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