git-difftool.perl

   1 #!/usr/bin/perl
   2 # Copyright (c) 2009, 2010 David Aguilar
   3 # Copyright (c) 2012 Tim Henigan
   4 #
   5 # This is a wrapper around the GIT_EXTERNAL_DIFF-compatible
   6 # git-difftool--helper script.
   7 #
   8 # This script exports GIT_EXTERNAL_DIFF and GIT_PAGER for use by git.
   9 # The GIT_DIFF* variables are exported for use by git-difftool--helper.
  10 #
  11 # Any arguments that are unknown to this script are forwarded to 'git diff'.
  12
  13 use 5.008;
  14 use strict;
  15 use warnings;
  16 use Error qw(:try);
  17 use File::Basename qw(dirname);
  18 use File::Copy;
  19 use File::Find;
  20 use File::stat;
  21 use File::Path qw(mkpath rmtree);
  22 use File::Temp qw(tempdir);
  23 use Getopt::Long qw(:config pass_through);
  24 use Git;
  25
  26 sub usage
  27 {
  28         my $exitcode = shift;
  29         print << 'USAGE';
  30 usage: git difftool [-t|--tool=<tool>] [--tool-help]
  31                     [-x|--extcmd=<cmd>]
  32                     [-g|--gui] [--no-gui]
  33                     [--prompt] [-y|--no-prompt]
  34                     [-d|--dir-diff]
  35                     ['git diff' options]
  36 USAGE
  37         exit($exitcode);
  38 }
  39
  40 sub find_worktree
  41 {
  42         my ($repo) = @_;
  43
  44         # Git->repository->wc_path() does not honor changes to the working
  45         # tree location made by $ENV{GIT_WORK_TREE} or the 'core.worktree'
  46         # config variable.
  47         my $worktree;
  48         my $env_worktree = $ENV{GIT_WORK_TREE};
  49         my $core_worktree = Git::config('core.worktree');
  50
  51         if (defined($env_worktree) and (length($env_worktree) > 0)) {
  52                 $worktree = $env_worktree;
  53         } elsif (defined($core_worktree) and (length($core_worktree) > 0)) {
  54                 $worktree = $core_worktree;
  55         } else {
  56                 $worktree = $repo->wc_path();
  57         }
  58
  59         return $worktree;
  60 }
  61
  62 sub print_tool_help
  63 {
  64         my $cmd = 'TOOL_MODE=diff';
  65         $cmd .= ' && . "$(git --exec-path)/git-mergetool--lib"';
  66         $cmd .= ' && show_tool_help';
  67
  68         # See the comment at the bottom of file_diff() for the reason behind
  69         # using system() followed by exit() instead of exec().
  70         my $rc = system('sh', '-c', $cmd);
  71         exit($rc | ($rc >> 8));
  72 }
  73
  74 sub exit_cleanup
  75 {
  76         my ($tmpdir, $status) = @_;
  77         my $errno = $!;
  78         rmtree($tmpdir);
  79         if ($status and $errno) {
  80                 my ($package, $file, $line) = caller();
  81                 warn "$file line $line: $errno\n";
  82         }
  83         exit($status | ($status >> 8));
  84 }
  85
  86 sub use_wt_file
  87 {
  88         my ($repo, $workdir, $file, $sha1, $symlinks) = @_;
  89         my $null_sha1 = '0' x 40;
  90
  91         if ($sha1 ne $null_sha1 and not $symlinks) {
  92                 return 0;
  93         }
  94
  95         if (! -e "$workdir/$file") {
  96                 # If the file doesn't exist in the working tree, we cannot
  97                 # use it.
