir)
goto done;
name = scandev(dir, comparedev);
closedir(dir);
if (!name) {
name = (char *) (device && *device ? device : ttyname(fallback));
if (!name)
name = "/dev/tty1";
name = strdup(name);
if (!name) {
rc = -ENOMEM;
goto done;
}
}
rc = append_console(consoles, name);
free(name);
if (rc < 0)
goto done;
if (list_empty(consoles)) {
rc = 1;
goto done;
}
console = list_last_entry(consoles, struct console, entry);
if (console && (!device || !*device))
console->fd = fallback;
done:
if (fd >= 0)
close(fd);
DBG(dbgprint("[tiocgdev rc=%d]", rc));
return rc;
}
#endif /* TIOCGDEV */
#endif /* __linux__ */
/*
* Try to detect the real device(s) used for the system console
* /dev/console if but only if /dev/console is used. On Linux
* this can be more than one device, e.g. a serial line as well
* as a virtual console as well as a simple printer.
*
* Returns 1 if stdout and stderr should be reconnected and 0
* otherwise or less than zero on error.
*/
int detect_consoles(const char *device, const int fallback, struct list_head *consoles)
{
int fd, reconnect = 0, rc;
dev_t comparedev = 0;
consoles_debug = getenv("CONSOLES_DEBUG") ? 1 : 0;
if (!device || !*device)
fd = fallback >= 0 ? dup(fallback) : - 1;
else {
fd = open(device, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC);
reconnect = 1;
}
DBG(dbgprint("detection started [device=%s, fallback=%d]",
device, fallback));
if (fd >= 0) {
DIR *dir;
char *name;
struct stat st;
#ifdef TIOCGDEV
unsigned int devnum;
#endif
#ifdef __GNU__
/*
* The Hurd always gives st_rdev as 0, which causes this
* method to select the first terminal it finds.
*/
close(fd);
goto fallback;
#endif
DBG(dbgprint("trying device/fallback file descriptor"));
if (fstat(fd, &st) < 0) {
close(fd);
goto fallback;
}
comparedev = st.st_rdev;
if (reconnect &&
(fstat(fallback, &st) < 0 || comparedev != st.st_rdev))
dup2(fd, fallback);
#ifdef __linux__
/*
* Check if the device detection for Linux system console should be used.
*/
if (comparedev == makedev(TTYAUX_MAJOR, 0)) { /* /dev/tty */
close(fd);
device = "/dev/tty";
goto fallback;
}
if (comparedev == makedev(TTYAUX_MAJOR, 1)) { /* /dev/console */
close(fd);
goto console;
}
if (comparedev == makedev(TTYAUX_MAJOR, 2)) { /* /dev/ptmx */
close(fd);
device = "/dev/tty";
goto fallback;
}
if (comparedev == makedev(TTY_MAJOR, 0)) { /* /dev/tty0 */
struct vt_stat vt;
if (ioctl(fd, VT_GETSTATE, &vt) < 0) {
close(fd);
goto fallback;
}
comparedev = makedev(TTY_MAJOR, (int)vt.v_active);
}
#endif
#ifdef TIOCGDEV
if (ioctl (fd, TIOCGDEV, &devnum) < 0) {
close(fd);
goto fallback;
}
comparedev = (dev_t)devnum;
#endif
close(fd);
dir = opendir("/dev");
if (!dir)
goto fallback;
name = scandev(dir, comparedev);
closedir(dir);
if (name) {
rc = append_console(consoles, name);
free(name);
if (rc < 0)
return rc;
}
if (list_empty(consoles))
goto fallback;
DBG(dbgprint("detection success [rc=%d]", reconnect));
return reconnect;
}
#ifdef __linux__
console:
/*
* Detection of devices used for Linux system console using
* the /proc/consoles API with kernel 2.6.38 and higher.
*/
rc = detect_consoles_from_proc(consoles);
if (rc == 0)
return reconnect; /* success */
if (rc < 0)
return rc; /* fatal error */
/*
* Detection of devices used for Linux system console using
* the sysfs /sys/class/tty/ API with kernel 2.6.37 and higher.
*/
rc = detect_consoles_from_sysfs(consoles);
if (rc == 0)
return reconnect; /* success */
if (rc < 0)
return rc; /* fatal error */
/*
* Detection of devices used for Linux system console using
* kernel parameter on the kernels command line.
*/
rc = detect_consoles_from_cmdline(consoles);
if (rc == 0)
return reconnect; /* success */
if (rc < 0)
return rc; /* fatal error */
/*
* Detection of the device used for Linux system console using
* the ioctl TIOCGDEV if available (e.g. official 2.6.38).
*/
#ifdef TIOCGDEV
rc = detect_consoles_from_tiocgdev(consoles, fallback, device);
if (rc == 0)
return reconnect; /* success */
if (rc < 0)
return rc; /* fatal error */
#endif
if (!list_empty(consoles)) {
DBG(dbgprint("detection success [rc=%d]", reconnect));
return reconnect;
}
#endif /* __linux __ */
fallback:
if (fallback >= 0) {
const char *name;
char *n;
struct console *console;
if (device && *device != '\0')
name = device;
else name = ttyname(fallback);
if (!name)
name = "/dev/tty";
n = strdup(name);
if (!n)
return -ENOMEM;
rc = append_console(consoles, n);
free(n);
if (rc < 0)
return rc;
if (list_empty(consoles))
return 1;
console = list_last_entry(consoles, struct console, entry);
if (console)
console->fd = fallback;
}
DBG(dbgprint("detection done by fallback [rc=%d]", reconnect));
return reconnect;
}
#ifdef TEST_PROGRAM
int main(int argc, char *argv[])
{
char *name = NULL;
int fd, re;
struct list_head *p, consoles;
if (argc == 2) {
name = argv[1];
fd = open(name, O_RDWR);
} else {
name = ttyname(STDIN_FILENO);
fd = STDIN_FILENO;
}
if (!name)
errx(EXIT_FAILURE, "usage: %s [<tty>]\n", program_invocation_short_name);
INIT_LIST_HEAD(&consoles);
re = detect_consoles(name, fd, &consoles);
list_for_each(p, &consoles) {
struct console *c = list_entry(p, struct console, entry);
printf("%s: id=%d %s\n", c->tty, c->id, re ? "(reconnect) " : "");
}
return 0;
}
#endif