diff --git a/src/parser/ArcanistDiffParser.php b/src/parser/ArcanistDiffParser.php
index a310fb41..1d213846 100644
--- a/src/parser/ArcanistDiffParser.php
+++ b/src/parser/ArcanistDiffParser.php
@@ -1,1392 +1,1398 @@
 <?php
 
 /**
  * Parses diffs from a working copy.
  */
 final class ArcanistDiffParser extends Phobject {
 
   protected $repositoryAPI;
   protected $text;
   protected $line;
   protected $lineSaved;
   protected $isGit;
   protected $isMercurial;
   protected $isRCS;
   protected $detectBinaryFiles = false;
   protected $tryEncoding;
   protected $rawDiff;
   protected $writeDiffOnFailure;
 
   protected $changes = array();
   private $forcePath;
 
   public function setRepositoryAPI(ArcanistRepositoryAPI $repository_api) {
     $this->repositoryAPI = $repository_api;
     return $this;
   }
 
   public function setDetectBinaryFiles($detect) {
     $this->detectBinaryFiles = $detect;
     return $this;
   }
 
   public function setTryEncoding($encoding) {
     $this->tryEncoding = $encoding;
     return $this;
   }
 
   public function forcePath($path) {
     $this->forcePath = $path;
     return $this;
   }
 
   public function setChanges(array $changes) {
     assert_instances_of($changes, 'ArcanistDiffChange');
     $this->changes = mpull($changes, null, 'getCurrentPath');
     return $this;
   }
 
   public function parseSubversionDiff(ArcanistSubversionAPI $api, $paths) {
     $this->setRepositoryAPI($api);
 
     $diffs = array();
 
     foreach ($paths as $path => $status) {
       if ($status & ArcanistRepositoryAPI::FLAG_UNTRACKED ||
           $status & ArcanistRepositoryAPI::FLAG_CONFLICT ||
           $status & ArcanistRepositoryAPI::FLAG_MISSING) {
         unset($paths[$path]);
       }
     }
 
     $root = null;
     $from = array();
     foreach ($paths as $path => $status) {
       $change = $this->buildChange($path);
 
       if ($status & ArcanistRepositoryAPI::FLAG_ADDED) {
         $change->setType(ArcanistDiffChangeType::TYPE_ADD);
       } else if ($status & ArcanistRepositoryAPI::FLAG_DELETED) {
         $change->setType(ArcanistDiffChangeType::TYPE_DELETE);
       } else {
         $change->setType(ArcanistDiffChangeType::TYPE_CHANGE);
       }
 
       $is_dir = is_dir($api->getPath($path));
       if ($is_dir) {
         $change->setFileType(ArcanistDiffChangeType::FILE_DIRECTORY);
         // We have to go hit the diff even for directories because they may
         // have property changes or moves, etc.
       }
       $is_link = is_link($api->getPath($path));
       if ($is_link) {
         $change->setFileType(ArcanistDiffChangeType::FILE_SYMLINK);
       }
 
       $diff = $api->getRawDiffText($path);
       if ($diff) {
         $this->parseDiff($diff);
       }
 
       $info = $api->getSVNInfo($path);
       if (idx($info, 'Copied From URL')) {
         if (!$root) {
           $rinfo = $api->getSVNInfo('.');
           $root = $rinfo['URL'].'/';
         }
         $cpath = $info['Copied From URL'];
         $root_len = strlen($root);
         if (!strncmp($cpath, $root, $root_len)) {
           $cpath = substr($cpath, $root_len);
           // The user can "svn cp /path/to/file@12345 x", which pulls a file out
           // of version history at a specific revision. If we just use the path,
           // we'll collide with possible changes to that path in the working
           // copy below. In particular, "svn cp"-ing a path which no longer
           // exists somewhere in the working copy and then adding that path
           // gets us to the "origin change type" branches below with a
           // TYPE_ADD state on the path. To avoid this, append the origin
           // revision to the path so we'll necessarily generate a new change.
           // TODO: In theory, you could have an '@' in your path and this could
           // cause a collision, e.g. two files named 'f' and 'f@12345'. This is
           // at least somewhat the user's fault, though.
           if ($info['Copied From Rev']) {
             if ($info['Copied From Rev'] != $info['Revision']) {
               $cpath .= '@'.$info['Copied From Rev'];
             }
           }
           $change->setOldPath($cpath);
           $from[$path] = $cpath;
         }
       }
 
