perl/Git.pm

   1 =head1 NAME
   2
   3 Git - Perl interface to the Git version control system
   4
   5 =cut
   6
   7
   8 package Git;
   9
  10 use strict;
  11
  12
  13 BEGIN {
  14
  15 our ($VERSION, @ISA, @EXPORT, @EXPORT_OK);
  16
  17 # Totally unstable API.
  18 $VERSION = '0.01';
  19
  20
  21 =head1 SYNOPSIS
  22
  23   use Git;
  24
  25   my $version = Git::command_oneline('version');
  26
  27   Git::command_noisy('update-server-info');
  28
  29   my $repo = Git->repository (Directory => '/srv/git/cogito.git');
  30
  31
  32   my @revs = $repo->command('rev-list', '--since=last monday', '--all');
  33
  34   my $fh = $repo->command_pipe('rev-list', '--since=last monday', '--all');
  35   my $lastrev = <$fh>; chomp $lastrev;
  36   close $fh; # You may want to test rev-list exit status here
  37
  38   my $lastrev = $repo->command_oneline('rev-list', '--all');
  39
  40 =cut
  41
  42
  43 require Exporter;
  44
  45 @ISA = qw(Exporter);
  46
  47 @EXPORT = qw();
  48
  49 # Methods which can be called as standalone functions as well:
  50 @EXPORT_OK = qw(command command_oneline command_pipe command_noisy
  51                 exec_path hash_object);
  52
  53
  54 =head1 DESCRIPTION
  55
  56 This module provides Perl scripts easy way to interface the Git version control
  57 system. The modules have an easy and well-tested way to call arbitrary Git
  58 commands; in the future, the interface will also provide specialized methods
  59 for doing easily operations which are not totally trivial to do over
  60 the generic command interface.
  61
  62 While some commands can be executed outside of any context (e.g. 'version'
  63 or 'init-db'), most operations require a repository context, which in practice
  64 means getting an instance of the Git object using the repository() constructor.
  65 (In the future, we will also get a new_repository() constructor.) All commands
  66 called as methods of the object are then executed in the context of the
  67 repository.
  68
  69 TODO: In the future, we might also do
  70
  71         my $subdir = $repo->subdir('Documentation');
  72         # Gets called in the subdirectory context:
  73         $subdir->command('status');
  74
  75         my $remoterepo = $repo->remote_repository (Name => 'cogito', Branch => 'master');
  76         $remoterepo ||= Git->remote_repository ('http://git.or.cz/cogito.git/');
  77         my @refs = $remoterepo->refs();
  78
  79 So far, all functions just die if anything goes wrong. If you don't want that,
  80 make appropriate provisions to catch the possible deaths. Better error recovery
  81 mechanisms will be provided in the future.
  82
  83 Currently, the module merely wraps calls to external Git tools. In the future,
  84 it will provide a much faster way to interact with Git by linking directly
  85 to libgit. This should be completely opaque to the user, though (performance
  86 increate nonwithstanding).
  87
  88 =cut
  89
  90
  91 use Carp qw(carp croak);
  92
  93 require XSLoader;
  94 XSLoader::load('Git', $VERSION);
  95
  96 }
  97
  98
  99 =head1 CONSTRUCTORS
 100
 101 =over 4
 102
 103 =item repository ( OPTIONS )
 104
 105 =item repository ( DIRECTORY )
 106
 107 =item repository ()
 108
 109 Construct a new repository object.
 110 C<OPTIONS> are passed in a hash like fashion, using key and value pairs.
 111 Possible options are:
 112
 113 B<Repository> - Path to the Git repository.
 114
 115 B<WorkingCopy> - Path to the associated working copy; not strictly required
 116 as many commands will happily crunch on a bare repository.
 117
 118 B<Directory> - Path to the Git working directory in its usual setup. This
 119 is just for convenient setting of both C<Repository> and C<WorkingCopy>
 120 at once: If the directory as a C<.git> subdirectory, C<Repository> is pointed
 121 to the subdirectory and the directory is assumed to be the working copy.
 122 If the directory does not have the subdirectory, C<WorkingCopy> is left
 123 undefined and C<Repository> is pointed to the directory itself.
 124
 125 You should not use both C<Directory> and either of C<Repository> and
 126 C<WorkingCopy> - the results of that are undefined.
 127
 128 Alternatively, a directory path may be passed as a single scalar argument
 129 to the constructor; it is equivalent to setting only the C<Directory> option
 130 field.
 131
 132 Calling the constructor with no options whatsoever is equivalent to
 133 calling it with C<< Directory => '.' >>.
