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cttyhack: move /sys/class/tty/console/active check to the front

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2011-10-31 16:57:04 +01:00
parent 156840c249
commit f8a5b792ba
1 changed files with 18 additions and 13 deletions
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31
shell/cttyhack.c
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@ -117,7 +117,24 @@ int cttyhack_main(int argc UNUSED_PARAM, char **argv)
/* We don't have ctty (or don't have "/dev/tty" node...) */
do {
#ifdef __linux__
int s;
/* Note that this method does not use _stdin_.
* Thus, "cttyhack </dev/something" can't be used.
* However, this method is more reliable than
* TIOCGSERIAL check, which assumes that all
* serial lines follow /dev/ttySn convention -
* which is not always the case.
* Therefore, we use this methos first:
*/
int s = open_read_close("/sys/class/tty/console/active",
console + 5, sizeof(console) - 5);
if (s > 0) {
/* found active console via sysfs (Linux 2.6.38+)
* sysfs string looks like "ttyS0\n" so zap the newline:
*/
console[4 + s] = '\0';
break;
}
if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
/* this is linux virtual tty */
sprintf(console + 8, "S%u" + 1, (int)u.vt.v_active);
@ -130,18 +147,6 @@ int cttyhack_main(int argc UNUSED_PARAM, char **argv)
sprintf(console + 8, "S%u", (int)u.sr.line);
break;
}
#endif
#ifdef __linux__
/* Note that this method is not related to _stdin_ */
s = open_read_close("/sys/class/tty/console/active",
console + 5, sizeof(console) - 5);
if (s > 0) {
/* found active console via sysfs (Linux 2.6.38+)
* sysfs string looks like "ttyS0\n" so zap the newline:
*/
console[4 + s] = '\0';
break;
}
#endif
/* nope, could not find it */
console[0] = '\0';