  98                 return (0, $null_sha1);
  99         }
 100
 101         my $wt_sha1 = $repo->command_oneline('hash-object', "$workdir/$file");
 102         my $use = ($sha1 eq $null_sha1) || ($sha1 eq $wt_sha1);
 103         return ($use, $wt_sha1);
 104 }
 105
 106 sub changed_files
 107 {
 108         my ($repo_path, $index, $worktree) = @_;
 109         $ENV{GIT_INDEX_FILE} = $index;
 110         $ENV{GIT_WORK_TREE} = $worktree;
 111         my $must_unset_git_dir = 0;
 112         if (not defined($ENV{GIT_DIR})) {
 113                 $must_unset_git_dir = 1;
 114                 $ENV{GIT_DIR} = $repo_path;
 115         }
 116
 117         my @refreshargs = qw/update-index --really-refresh -q --unmerged/;
 118         my @gitargs = qw/diff-files --name-only -z/;
 119         try {
 120                 Git::command_oneline(@refreshargs);
 121         } catch Git::Error::Command with {};
 122
 123         my $line = Git::command_oneline(@gitargs);
 124         my @files;
 125         if (defined $line) {
 126                 @files = split('\0', $line);
 127         } else {
 128                 @files = ();
 129         }
 130
 131         delete($ENV{GIT_INDEX_FILE});
 132         delete($ENV{GIT_WORK_TREE});
 133         delete($ENV{GIT_DIR}) if ($must_unset_git_dir);
 134
 135         return map { $_ => 1 } @files;
 136 }
 137
 138 sub setup_dir_diff
 139 {
 140         my ($repo, $workdir, $symlinks) = @_;
 141
 142         # Run the diff; exit immediately if no diff found
 143         # 'Repository' and 'WorkingCopy' must be explicitly set to insure that
 144         # if $GIT_DIR and $GIT_WORK_TREE are set in ENV, they are actually used
 145         # by Git->repository->command*.
 146         my $repo_path = $repo->repo_path();
 147         my %repo_args = (Repository => $repo_path, WorkingCopy => $workdir);
 148         my $diffrepo = Git->repository(%repo_args);
 149
 150         my @gitargs = ('diff', '--raw', '--no-abbrev', '-z', @ARGV);
 151         my $diffrtn = $diffrepo->command_oneline(@gitargs);
 152         exit(0) unless defined($diffrtn);
 153
 154         # Build index info for left and right sides of the diff
 155         my $submodule_mode = '160000';
 156         my $symlink_mode = '120000';
 157         my $null_mode = '0' x 6;
 158         my $null_sha1 = '0' x 40;
 159         my $lindex = '';
 160         my $rindex = '';
 161         my $wtindex = '';
 162         my %submodule;
 163         my %symlink;
 164         my @working_tree = ();
 165         my @rawdiff = split('\0', $diffrtn);
 166
 167         my $i = 0;
 168         while ($i < $#rawdiff) {
 169                 if ($rawdiff[$i] =~ /^::/) {
 170                         warn << 'EOF';
 171 Combined diff formats ('-c' and '--cc') are not supported in
 172 directory diff mode ('-d' and '--dir-diff').
 173 EOF
 174                         exit(1);
 175                 }
 176
 177                 my ($lmode, $rmode, $lsha1, $rsha1, $status) =
 178                         split(' ', substr($rawdiff[$i], 1));
 179                 my $src_path = $rawdiff[$i + 1];
 180                 my $dst_path;
 181
 182                 if ($status =~ /^[CR]/) {
 183                         $dst_path = $rawdiff[$i + 2];
 184                         $i += 3;
 185                 } else {
 186                         $dst_path = $src_path;
 187                         $i += 2;
 188                 }
 189
 190                 if ($lmode eq $submodule_mode or $rmode eq $submodule_mode) {
 191                         $submodule{$src_path}{left} = $lsha1;
 192                         if ($lsha1 ne $rsha1) {
 193                                 $submodule{$dst_path}{right} = $rsha1;
 194                         } else {
 195                                 $submodule{$dst_path}{right} = "$rsha1-dirty";
 196                         }
 197                         next;
 198                 }
 199
 200                 if ($lmode eq $symlink_mode) {
 201                         $symlink{$src_path}{left} =
 202                                 $diffrepo->command_oneline('show', "$lsha1");
 203                 }
 204
 205                 if ($rmode eq $symlink_mode) {
 206                         $symlink{$dst_path}{right} =
 207                                 $diffrepo->command_oneline('show', "$rsha1");
 208                 }
 209
 210                 if ($lmode ne $null_mode and $status !~ /^C/) {
 211                         $lindex .= "$lmode $lsha1\t$src_path\0";
 212                 }
 213
 214                 if ($rmode ne $null_mode) {
 215                         my ($use, $wt_sha1) = use_wt_file($repo, $workdir,
 216                                                           $dst_path, $rsha1,
 217                                                           $symlinks);
 218                         if ($use) {
 219                                 push @working_tree, $dst_path;
 220                                 $wtindex .= "$rmode $wt_sha1\t$dst_path\0";
 221                         } else {
 222                                 $rindex .= "$rmode $rsha1\t$dst_path\0";
 223                         }
 224                 }
 225         }
 226
 227         # Setup temp directories
 228         my $tmpdir = tempdir('git-difftool.XXXXX', CLEANUP => 0, TMPDIR => 1);
 229         my $ldir = "$tmpdir/left";
 230         my $rdir = "$tmpdir/right";
 231         mkpath($ldir) or exit_cleanup($tmpdir, 1);
 232         mkpath($rdir) or exit_cleanup($tmpdir, 1);
 233
 234         # If $GIT_DIR is not set prior to calling 'git update-index' and
 235         # 'git checkout-index', then those commands will fail if difftool
 236         # is called from a directory other than the repo root.
