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NAME

       Git - Perl interface to the Git version control system

SYNOPSIS

         use Git;

         my $version = Git::command_oneline('version');

         git_cmd_try { Git::command_noisy('update-server-info') }
                     '%s failed w/ code %d';

         my $repo = Git->repository (Directory => '/srv/git/cogito.git');

         my @revs = $repo->command('rev-list', '--since=last monday', '--all');

         my ($fh, $c) = $repo->command_output_pipe('rev-list', '--since=last monday', '--all');
         my $lastrev = <$fh>; chomp $lastrev;
         $repo->command_close_pipe($fh, $c);

         my $lastrev = $repo->command_oneline( [ 'rev-list', '--all' ],
                                               STDERR => 0 );

         my $sha1 = $repo->hash_and_insert_object('file.txt');
         my $tempfile = tempfile();
         my $size = $repo->cat_blob($sha1, $tempfile);

DESCRIPTION

       This module provides Perl scripts easy way to interface the Git version control system.
       The modules have an easy and well-tested way to call arbitrary Git commands; in the
       future, the interface will also provide specialized methods for doing easily operations
       which are not totally trivial to do over the generic command interface.

       While some commands can be executed outside of any context (e.g. 'version' or 'init'),
       most operations require a repository context, which in practice means getting an instance
       of the Git object using the repository() constructor.  (In the future, we will also get a
       new_repository() constructor.) All commands called as methods of the object are then
       executed in the context of the repository.

       Part of the "repository state" is also information about path to the attached working copy
       (unless you work with a bare repository). You can also navigate inside of the working copy
       using the "wc_chdir()" method. (Note that the repository object is self-contained and will
       not change working directory of your process.)

       TODO: In the future, we might also do

               my $remoterepo = $repo->remote_repository (Name => 'cogito', Branch => 'master');
               $remoterepo ||= Git->remote_repository ('http://git.or.cz/cogito.git/');
               my @refs = $remoterepo->refs();

       Currently, the module merely wraps calls to external Git tools. In the future, it will
       provide a much faster way to interact with Git by linking directly to libgit. This should
       be completely opaque to the user, though (performance increase notwithstanding).

CONSTRUCTORS

       repository ( OPTIONS )
       repository ( DIRECTORY )
       repository ()
           Construct a new repository object.  "OPTIONS" are passed in a hash like fashion, using
           key and value pairs.  Possible options are:

           Repository - Path to the Git repository.

           WorkingCopy - Path to the associated working copy; not strictly required as many
           commands will happily crunch on a bare repository.

           WorkingSubdir - Subdirectory in the working copy to work inside.  Just left undefined
           if you do not want to limit the scope of operations.

           Directory - Path to the Git working directory in its usual setup.  The ".git"
           directory is searched in the directory and all the parent directories; if found,
           "WorkingCopy" is set to the directory containing it and "Repository" to the ".git"
           directory itself. If no ".git" directory was found, the "Directory" is assumed to be a
           bare repository, "Repository" is set to point at it and "WorkingCopy" is left
           undefined.  If the $GIT_DIR environment variable is set, things behave as expected as
           well.

           You should not use both "Directory" and either of "Repository" and "WorkingCopy" - the
           results of that are undefined.

           Alternatively, a directory path may be passed as a single scalar argument to the
           constructor; it is equivalent to setting only the "Directory" option field.

           Calling the constructor with no options whatsoever is equivalent to calling it with
           "Directory => '.'". In general, if you are building a standard porcelain command,
           simply doing "Git->repository()" should do the right thing and setup the object to
           reflect exactly where the user is right now.

METHODS

       command ( COMMAND [, ARGUMENTS... ] )
       command ( [ COMMAND, ARGUMENTS... ], { Opt => Val ... } )
           Execute the given Git "COMMAND" (specify it without the 'git-' prefix), optionally
           with the specified extra "ARGUMENTS".

           The second more elaborate form can be used if you want to further adjust the command
           execution. Currently, only one option is supported:

           STDERR - How to deal with the command's error output. By default ("undef") it is
           delivered to the caller's "STDERR". A false value (0 or '') will cause it to be thrown
           away. If you want to process it, you can get it in a filehandle you specify, but you
           must be extremely careful; if the error output is not very short and you want to read
           it in the same process as where you called "command()", you are set up for a nice
           deadlock!

