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-rw-r--r--shell/Config.in20
-rw-r--r--shell/Kbuild2
-rw-r--r--shell/cttyhack.c73
3 files changed, 95 insertions, 0 deletions
diff --git a/shell/Config.in b/shell/Config.in
index 027993483..253752bc3 100644
--- a/shell/Config.in
+++ b/shell/Config.in
@@ -270,4 +270,24 @@ config FEATURE_SH_STANDALONE
# that exact location with that exact name, this option will not work at
# all.
+config CTTYHACK
+ bool "cttyhack"
+ default n
+ help
+ One common problem reported on the mailing list is "can't access tty;
+ job control turned off" error message which typically appears when
+ one tries to use shell with stdin/stdout opened to /dev/console.
+ This device is special - it cannot be a controlling tty.
+
+ Proper solution is to use correct device instead of /dev/console.
+
+ cttyhack provides "quick and dirty" solution to this problem.
+ It analyzes stdin with various ioctls, trying to determine whether
+ it is a /dev/ttyN or /dev/ttySN (virtual terminal or serial line).
+ If it detects one, it closes stdin/out/err and reopens that device.
+ Then it executes given program. Usage example for /etc/inittab
+ (for busybox init):
+
+ ::respawn:/bin/cttyhack /bin/sh
+
endmenu
diff --git a/shell/Kbuild b/shell/Kbuild
index 6b58040fc..944eaff51 100644
--- a/shell/Kbuild
+++ b/shell/Kbuild
@@ -9,3 +9,5 @@ lib-$(CONFIG_ASH) += ash.o
lib-$(CONFIG_HUSH) += hush.o
lib-$(CONFIG_LASH) += lash.o
lib-$(CONFIG_MSH) += msh.o
+
+lib-$(CONFIG_CTTYHACK) += cttyhack.o
diff --git a/shell/cttyhack.c b/shell/cttyhack.c
new file mode 100644
index 000000000..cdd0ed1d6
--- /dev/null
+++ b/shell/cttyhack.c
@@ -0,0 +1,73 @@
+/* This code is adapted from busybox project
+ *
+ * Licensed under GPLv2
+ */
+#include "libbb.h"
+
+/* From <linux/vt.h> */
+struct vt_stat {
+ unsigned short v_active; /* active vt */
+ unsigned short v_signal; /* signal to send */
+ unsigned short v_state; /* vt bitmask */
+};
+enum { VT_GETSTATE = 0x5603 }; /* get global vt state info */
+
+/* From <linux/serial.h> */
+struct serial_struct {
+ int type;
+ int line;
+ unsigned int port;
+ int irq;
+ int flags;
+ int xmit_fifo_size;
+ int custom_divisor;
+ int baud_base;
+ unsigned short close_delay;
+ char io_type;
+ char reserved_char[1];
+ int hub6;
+ unsigned short closing_wait; /* time to wait before closing */
+ unsigned short closing_wait2; /* no longer used... */
+ unsigned char *iomem_base;
+ unsigned short iomem_reg_shift;
+ unsigned int port_high;
+ unsigned long iomap_base; /* cookie passed into ioremap */
+ int reserved[1];
+};
+
+int cttyhack_main(int argc, char **argv) ATTRIBUTE_NORETURN;
+int cttyhack_main(int argc, char **argv)
+{
+ int fd;
+ char console[sizeof(int)*3 + 16];
+ union {
+ struct vt_stat vt;
+ struct serial_struct sr;
+ char paranoia[sizeof(struct serial_struct) * 3];
+ } u;
+
+ if (!*++argv) {
+ bb_show_usage();
+ }
+
+ strcpy(console, "/dev/tty");
+ if (ioctl(0, TIOCGSERIAL, &u.sr) == 0) {
+ /* this is a serial console */
+ sprintf(console + 8, "S%d", u.sr.line);
+ } else if (ioctl(0, VT_GETSTATE, &u.vt) == 0) {
+ /* this is linux virtual tty */
+ sprintf(console + 8, "S%d" + 1, u.vt.v_active);
+ }
+
+ if (console[8]) {
+ fd = xopen(console, O_RDWR);
+ //bb_error_msg("switching to '%s'", console);
+ dup2(fd, 0);
+ dup2(fd, 1);
+ dup2(fd, 2);
+ while (fd > 2) close(fd--);
+ }
+
+ execvp(argv[0], argv);
+ bb_perror_msg_and_die("cannot exec '%s'", argv[0]);
+}