 134
 135 =cut
 136
 137 sub repository {
 138         my $class = shift;
 139         my @args = @_;
 140         my %opts = ();
 141         my $self;
 142
 143         if (defined $args[0]) {
 144                 if ($#args % 2 != 1) {
 145                         # Not a hash.
 146                         $#args == 0 or croak "bad usage";
 147                         %opts = (Directory => $args[0]);
 148                 } else {
 149                         %opts = @args;
 150                 }
 151
 152                 if ($opts{Directory}) {
 153                         -d $opts{Directory} or croak "Directory not found: $!";
 154                         if (-d $opts{Directory}."/.git") {
 155                                 # TODO: Might make this more clever
 156                                 $opts{WorkingCopy} = $opts{Directory};
 157                                 $opts{Repository} = $opts{Directory}."/.git";
 158                         } else {
 159                                 $opts{Repository} = $opts{Directory};
 160                         }
 161                         delete $opts{Directory};
 162                 }
 163         }
 164
 165         $self = { opts => \%opts };
 166         bless $self, $class;
 167 }
 168
 169
 170 =back
 171
 172 =head1 METHODS
 173
 174 =over 4
 175
 176 =item command ( COMMAND [, ARGUMENTS... ] )
 177
 178 Execute the given Git C<COMMAND> (specify it without the 'git-'
 179 prefix), optionally with the specified extra C<ARGUMENTS>.
 180
 181 The method can be called without any instance or on a specified Git repository
 182 (in that case the command will be run in the repository context).
 183
 184 In scalar context, it returns all the command output in a single string
 185 (verbatim).
 186
 187 In array context, it returns an array containing lines printed to the
 188 command's stdout (without trailing newlines).
 189
 190 In both cases, the command's stdin and stderr are the same as the caller's.
 191
 192 =cut
 193
 194 sub command {
 195         my $fh = command_pipe(@_);
 196
 197         if (not defined wantarray) {
 198                 _cmd_close($fh);
 199
 200         } elsif (not wantarray) {
 201                 local $/;
 202                 my $text = <$fh>;
 203                 _cmd_close($fh);
 204                 return $text;
 205
 206         } else {
 207                 my @lines = <$fh>;
 208                 _cmd_close($fh);
 209                 chomp @lines;
 210                 return @lines;
 211         }
 212 }
 213
 214
 215 =item command_oneline ( COMMAND [, ARGUMENTS... ] )
 216
 217 Execute the given C<COMMAND> in the same way as command()
 218 does but always return a scalar string containing the first line
 219 of the command's standard output.
 220
 221 =cut
 222
 223 sub command_oneline {
 224         my $fh = command_pipe(@_);
 225
 226         my $line = <$fh>;
 227         _cmd_close($fh);
 228
 229         chomp $line;
 230         return $line;
 231 }
 232
 233
 234 =item command_pipe ( COMMAND [, ARGUMENTS... ] )
 235
 236 Execute the given C<COMMAND> in the same way as command()
 237 does but return a pipe filehandle from which the command output can be
 238 read.
 239
 240 =cut
 241
 242 sub command_pipe {
 243         my ($self, $cmd, @args) = _maybe_self(@_);
 244
 245         $cmd =~ /^[a-z0-9A-Z_-]+$/ or croak "bad command: $cmd";
 246
 247         my $pid = open(my $fh, "-|");
 248         if (not defined $pid) {
 249                 croak "open failed: $!";
 250         } elsif ($pid == 0) {
 251                 _cmd_exec($self, $cmd, @args);
 252         }
 253         return $fh;
 254 }
 255
 256
 257 =item command_noisy ( COMMAND [, ARGUMENTS... ] )
 258
 259 Execute the given C<COMMAND> in the same way as command() does but do not
 260 capture the command output - the standard output is not redirected and goes
 261 to the standard output of the caller application.
 262
 263 While the method is called command_noisy(), you might want to as well use
 264 it for the most silent Git commands which you know will never pollute your
 265 stdout but you want to avoid the overhead of the pipe setup when calling them.
 266
 267 The function returns only after the command has finished running.
 268
 269 =cut
 270
 271 sub command_noisy {
 272         my ($self, $cmd, @args) = _maybe_self(@_);
 273
 274         $cmd =~ /^[a-z0-9A-Z_-]+$/ or croak "bad command: $cmd";
 275
 276         my $pid = fork;
 277         if (not defined $pid) {
 278                 croak "fork failed: $!";
 279         } elsif ($pid == 0) {
 280                 _cmd_exec($self, $cmd, @args);
 281         }
 282         if (waitpid($pid, 0) > 0 and $? != 0) {
 283                 croak "exit status: $?";
 284         }
 285 }
 286
 287
 288 =item exec_path ()
 289
 290 Return path to the git sub-command executables (the same as
 291 C<git --exec-path>). Useful mostly only internally.
 292
 293 Implementation of this function is very fast; no external command calls
 294 are involved.
