| 0,0 → 1,159 |
|---|
| /* |
| * esh - the 'extensible' shell. |
| * |
| * Utility functions for system calls. |
| * |
| * Developed by Godmar Back for CS 3214 Fall 2009 |
| * Virginia Tech. |
| */ |
| |
| #include <termios.h> |
| #include <stdio.h> |
| #include <errno.h> |
| #include <string.h> |
| #include <stdarg.h> |
| #include <unistd.h> |
| #include <fcntl.h> |
| #include <stdlib.h> |
| #include <signal.h> |
| #include <assert.h> |
| |
| #include "esh-sys-utils.h" |
| |
| static const char rcsid [] = "$Id: esh-sys-utils.c,v 1.4 2011/01/21 20:13:06 cs3214 Exp $"; |
| |
| /* Utility function for esh_sys_fatal_error and esh_sys_error */ |
| static void |
| vesh_sys_error(char *fmt, va_list ap) |
| { |
| char errmsg[1024]; |
| |
| strerror_r(errno, errmsg, sizeof errmsg); |
| vfprintf(stderr, fmt, ap); |
| fprintf(stderr, "%s\n", errmsg); |
| } |
| |
| /* Print information about the last syscall error */ |
| void |
| esh_sys_error(char *fmt, ...) |
| { |
| va_list ap; |
| va_start(ap, fmt); |
| vesh_sys_error(fmt, ap); |
| va_end(ap); |
| } |
| |
| /* Print information about the last syscall error and then exit */ |
| void |
| esh_sys_fatal_error(char *fmt, ...) |
| { |
| va_list ap; |
| va_start(ap, fmt); |
| vesh_sys_error(fmt, ap); |
| va_end(ap); |
| exit(EXIT_FAILURE); |
| } |
| |
| static int terminal_fd = -1; /* the controlling terminal */ |
| static struct termios saved_tty_state; /* the state of the terminal when shell |
| was started. */ |
| |
| /* Initialize tty support. Return pointer to saved initial terminal state */ |
| struct termios * |
| esh_sys_tty_init(void) |
| { |
| char *tty; |
| assert(terminal_fd == -1 || !!!"esh_sys_tty_init already called"); |
| |
| terminal_fd = open(tty = ctermid(NULL), O_RDWR); |
| if (terminal_fd == -1) |
| esh_sys_fatal_error("opening controlling terminal %s failed: ", tty); |
| |
| esh_sys_tty_save(&saved_tty_state); |
| return &saved_tty_state; |
| } |
| |
| /* Save current terminal settings. |
| * This function is used when a job is suspended.*/ |
| void |
| esh_sys_tty_save(struct termios *saved_tty_state) |
| { |
| int rc = tcgetattr(terminal_fd, saved_tty_state); |
| if (rc == -1) |
| esh_sys_fatal_error("tcgetattr failed: "); |
| } |
| |
| /* Restore terminal to saved settings. |
| * This function is used when resuming a suspended job. */ |
| void |
| esh_sys_tty_restore(struct termios *saved_tty_state) |
| { |
| int rc = tcsetattr(terminal_fd, TCSADRAIN, saved_tty_state); |
| if (rc == -1) |
| esh_sys_fatal_error("could not restore tty attributes tcsetattr: "); |
| } |
| |
| /* Get a file descriptor that refers to controlling terminal */ |
| int |
| esh_sys_tty_getfd(void) |
| { |
| assert(terminal_fd != -1 || !!!"esh_sys_tty_init() must be called"); |
| return terminal_fd; |
| } |
| |
| /* Return true if this signal is blocked */ |
| bool |
| esh_signal_is_blocked(int sig) |
| { |
| sigset_t mask; |
| if (sigprocmask(0, NULL, &mask) == -1) |
| esh_sys_error("sigprocmask failed while retrieving current mask"); |
| |
| return sigismember(&mask, sig); |
| } |
| |
| /* Helper for esh_signal_block and esh_signal_unblock */ |
| static bool |
| __mask_signal(int sig, int how) |
| { |
| sigset_t mask, omask; |
| sigemptyset(&mask); |
| sigaddset(&mask, sig); |
| if (sigprocmask(how, &mask, &omask) != 0) |
| esh_sys_error("sigprocmask failed for %d/%d", sig, how); |
| return sigismember(&omask, sig); |
| } |
| |
| /* Block a signal. Returns true it was blocked before */ |
| bool |
| esh_signal_block(int sig) |
| { |
| return __mask_signal(sig, SIG_BLOCK); |
| } |
| |
| /* Unblock a signal. Returns true it was blocked before */ |
| bool |
| esh_signal_unblock(int sig) |
| { |
| return __mask_signal(sig, SIG_UNBLOCK); |
| } |
| |
| /* Install signal handler for signal 'sig' */ |
| void |
| esh_signal_sethandler(int sig, sa_sigaction_t handler) |
| { |
| sigset_t emptymask; |
| |
| sigemptyset(&emptymask); |
| struct sigaction sa = { |
| .sa_sigaction = handler, |
| /* do not block any additional signals (besides 'sig') when |
| * signal handler is entered. */ |
| .sa_mask = emptymask, |
| /* restart system calls when possible */ |
| .sa_flags = SA_RESTART | SA_SIGINFO |
| }; |
| |
| if (sigaction(sig, &sa, NULL) != 0) |
| esh_sys_fatal_error("sigaction failed for signal %d", sig); |
| } |