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