#!/usr/bin/perl -w

# Copyright (C) 2005, 2006, 2007 Apple Inc.  All rights reserved.

#

# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions

# are met:

#

# 1.  Redistributions of source code must retain the above copyright

#     notice, this list of conditions and the following disclaimer. 

# 2.  Redistributions in binary form must reproduce the above copyright

#     notice, this list of conditions and the following disclaimer in the

#     documentation and/or other materials provided with the distribution. 

# 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of

#     its contributors may be used to endorse or promote products derived

#     from this software without specific prior written permission. 

#

# THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY

# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

# DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY

# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

# "unpatch" script for Web Kit Open Source Project, used to remove patches.

# Differences from invoking "patch -p0 -R":

#

#   Handles added files (does a svn revert with additional logic to handle local changes). 

#   Handles added directories (does a svn revert and a rmdir).

#   Handles removed files (does a svn revert with additional logic to handle local changes). 

#   Handles removed directories (does a svn revert). 

#   Paths from Index: lines are used rather than the paths on the patch lines, which

#       makes patches generated by "cvs diff" work (increasingly unimportant since we

#       use Subversion now).

#   ChangeLog patches use --fuzz=3 to prevent rejects, and the entry date is reset in

#       the patch before it is applied (svn-apply sets it when applying a patch).

#   Handles binary files (requires patches made by svn-create-patch).

#   Handles copied and moved files (requires patches made by svn-create-patch).

#   Handles git-diff patches (without binary changes) created at the top-level directory

#

# Missing features:

#

#   Handle property changes.

#   Handle copied and moved directories (would require patches made by svn-create-patch).

#   Use version numbers in the patch file and do a 3-way merge.

#   When reversing an addition, check that the file matches what's being removed.

#   Notice a patch that's being unapplied at the "wrong level" and make it work anyway.

#   Do a dry run on the whole patch and don't do anything if part of the patch is

#       going to fail (probably too strict unless we exclude ChangeLog).

#   Handle git-diff patches with binary changes

use strict;

use warnings;

use Cwd;

use Digest::MD5;

use Fcntl qw(:DEFAULT :seek);

use File::Basename;

use File::Spec;

use File::Temp qw(tempfile);

use Getopt::Long;

sub checksum($);

sub fixChangeLogPatch($);

sub gitdiff2svndiff($);

sub patch($);

sub revertDirectories();

sub svnStatus($);

sub unapplyPatch($$;$);

sub unsetChangeLogDate($$);

my $showHelp = 0;

if (!GetOptions("help!" => \$showHelp) || $showHelp) {

    print STDERR basename($0) . " [-h|--help] patch1 [patch2 ...]\n";

    exit 1;

}

my @copiedFiles;

my %directoriesToCheck;

my $copiedFromPath;

my $filter;

my $indexPath;

my $patch;

while (<>) {

    s/\r//g;

    chomp;

    if (!defined($indexPath) && m#^diff --git a/#) {

        $filter = \&gitdiff2svndiff;

    }

    $_ = &$filter($_) if $filter;

    if (/^Index: (.*)/) {

        $indexPath = $1;

        if ($patch) {

            if ($copiedFromPath) {

                push @copiedFiles, $patch;

            } else {

                patch($patch);

            }

            $copiedFromPath = "";

            $patch = "";

        }

    }

    if ($indexPath) {

        # Fix paths on diff, ---, and +++ lines to match preceding Index: line.

        s/^--- \S+/--- $indexPath/;

        if (/^--- .+\(from (\S+):\d+\)$/) {

            $copiedFromPath = $1;

        }

        if (s/^\+\+\+ \S+/+++ $indexPath/) {

            $indexPath = "";

        }

    }

    $patch .= $_;

    $patch .= "\n";

}

if ($patch) {

    if ($copiedFromPath) {

        push @copiedFiles, $patch;

    } else {

        patch($patch);

    }

}

# Handle copied and moved files last since they may have had post-copy changes that have now been unapplied

for $patch (@copiedFiles) {

    patch($patch);

}

revertDirectories();

exit 0;

sub checksum($)

{

    my $file = shift;

    open(FILE, $file) or die "Can't open '$file': $!";

    binmode(FILE);

    my $checksum = Digest::MD5->new->addfile(*FILE)->hexdigest();

    close(FILE);

    return $checksum;

}

sub fixChangeLogPatch($)