 237         my $must_unset_git_dir = 0;
 238         if (not defined($ENV{GIT_DIR})) {
 239                 $must_unset_git_dir = 1;
 240                 $ENV{GIT_DIR} = $repo_path;
 241         }
 242
 243         # Populate the left and right directories based on each index file
 244         my ($inpipe, $ctx);
 245         $ENV{GIT_INDEX_FILE} = "$tmpdir/lindex";
 246         ($inpipe, $ctx) =
 247                 $repo->command_input_pipe(qw(update-index -z --index-info));
 248         print($inpipe $lindex);
 249         $repo->command_close_pipe($inpipe, $ctx);
 250
 251         my $rc = system('git', 'checkout-index', '--all', "--prefix=$ldir/");
 252         exit_cleanup($tmpdir, $rc) if $rc != 0;
 253
 254         $ENV{GIT_INDEX_FILE} = "$tmpdir/rindex";
 255         ($inpipe, $ctx) =
 256                 $repo->command_input_pipe(qw(update-index -z --index-info));
 257         print($inpipe $rindex);
 258         $repo->command_close_pipe($inpipe, $ctx);
 259
 260         $rc = system('git', 'checkout-index', '--all', "--prefix=$rdir/");
 261         exit_cleanup($tmpdir, $rc) if $rc != 0;
 262
 263         $ENV{GIT_INDEX_FILE} = "$tmpdir/wtindex";
 264         ($inpipe, $ctx) =
 265                 $repo->command_input_pipe(qw(update-index --info-only -z --index-info));
 266         print($inpipe $wtindex);
 267         $repo->command_close_pipe($inpipe, $ctx);
 268
 269         # If $GIT_DIR was explicitly set just for the update/checkout
 270         # commands, then it should be unset before continuing.
 271         delete($ENV{GIT_DIR}) if ($must_unset_git_dir);
 272         delete($ENV{GIT_INDEX_FILE});
 273
 274         # Changes in the working tree need special treatment since they are
 275         # not part of the index. Remove any trailing slash from $workdir
 276         # before starting to avoid double slashes in symlink targets.
 277         $workdir =~ s|/$||;
 278         for my $file (@working_tree) {
 279                 my $dir = dirname($file);
 280                 unless (-d "$rdir/$dir") {
 281                         mkpath("$rdir/$dir") or
 282                         exit_cleanup($tmpdir, 1);
 283                 }
 284                 if ($symlinks) {
 285                         symlink("$workdir/$file", "$rdir/$file") or
 286                         exit_cleanup($tmpdir, 1);
 287                 } else {
 288                         copy("$workdir/$file", "$rdir/$file") or
 289                         exit_cleanup($tmpdir, 1);
 290
 291                         my $mode = stat("$workdir/$file")->mode;
 292                         chmod($mode, "$rdir/$file") or
 293                         exit_cleanup($tmpdir, 1);
 294                 }
 295         }
 296
 297         # Changes to submodules require special treatment. This loop writes a
 298         # temporary file to both the left and right directories to show the
 299         # change in the recorded SHA1 for the submodule.
