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authorAlexander Shishkin <virtuoso@slind.org>2011-10-31 12:18:44 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2011-10-31 12:18:44 (GMT)
commit156840c249ddf761d9e60b06ca6d8aaa1bf88402 (patch)
tree927112b5656f671980e8db99d11cbb74a6457118
parentbcdae638752d5eac9185f69b88f49ed136cf39af (diff)
downloadbusybox-156840c249ddf761d9e60b06ca6d8aaa1bf88402.tar.gz
busybox-156840c249ddf761d9e60b06ca6d8aaa1bf88402.tar.bz2
cttyhack: print detected ctty name when called without parameters
Sometimes there's a need to figure out the controlling tty from a shell script, for example, to obtain a line for getty. In this case it's easier to call cttyhack than trying to repeat some of the cttyhack's logic. function old new delta cttyhack_main 283 327 +44 packed_usage 28911 28915 +4 Signed-off-by: Alexander Shishkin <virtuoso@slind.org> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--shell/cttyhack.c76
1 files changed, 42 insertions, 34 deletions
diff --git a/shell/cttyhack.c b/shell/cttyhack.c
index 6241c76..640f5b1 100644
--- a/shell/cttyhack.c
+++ b/shell/cttyhack.c
@@ -50,9 +50,12 @@
//config:
//config: # exec setsid sh -c 'exec sh </dev/tty1 >/dev/tty1 2>&1'
//config:
+//config: Starting getty on a controlling tty from a shell script:
+//config:
+//config: # getty 115200 $(cttyhack)
//usage:#define cttyhack_trivial_usage
-//usage: "PROG ARGS"
+//usage: "[PROG ARGS]"
//usage:#define cttyhack_full_usage "\n\n"
//usage: "Give PROG a controlling tty if possible."
//usage: "\nExample for /etc/inittab (for busybox init):"
@@ -108,61 +111,66 @@ int cttyhack_main(int argc UNUSED_PARAM, char **argv)
char paranoia[sizeof(struct serial_struct) * 3];
} u;
- if (!*++argv) {
- bb_show_usage();
- }
-
strcpy(console, "/dev/tty");
fd = open(console, O_RDWR);
- if (fd >= 0) {
- /* We already have ctty, nothing to do */
- close(fd);
- } else {
+ if (fd < 0) {
/* We don't have ctty (or don't have "/dev/tty" node...) */
do {
#ifdef __linux__
- 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;
- }
-
+ int s;
if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
/* this is linux virtual tty */
- sprintf(console + 8, "S%d" + 1, u.vt.v_active);
+ sprintf(console + 8, "S%u" + 1, (int)u.vt.v_active);
break;
}
#endif
#ifdef TIOCGSERIAL
if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
/* this is a serial console; assuming it is named /dev/ttySn */
- sprintf(console + 8, "S%d", u.sr.line);
+ 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 */
- goto ret;
+ console[0] = '\0';
} while (0);
+ }
+ argv++;
+ if (!argv[0]) {
+ if (!console[0])
+ return EXIT_FAILURE;
+ puts(console);
+ return EXIT_SUCCESS;
+ }
+
+ if (fd < 0) {
fd = open_or_warn(console, O_RDWR);
if (fd < 0)
goto ret;
- //bb_error_msg("switching to '%s'", console);
- dup2(fd, 0);
- dup2(fd, 1);
- dup2(fd, 2);
- while (fd > 2)
- close(fd--);
- /* Some other session may have it as ctty,
- * steal it from them:
- */
- ioctl(0, TIOCSCTTY, 1);
}
-
-ret:
+ //bb_error_msg("switching to '%s'", console);
+ dup2(fd, 0);
+ dup2(fd, 1);
+ dup2(fd, 2);
+ while (fd > 2)
+ close(fd--);
+ /* Some other session may have it as ctty,
+ * try to steal it from them:
+ */
+ ioctl(0, TIOCSCTTY, 1);
+ ret:
BB_EXECVP_or_die(argv);
}