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authorDenys Vlasenko <vda.linux@googlemail.com>2011-10-31 15:57:04 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2011-10-31 15:57:04 (GMT)
commitf8a5b792ba3cb0d11531902a04600fc274dff69e (patch)
tree69dbd76a465a225db03b4b5fa44be49f4ac78cda
parent156840c249ddf761d9e60b06ca6d8aaa1bf88402 (diff)
downloadbusybox-f8a5b792ba3cb0d11531902a04600fc274dff69e.tar.gz
busybox-f8a5b792ba3cb0d11531902a04600fc274dff69e.tar.bz2
cttyhack: move /sys/class/tty/console/active check to the front
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--shell/cttyhack.c31
1 files changed, 18 insertions, 13 deletions
diff --git a/shell/cttyhack.c b/shell/cttyhack.c
index 640f5b1..6ff8674 100644
--- a/shell/cttyhack.c
+++ b/shell/cttyhack.c
@@ -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);
@@ -131,18 +148,6 @@ int cttyhack_main(int argc UNUSED_PARAM, char **argv)
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';
} while (0);