+=item hash_and_insert_object ( FILENAME )
+
+Compute the SHA1 object id of the given C<FILENAME> and add the object to the
+object database.
+
+The function returns the SHA1 hash.
+
+=cut
+
+# TODO: Support for passing FILEHANDLE instead of FILENAME
+sub hash_and_insert_object {
+ my ($self, $filename) = @_;
+
+ carp "Bad filename \"$filename\"" if $filename =~ /[\r\n]/;
+
+ $self->_open_hash_and_insert_object_if_needed();
+ my ($in, $out) = ($self->{hash_object_in}, $self->{hash_object_out});
+
+ unless (print $out $filename, "\n") {
+ $self->_close_hash_and_insert_object();
+ throw Error::Simple("out pipe went bad");
+ }
+
+ chomp(my $hash = <$in>);
+ unless (defined($hash)) {
+ $self->_close_hash_and_insert_object();
+ throw Error::Simple("in pipe went bad");
+ }
+
+ return $hash;
+}
+
+sub _open_hash_and_insert_object_if_needed {
+ my ($self) = @_;
+
+ return if defined($self->{hash_object_pid});
+
+ ($self->{hash_object_pid}, $self->{hash_object_in},
+ $self->{hash_object_out}, $self->{hash_object_ctx}) =
+ command_bidi_pipe(qw(hash-object -w --stdin-paths));
+}
+
+sub _close_hash_and_insert_object {
+ my ($self) = @_;
+
+ return unless defined($self->{hash_object_pid});
+
+ my @vars = map { 'hash_object_' . $_ } qw(pid in out ctx);
+
+ command_close_bidi_pipe(@$self{@vars});
+ delete @$self{@vars};
+}
+
+=item cat_blob ( SHA1, FILEHANDLE )
+
+Prints the contents of the blob identified by C<SHA1> to C<FILEHANDLE> and
+returns the number of bytes printed.
+
+=cut
+
+sub cat_blob {
+ my ($self, $sha1, $fh) = @_;
+
+ $self->_open_cat_blob_if_needed();
+ my ($in, $out) = ($self->{cat_blob_in}, $self->{cat_blob_out});
+
+ unless (print $out $sha1, "\n") {
+ $self->_close_cat_blob();
+ throw Error::Simple("out pipe went bad");
+ }
+
+ my $description = <$in>;
+ if ($description =~ / missing$/) {
+ carp "$sha1 doesn't exist in the repository";
+ return -1;
+ }
+
+ if ($description !~ /^[0-9a-fA-F]{40} \S+ (\d+)$/) {
+ carp "Unexpected result returned from git cat-file";
+ return -1;
+ }
+
+ my $size = $1;
+
+ my $blob;
+ my $bytesRead = 0;
+
+ while (1) {
+ my $bytesLeft = $size - $bytesRead;
+ last unless $bytesLeft;
+
+ my $bytesToRead = $bytesLeft < 1024 ? $bytesLeft : 1024;
+ my $read = read($in, $blob, $bytesToRead, $bytesRead);
+ unless (defined($read)) {
+ $self->_close_cat_blob();
+ throw Error::Simple("in pipe went bad");
+ }
+
+ $bytesRead += $read;
+ }
+
+ # Skip past the trailing newline.
+ my $newline;
+ my $read = read($in, $newline, 1);
+ unless (defined($read)) {
+ $self->_close_cat_blob();
+ throw Error::Simple("in pipe went bad");
+ }
+ unless ($read == 1 && $newline eq "\n") {
+ $self->_close_cat_blob();
+ throw Error::Simple("didn't find newline after blob");
+ }
+
+ unless (print $fh $blob) {
+ $self->_close_cat_blob();
+ throw Error::Simple("couldn't write to passed in filehandle");
+ }
+
+ return $size;
+}
+
+sub _open_cat_blob_if_needed {
+ my ($self) = @_;
+
+ return if defined($self->{cat_blob_pid});
+
+ ($self->{cat_blob_pid}, $self->{cat_blob_in},
+ $self->{cat_blob_out}, $self->{cat_blob_ctx}) =
+ command_bidi_pipe(qw(cat-file --batch));
+}
+
+sub _close_cat_blob {
+ my ($self) = @_;
+
+ return unless defined($self->{cat_blob_pid});
+
+ my @vars = map { 'cat_blob_' . $_ } qw(pid in out ctx);
+
+ command_close_bidi_pipe(@$self{@vars});
+ delete @$self{@vars};
+}
+
+
+{ # %TEMP_* Lexical Context
+
+my (%TEMP_LOCKS, %TEMP_FILES);
+
+=item temp_acquire ( NAME )
+
+Attempts to retreive the temporary file mapped to the string C<NAME>. If an
+associated temp file has not been created this session or was closed, it is
+created, cached, and set for autoflush and binmode.
