about summary refs log tree commit homepage
path: root/script/public-inbox-init
diff options
authorEric Wong <e@80x24.org>2019-10-03 07:21:59 +0000
committerEric Wong <e@80x24.org>2019-10-05 06:54:00 +0000
commit6242da34fbe20940e3e258d2ec80e9aeef0438e1 (patch)
treec35bca08f9bf8f193debfd6f80902f640457abd6 /script/public-inbox-init
parent0e323a88eee90196392ef9a86bcd38159023550f (diff)
First, we use flock(2) to wait on parallel public-inbox-init(1)
invocations while we make multiple changes using git-config(1).
This flock allows -init processes to wait on each other if using
reasonable POSIX filesystems.

Then, we also need a git-config(1)-compatible lock to prevent
user-invoked git-config(1) processes from clobbering our
changes while we're holding the flock.
Diffstat (limited to 'script/public-inbox-init')
1 files changed, 24 insertions, 0 deletions
diff --git a/script/public-inbox-init b/script/public-inbox-init
index 39f2a067..8fd2f9dc 100755
--- a/script/public-inbox-init
+++ b/script/public-inbox-init
@@ -12,8 +12,10 @@ PublicInbox::Admin::require_or_die('-base');
 require PublicInbox::Config;
 require PublicInbox::InboxWritable;
 use File::Temp qw/tempfile/;
+use PublicInbox::Lock;
 use File::Basename qw/dirname/;
 use File::Path qw/mkpath/;
+use Fcntl qw(:DEFAULT);
 use Cwd qw/abs_path/;
 sub x { system(@_) and die join(' ', @_). " failed: $?\n" }
@@ -38,7 +40,29 @@ my %seen;
 my $pi_config = PublicInbox::Config->default_file;
 my $dir = dirname($pi_config);
 mkpath($dir); # will croak on fatal errors
+# first, we grab a flock to prevent simultaneous public-inbox-init
+# processes from trampling over each other, or exiting with 255 on
+# O_EXCL failure below.  This gets unlocked automatically on exit:
+my $lock_obj = { lock_path => "$pi_config.flock" };
+# git-config will operate on this (and rename on success):
 my ($fh, $pi_config_tmp) = tempfile('pi-init-XXXXXXXX', DIR => $dir);
+# Now, we grab another lock to use git-config(1) locking, so it won't
+# wait on the lock, unlike some of our internal flock()-based locks.
+# This is to prevent direct git-config(1) usage from clobbering our
+# changes.
+my $lockfile = "$pi_config.lock";
+my $lockfh;
+sysopen($lockfh, $lockfile, O_RDWR|O_CREAT|O_EXCL) or do {
+        $lockfh = undef;
+        warn "could not open config file: $lockfile: $!\n";
+        exit(255);
+END { unlink($lockfile) if $lockfh };
 my $perm;
 if (-e $pi_config) {
         open(my $oh, '<', $pi_config) or die "unable to read $pi_config: $!\n";