 300         for my $path (keys %submodule) {
 301                 my $ok;
 302                 if (defined($submodule{$path}{left})) {
 303                         $ok = write_to_file("$ldir/$path",
 304                                 "Subproject commit $submodule{$path}{left}");
 305                 }
 306                 if (defined($submodule{$path}{right})) {
 307                         $ok = write_to_file("$rdir/$path",
 308                                 "Subproject commit $submodule{$path}{right}");
 309                 }
 310                 exit_cleanup($tmpdir, 1) if not $ok;
 311         }
 312
 313         # Symbolic links require special treatment. The standard "git diff"
 314         # shows only the link itself, not the contents of the link target.
 315         # This loop replicates that behavior.
 316         for my $path (keys %symlink) {
 317                 my $ok;
 318                 if (defined($symlink{$path}{left})) {
 319                         $ok = write_to_file("$ldir/$path",
 320                                         $symlink{$path}{left});
 321                 }
 322                 if (defined($symlink{$path}{right})) {
 323                         $ok = write_to_file("$rdir/$path",
 324                                         $symlink{$path}{right});
 325                 }
 326                 exit_cleanup($tmpdir, 1) if not $ok;
 327         }
 328
 329         return ($ldir, $rdir, $tmpdir, @working_tree);
 330 }
 331
 332 sub write_to_file
 333 {
 334         my $path = shift;
 335         my $value = shift;
 336
 337         # Make sure the path to the file exists
 338         my $dir = dirname($path);
 339         unless (-d "$dir") {
 340                 mkpath("$dir") or return 0;
 341         }
 342
 343         # If the file already exists in that location, delete it.  This
 344         # is required in the case of symbolic links.
 345         unlink($path);
 346
 347         open(my $fh, '>', $path) or return 0;
 348         print($fh $value);
 349         close($fh);
 350
 351         return 1;
 352 }
 353
 354 sub main
 355 {
 356         # parse command-line options. all unrecognized options and arguments
 357         # are passed through to the 'git diff' command.
 358         my %opts = (
 359                 difftool_cmd => undef,
 360                 dirdiff => undef,
 361                 extcmd => undef,
 362                 gui => undef,
 363                 help => undef,
 364                 prompt => undef,
 365                 symlinks => $^O ne 'cygwin' &&
 366                                 $^O ne 'MSWin32' && $^O ne 'msys',
 367                 tool_help => undef,
 368         );
 369         GetOptions('g|gui!' => \$opts{gui},
 370                 'd|dir-diff' => \$opts{dirdiff},
 371                 'h' => \$opts{help},
 372                 'prompt!' => \$opts{prompt},
 373                 'y' => sub { $opts{prompt} = 0; },
 374                 'symlinks' => \$opts{symlinks},
 375                 'no-symlinks' => sub { $opts{symlinks} = 0; },
 376                 't|tool:s' => \$opts{difftool_cmd},
 377                 'tool-help' => \$opts{tool_help},
 378                 'x|extcmd:s' => \$opts{extcmd});
 379
 380         if (defined($opts{help})) {
 381                 usage(0);
 382         }
 383         if (defined($opts{tool_help})) {
 384                 print_tool_help();
 385         }
 386         if (defined($opts{difftool_cmd})) {
 387                 if (length($opts{difftool_cmd}) > 0) {
 388                         $ENV{GIT_DIFF_TOOL} = $opts{difftool_cmd};
 389                 } else {
 390                         print "No <tool> given for --tool=<tool>\n";
 391                         usage(1);
 392                 }
 393         }
 394         if (defined($opts{extcmd})) {
 395                 if (length($opts{extcmd}) > 0) {
 396                         $ENV{GIT_DIFFTOOL_EXTCMD} = $opts{extcmd};
 397                 } else {
 398                         print "No <cmd> given for --extcmd=<cmd>\n";
 399                         usage(1);
 400                 }
 401         }
 402         if ($opts{gui}) {
 403                 my $guitool = Git::config('diff.guitool');
 404                 if (defined($guitool) && length($guitool) > 0) {
 405                         $ENV{GIT_DIFF_TOOL} = $guitool;
 406                 }
 407         }
 408
 409         # In directory diff mode, 'git-difftool--helper' is called once
 410         # to compare the a/b directories.  In file diff mode, 'git diff'
 411         # will invoke a separate instance of 'git-difftool--helper' for
 412         # each file that changed.
