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/*
* iexec.c: run a program and restart on file change
*
* Copyright (c) 2017, Přemysl Eric Janouch <p@janouch.name>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "config.h"
#undef PROGRAM_NAME
#define PROGRAM_NAME "iexec"
#include "liberty/liberty.c"
// This can also work on BSD if someone puts in the effort to support kqueue
#include <sys/inotify.h>
static pid_t g_child;
static bool g_restarting = false;
static int g_inotify_fd, g_inotify_wd;
static void
handle_file_change (const char *base)
{
char buf[4096]; ssize_t len; const struct inotify_event *e;
while ((len = read (g_inotify_fd, buf, sizeof buf)) > 0)
for (char *ptr = buf; ptr < buf + len; ptr += sizeof *e + e->len)
{
e = (const struct inotify_event *) buf;
if (e->wd != g_inotify_wd || strcmp (e->name, base))
continue;
print_debug ("file changed, killing child");
g_restarting = true;
if (kill (g_child, SIGINT))
print_error ("kill: %s", strerror (errno));
}
}
static void
spawn (char *argv[])
{
if ((g_child = fork ()) == -1)
exit_fatal ("fork: %s", strerror (errno));
else if (g_child)
return;
// A linker can create spurious CLOSE_WRITEs, wait until it's executable
while (1)
{
execvp (argv[0], argv);
print_error ("execvp: %s", strerror (errno));
sleep (1);
}
}
static bool
check_child_death (char *argv[])
{
if (waitpid (g_child, NULL, WNOHANG) != g_child)
return true;
if (!g_restarting)
{
print_debug ("child died on its own, not respawning");
return false;
}
else
{
print_debug ("child died on request, respawning");
spawn (argv);
g_restarting = false;
return true;
}
}
static void
sigchld_handler (int signum)
{
// We need to have this handler so that pselect() can return EINTR
(void) signum;
}
int
main (int argc, char *argv[])
{
static const struct opt opts[] =
{
{ 'd', "debug", NULL, 0, "run in debug mode" },
{ 'h', "help", NULL, 0, "display this help and exit" },
{ 'V', "version", NULL, 0, "output version information and exit" },
{ 0, NULL, NULL, 0, NULL }
};
struct opt_handler oh = opt_handler_make (argc, argv, opts,
"PROGRAM [ARG...]", "Run a program and restart on file change.");
// We have to turn that off as it causes more trouble than what it's worth
cstr_set (&oh.opt_string, xstrdup_printf ("+%s", oh.opt_string));
int c;
while ((c = opt_handler_get (&oh)) != -1)
switch (c)
{
case 'd':
g_debug_mode = true;
break;
case 'h':
opt_handler_usage (&oh, stdout);
exit (EXIT_SUCCESS);
case 'V':
printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
exit (EXIT_SUCCESS);
default:
print_error ("wrong options");
opt_handler_usage (&oh, stderr);
exit (EXIT_FAILURE);
}
if (argc == optind)
{
opt_handler_usage (&oh, stderr);
exit (EXIT_FAILURE);
}
opt_handler_free (&oh);
argc -= optind;
argv += optind;
(void) signal (SIGPIPE, SIG_IGN);
struct sigaction sa = { .sa_handler = sigchld_handler };
sigemptyset (&sa.sa_mask);
if (sigaction (SIGCHLD, &sa, NULL))
exit_fatal ("sigaction: %s", strerror (errno));
sigset_t chld, orig;
sigemptyset (&chld);
sigaddset (&chld, SIGCHLD);
if (sigprocmask (SIG_BLOCK, &chld, &orig))
exit_fatal ("sigprocmask: %s", strerror (errno));
char *path = xstrdup (argv[0]);
if ((g_inotify_fd = inotify_init1 (IN_NONBLOCK)) < 0)
exit_fatal ("inotify_init1: %s", strerror (errno));
if ((g_inotify_wd = inotify_add_watch (g_inotify_fd,
dirname (path), IN_MOVED_TO | IN_CLOSE_WRITE)) < 0)
exit_fatal ("inotify_add_watch: %s", strerror (errno));
free (path);
char *base = basename ((path = xstrdup (argv[0])));
spawn (argv);
do
{
fd_set r; FD_SET (g_inotify_fd, &r);
(void) pselect (g_inotify_fd + 1, &r, NULL, NULL, NULL, &orig);
handle_file_change (base);
}
while (check_child_death (argv));
free (path);
close (g_inotify_fd);
return EXIT_SUCCESS;
}
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