From 30afcadb13f446c99952883bbaa54e102757b682 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Mon, 30 Dec 2019 05:04:15 +0000
Subject: spawn: support chdir via -C option

This simplifies our admin module a bit and allows solver to be
used with v1 inboxes using git versions prior to v1.8.5 (but
still >= git v1.8.0).
---
 lib/PublicInbox/Admin.pm     | 31 +++++++++----------------------
 lib/PublicInbox/SolverGit.pm |  6 +++---
 lib/PublicInbox/Spawn.pm     |  8 ++++++--
 lib/PublicInbox/SpawnPP.pm   |  7 +++++--
 4 files changed, 23 insertions(+), 29 deletions(-)

diff --git a/lib/PublicInbox/Admin.pm b/lib/PublicInbox/Admin.pm
index 5a3554cf..44b44b6e 100644
--- a/lib/PublicInbox/Admin.pm
+++ b/lib/PublicInbox/Admin.pm
@@ -10,6 +10,7 @@ use Cwd 'abs_path';
 use base qw(Exporter);
 our @EXPORT_OK = qw(resolve_repo_dir);
 require PublicInbox::Config;
+use PublicInbox::Spawn qw(popen_rd);
 
 sub resolve_repo_dir {
 	my ($cd, $ver) = @_;
@@ -18,28 +19,14 @@ sub resolve_repo_dir {
 		$$ver = 2 if $ver;
 		return abs_path($prefix);
 	}
-
-	my @cmd = qw(git rev-parse --git-dir);
-	my $cmd = join(' ', @cmd);
-	my $pid = open my $fh, '-|';
-	defined $pid or die "forking $cmd failed: $!\n";
-	if ($pid == 0) {
-		if (defined $cd) {
-			chdir $cd or die "chdir $cd failed: $!\n";
-		}
-		exec @cmd;
-		die "Failed to exec $cmd: $!\n";
-	} else {
-		my $dir = eval {
-			local $/;
-			<$fh>;
-		};
-		close $fh or die "error in $cmd (cwd:$cd): $!\n";
-		chomp $dir;
-		$$ver = 1 if $ver;
-		return abs_path($cd) if ($dir eq '.' && defined $cd);
-		abs_path($dir);
-	}
+	my $cmd = [ qw(git rev-parse --git-dir) ];
+	my $fh = popen_rd($cmd, undef, {-C => $cd});
+	my $dir = do { local $/; <$fh> };
+	close $fh or die "error in ".join(' ', @$cmd)." (cwd:$cd): $!\n";
+	chomp $dir;
+	$$ver = 1 if $ver;
+	return abs_path($cd) if ($dir eq '.' && defined $cd);
+	abs_path($dir);
 }
 
 # for unconfigured inboxes
diff --git a/lib/PublicInbox/SolverGit.pm b/lib/PublicInbox/SolverGit.pm
index 03666646..c57fb4c6 100644
--- a/lib/PublicInbox/SolverGit.pm
+++ b/lib/PublicInbox/SolverGit.pm
@@ -472,7 +472,7 @@ sub do_git_apply ($) {
 	my $patches = $self->{patches};
 
 	# we need --ignore-whitespace because some patches are CRLF
-	my @cmd = (qw(git -C), $dn, qw(apply --cached --ignore-whitespace
+	my @cmd = (qw(git apply --cached --ignore-whitespace
 			--unidiff-zero --whitespace=warn --verbose));
 	my $len = length(join(' ', @cmd));
 	my $total = $self->{tot};
@@ -491,8 +491,8 @@ sub do_git_apply ($) {
 	} while (@$patches && $len < $ARG_SIZE_MAX &&
 		 !oids_same_ish($patches->[0]->{oid_b}, $prv_oid_b));
 
-	my $rdr = { 2 => 1 };
-	my $qsp = PublicInbox::Qspawn->new(\@cmd, $self->{git_env}, $rdr);
+	my $opt = { 2 => 1, -C => $dn };
+	my $qsp = PublicInbox::Qspawn->new(\@cmd, $self->{git_env}, $opt);
 	$self->{-cur_di} = $di;
 	$self->{-qsp} = $qsp;
 	$qsp->psgi_qx($self->{psgi_env}, undef, \&apply_result, $self);
diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 6d42d5bc..d624c521 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -84,7 +84,8 @@ static void xerr(const char *msg)
  * whatever we'll need in the future.
  * Be sure to update PublicInbox::SpawnPP if this changes
  */
-int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref)
+int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
+		 const char *cd)
 {
 	AV *redir = (AV *)SvRV(redirref);
 	AV *cmd = (AV *)SvRV(cmdref);
@@ -118,6 +119,8 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref)
 		}
 		for (sig = 1; sig < NSIG; sig++)
 			signal(sig, SIG_DFL); /* ignore errors on signals */
+		if (*cd && chdir(cd) < 0)
+			xerr("chdir");
 
 		max = av_len(rlim);
 		for (i = 0; i < max; i += 3) {
@@ -216,7 +219,8 @@ sub spawn ($;$$) {
 		}
 		push @$rlim, $r, @$v;
 	}
-	my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim);
+	my $cd = $opts->{'-C'} // ''; # undef => NULL mapping doesn't work?
+	my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim, $cd);
 	$pid < 0 ? undef : $pid;
 }
 
diff --git a/lib/PublicInbox/SpawnPP.pm b/lib/PublicInbox/SpawnPP.pm
index 2ac02c56..cd682a6b 100644
--- a/lib/PublicInbox/SpawnPP.pm
+++ b/lib/PublicInbox/SpawnPP.pm
@@ -9,8 +9,8 @@ use warnings;
 use POSIX qw(dup2 :signal_h);
 
 # Pure Perl implementation for folks that do not use Inline::C
-sub pi_fork_exec ($$$$$) {
-	my ($redir, $f, $cmd, $env, $rlim) = @_;
+sub pi_fork_exec ($$$$$$) {
+	my ($redir, $f, $cmd, $env, $rlim, $cd) = @_;
 	my $old = POSIX::SigSet->new();
 	my $set = POSIX::SigSet->new();
 	$set->fillset or die "fillset failed: $!";
@@ -33,6 +33,9 @@ sub pi_fork_exec ($$$$$) {
 			dup2($parent_fd, $child_fd) or
 				die "dup2($parent_fd, $child_fd): $!\n";
 		}
+		if ($cd ne '') {
+			chdir $cd or die "chdir $cd: $!";
+		}
 		if ($ENV{MOD_PERL}) {
 			exec which('env'), '-i', @$env, @$cmd;
 			die "exec env -i ... $cmd->[0] failed: $!\n";
-- 
cgit v1.2.3-24-ge0c7