 413         if (defined($opts{dirdiff})) {
 414                 dir_diff($opts{extcmd}, $opts{symlinks});
 415         } else {
 416                 file_diff($opts{prompt});
 417         }
 418 }
 419
 420 sub dir_diff
 421 {
 422         my ($extcmd, $symlinks) = @_;
 423         my $rc;
 424         my $error = 0;
 425         my $repo = Git->repository();
 426         my $workdir = find_worktree($repo);
 427         my ($a, $b, $tmpdir, @worktree) =
 428                 setup_dir_diff($repo, $workdir, $symlinks);
 429
 430         if (defined($extcmd)) {
 431                 $rc = system($extcmd, $a, $b);
 432         } else {
 433                 $ENV{GIT_DIFFTOOL_DIRDIFF} = 'true';
 434                 $rc = system('git', 'difftool--helper', $a, $b);
 435         }
 436         # If the diff including working copy files and those
 437         # files were modified during the diff, then the changes
 438         # should be copied back to the working tree.
 439         # Do not copy back files when symlinks are used and the
 440         # external tool did not replace the original link with a file.
 441         #
 442         # These hashes are loaded lazily since they aren't needed
 443         # in the common case of --symlinks and the difftool updating
 444         # files through the symlink.
 445         my %wt_modified;
 446         my %tmp_modified;
 447         my $indices_loaded = 0;
 448
 449         for my $file (@worktree) {
 450                 next if $symlinks && -l "$b/$file";
 451                 next if ! -f "$b/$file";
 452
 453                 if (!$indices_loaded) {
 454                         %wt_modified = changed_files($repo->repo_path(),
 455                                 "$tmpdir/wtindex", "$workdir");
 456                         %tmp_modified = changed_files($repo->repo_path(),
 457                                 "$tmpdir/wtindex", "$b");
 458                         $indices_loaded = 1;
 459                 }
 460
 461                 if (exists $wt_modified{$file} and exists $tmp_modified{$file}) {
 462                         my $errmsg = "warning: Both files modified: ";
 463                         $errmsg .= "'$workdir/$file' and '$b/$file'.\n";
 464                         $errmsg .= "warning: Working tree file has been left.\n";
 465                         $errmsg .= "warning:\n";
 466                         warn $errmsg;
 467                         $error = 1;
 468                 } elsif (exists $tmp_modified{$file}) {
 469                         my $mode = stat("$b/$file")->mode;
 470                         copy("$b/$file", "$workdir/$file") or
 471                         exit_cleanup($tmpdir, 1);
 472
 473                         chmod($mode, "$workdir/$file") or
 474                         exit_cleanup($tmpdir, 1);
 475                 }
 476         }
 477         if ($error) {
 478                 warn "warning: Temporary files exist in '$tmpdir'.\n";
 479                 warn "warning: You may want to cleanup or recover these.\n";
 480                 exit(1);
 481         } else {
 482                 exit_cleanup($tmpdir, $rc);
 483         }
 484 }
 485
 486 sub file_diff
 487 {
 488         my ($prompt) = @_;
 489
 490         if (defined($prompt)) {
 491                 if ($prompt) {
 492                         $ENV{GIT_DIFFTOOL_PROMPT} = 'true';
 493                 } else {
 494                         $ENV{GIT_DIFFTOOL_NO_PROMPT} = 'true';
 495                 }
 496         }
 497
 498         $ENV{GIT_PAGER} = '';
 499         $ENV{GIT_EXTERNAL_DIFF} = 'git-difftool--helper';
 500
 501         # ActiveState Perl for Win32 does not implement POSIX semantics of
 502         # exec* system call. It just spawns the given executable and finishes
 503         # the starting program, exiting with code 0.
 504         # system will at least catch the errors returned by git diff,
 505         # allowing the caller of git difftool better handling of failures.
 506         my $rc = system('git', 'diff', @ARGV);
 507         exit($rc | ($rc >> 8));
 508 }
 509
 510 main();