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commit 8e4ae12b4d0559a827f740f60b11f386f27f89dd
Author: nicm <nicm>
Date: Mon Jul 21 10:52:48 2014 +0000
lockf is entirely useless and it was a mistake to change to it, go back
to using flock which actually works sensibly. Also always retry the lock
to fix a potential race, and add some extra logging.
--- a/client.c
+++ b/client.c
@@ -78,13 +78,18 @@
if ((lockfd = open(lockfile, O_WRONLY|O_CREAT, 0600)) == -1)
fatal("open failed");
+ log_debug("lock file is %s", lockfile);
- if (lockf(lockfd, F_TLOCK, 0) == -1 && errno == EAGAIN) {
- while (lockf(lockfd, F_LOCK, 0) == -1 && errno == EINTR)
+ if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
+ log_debug("flock failed: %s", strerror(errno));
+ if (errno != EAGAIN)
+ return (lockfd);
+ while (flock(lockfd, LOCK_EX) == -1 && errno == EINTR)
/* nothing */;
close(lockfd);
return (-1);
}
+ log_debug("flock succeeded");
return (lockfd);
}
@@ -95,8 +100,8 @@
{
struct sockaddr_un sa;
size_t size;
- int fd, lockfd;
- char *lockfile;
+ int fd, lockfd = -1, locked = 0;
+ char *lockfile = NULL;
memset(&sa, 0, sizeof sa);
sa.sun_family = AF_UNIX;
@@ -105,29 +110,48 @@
errno = ENAMETOOLONG;
return (-1);
}
+ log_debug("socket is %s", path);
retry:
if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
fatal("socket failed");
+ log_debug("trying connect");
if (connect(fd, (struct sockaddr *) &sa, SUN_LEN(&sa)) == -1) {
+ log_debug("connect failed: %s", strerror(errno));
if (errno != ECONNREFUSED && errno != ENOENT)
goto failed;
if (!start_server)
goto failed;
close(fd);
- xasprintf(&lockfile, "%s.lock", path);
- if ((lockfd = client_get_lock(lockfile)) == -1) {
- free(lockfile);
+ if (!locked) {
+ xasprintf(&lockfile, "%s.lock", path);
+ if ((lockfd = client_get_lock(lockfile)) == -1) {
+ log_debug("didn't get lock");
+ free(lockfile);
+ goto retry;
+ }
+ log_debug("got lock");
+
+ /*
+ * Always retry at least once, even if we got the lock,
+ * because another client could have taken the lock,
+ * started the server and released the lock between our
+ * connect() and flock().
+ */
+ locked = 1;
goto retry;
}
+
if (unlink(path) != 0 && errno != ENOENT) {
free(lockfile);
close(lockfd);
return (-1);
}
fd = server_start(lockfd, lockfile);
+ }
+ if (locked) {
free(lockfile);
close(lockfd);
}
@@ -234,7 +234,13 @@
return (1);
}
- /* Initialise the client socket and start the server. */
+ /* Set process title, log and signals now this is the client. */
+#ifdef HAVE_SETPROCTITLE
+ setproctitle("client (%s)", socket_path);
+#endif
+ logfile("client");
+
+ /* Initialize the client socket and start the server. */
fd = client_connect(socket_path, cmdflags & CMD_STARTSERVER);
if (fd == -1) {
fprintf(stderr, "failed to connect to server: %s\n",
@@ -242,12 +248,6 @@
return (1);
}
- /* Set process title, log and signals now this is the client. */
-#ifdef HAVE_SETPROCTITLE
- setproctitle("client (%s)", socket_path);
-#endif
- logfile("client");
-
/* Create imsg. */
imsg_init(&client_ibuf, fd);
event_set(&client_event, fd, EV_READ, client_callback, shell_cmd);
--- a/server.c
+++ b/server.c
@@ -112,6 +112,7 @@
/* The first client is special and gets a socketpair; create it. */
if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pair) != 0)
fatal("socketpair failed");
+ log_debug("starting server");
switch (fork()) {
case -1:
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