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