#! /usr/bin/perl -w
#
# Written by Adam Byrtek <alpha@debian.org>, 2002
#
# Extfs to handle patches in context and unified diff format.
# Known issues: When name of file to patch is modified during editing, 
# hunk is duplicated on copyin. It is unavoidable.

use bytes;
use strict;
use POSIX;
use File::Temp 'tempfile';

# standard binaries
my $bzip = 'bzip2';
my $gzip = 'gzip';
my $fileutil = 'file';

# date parsing requires Date::Parse from TimeDate module
my $parsedates = eval 'require Date::Parse';

# regular expressions
my $unified_header=qr/^--- .*\n\+\+\+ .*\n@@ .* @@.*\n$/;
my $unified_extract=qr/^--- ([^\s]+).*\n\+\+\+ ([^\s]+)\s*([^\t\n]*)/;
my $unified_contents=qr/^([+\-\\ \n]|@@ .* @@)/;

my $context_header=qr/^\*\*\* .*\n--- .*\n\*{15}\n$/;
my $context_extract=qr/^\*\*\* ([^\s]+).*\n--- ([^\s]+)\s*([^\t\n]*)/;
my $context_contents=qr/^([!+\-\\ \n]|-{3} .* -{4}|\*{3} .* \*{4}|\*{15})/;

my $ls_extract_id=qr/^[^\s]+\s+[^\s]+\s+([^\s]+)\s+([^\s]+)/;
my $basename=qr|^(.*/)*([^/]+)$|;


# output unix date in a mc-readable format
sub timef
{
    my @time=localtime($_[0]);
    return sprintf '%02d-%02d-%02d %02d:%02d', $time[4]+1, $time[3],
		   $time[5]+1900, $time[2], $time[1];
}

# parse given string as a date and return unix time
sub datetime
{
    # in case of problems fall back to 0 in unix time
    # note: str2time interprets some wrong values (eg. " ") as 'today'
    if ($parsedates && defined (my $t=str2time($_[0]))) {
	return timef($t);
    }
    return timef(time);
}

# print message on stderr and exit
sub error
{
    print STDERR $_[0], "\n";
    exit 1;
}

# (compressed) input
sub myin
{
    my ($qfname)=(quotemeta $_[0]);

    $_=`$fileutil $qfname`;
    if (/bzip/) {
	return "$bzip -dc $qfname";
    } elsif (/gzip/) {
	return "$gzip -dc $qfname";
    } else {
	return "cat $qfname";
    }
}

# (compressed) output
sub myout
{
    my ($qfname,$append)=(quotemeta $_[0],$_[1]);
    my ($sep) = $append ? '>>' : '>';

    $_=`$fileutil $qfname`;
    if (/bzip/) {
	return "$bzip -c $sep $qfname";
    } elsif (/gzip/) {
	return "$gzip -c $sep $qfname";
    } else {
	return "cat $sep $qfname";
    }
}

# select diff filename conforming with rules found in diff.info
sub diff_filename
{
    my ($fsrc,$fdst)=@_;

    if (!$fdst && !$fsrc) {
	error 'Index: not yet implemented';
    } elsif (!$fsrc || $fsrc eq '/dev/null') {
	return ($fdst,'PATCH-CREATE/');
    } elsif (!$fdst || $fdst eq '/dev/null') {
	return ($fsrc,'PATCH-REMOVE/');
    } elsif (($fdst eq '/dev/null') && ($fsrc eq '/dev/null')) {
	error 'Malformed diff';
    } else {
	# fewest path name components
	if ($fdst=~s|/|/|g < $fsrc=~s|/|/|g) {
	    return ($fdst,'');
	} elsif ($fdst=~s|/|/|g > $fsrc=~s|/|/|g) {
	    return ($fsrc,'');
	} else {
	    # shorter base name
	    if (($fdst=~/$basename/,length $2) < ($fsrc=~/$basename/,length $2)) {
		return ($fdst,'');
	    } elsif (($fdst=~/$basename/,length $2) > ($fsrc=~/$basename/,length $2)) {
		return ($fsrc,'');
	    } else {
		# shortest names
		if (length $fdst < length $fsrc) {
		    return ($fdst,'');
		} else {
		    return ($fsrc,'');
		}
	    }
	}
    }
}

# parse unified or context header
sub parse_header
{
    my ($unified,$context,$buf)=@_;

    if ($unified) {
	error "Can't parse unified diff header"
	  unless ((($$buf.=<I>).=<I>)=~/$unified_header/);
	return $$buf=~/$unified_extract/;
    } elsif ($context) {
	error "Can't parse context diff header"
	  unless ((($$buf.=<I>).=<I>)=~/$context_header/);
	return $$buf=~/$context_extract/;
    }
}

# list files affected by patch
sub list
{
    my ($archive)=(quotemeta $_[0]);
    my ($state,$pos,$len,$time);
    my ($f,$fsrc,$fdst,$prefix);
    my ($unified,$context)=(0,0);

    # use uid and gid from file
    my ($uid,$gid)=(`ls -l $archive`=~/$ls_extract_id/);

    import Date::Parse if ($parsedates);
    
    # state==1 means diff contents, state==0 means comments
    $state=0; $len=0; $f='';
    while (<I>) {

	# recognize diff type
	if (!$unified && !$context) {
	    $unified=1 if (/^--- /);
	    $context=1 if (/^\*\*\* /);
	    if (!$unified && !$context) {
		$len+=length;
		next;
	    }
	}

	if (($unified && /^--- /) || ($context && /^\*\*\* [^\*]*$/)) {
	    # start of new file
	    if ($state==1) {
		printf "-rw-r--r-- 1 %s %s %d %s %s%s\n", $uid, $gid, $len, datetime($time), $prefix, $f
		  if $f;
		$len=0;
	    }
	    $state=1;

