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terminal-unix: make stop/cont sighandlers pipe based

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there are currently some silly data-races in the stop/cont sighandler
due to the fact that the signal handler might get invoked in a different
thread.

this changes those sighandlers to a pipe-based approach similar to the
existing "quit" sighandler.
This commit is contained in:
NRK 2023-10-09 03:41:39 +06:00 committed by sfan5
parent c2d0a4a80f
commit fa9e1f06ff
1 changed files with 37 additions and 16 deletions
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53
osdep/terminal-unix.c
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@ -272,8 +272,8 @@ static void process_input(struct input_ctx *input_ctx, bool timeout)
read_more: ; /* need more bytes */
}
static volatile int getch2_active = 0;
static volatile int getch2_enabled = 0;
static int getch2_active = 0;
static int getch2_enabled = 0;
static bool read_terminal;
static void enable_kx(bool enable)
@ -349,10 +349,16 @@ static void getch2_poll(void)
do_deactivate_getch2();
}
static pthread_t input_thread;
static struct input_ctx *input_ctx;
static int death_pipe[2] = {-1, -1};
enum { PIPE_STOP, PIPE_CONT };
static int stop_cont_pipe[2] = {-1, -1};
static void stop_sighandler(int signum)
{
int saved_errno = errno;
do_deactivate_getch2();
(void)write(stop_cont_pipe[1], &(char){PIPE_STOP}, 1);
errno = saved_errno;
// note: for this signal, we use SA_RESETHAND but do NOT mask signals
@ -366,20 +372,22 @@ static void continue_sighandler(int signum)
// SA_RESETHAND has reset SIGTSTP, so we need to restore it here
setsigaction(SIGTSTP, stop_sighandler, SA_RESETHAND, false);
getch2_poll();
(void)write(stop_cont_pipe[1], &(char){PIPE_CONT}, 1);
errno = saved_errno;
}
static pthread_t input_thread;
static struct input_ctx *input_ctx;
static int death_pipe[2] = {-1, -1};
static void safe_close(int *p)
{
if (*p >= 0)
close(*p);
*p = -1;
}
static void close_death_pipe(void)
static void close_sig_pipes(void)
{
for (int n = 0; n < 2; n++) {
if (death_pipe[n] >= 0)
close(death_pipe[n]);
death_pipe[n] = -1;
safe_close(&death_pipe[n]);
safe_close(&stop_cont_pipe[n]);
}
}
@ -404,8 +412,9 @@ static void *terminal_thread(void *ptr)
bool stdin_ok = read_terminal; // if false, we still wait for SIGTERM
while (1) {
getch2_poll();
struct pollfd fds[2] = {
struct pollfd fds[3] = {
{ .events = POLLIN, .fd = death_pipe[0] },
{ .events = POLLIN, .fd = stop_cont_pipe[0] },
{ .events = POLLIN, .fd = tty_in }
};
/*
@ -419,12 +428,20 @@ static void *terminal_thread(void *ptr)
* care of it so it's fine.
*/
bool is_fg = tcgetpgrp(tty_in) == getpgrp();
int r = polldev(fds, stdin_ok && is_fg ? 2 : 1, buf.len ? ESC_TIMEOUT : INPUT_TIMEOUT);
int r = polldev(fds, stdin_ok && is_fg ? 3 : 2, buf.len ? ESC_TIMEOUT : INPUT_TIMEOUT);
if (fds[0].revents) {
do_deactivate_getch2();
break;
}
if (fds[1].revents) {
if (fds[1].revents & POLLIN) {
int8_t c = -1;
read(stop_cont_pipe[0], &c, 1);
if (c == PIPE_STOP)
do_deactivate_getch2();
else if (c == PIPE_CONT)
getch2_poll();
}
if (fds[2].revents) {
int retval = read(tty_in, &buf.b[buf.len], BUF_LEN - buf.len);
if (!retval || (retval == -1 && errno != EINTR && errno != EAGAIN && errno != EIO))
break; // EOF/closed
@ -454,6 +471,10 @@ void terminal_setup_getch(struct input_ctx *ictx)
if (mp_make_wakeup_pipe(death_pipe) < 0)
return;
if (mp_make_wakeup_pipe(stop_cont_pipe) < 0) {
close_sig_pipes();
return;
}
// Disable reading from the terminal even if stdout is not a tty, to make
// mpv ... | less
@ -464,7 +485,7 @@ void terminal_setup_getch(struct input_ctx *ictx)
if (pthread_create(&input_thread, NULL, terminal_thread, NULL)) {
input_ctx = NULL;
close_death_pipe();
close_sig_pipes();
close_tty();
return;
}
@ -491,7 +512,7 @@ void terminal_uninit(void)
if (input_ctx) {
(void)write(death_pipe[1], &(char){0}, 1);
pthread_join(input_thread, NULL);
close_death_pipe();
close_sig_pipes();
input_ctx = NULL;
}