Extract some utilities from git-svn to allow extracting Git::SVN.

Put them in a new module called Git::SVN::Utils.  Yeah, not terribly
original and it will be a dumping ground.  But its better than having
them in the main git-svn program.  At least they can be documented
and tested.

* fatal() is used by many classes.
* Change the $can_compress lexical into a function.

This should be enough to extract Git::SVN.

Signed-off-by: Michael G. Schwern <schwern@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Eric Wong <normalperson@yhbt.net>

git-svn.perl

@@ -10,6 +10,8 @@ use vars qw/	$AUTHOR $VERSION
 $AUTHOR = 'Eric Wong <normalperson@yhbt.net>';
 $VERSION = '@@GIT_VERSION@@';
 
+use Git::SVN::Utils qw(fatal can_compress);
+
 # From which subdir have we been invoked?
 my $cmd_dir_prefix = eval {
 	command_oneline([qw/rev-parse --show-prefix/], STDERR => 0)
@@ -35,8 +37,6 @@ $Git::SVN::Log::TZ = $ENV{TZ};
 $ENV{TZ} = 'UTC';
 $| = 1; # unbuffer STDOUT
 
-sub fatal (@) { print STDERR "@_\n"; exit 1 }
-
 # All SVN commands do it.  Otherwise we may die on SIGPIPE when the remote
 # repository decides to close the connection which we expect to be kept alive.
 $SIG{PIPE} = 'IGNORE';
@@ -66,7 +66,7 @@ sub _req_svn {
 		fatal "Need SVN::Core 1.1.0 or better (got $SVN::Core::VERSION)";
 	}
 }
-my $can_compress = eval { require Compress::Zlib; 1};
+
 use Carp qw/croak/;
 use Digest::MD5;
 use IO::File qw//;
@@ -1578,7 +1578,7 @@ sub cmd_reset {
 }
 
 sub cmd_gc {
-	if (!$can_compress) {
+	if (!can_compress()) {
 		warn "Compress::Zlib could not be found; unhandled.log " .
 		     "files will not be compressed.\n";
 	}
@@ -2013,13 +2013,13 @@ sub md5sum {
 	} elsif (!$ref) {
 		$md5->add($arg) or croak $!;
 	} else {
-		::fatal "Can't provide MD5 hash for unknown ref type: '", $ref, "'";
+		fatal "Can't provide MD5 hash for unknown ref type: '", $ref, "'";
 	}
 	return $md5->hexdigest();
 }
 
 sub gc_directory {
-	if ($can_compress && -f $_ && basename($_) eq "unhandled.log") {
+	if (can_compress() && -f $_ && basename($_) eq "unhandled.log") {
 		my $out_filename = $_ . ".gz";
 		open my $in_fh, "<", $_ or die "Unable to open $_: $!\n";
 		binmode $in_fh;
@@ -2054,6 +2054,9 @@ use Time::Local;
 use Memoize;  # core since 5.8.0, Jul 2002
 use Memoize::Storable;
 use POSIX qw(:signal_h);
+
+use Git::SVN::Utils qw(fatal can_compress);
+
 my $can_use_yaml;
 BEGIN {
 	$can_use_yaml = eval { require Git::SVN::Memoize::YAML; 1};
@@ -2879,8 +2882,8 @@ sub assert_index_clean {
 		command_noisy('read-tree', $treeish);
 		$x = command_oneline('write-tree');
 		if ($y ne $x) {
-			::fatal "trees ($treeish) $y != $x\n",
-			        "Something is seriously wrong...";
+			fatal "trees ($treeish) $y != $x\n",
+			      "Something is seriously wrong...";
 		}
 	});
 }
@@ -3235,7 +3238,7 @@ sub mkemptydirs {
 	my %empty_dirs = ();
 	my $gz_file = "$self->{dir}/unhandled.log.gz";
 	if (-f $gz_file) {
-		if (!$can_compress) {
+		if (!can_compress()) {
 			warn "Compress::Zlib could not be found; ",
 			     "empty directories in $gz_file will not be read\n";
 		} else {
@@ -3918,7 +3921,7 @@ sub set_tree {
 	my ($self, $tree) = (shift, shift);
 	my $log_entry = ::get_commit_entry($tree);
 	unless ($self->{last_rev}) {
-		::fatal("Must have an existing revision to commit");
+		fatal("Must have an existing revision to commit");
 	}
 	my %ed_opts = ( r => $self->{last_rev},
 	                log => $log_entry->{log},
@@ -4347,6 +4350,7 @@ sub remove_username {
 package Git::SVN::Log;
 use strict;
 use warnings;
+use Git::SVN::Utils qw(fatal);
 use POSIX qw/strftime/;
 use constant commit_log_separator => ('-' x 72) . "\n";
 use vars qw/$TZ $limit $color $pager $non_recursive $verbose $oneline
@@ -4445,15 +4449,15 @@ sub config_pager {
 sub run_pager {
 	return unless defined $pager;
 	pipe my ($rfd, $wfd) or return;
-	defined(my $pid = fork) or ::fatal "Can't fork: $!";
+	defined(my $pid = fork) or fatal "Can't fork: $!";
 	if (!$pid) {
 		open STDOUT, '>&', $wfd or
-		                     ::fatal "Can't redirect to stdout: $!";
+		                     fatal "Can't redirect to stdout: $!";
 		return;
 	}
-	open STDIN, '<&', $rfd or ::fatal "Can't redirect stdin: $!";
+	open STDIN, '<&', $rfd or fatal "Can't redirect stdin: $!";
 	$ENV{LESS} ||= 'FRSX';
-	exec $pager or ::fatal "Can't run pager: $! ($pager)";
+	exec $pager or fatal "Can't run pager: $! ($pager)";
 }
 