+
+Internally locks the file mapped to C<NAME>. This lock must be released with
+C<temp_release()> when the temp file is no longer needed. Subsequent attempts
+to retrieve temporary files mapped to the same C<NAME> while still locked will
+cause an error. This locking mechanism provides a weak guarantee and is not
+threadsafe. It does provide some error checking to help prevent temp file refs
+writing over one another.
+
+In general, the L<File::Handle> returned should not be closed by consumers as
+it defeats the purpose of this caching mechanism. If you need to close the temp
+file handle, then you should use L<File::Temp> or another temp file faculty
+directly. If a handle is closed and then requested again, then a warning will
+issue.
+
+=cut
+
+sub temp_acquire {
+ my ($self, $name) = _maybe_self(@_);
+
+ my $temp_fd = _temp_cache($name);
+
+ $TEMP_LOCKS{$temp_fd} = 1;
+ $temp_fd;
+}
+
+=item temp_release ( NAME )
+
+=item temp_release ( FILEHANDLE )
+
+Releases a lock acquired through C<temp_acquire()>. Can be called either with
+the C<NAME> mapping used when acquiring the temp file or with the C<FILEHANDLE>
+referencing a locked temp file.
+
+Warns if an attempt is made to release a file that is not locked.
+
+The temp file will be truncated before being released. This can help to reduce
+disk I/O where the system is smart enough to detect the truncation while data
+is in the output buffers. Beware that after the temp file is released and
+truncated, any operations on that file may fail miserably until it is
+re-acquired. All contents are lost between each release and acquire mapped to
+the same string.
+
+=cut
+
+sub temp_release {
+ my ($self, $temp_fd, $trunc) = _maybe_self(@_);
+
+ if (ref($temp_fd) ne 'File::Temp') {
+ $temp_fd = $TEMP_FILES{$temp_fd};
+ }
+ unless ($TEMP_LOCKS{$temp_fd}) {
+ carp "Attempt to release temp file '",
+ $temp_fd, "' that has not been locked";
+ }
+ temp_reset($temp_fd) if $trunc and $temp_fd->opened;
+
+ $TEMP_LOCKS{$temp_fd} = 0;
+ undef;
+}
+
+sub _temp_cache {
+ my ($name) = @_;
+
+ my $temp_fd = \$TEMP_FILES{$name};
+ if (defined $$temp_fd and $$temp_fd->opened) {
+ if ($TEMP_LOCKS{$$temp_fd}) {
+ throw Error::Simple("Temp file with moniker '",
+ $name, "' already in use");
+ }
+ } else {
+ if (defined $$temp_fd) {
+ # then we're here because of a closed handle.
+ carp "Temp file '", $name,
+ "' was closed. Opening replacement.";
+ }
+ $$temp_fd = File::Temp->new(
+ TEMPLATE => 'Git_XXXXXX',
+ DIR => File::Spec->tmpdir
+ ) or throw Error::Simple("couldn't open new temp file");
+ $$temp_fd->autoflush;
+ binmode $$temp_fd;
+ }
+ $$temp_fd;
+}
+
+=item temp_reset ( FILEHANDLE )
+
+Truncates and resets the position of the C<FILEHANDLE>.
+
+=cut
+
+sub temp_reset {
+ my ($self, $temp_fd) = _maybe_self(@_);
+
+ truncate $temp_fd, 0
+ or throw Error::Simple("couldn't truncate file");
+ sysseek($temp_fd, 0, SEEK_SET) and seek($temp_fd, 0, SEEK_SET)
+ or throw Error::Simple("couldn't seek to beginning of file");
+ sysseek($temp_fd, 0, SEEK_CUR) == 0 and tell($temp_fd) == 0
+ or throw Error::Simple("expected file position to be reset");
+}
+
+sub END {
+ unlink values %TEMP_FILES if %TEMP_FILES;
+}
+
+} # %TEMP_* Lexical Context