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