 295
 296 =cut
 297
 298 # Implemented in Git.xs.
 299
 300
 301 =item hash_object ( FILENAME [, TYPE ] )
 302
 303 =item hash_object ( FILEHANDLE [, TYPE ] )
 304
 305 Compute the SHA1 object id of the given C<FILENAME> (or data waiting in
 306 C<FILEHANDLE>) considering it is of the C<TYPE> object type (C<blob>
 307 (default), C<commit>, C<tree>).
 308
 309 In case of C<FILEHANDLE> passed instead of file name, all the data
 310 available are read and hashed, and the filehandle is automatically
 311 closed. The file handle should be freshly opened - if you have already
 312 read anything from the file handle, the results are undefined (since
 313 this function works directly with the file descriptor and internal
 314 PerlIO buffering might have messed things up).
 315
 316 The method can be called without any instance or on a specified Git repository,
 317 it makes zero difference.
 318
 319 The function returns the SHA1 hash.
 320
 321 Implementation of this function is very fast; no external command calls
 322 are involved.
 323
 324 =cut
 325
 326 # Implemented in Git.xs.
 327
 328
 329 =back
 330
 331 =head1 TODO
 332
 333 This is still fairly crude.
 334 We need some good way to report errors back except just dying.
 335
 336 =head1 COPYRIGHT
 337
 338 Copyright 2006 by Petr Baudis E<lt>pasky@suse.czE<gt>.
 339
 340 This module is free software; it may be used, copied, modified
 341 and distributed under the terms of the GNU General Public Licence,
 342 either version 2, or (at your option) any later version.
 343
 344 =cut
 345
 346
 347 # Take raw method argument list and return ($obj, @args) in case
 348 # the method was called upon an instance and (undef, @args) if
 349 # it was called directly.
 350 sub _maybe_self {
 351         # This breaks inheritance. Oh well.
 352         ref $_[0] eq 'Git' ? @_ : (undef, @_);
 353 }
 354
 355 # When already in the subprocess, set up the appropriate state
 356 # for the given repository and execute the git command.
 357 sub _cmd_exec {
 358         my ($self, @args) = @_;
 359         if ($self) {
 360                 $self->{opts}->{Repository} and $ENV{'GIT_DIR'} = $self->{opts}->{Repository};
 361                 $self->{opts}->{WorkingCopy} and chdir($self->{opts}->{WorkingCopy});
 362         }
 363         xs__execv_git_cmd(@args);
 364         croak "exec failed: $!";
 365 }
 366
 367 # Execute the given Git command ($_[0]) with arguments ($_[1..])
 368 # by searching for it at proper places.
 369 # _execv_git_cmd(), implemented in Git.xs.
 370
 371 # Close pipe to a subprocess.
 372 sub _cmd_close {
 373         my ($fh) = @_;
 374         if (not close $fh) {
 375                 if ($!) {
 376                         # It's just close, no point in fatalities
 377                         carp "error closing pipe: $!";
 378                 } elsif ($? >> 8) {
 379                         croak "exit status: ".($? >> 8);
 380                 }
 381                 # else we might e.g. closed a live stream; the command
 382                 # dying of SIGPIPE would drive us here.
 383         }
 384 }
 385
 386
 387 # Trickery for .xs routines: In order to avoid having some horrid
 388 # C code trying to do stuff with undefs and hashes, we gate all
 389 # xs calls through the following and in case we are being ran upon
 390 # an instance call a C part of the gate which will set up the
 391 # environment properly.
 392 sub _call_gate {
 393         my $xsfunc = shift;
 394         my ($self, @args) = _maybe_self(@_);
 395
 396         if (defined $self) {
 397                 # XXX: We ignore the WorkingCopy! To properly support
 398                 # that will require heavy changes in libgit.
 399
 400                 # XXX: And we ignore everything else as well. libgit
 401                 # at least needs to be extended to let us specify
 402                 # the $GIT_DIR instead of looking it up in environment.
 403                 #xs_call_gate($self->{opts}->{Repository});
 404         }
 405
 406         &$xsfunc(@args);
 407 }
 408
 409 sub AUTOLOAD {
 410         my $xsname;
 411         our $AUTOLOAD;
 412         ($xsname = $AUTOLOAD) =~ s/.*:://;
 413         croak "&Git::$xsname not defined" if $xsname =~ /^xs_/;
 414         $xsname = 'xs_'.$xsname;
 415         _call_gate(\&$xsname, @_);
 416 }
 417
 418 sub DESTROY { }
 419
 420
 421 1; # Famous last words