{

    my $patch = shift;

    my $contextLineCount = 3;

    return $patch if $patch !~ /\n@@ -1,(\d+) \+1,(\d+) @@\n( .*\n)+(\+.*\n)+( .*\n){$contextLineCount}$/m;

    my ($oldLineCount, $newLineCount) = ($1, $2);

    return $patch if $oldLineCount <= $contextLineCount;

    # The diff(1) command is greedy when matching lines, so a new ChangeLog entry will

    # have lines of context at the top of a patch when the existing entry has the same

    # date and author as the new entry.  This nifty loop alters a ChangeLog patch so

    # that the added lines ("+") in the patch always start at the beginning of the

    # patch and there are no initial lines of context.

    my $newPatch;

    my $lineCountInState = 0;

    my $oldContentLineCountReduction = $oldLineCount - $contextLineCount;

    my $newContentLineCountWithoutContext = $newLineCount - $oldLineCount - $oldContentLineCountReduction;

    my ($stateHeader, $statePreContext, $stateNewChanges, $statePostContext) = (1..4);

    my $state = $stateHeader;

    foreach my $line (split(/\n/, $patch)) {

        $lineCountInState++;

        if ($state == $stateHeader && $line =~ /^@@ -1,$oldLineCount \+1,$newLineCount @\@$/) {

            $line = "@@ -1,$contextLineCount +1," . ($newLineCount - $oldContentLineCountReduction) . " @@";

            $lineCountInState = 0;

            $state = $statePreContext;

        } elsif ($state == $statePreContext && substr($line, 0, 1) eq " ") {

            $line = "+" . substr($line, 1);

            if ($lineCountInState == $oldContentLineCountReduction) {

                $lineCountInState = 0;

                $state = $stateNewChanges;

            }

        } elsif ($state == $stateNewChanges && substr($line, 0, 1) eq "+") {

            # No changes to these lines

            if ($lineCountInState == $newContentLineCountWithoutContext) {

                $lineCountInState = 0;

                $state = $statePostContext;

            }

        } elsif ($state == $statePostContext) {

            if (substr($line, 0, 1) eq "+" && $lineCountInState <= $oldContentLineCountReduction) {

                $line = " " . substr($line, 1);

            } elsif ($lineCountInState > $contextLineCount && substr($line, 0, 1) eq " ") {

                next; # Discard

            }

        }

        $newPatch .= $line . "\n";

    }

    return $newPatch;

}

sub gitdiff2svndiff($)

{

    $_ = shift @_;

    if (m#^diff --git a/(.+) b/(.+)#) {

        return "Index: $1";

    } elsif (m/^new file.*/) {

        return "";

    } elsif (m#^index [0-9a-f]{7}\.\.[0-9a-f]{7} [0-9]{6}#) {

        return "===================================================================";

    } elsif (m#^--- a/(.+)#) {

        return "--- $1";

    } elsif (m#^\+\+\+ b/(.+)#) {

        return "+++ $1";

    }

    return $_;

}

sub patch($)

{

    my ($patch) = @_;

    return if !$patch;

    $patch =~ m|^Index: ([^\n]+)| or die "Failed to find Index: in \"$patch\"\n";

    my $fullPath = $1;

    $directoriesToCheck{dirname($fullPath)} = 1;

    my $deletion = 0;

    my $addition = 0;

    my $isBinary = 0;

    $addition = 1 if ($patch =~ /\n--- .+\(revision 0\)\n/ || $patch =~ /\n@@ -0,0 .* @@/);

    $deletion = 1 if $patch =~ /\n@@ .* \+0,0 @@/;

    $isBinary = 1 if $patch =~ /\nCannot display: file marked as a binary type\./;

    if (!$addition && !$deletion && !$isBinary) {

        # Standard patch, patch tool can handle this.

        if (basename($fullPath) eq "ChangeLog") {

            my $changeLogDotOrigExisted = -f "${fullPath}.orig";

            unapplyPatch(unsetChangeLogDate($fullPath, fixChangeLogPatch($patch)), $fullPath, ["--fuzz=3"]);

            unlink("${fullPath}.orig") if (! $changeLogDotOrigExisted);

        } else {

            unapplyPatch($patch, $fullPath);

        }

    } else {

        # Either a deletion, an addition or a binary change.

        if ($isBinary) {

            # Reverse binary change

            unlink($fullPath) if (-e $fullPath);

            system "svn", "revert", $fullPath;

