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