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