        } elsif ($deletion) {

            # Reverse deletion

            rename($fullPath, "$fullPath.orig") if -e $fullPath;

            unapplyPatch($patch, $fullPath);

            # If we don't ask for the filehandle here, we always get a warning.

            my ($fh, $tempPath) = tempfile(basename($fullPath) . "-XXXXXXXX",

                                           DIR => dirname($fullPath), UNLINK => 1);

            close($fh);

            # Keep the version from the patch in case it's different from svn.

            rename($fullPath, $tempPath);

            system "svn", "revert", $fullPath;

            rename($tempPath, $fullPath);

            # This works around a bug in the svn client.

            # [Issue 1960] file modifications get lost due to FAT 2s time resolution

            # http://subversion.tigris.org/issues/show_bug.cgi?id=1960

            system "touch", $fullPath;

            # Remove $fullPath.orig if it is the same as $fullPath

            unlink("$fullPath.orig") if -e "$fullPath.orig" && checksum($fullPath) eq checksum("$fullPath.orig");

            # Show status if the file is modifed

            system "svn", "stat", $fullPath;

        } else {

            # Reverse addition

            unapplyPatch($patch, $fullPath, ["--force"]);

            unlink($fullPath) if -z $fullPath;

            system "svn", "revert", $fullPath;

        }

    }

}

sub revertDirectories()

{

    my %checkedDirectories;

    foreach my $path (reverse sort keys %directoriesToCheck) {

        my @dirs = File::Spec->splitdir($path);

        while (scalar @dirs) {

            my $dir = File::Spec->catdir(@dirs);

            pop(@dirs);

            next if (exists $checkedDirectories{$dir});

            if (-d $dir) {

                my $svnOutput = svnStatus($dir);

                if ($svnOutput && $svnOutput =~ m#A\s+$dir\n#) {

                   system "svn", "revert", $dir;

                   rmdir $dir;

                }

                elsif ($svnOutput && $svnOutput =~ m#D\s+$dir\n#) {

                   system "svn", "revert", $dir;

                }

                else {

                    # Modification

                    print $svnOutput if $svnOutput;

                }

                $checkedDirectories{$dir} = 1;

            }

            else {

                die "'$dir' is not a directory";

            }

        }

    }

}

sub svnStatus($)

{

    my ($fullPath) = @_;

    my $svnStatus;

    open SVN, "svn status --non-interactive --non-recursive '$fullPath' |" or die;

    if (-d $fullPath) {

        # When running "svn stat" on a directory, we can't assume that only one

        # status will be returned (since any files with a status below the

        # directory will be returned), and we can't assume that the directory will

        # be first (since any files with unknown status will be listed first).

        my $normalizedFullPath = File::Spec->catdir(File::Spec->splitdir($fullPath));

        while (<SVN>) {

            chomp;

            my $normalizedStatPath = File::Spec->catdir(File::Spec->splitdir(substr($_, 7)));

            if ($normalizedFullPath eq $normalizedStatPath) {

                $svnStatus = $_;

                last;

            }

        }

        # Read the rest of the svn command output to avoid a broken pipe warning.

        local $/ = undef;

        <SVN>;

    }

    else {

        # Files will have only one status returned.

        $svnStatus = <SVN>;

    }

    close SVN;

    return $svnStatus;

}

sub unapplyPatch($$;$)

{

    my ($patch, $fullPath, $options) = @_;

    $options = [] if (! $options);

    my $command = "patch " . join(" ", "-p0", "-R", @{$options});

    open PATCH, "| $command" or die "Failed to patch $fullPath: $!";

    print PATCH $patch;

    close PATCH;

}

sub unsetChangeLogDate($$)

{

    my $fullPath = shift;

    my $patch = shift;

    my $newDate;

    sysopen(CHANGELOG, $fullPath, O_RDONLY) or die "Failed to open $fullPath: $!";

    sysseek(CHANGELOG, 0, SEEK_SET);

    my $byteCount = sysread(CHANGELOG, $newDate, 10);

    die "Failed reading $fullPath: $!" if !$byteCount || $byteCount != 10;

    close(CHANGELOG);

    $patch =~ s/(\n\+)\d{4}-[^-]{2}-[^-]{2}(  )/$1$newDate$2/;

    return $patch;

}