	    ($fsrc,$fdst,$time)=parse_header($unified,$context,\$_);
	    ($f,$prefix)=diff_filename($fsrc,$fdst);
	    $f=$f.".diff";

	} elsif ($state==1 && (($unified && !/$unified_contents/) || ($context && !/$context_contents/))) {
	    # start of comments, end of diff contents
	    printf "-rw-r--r-- 1 %s %s %d %s %s%s\n", $uid, $gid, $len, datetime($time), $prefix, $f
	      if $f;
	    $state=$len=0;
	}

	$len+=length;
    }
    printf "-rw-r--r-- 1 %s %s %d %s %s%s\n", $uid, $gid, $len, datetime($time), $prefix, $f
      if ($f && $state==1);
}

# extract diff from patch
sub copyout
{
    my ($file,$out)=@_;
    my ($fsrc,$fdst,$found,$state,$buf);
    my ($unified,$context)=(0,0);

    $file=~s/^(PATCH-(CREATE|REMOVE)\/)?(.*)\.diff$/$3/;
    
    # state==1 means diff contents, state==0 mens comments
    $state=0; $found=0; $buf='';
    while (<I>) {

	# recognize diff type
	if (!$unified && !$context) {
	    $unified=1 if (/^--- /);
	    $context=1 if (/^\*\*\* /);
	    if (!$unified && !$context) {
		$buf.=$_;
		next;
	    }
	}

	if (($unified && /^--- /) || ($context && /^\*\*\* [^\*]*$/)) {
	    last if ($state==1 && $found);
	    $state=1;

	    ($fsrc,$fdst,)=parse_header($unified,$context,\$_);
	    $found=1 if (($fsrc eq $file) || ($fdst eq $file));

	} elsif ($state==1 && (($unified && !/$unified_contents/) || ($context && !/$context_contents/))) {
	    # start of comments, end of diff contents
	    last if ($found);
	    $state=0;
	    $buf='';
	}

	$buf.=$_ if ($found || $state==0)
    }
    if ($found) {
	open O, "> $out";
	print O $buf;
	close O;
    }
}

# remove diff(s) from patch
sub rm
{
    my ($archive)=(shift);
    my ($fsrc,$fdst,$found,$state,$buf);
    my ($tmp,$tmpname)=tempfile();
    my ($unified,$context)=(0,0);

    @_=map {scalar(s/^(PATCH-(CREATE|REMOVE)\/)?(.*)\.diff$/$3/,$_)} @_;

    # state==1 means diff contents, state==0 mens comments
    $state=0; $found=0; $buf='';
    while (<I>) {

	# recognize diff type
	if (!$unified && !$context) {
	    $unified=1 if (/^--- /);
	    $context=1 if (/^\*\*\* /);
	    if (!$unified && !$context) {
		$buf.=$_;
		next;
	    }
	}

	if (($unified && /^--- /) || ($context && /^\*\*\* [^\*]*$/)) {
	    $state=1;

	    ($fsrc,$fdst,)=parse_header($unified,$context,\$_);

	    # remove listed files
	    foreach (@_) {
		if (($fsrc eq $_) || ($fdst eq $_)) {
		    $found=1;
		    last;
		}
	    }
	    if (!$found) {
		print $tmp $buf;
		$buf='';
	    }

	} elsif ($state==1 && (($unified && !/$unified_contents/) || ($context && !/$context_contents/))) {
	    # start of comments, end of diff contents
	    $found=0;
	    $state=0;
	    $buf='';
	}

	if ($state==0) {
	    $buf.=$_;
	} elsif (!$found) {
	    print $tmp $_;
	}
    }
    print $tmp $buf if (!$found);
    close $tmp;
    close I;

    # replace archive with temporary file
    system('cat '.quotemeta($tmpname).'|'.myout($archive,0))==0
      or error "Can't write to archive";
    system 'rm -f '.quotemeta($tmpname);
}

# append diff to archive
sub copyin
{
    my ($archive,$name,$src)=(@_);
    my ($fsrc,$fdst,$f,@files);
    my ($unified,$context)=(0,0);

    # build filelist
    open I, myin($src).'|';
    while (<I>) {
	# recognize diff type
	if (!$unified && !$context) {
	    $unified=1 if (/^--- /);
	    $context=1 if (/^\*\*\* /);
	}

	if (($unified && /^--- /) || ($context && /^\*\*\* [^\*]*$/)) {
	    ($fsrc,$fdst,)=parse_header($unified,$context,\$_);
	    ($f,)=diff_filename($fsrc,$fdst);
	    push(@files,$f);
	}
    }
    close I;

    # remove overwrited files
    open I, myin($archive).'|';
    rm ($archive, map($_.'.diff',@files));
    close I;

    my $cmd1=myin($src);
    my $cmd2=myout($archive,1);
    system("$cmd1 | $cmd2")==0
      or error "Can't write to archive";
}


if ($ARGV[0] eq 'list') {
    open I, myin($ARGV[1]).'|';
    list $ARGV[1];
    exit 0;
} if ($ARGV[0] eq 'copyout') {
    open I, myin($ARGV[1])."|";
    copyout ($ARGV[2], $ARGV[3]);
    exit 0;
} if ($ARGV[0] eq 'rm') {
    open I, myin($ARGV[1])."|";
    rm ($ARGV[1], $ARGV[2]);
    exit 0;
} if ($ARGV[0] eq 'rmdir') {
    exit 0;
} if ($ARGV[0] eq 'mkdir') {
    exit 0;
} if ($ARGV[0] eq 'copyin') {
    copyin ($ARGV[1], $ARGV[2], $ARGV[3]);
    exit 0;
}
exit 1;
