cttyhack: new applet.

1 files changed, 73 insertions, 0 deletions

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]);
+}