           The method can be called without any instance or on a specified Git repository (in
           that case the command will be run in the repository context).

           In scalar context, it returns all the command output in a single string (verbatim).

           In array context, it returns an array containing lines printed to the command's stdout
           (without trailing newlines).

           In both cases, the command's stdin and stderr are the same as the caller's.

       command_oneline ( COMMAND [, ARGUMENTS... ] )
       command_oneline ( [ COMMAND, ARGUMENTS... ], { Opt => Val ... } )
           Execute the given "COMMAND" in the same way as command() does but always return a
           scalar string containing the first line of the command's standard output.

       command_output_pipe ( COMMAND [, ARGUMENTS... ] )
       command_output_pipe ( [ COMMAND, ARGUMENTS... ], { Opt => Val ... } )
           Execute the given "COMMAND" in the same way as command() does but return a pipe
           filehandle from which the command output can be read.

           The function can return "($pipe, $ctx)" in array context.  See "command_close_pipe()"
           for details.

       command_input_pipe ( COMMAND [, ARGUMENTS... ] )
       command_input_pipe ( [ COMMAND, ARGUMENTS... ], { Opt => Val ... } )
           Execute the given "COMMAND" in the same way as command_output_pipe() does but return
           an input pipe filehandle instead; the command output is not captured.

           The function can return "($pipe, $ctx)" in array context.  See "command_close_pipe()"
           for details.

       command_close_pipe ( PIPE [, CTX ] )
           Close the "PIPE" as returned from "command_*_pipe()", checking whether the command
           finished successfully. The optional "CTX" argument is required if you want to see the
           command name in the error message, and it is the second value returned by
           "command_*_pipe()" when called in array context. The call idiom is:

                   my ($fh, $ctx) = $r->command_output_pipe('status');
                   while (<$fh>) { ... }
                   $r->command_close_pipe($fh, $ctx);

           Note that you should not rely on whatever actually is in "CTX"; currently it is simply
           the command name but in future the context might have more complicated structure.

       command_bidi_pipe ( COMMAND [, ARGUMENTS... ] )
           Execute the given "COMMAND" in the same way as command_output_pipe() does but return
           both an input pipe filehandle and an output pipe filehandle.

           The function will return return "($pid, $pipe_in, $pipe_out, $ctx)".  See
           "command_close_bidi_pipe()" for details.

       command_close_bidi_pipe ( PID, PIPE_IN, PIPE_OUT [, CTX] )
           Close the "PIPE_IN" and "PIPE_OUT" as returned from "command_bidi_pipe()", checking
           whether the command finished successfully. The optional "CTX" argument is required if
           you want to see the command name in the error message, and it is the fourth value
           returned by "command_bidi_pipe()".  The call idiom is:

                   my ($pid, $in, $out, $ctx) = $r->command_bidi_pipe('cat-file --batch-check');
                   print $out "000000000\n";
                   while (<$in>) { ... }
                   $r->command_close_bidi_pipe($pid, $in, $out, $ctx);

           Note that you should not rely on whatever actually is in "CTX"; currently it is simply
           the command name but in future the context might have more complicated structure.

           "PIPE_IN" and "PIPE_OUT" may be "undef" if they have been closed prior to calling this
           function.  This may be useful in a query-response type of commands where caller first
           writes a query and later reads response, eg:

                   my ($pid, $in, $out, $ctx) = $r->command_bidi_pipe('cat-file --batch-check');
                   print $out "000000000\n";
                   close $out;
                   while (<$in>) { ... }
                   $r->command_close_bidi_pipe($pid, $in, undef, $ctx);

           This idiom may prevent potential dead locks caused by data sent to the output pipe not
           being flushed and thus not reaching the executed command.

       command_noisy ( COMMAND [, ARGUMENTS... ] )
           Execute the given "COMMAND" in the same way as command() does but do not capture the
           command output - the standard output is not redirected and goes to the standard output
           of the caller application.

