diff options
Diffstat (limited to 'shell')
| -rw-r--r-- | shell/Config.in | 20 | ||||
| -rw-r--r-- | shell/Kbuild | 2 | ||||
| -rw-r--r-- | shell/cttyhack.c | 73 |
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]); +} |