* client (C wrapper) connects to server
* (including reading ack byte)
* if fails or garbage
- * === acquire lock ===
- * makes new listening socket
- * makes first-instance socketpair
- * makes watcher pipes
+ * === acquires lock ===
+ * makes new listening socket
+ * makes watcher pipes
* forks watcher and awaits
+ * makes first-instance socketpair
* forks setup (script, sock fds indicated in env)
* fd0, fd1, fd2: from-outer
* other fd: call(client-end)(fake)
* starts watch on socket path
* sets stderr to line buffered
* sets stdin to nonblocking
- * daemonises
+ * daemonises (one fork, becomes session leader)
* when socket stat changes, quit
*
* setup (pre-exec) fd0: null,
*
* server (pm) [1] [fd0: null],
* [fd[12]: fd2-from-outer]
+ * setsid
* right away, forks init monitor
* [2] closes outer caller fds and call(fake)
* [server (pm)] fd[012]: null
#include <arpa/inet.h>
+#include <uv.h>
+
#include "prefork.h"
const char our_name[] = "prefork-interp";
}
static int laundering;
+static struct stat initial_stab;
const struct cmdinfo cmdinfos[]= {
PREFORK_CMDINFOS
return 0;
}
+static void watcher_cb_stdin(uv_poll_t *handle, int status, int events) {
+ char c;
+ int r;
+
+ if ((errno = -status)) diee("watcher: poll stdin");
+ for (;;) {
+ r= read(0, &c, 1);
+ if (r!=-1) _exit(0);
+ if (!(errno==EINTR || errno==EWOULDBLOCK || errno==EAGAIN))
+ diee("watcher: read sentinel stdin");
+ }
+}
+
+static void watcher_cb_sockpath(uv_fs_event_t *handle, const char *filename,
+ int events, int status) {
+ int r;
+ struct stat now_stab;
+
+ if ((errno = -status)) diee("watcher: poll stdin");
+ for (;;) {
+ r= stat(socket_path, &now_stab);
+ if (r==-1) {
+ if (errno==ENOENT) _exit(0);
+ if (errno==EINTR) continue;
+ diee("stat socket: %s", socket_path);
+ }
+ if (!(now_stab.st_dev == initial_stab.st_dev &&
+ now_stab.st_ino == initial_stab.st_ino))
+ _exit(0);
+ }
+}
+
+// On entry, stderr is still inherited, but 0 and 1 are the pipes
+static __attribute__((noreturn))
+void become_watcher(void) {
+ uv_loop_t loop;
+ uv_poll_t uvhandle_stdin;
+ uv_fs_event_t uvhandle_sockpath;
+ int r;
+
+ if (fcntl(0, F_SETFL, O_NONBLOCK)) diee("watcher set stdin nonblocking");
+
+ errno= -uv_loop_init(&loop);
+ if (errno) diee("watcher: uv_loop_init");
+
+ errno= -uv_poll_init(&loop, &uvhandle_stdin, 0);
+ if (errno) diee("watcher: uv_poll_init");
+ errno= -uv_poll_start(&uvhandle_stdin,
+ UV_READABLE | UV_WRITABLE | UV_DISCONNECT,
+ watcher_cb_stdin);
+ if (errno) diee("watcher: uv_poll_start");
+
+ errno= -uv_fs_event_init(&loop, &uvhandle_sockpath);
+ if (errno) diee("watcher: uv_fs_event_init");
+
+ errno= -uv_fs_event_start(&uvhandle_sockpath, watcher_cb_sockpath,
+ socket_path, 0);
+ if (errno) diee("watcher: uv_fs_event_start");
+
+ // OK everything is set up, let us daemonise
+ if (dup2(1,2) != 2) diee("watcher: set daemonised stderr");
+ r= setvbuf(stderr, 0, _IOLBF, BUFSIZ);
+ if (r) diee("watcher: setvbuf stderr");
+
+ pid_t child = fork();
+ if (child == (pid_t)-1) diee("watcher: fork");
+ if (child) _exit(0);
+
+ if (setsid() == (pid_t)-1) diee("watcher: setsid");
+
+ r= uv_run(&loop, UV_RUN_DEFAULT);
+ die("uv_run returned (%d)", r);
+}
+
static __attribute__((noreturn))
-void become_setup(int sfd, int fake_pair[2]) {
+void become_setup(int sfd, int fake_pair[2],
+ int watcher_stdin, int watcher_stderr) {
close(fake_pair[0]);
int call_fd = fake_pair[1];
// next to "v1". Simple extension can be done by having the script
// side say something about it in the ack xdata, which we currently ignore.
putenv(m_asprintf("PREFORK_INTERP=v1 %d,%d %s",
- sfd, call_fd, socket_path));
+ sfd, call_fd, socket_path, watcher_stdin, watcher_stderr));
execvp(executor_argv[0], (char**)executor_argv);
diee("execute %s", executor_argv[0]);
r= bind(sfd, (const struct sockaddr*)&sockaddr_sun, salen);
if (r<0) diee("bind() on new listener");
+ r= stat(socket_path, &initial_stab);
+ if (r<0) diee("stat() fresh socket");
+
// We never want callers to get ECONNREFUSED. But:
// There is a race here: from my RTFM they may get ECONNREFUSED
// if they try between our bind() and listen(). But if they do, they'll
r = listen(sfd, INT_MAX);
if (r<0) diee("listen() for new listener");
+ // Fork watcher
+
+ int watcher_stdin[2];
+ int watcher_stderr[2];
+ if (pipe(watcher_stdin) || pipe(watcher_stderr))
+ diee("pipe() for socket inode watcher");
+
+ pid_t watcher = fork();
+ if (watcher == (pid_t)-1) diee("fork for watcher");
+ if (!watcher) {
+ close(sfd);
+ close(lockfd);
+ close(watcher_stdin[1]);
+ close(watcher_stderr[0]);
+ if (dup2(watcher_stdin[0], 0) != 0 ||
+ dup2(watcher_stderr[1], 1) != 0)
+ diee("initial dup2() for watcher");
+ close(watcher_stdin[0]);
+ close(watcher_stderr[1]);
+ become_watcher();
+ }
+
+ close(watcher_stdin[0]);
+ close(watcher_stderr[1]);
+ if (fcntl(watcher_stderr[0], F_SETFL, O_NONBLOCK))
+ diee("parent set watcher stderr nonblocking");
+
+ // Fork setup
+
int fake_pair[2];
r = socketpair(AF_UNIX, SOCK_STREAM, 0, fake_pair);
if (r<0) diee("socketpair() for fake initial connection");
pid_t setup_pid = fork();
if (setup_pid == (pid_t)-1) diee("fork for spawn setup");
- if (!setup_pid) become_setup(sfd, fake_pair);
+ if (!setup_pid) become_setup(sfd, fake_pair,
+ watcher_stdin[1], watcher_stderr[0]);
close(fake_pair[1]);
close(sfd);
~ian / chiark-utils.git / commitdiff