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lightningd: split pidfile handling.

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We want to try it before --daemon, in case we error, but we don't know
the pid yet, so we split into 'lock' and 'write'.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
2018-09-14 10:04:54 +09:30
committed by Christian Decker
parent f1e931f7bb
commit bdb8416446
1 changed files with 24 additions and 13 deletions
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37
lightningd/lightningd.c
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@@ -493,9 +493,8 @@ static void daemonize_but_keep_dir(struct lightningd *ld)
* file-lock a pidfile. This not only prevents accidentally running multiple
* daemons on the same database at once, but lets nosy sysadmins see what pid
* the currently-running daemon is supposed to be. */
static void pidfile_create(const struct lightningd *ld)
static int pidfile_create(const struct lightningd *ld)
{
char *pid;
int pid_fd;
/* Create PID file */
@@ -508,6 +507,18 @@ static void pidfile_create(const struct lightningd *ld)
/* Problem locking file */
err(1, "lightningd already running? Error locking PID file");
/*~ As closing the file will remove the lock, we need to keep it open;
* the OS will close it implicitly when we exit for any reason. */
return pid_fd;
}
/*~ Writing the pid into the lockfile provides a useful clue to users as to
* what created it; however, we can't do that until we've got a stable process
* id, and if --daemon is specified, that's quite late. */
static void pidfile_write(const struct lightningd *ld, int pid_fd)
{
char *pid;
/*~ Note that tal_fmt() is what asprintf() dreams of being. */
pid = tal_fmt(tmpctx, "%d\n", getpid());
/*~ CCAN's write_all writes to a file descriptor, looping if necessary
@@ -516,9 +527,6 @@ static void pidfile_create(const struct lightningd *ld)
* which write() is when FORTIFY_SOURCE is defined, so we're allowed
* to ignore the result without jumping through hoops. */
write_all(pid_fd, pid, strlen(pid));
/*~ As closing the file will remove the lock, we need to keep it open;
* the OS will close it implicitly when we exit for any reason. */
}
/*~ ccan/io allows overriding the poll() function that is the very core
@@ -550,7 +558,7 @@ int main(int argc, char *argv[])
{
struct lightningd *ld;
u32 min_blockheight, max_blockheight;
int connectd_gossipd_fd;
int connectd_gossipd_fd, pid_fd;
/*~ What happens in strange locales should stay there. */
setup_locale();
@@ -664,6 +672,14 @@ int main(int argc, char *argv[])
setup_topology(ld->topology, &ld->timers,
min_blockheight, max_blockheight);
/*~ Now create the PID file: this errors out if there's already a
* daemon running, so we call before trying to create an RPC socket. */
pid_fd = pidfile_create(ld);
/*~ Create RPC socket: now lightning-cli can send us JSON RPC commands
* over a UNIX domain socket specified by `ld->rpc_filename`. */
setup_jsonrpc(ld, ld->rpc_filename);
/*~ We defer --daemon until we've completed most initialization: that
* way we'll exit with an error rather than silently exiting 0, then
* realizing we can't start and forcing the confused user to read the
@@ -671,13 +687,8 @@ int main(int argc, char *argv[])
if (ld->daemon)
daemonize_but_keep_dir(ld);
/*~ Now create the PID file: this has to be after daemonize, since that
* changes our pid! */
pidfile_create(ld);
/*~ Create RPC socket: now lightning-cli can send us JSON RPC commands
* over a UNIX domain socket specified by `ld->rpc_filename`. */
setup_jsonrpc(ld, ld->rpc_filename);
/*~ We have to do this after daemonize, since that changes our pid! */
pidfile_write(ld, pid_fd);
/*~ Activate connect daemon. Needs to be after the initialization of
* chaintopology, otherwise peers may connect and ask for