lei import|convert: support mbox locking on reads

In case somebody is writing non-atomically, ensure we
take read locks when opening mbox files for reading.

v2: squash: load MboxLock even for .eml files

3 files changed, 22 insertions, 13 deletions

diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index b5bdda21..0da24499 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -172,12 +172,12 @@ our %CMD = ( # sorted in order of importance/use:
 'import' => [ 'LOCATION...|--stdin',
         'one-time import/update from URL or filesystem',
         qw(stdin| offset=i recursive|r exclude=s include|I=s
-        in-format|F=s kw|keywords|flags! C=s@),
+        lock=s@ in-format|F=s kw|keywords|flags! C=s@),
         ],
 'convert' => [ 'LOCATION...|--stdin',
         'one-time conversion from URL or filesystem to another format',
         qw(stdin| in-format|F=s out-format|f=s output|mfolder|o=s quiet|q
-        kw|keywords|flags! C=s@),
+        lock=s@ kw|keywords|flags! C=s@),
         ],
 'config' => [ '[...]', sub {
                 'git-config(1) wrapper for '._config_path($_[0]);
@@ -218,6 +218,9 @@ my %OPTDESC = (
 'help|h' => 'show this built-in help',
 'C=s@' => [ 'DIR', 'chdir to specify to directory' ],
 'quiet|q' => 'be quiet',
+'lock=s@' => [ 'METHOD|dotlock|fcntl|flock|none',
+        'mbox(5) locking method(s) to use (default: fcntl,dotlock)' ],
+
 'globoff|g' => "do not match locations using '*?' wildcards ".
                 "and\xa0'[]'\x{a0}ranges",
 'verbose|v+' => 'be more verbose',
@@ -407,11 +410,13 @@ sub check_input_format ($;$) {
                 my $err = $files ? "regular file(s):\n@$files" : '--stdin';
                 return fail($self, "--$opt_key unset for $err");
         }
+        require PublicInbox::MboxLock if $files;
         return 1 if $fmt eq 'eml';
         # XXX: should this handle {gz,bz2,xz}? that's currently in LeiToMail
         require PublicInbox::MboxReader;
-        PublicInbox::MboxReader->can($fmt) ||
-                                fail($self, "--$opt_key=$fmt unrecognized");
+        PublicInbox::MboxReader->can($fmt) or
+                return fail($self, "--$opt_key=$fmt unrecognized");
+        1;
 }
 
 sub out ($;@) {
diff --git a/lib/PublicInbox/LeiConvert.pm b/lib/PublicInbox/LeiConvert.pm
index 45d42c9c..4c0bbd88 100644
--- a/lib/PublicInbox/LeiConvert.pm
+++ b/lib/PublicInbox/LeiConvert.pm
@@ -62,9 +62,11 @@ sub do_convert { # via wq_do
                         $ifmt = lc $1;
                 }
                 if (-f $input) {
-                        open my $fh, '<', $input or
-                                        return $lei->fail("open $input: $!");
-                        convert_fh($self, $ifmt, $fh, $input);
+                        my $m = $lei->{opt}->{'lock'} //
+                                        ($ifmt eq 'eml' ? ['none'] :
+                                        PublicInbox::MboxLock->defaults);
+                        my $mbl = PublicInbox::MboxLock->acq($input, 0, $m);
+                        convert_fh($self, $ifmt, $mbl->{fh}, $input);
                 } elsif (-d _) {
                         PublicInbox::MdirReader::maildir_each_eml($input,
                                                         \&mdir_cb, $self);
@@ -109,6 +111,7 @@ sub call { # the main "lei convert" method
 
                         }
                         if (-f $input_path) {
+                                require PublicInbox::MboxLock;
                                 require PublicInbox::MboxReader;
                                 PublicInbox::MboxReader->can($ifmt) or return
                                         $lei->fail("$ifmt not supported");
diff --git a/lib/PublicInbox/LeiImport.pm b/lib/PublicInbox/LeiImport.pm
index 7f247b64..c2c98030 100644
--- a/lib/PublicInbox/LeiImport.pm
+++ b/lib/PublicInbox/LeiImport.pm
@@ -80,10 +80,11 @@ sub call { # the main "lei import" method
                         my $ifmt = lc $1;
                         if (($fmt // $ifmt) ne $ifmt) {
                                 return $lei->fail(<<"");
---format=$fmt and `$ifmt:' conflict
+--in-format=$fmt and `$ifmt:' conflict
 
                         }
                         if (-f $input_path) {
+                                require PublicInbox::MboxLock;
                                 require PublicInbox::MboxReader;
                                 PublicInbox::MboxReader->can($ifmt) or return
                                         $lei->fail("$ifmt not supported");
@@ -142,7 +143,7 @@ error reading $input: $!
                         $cb->(undef, $fh, \&_import_eml, $lei->{sto}, $set_kw);
                 }
         };
-        $lei->child_error(1 << 8, "<stdin>: $@") if $@;
+        $lei->child_error(1 << 8, "$input: $@") if $@;
 }
 
 sub _import_maildir { # maildir_each_file cb
@@ -171,10 +172,10 @@ sub import_path_url {
                 $ifmt = lc $1;
         }
         if (-f $input) {
-                open my $fh, '<', $input or return $lei->child_error(1 << 8, <<"");
-unable to open $input: $!
-
-                _import_fh($lei, $fh, $input, $ifmt);
+                my $m = $lei->{opt}->{'lock'} // ($ifmt eq 'eml' ? ['none'] :
+                                PublicInbox::MboxLock->defaults);
+                my $mbl = PublicInbox::MboxLock->acq($input, 0, $m);
+                _import_fh($lei, $mbl->{fh}, $input, $ifmt);
         } elsif (-d _ && (-d "$input/cur" || -d "$input/new")) {
                 return $lei->fail(<<EOM) if $ifmt && $ifmt ne 'maildir';
 $input appears to a be a maildir, not $ifmt