156840c24
Alexander Shishkin
2011-10-31
Subject
cttyhack: print detected ctty name when called without parameters
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shell/cttyhack.c+42 -34
| @@ -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); | |
| } | |