git: support an error tmpfile for stashing stderr output

This should allow us to avoid polluting stderr output when
HTTP clients inevitably request broken revisions.

1 files changed, 21 insertions, 1 deletions

diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index bd945007..2b6782a7 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -12,6 +12,8 @@ use warnings;
 use POSIX qw(dup2);
 require IO::Handle;
 use PublicInbox::Spawn qw(spawn popen_rd);
+use IO::File;
+use Fcntl qw(:seek);
 
 # Documentation/SubmittingPatches recommends 12 (Linux v4.4)
 my $abbrev = `git config core.abbrev` || 12;
@@ -20,7 +22,25 @@ sub abbrev { "--abbrev=$abbrev" }
 
 sub new {
         my ($class, $git_dir) = @_;
-        bless { git_dir => $git_dir }, $class
+        bless { git_dir => $git_dir, err => IO::File->new_tmpfile }, $class
+}
+
+sub err_begin ($) {
+        my $err = $_[0]->{err};
+        sysseek($err, 0, SEEK_SET) or die "sysseek failed: $!";
+        truncate($err, 0) or die "truncate failed: $!";
+        my $ret = fileno($err);
+        defined $ret or die "fileno failed: $!";
+        $ret;
+}
+
+sub err ($) {
+        my $err = $_[0]->{err};
+        sysseek($err, 0, SEEK_SET) or die "sysseek failed: $!";
+        defined(sysread($err, my $buf, -s $err)) or die "sysread failed: $!";
+        sysseek($err, 0, SEEK_SET) or die "sysseek failed: $!";
+        truncate($err, 0) or die "truncate failed: $!";
+        $buf;
 }
 
 sub _bidi_pipe {