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unix: make uv_tty_reset_mode() async signal-safe

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Make it possible to call uv_tty_reset_mode() from inside a signal
handler.  The primary motivation is to make it possible to restore
the TTY from inside a SIGINT or SIGTERM signal handler.

Fixes #954.
This commit is contained in:
Ben Noordhuis 2013-10-18 16:23:57 +02:00
parent 372e9229ad
commit 777019b768
3 changed files with 27 additions and 8 deletions
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5
include/uv.h
View File

@ -1074,8 +1074,11 @@ UV_EXTERN int uv_tty_set_mode(uv_tty_t*, int mode);
/*
* To be called when the program exits. Resets TTY settings to default
* values for the next process to take over.
*
* This function is async signal-safe on UNIX platforms but can fail with error
* code UV_EBUSY if you call it when execution is inside uv_tty_set_mode().
*/
UV_EXTERN void uv_tty_reset_mode(void);
UV_EXTERN int uv_tty_reset_mode(void);
/*
* Gets the current Window size. On success zero is returned.

26
src/unix/tty.c
View File

@ -21,6 +21,7 @@
#include "uv.h"
#include "internal.h"
#include "spinlock.h"
#include <assert.h>
#include <unistd.h>
@ -28,9 +29,9 @@
#include <errno.h>
#include <sys/ioctl.h>
static int orig_termios_fd = -1;
static struct termios orig_termios;
static uv_spinlock_t termios_spinlock = UV_SPINLOCK_INITIALIZER;
int uv_tty_init(uv_loop_t* loop, uv_tty_t* tty, int fd, int readable) {
@ -69,10 +70,12 @@ int uv_tty_set_mode(uv_tty_t* tty, int mode) {
return -errno;
/* This is used for uv_tty_reset_mode() */
uv_spinlock_lock(&termios_spinlock);
if (orig_termios_fd == -1) {
orig_termios = tty->orig_termios;
orig_termios_fd = fd;
}
uv_spinlock_unlock(&termios_spinlock);
raw = tty->orig_termios;
raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
@ -161,8 +164,21 @@ uv_handle_type uv_guess_handle(uv_file file) {
}
void uv_tty_reset_mode(void) {
if (orig_termios_fd >= 0) {
tcsetattr(orig_termios_fd, TCSANOW, &orig_termios);
}
/* This function is async signal-safe, meaning that it's safe to call from
* inside a signal handler _unless_ execution was inside uv_tty_set_mode()'s
* critical section when the signal was raised.
*/
int uv_tty_reset_mode(void) {
int err;
if (!uv_spinlock_trylock(&termios_spinlock))
return -EBUSY; /* In uv_tty_set_mode(). */
err = 0;
if (orig_termios_fd != -1)
if (tcsetattr(orig_termios_fd, TCSANOW, &orig_termios))
err = -errno;
uv_spinlock_unlock(&termios_spinlock);
return err;
}

4
src/win/tty.c
View File

@ -1866,7 +1866,7 @@ void uv_process_tty_connect_req(uv_loop_t* loop, uv_tty_t* handle,
}
void uv_tty_reset_mode(void) {
int uv_tty_reset_mode(void) {
/* Not necessary to do anything. */
;
return 0;
}