           While the method is called command_noisy(), you might want to as well use it for the
           most silent Git commands which you know will never pollute your stdout but you want to
           avoid the overhead of the pipe setup when calling them.

           The function returns only after the command has finished running.

       version ()
           Return the Git version in use.

       exec_path ()
           Return path to the Git sub-command executables (the same as "git --exec-path"). Useful
           mostly only internally.

       html_path ()
           Return path to the Git html documentation (the same as "git --html-path"). Useful
           mostly only internally.

       get_tz_offset ( TIME )
           Return the time zone offset from GMT in the form +/-HHMM where HH is the number of
           hours from GMT and MM is the number of minutes.  This is the equivalent of what
           strftime("%z", ...) would provide on a GNU platform.

           If TIME is not supplied, the current local time is used.

       prompt ( PROMPT , ISPASSWORD  )
           Query user "PROMPT" and return answer from user.

           Honours GIT_ASKPASS and SSH_ASKPASS environment variables for querying the user. If no
           *_ASKPASS variable is set or an error occoured, the terminal is tried as a fallback.
           If "ISPASSWORD" is set and true, the terminal disables echo.

       repo_path ()
           Return path to the git repository. Must be called on a repository instance.

       wc_path ()
           Return path to the working copy. Must be called on a repository instance.

       wc_subdir ()
           Return path to the subdirectory inside of a working copy. Must be called on a
           repository instance.

       wc_chdir ( SUBDIR )
           Change the working copy subdirectory to work within. The "SUBDIR" is relative to the
           working copy root directory (not the current subdirectory).  Must be called on a
           repository instance attached to a working copy and the directory must exist.

       config ( VARIABLE )
           Retrieve the configuration "VARIABLE" in the same manner as "config" does. In scalar
           context requires the variable to be set only one time (exception is thrown otherwise),
           in array context returns allows the variable to be set multiple times and returns all
           the values.

       config_bool ( VARIABLE )
           Retrieve the bool configuration "VARIABLE". The return value is usable as a boolean in
           perl (and "undef" if it's not defined, of course).

       config_path ( VARIABLE )
           Retrieve the path configuration "VARIABLE". The return value is an expanded path or
           "undef" if it's not defined.

       config_int ( VARIABLE )
           Retrieve the integer configuration "VARIABLE". The return value is simple decimal
           number.  An optional value suffix of 'k', 'm', or 'g' in the config file will cause
           the value to be multiplied by 1024, 1048576 (1024^2), or 1073741824 (1024^3) prior to
           output.  It would return "undef" if configuration variable is not defined,

       get_colorbool ( NAME )
           Finds if color should be used for NAMEd operation from the configuration, and returns
           boolean (true for "use color", false for "do not use color").

       get_color ( SLOT, COLOR )
           Finds color for SLOT from the configuration, while defaulting to COLOR, and returns
           the ANSI color escape sequence:

                   print $repo->get_color("color.interactive.prompt", "underline blue white");
                   print "some text";
                   print $repo->get_color("", "normal");

       remote_refs ( REPOSITORY [, GROUPS [, REFGLOBS ] ] )
           This function returns a hashref of refs stored in a given remote repository.  The hash
           is in the format "refname =\" hash>. For tags, the "refname" entry contains the tag
           object while a "refname^{}" entry gives the tagged objects.

           "REPOSITORY" has the same meaning as the appropriate "git-ls-remote" argument; either
           a URL or a remote name (if called on a repository instance).  "GROUPS" is an optional
           arrayref that can contain 'tags' to return all the tags and/or 'heads' to return all
           the heads. "REFGLOB" is an optional array of strings containing a shell-like glob to
           further limit the refs returned in the hash; the meaning is again the same as the
           appropriate "git-ls-remote" argument.

           This function may or may not be called on a repository instance. In the former case,
           remote names as defined in the repository are recognized as repository specifiers.

       ident ( TYPE | IDENTSTR )
       ident_person ( TYPE | IDENTSTR | IDENTARRAY )
           This suite of functions retrieves and parses ident information, as stored in the
           commit and tag objects or produced by "var GIT_type_IDENT" (thus "TYPE" can be either
           author or committer; case is insignificant).

