/*
* 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>
*
* 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>
#endif
#include <fcntl.h>
#include <dirent.h>
#include <unistd.h>
#include "c.h"
#include "canonicalize.h"
#include "consoles.h"
#ifdef __linux__
# include <linux/major.h>
#endif
#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))
/*
* Read and allocate one line from file,
* the caller has to free the result
*/
static __attribute__((__nonnull__))
char *oneline(const char *file)
{
FILE *fp;
char *ret = NULL;
size_t len = 0;
if (!(fp = fopen(file, "re")))
return NULL;
if (getline(&ret, &len, fp) >= 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 *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 *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 characer device in `dev_t comparedev' variable.
*/
static
#ifdef __GNUC__
__attribute__((__nonnull__,__malloc__,__hot__))
#endif
char* scandev(DIR *dir, dev_t comparedev)
{
char *name = NULL;
struct dirent *dent;
int fd;
fd = dirfd(dir);
rewinddir(dir);
while ((dent = readdir(dir))) {
char path[PATH_MAX];
struct stat st;
if (fstatat(fd, dent->d_name, &st, 0) < 0)
continue;
if (!S_ISCHR(st.st_mode))
continue;
if (comparedev != st.st_rdev)
continue;
if ((size_t)snprintf(path, sizeof(path), "/dev/%s", dent->d_name) >= sizeof(path))
continue;
name = canonicalize_path(path);
break;
}
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__((__nonnull__,__hot__))
#endif
int append_console(struct console **list, char * name)
{
static const struct chardata initcp = {
.erase = CERASE,
.kill = CKILL,
.eol = CTRL('r'),
.parity = 0
};
struct console *restrict tail;
struct console *last;
if (posix_memalign((void*)&tail, sizeof(void*), alignof(typeof(struct console))) != 0)
return -ENOMEM;
for (last = *list; last && last->next; last = last->next);
tail->next = NULL;
tail->tty = name;
tail->file = (FILE*)0;
tail->flags = 0;
tail->fd = -1;
tail->id = last ? last->id + 1 : 0;
tail->pid = 0;
memset(&tail->tio, 0, sizeof(tail->tio));
memcpy(&tail->cp, &initcp, sizeof(struct chardata));
if (!last)
*list = tail;
else
last->next = tail;
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 console **consoles)
{
char fbuf[16 + 1];
DIR *dir = NULL;
FILE *fc = NULL;
int maj, min, rc = 1;
fc = fopen("/proc/consoles", "re");
if (!fc)
return 2;
dir = opendir("/dev");
if (!dir)
goto done;
while (fscanf(fc, "%*s %*s (%16[^)]) %d:%d", fbuf, &maj, &min) == 3) {
char *name;
dev_t comparedev;
if (!strchr(fbuf, 'E'))
continue;
comparedev = makedev(maj, min);
name = scandev(dir, comparedev);
if (!name)
continue;
rc = append_console(consoles, name);
if (rc < 0)
goto done;
}
rc = *consoles ? 0 : 1;
done:
if (dir)
closedir(dir);
if (fc)
fclose(fc);
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 console **consoles)
{
char *attrib = NULL, *words, *token;
DIR *dir = NULL;
int rc = 1;
attrib = actattr("console");
if (!attrib)
return 2;
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);
if (rc < 0)
goto done;
}
rc = *consoles ? 0 : 1;
done:
free(attrib);
if (dir)
closedir(dir);
return rc;
}
static int detect_consoles_from_cmdline(struct console **consoles)
{
char *cmdline, *words, *token;
dev_t comparedev;
DIR *dir;
int rc = 1, fd;
cmdline = oneline("/proc/cmdline");
if (!cmdline)
return 2;
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);
if (rc < 0)
goto done;
}
rc = *consoles ? 0 : 1;
done:
if (dir)
closedir(dir);
free(cmdline);
return rc;
}
#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, int fallback, struct console **consoles)
{
int fd, reconnect = 0, rc;
dev_t comparedev = 0;
if (!device || !*device)
fd = dup(fallback);
else {
fd = open(device, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC);
reconnect = 1;
}
if (fd >= 0) {
DIR *dir;
char *name;
struct stat st;
#ifdef TIOCGDEV
unsigned int devnum;
#endif
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);
if (name) {
rc = append_console(consoles, name);
if (rc < 0)
return rc;
}
closedir(dir);
if (!*consoles)
goto fallback;
return reconnect;
}
#ifdef __linux__
console:
/*
* Detection of devices used for Linux system consolei 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 */
if (rc == 1)
goto fallback; /* detection 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 */
if (rc == 1)
goto fallback; /* detection 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 */
if (rc == 1)
goto fallback; /* detection error */
/*
* Detection of the device used for Linux system console using
* the ioctl TIOCGDEV if available (e.g. official 2.6.38).
*/
if (!*consoles) {
#ifdef TIOCGDEV
unsigned int devnum;
const char *name;
if (!device || *device == '\0')
fd = dup(fallback);
else fd = open(device, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC);
if (fd < 0)
goto fallback;
if (ioctl (fd, TIOCGDEV, &devnum) < 0) {
close(fd);
goto fallback;
}
comparedev = (dev_t)devnum;
close(fd);
if (device && *device != '\0')
name = device;
else name = ttyname(fallback);
if (!name)
name = "/dev/tty1";
rc = append_console(consoles, strdup(name));
if (rc < 0)
return rc;
if (*consoles) {
if (!device || *device == '\0')
(*consoles)->fd = fallback;
return reconnect;
}
#endif
goto fallback;
}
return reconnect;
#endif /* __linux __ */
fallback:
if (fallback >= 0) {
const char *name;
if (device && *device != '\0')
name = device;
else name = ttyname(fallback);
if (!name)
name = "/dev/tty";
rc = append_console(consoles, strdup(name));
if (rc < 0)
return rc;
if (*consoles)
(*consoles)->fd = fallback;
}
return reconnect;
}
#ifdef TEST_PROGRAM
int main(int argc, char *argv[])
{
char *name = NULL;
int fd, re;
struct console *p, *consoles = NULL;
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);
re = detect_consoles(name, fd, &consoles);
for (p = consoles; p; p = p->next)
printf("%s: id=%d %s\n", p->tty, p->id, re ? "(reconnect) " : "");
return 0;
}
#endif