 sub format_svn_date {
@@ -4602,7 +4606,7 @@ sub cmd_show_log {
 		} elsif ($::_revision =~ /^\d+$/) {
 			$r_min = $r_max = $::_revision;
 		} else {
-			::fatal "-r$::_revision is not supported, use ",
+			fatal "-r$::_revision is not supported, use ",
 				"standard 'git log' arguments instead";
 		}
 	}

perl/Git/SVN/Utils.pm

@@ -0,0 +1,59 @@
+package Git::SVN::Utils;
+
+use strict;
+use warnings;
+
+use base qw(Exporter);
+
+our @EXPORT_OK = qw(fatal can_compress);
+
+
+=head1 NAME
+
+Git::SVN::Utils - utility functions used across Git::SVN
+
+=head1 SYNOPSIS
+
+    use Git::SVN::Utils qw(functions to import);
+
+=head1 DESCRIPTION
+
+This module contains functions which are useful across many different
+parts of Git::SVN.  Mostly it's a place to put utility functions
+rather than duplicate the code or have classes grabbing at other
+classes.
+
+=head1 FUNCTIONS
+
+All functions can be imported only on request.
+
+=head3 fatal
+
+    fatal(@message);
+
+Display a message and exit with a fatal error code.
+
+=cut
+
+# Note: not certain why this is in use instead of die.  Probably because
+# the exit code of die is 255?  Doesn't appear to be used consistently.
+sub fatal (@) { print STDERR "@_\n"; exit 1 }
+
+
+=head3 can_compress
+
+    my $can_compress = can_compress;
+
+Returns true if Compress::Zlib is available, false otherwise.
+
+=cut
+
+my $can_compress;
+sub can_compress {
+	return $can_compress if defined $can_compress;
+
+	return $can_compress = eval { require Compress::Zlib; };
+}
+
+
+1;

perl/Makefile

@@ -34,6 +34,7 @@ modules += Git/SVN/Fetcher
 modules += Git/SVN/Editor
 modules += Git/SVN/Prompt
 modules += Git/SVN/Ra
+modules += Git/SVN/Utils
 
 $(makfile): ../GIT-CFLAGS Makefile
 	echo all: private-Error.pm Git.pm Git/I18N.pm > $@

t/Git-SVN/00compile.t

@@ -0,0 +1,8 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 1;
+
+require_ok 'Git::SVN::Utils';

t/Git-SVN/Utils/can_compress.t

@@ -0,0 +1,11 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More 'no_plan';
+
+use Git::SVN::Utils qw(can_compress);
+
+# !! is the "convert this to boolean" operator.
+is !!can_compress(), !!eval { require Compress::Zlib };

t/Git-SVN/Utils/fatal.t

@@ -0,0 +1,34 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More 'no_plan';
+
+BEGIN {
+	# Override exit at BEGIN time before Git::SVN::Utils is loaded
+	# so it will see our local exit later.
+	*CORE::GLOBAL::exit = sub(;$) {
+	return @_ ? CORE::exit($_[0]) : CORE::exit();
+	};
+}
+
+use Git::SVN::Utils qw(fatal);
+
+# fatal()
+{
+	# Capture the exit code and prevent exit.
+	my $exit_status;
+	no warnings 'redefine';
+	local *CORE::GLOBAL::exit = sub { $exit_status = $_[0] || 0 };
+
+	# Trap fatal's message to STDERR
+	my $stderr;
+	close STDERR;
+	ok open STDERR, ">", \$stderr;
+
+	fatal "Some", "Stuff", "Happened";
+
+	is $stderr, "Some Stuff Happened\n";
+	is $exit_status, 1;
+}