           The "ident" method retrieves the ident information from "git var" and either returns
           it as a scalar string or as an array with the fields parsed.  Alternatively, it can
           take a prepared ident string (e.g. from the commit object) and just parse it.

           "ident_person" returns the person part of the ident - name and email; it can take the
           same arguments as "ident" or the array returned by "ident".

           The synopsis is like:

                   my ($name, $email, $time_tz) = ident('author');
                   "$name <$email>" eq ident_person('author');
                   "$name <$email>" eq ident_person($name);
                   $time_tz =~ /^\d+ [+-]\d{4}$/;

       hash_object ( TYPE, FILENAME )
           Compute the SHA1 object id of the given "FILENAME" considering it is of the "TYPE"
           object type ("blob", "commit", "tree").

           The method can be called without any instance or on a specified Git repository, it
           makes zero difference.

           The function returns the SHA1 hash.

       hash_and_insert_object ( FILENAME )
           Compute the SHA1 object id of the given "FILENAME" and add the object to the object
           database.

           The function returns the SHA1 hash.

       cat_blob ( SHA1, FILEHANDLE )
           Prints the contents of the blob identified by "SHA1" to "FILEHANDLE" and returns the
           number of bytes printed.

       credential_read( FILEHANDLE )
           Reads credential key-value pairs from "FILEHANDLE".  Reading stops at EOF or when an
           empty line is encountered.  Each line must be of the form "key=value" with a non-empty
           key.  Function returns hash with all read values.  Any white space (other than new-
           line character) is preserved.

       credential_write( FILEHANDLE, CREDENTIAL_HASHREF )
           Writes credential key-value pairs from hash referenced by "CREDENTIAL_HASHREF" to
           "FILEHANDLE".  Keys and values cannot contain new-lines or NUL bytes characters, and
           key cannot contain equal signs nor be empty (if they do Error::Simple is thrown).  Any
           white space is preserved.  If value for a key is "undef", it will be skipped.

           If 'url' key exists it will be written first.  (All the other key-value pairs are
           written in sorted order but you should not depend on that).  Once all lines are
           written, an empty line is printed.

       credential( CREDENTIAL_HASHREF [, OPERATION ] )
       credential( CREDENTIAL_HASHREF, CODE )
           Executes "git credential" for a given set of credentials and specified operation.  In
           both forms "CREDENTIAL_HASHREF" needs to be a reference to a hash which stores
           credentials.  Under certain conditions the hash can change.

           In the first form, "OPERATION" can be 'fill', 'approve' or 'reject', and function will
           execute corresponding "git credential" sub-command.  If it's omitted 'fill' is
           assumed.  In case of 'fill' the values stored in "CREDENTIAL_HASHREF" will be changed
           to the ones returned by the "git credential fill" command.  The usual usage would look
           something like:

                   my %cred = (
                           'protocol' => 'https',
                           'host' => 'example.com',
                           'username' => 'bob'
                   );
                   Git::credential \%cred;
                   if (try_to_authenticate($cred{'username'}, $cred{'password'})) {
                           Git::credential \%cred, 'approve';
                           ... do more stuff ...
                   } else {
                           Git::credential \%cred, 'reject';
                   }

           In the second form, "CODE" needs to be a reference to a subroutine.  The function will
           execute "git credential fill" to fill the provided credential hash, then call "CODE"
           with "CREDENTIAL_HASHREF" as the sole argument.  If "CODE"'s return value is defined,
           the function will execute "git credential approve" (if return value yields true) or
           "git credential reject" (if return value is false).  If the return value is undef,
           nothing at all is executed; this is useful, for example, if the credential could
           neither be verified nor rejected due to an unrelated network error.  The return value
           is the same as what "CODE" returns.  With this form, the usage might look as follows:

                   if (Git::credential {
                           'protocol' => 'https',
                           'host' => 'example.com',
                           'username' => 'bob'
                   }, sub {
                           my $cred = shift;
                           return !!try_to_authenticate($cred->{'username'},
                                                        $cred->{'password'});
                   }) {
                           ... do more stuff ...
                   }

       temp_acquire ( NAME )
           Attempts to retrieve the temporary file mapped to the string "NAME". If an associated
           temp file has not been created this session or was closed, it is created, cached, and
           set for autoflush and binmode.

           Internally locks the file mapped to "NAME". This lock must be released with
           "temp_release()" when the temp file is no longer needed. Subsequent attempts to
           retrieve temporary files mapped to the same "NAME" while still locked will cause an
           error. This locking mechanism provides a weak guarantee and is not threadsafe. It does
           provide some error checking to help prevent temp file refs writing over one another.

           In general, the File::Handle returned should not be closed by consumers as it defeats
           the purpose of this caching mechanism. If you need to close the temp file handle, then
           you should use File::Temp or another temp file faculty directly. If a handle is closed
           and then requested again, then a warning will issue.

       temp_is_locked ( NAME )
           Returns true if the internal lock created by a previous "temp_acquire()" call with
           "NAME" is still in effect.

           When temp_acquire is called on a "NAME", it internally locks the temporary file mapped
           to "NAME".  That lock will not be released until "temp_release()" is called with
           either the original "NAME" or the File::Handle that was returned from the original
           call to temp_acquire.

           Subsequent attempts to call "temp_acquire()" with the same "NAME" will fail unless
           there has been an intervening "temp_release()" call for that "NAME" (or its
           corresponding File::Handle that was returned by the original "temp_acquire()" call).

           If true is returned by "temp_is_locked()" for a "NAME", an attempt to "temp_acquire()"
           the same "NAME" will cause an error unless "temp_release" is first called on that
           "NAME" (or its corresponding File::Handle that was returned by the original
           "temp_acquire()" call).

       temp_release ( NAME )
       temp_release ( FILEHANDLE )
           Releases a lock acquired through "temp_acquire()". Can be called either with the
           "NAME" mapping used when acquiring the temp file or with the "FILEHANDLE" referencing
           a locked temp file.

           Warns if an attempt is made to release a file that is not locked.

           The temp file will be truncated before being released. This can help to reduce disk
           I/O where the system is smart enough to detect the truncation while data is in the
           output buffers. Beware that after the temp file is released and truncated, any
           operations on that file may fail miserably until it is re-acquired. All contents are
           lost between each release and acquire mapped to the same string.

       temp_reset ( FILEHANDLE )
           Truncates and resets the position of the "FILEHANDLE".

       temp_path ( NAME )
       temp_path ( FILEHANDLE )
           Returns the filename associated with the given tempfile.

ERROR HANDLING

       All functions are supposed to throw Perl exceptions in case of errors.  See the Error
       module on how to catch those. Most exceptions are mere Error::Simple instances.

       However, the "command()", "command_oneline()" and "command_noisy()" functions suite can
       throw "Git::Error::Command" exceptions as well: those are thrown when the external command
       returns an error code and contain the error code as well as access to the captured
       command's output. The exception class provides the usual "stringify" and "value"
       (command's exit code) methods and in addition also a "cmd_output" method that returns
       either an array or a string with the captured command output (depending on the original
       function call context; "command_noisy()" returns "undef") and $<cmdline> which returns the
       command and its arguments (but without proper quoting).

       Note that the "command_*_pipe()" functions cannot throw this exception since it has no
       idea whether the command failed or not. You will only find out at the time you "close" the
       pipe; if you want to have that automated, use "command_close_pipe()", which can throw the
       exception.

       git_cmd_try { CODE } ERRMSG
           This magical statement will automatically catch any "Git::Error::Command" exceptions
           thrown by "CODE" and make your program die with "ERRMSG" on its lips; the message will
           have %s substituted for the command line and %d for the exit status. This statement is
           useful mostly for producing more user-friendly error messages.

           In case of no exception caught the statement returns "CODE"'s return value.

           Note that this is the only auto-exported function.

COPYRIGHT

       Copyright 2006 by Petr Baudis <pasky@suse.cz>.

       This module is free software; it may be used, copied, modified and distributed under the
       terms of the GNU General Public Licence, either version 2, or (at your option) any later
       version.