       $type = $change->getType();
       if (($type === ArcanistDiffChangeType::TYPE_MOVE_AWAY ||
            $type === ArcanistDiffChangeType::TYPE_DELETE) &&
           idx($info, 'Node Kind') === 'directory') {
         $change->setFileType(ArcanistDiffChangeType::FILE_DIRECTORY);
       }
     }
 
     foreach ($paths as $path => $status) {
       $change = $this->buildChange($path);
       if (empty($from[$path])) {
         continue;
       }
 
       if (empty($this->changes[$from[$path]])) {
         if ($change->getType() == ArcanistDiffChangeType::TYPE_COPY_HERE) {
           // If the origin path wasn't changed (or isn't included in this diff)
           // and we only copied it, don't generate a changeset for it. This
           // keeps us out of trouble when we go to 'arc commit' and need to
           // figure out which files should be included in the commit list.
           continue;
         }
       }
 
       $origin = $this->buildChange($from[$path]);
       $origin->addAwayPath($change->getCurrentPath());
 
       $type = $origin->getType();
       switch ($type) {
         case ArcanistDiffChangeType::TYPE_MULTICOPY:
         case ArcanistDiffChangeType::TYPE_COPY_AWAY:
         // "Add" is possible if you do some bizarre tricks with svn:ignore and
         // "svn copy"'ing URLs straight from the repository; you can end up with
         // a file that is a copy of itself. See T271.
         case ArcanistDiffChangeType::TYPE_ADD:
           break;
         case ArcanistDiffChangeType::TYPE_DELETE:
           $origin->setType(ArcanistDiffChangeType::TYPE_MOVE_AWAY);
           break;
         case ArcanistDiffChangeType::TYPE_MOVE_AWAY:
           $origin->setType(ArcanistDiffChangeType::TYPE_MULTICOPY);
           break;
         case ArcanistDiffChangeType::TYPE_CHANGE:
           $origin->setType(ArcanistDiffChangeType::TYPE_COPY_AWAY);
           break;
         default:
           throw new Exception(pht('Bad origin state %s.', $type));
       }
 
       $type = $origin->getType();
       switch ($type) {
         case ArcanistDiffChangeType::TYPE_MULTICOPY:
         case ArcanistDiffChangeType::TYPE_MOVE_AWAY:
           $change->setType(ArcanistDiffChangeType::TYPE_MOVE_HERE);
           break;
         case ArcanistDiffChangeType::TYPE_ADD:
         case ArcanistDiffChangeType::TYPE_COPY_AWAY:
           $change->setType(ArcanistDiffChangeType::TYPE_COPY_HERE);
           break;
         default:
           throw new Exception(pht('Bad origin state %s.', $type));
       }
     }
 
     return $this->changes;
   }
 
   public function parseDiff($diff) {
     if (!strlen(trim($diff))) {
       throw new Exception(pht("Can't parse an empty diff!"));
     }
 
     // Detect `git-format-patch`, by looking for a "---" line somewhere in
     // the file and then a footer with Git version number, which looks like
     // this:
     //
     //   --
     //   1.8.4.2
     //
     // Note that `git-format-patch` adds a space after the "--", but we don't
     // require it when detecting patches, as trailing whitespace can easily be
     // lost in transit.
     $detect_patch = '/^---$.*^-- ?[\s\d.]+\z/ms';
     $message = null;
     if (preg_match($detect_patch, $diff)) {
       list($message, $diff) = $this->stripGitFormatPatch($diff);
     }
 
     $this->didStartParse($diff);
 
     // Strip off header comments. While `patch` allows comments anywhere in the
     // file, `git apply` is more strict. We get these comments in `hg export`
     // diffs, and Eclipse can also produce them.
     $line = $this->getLineTrimmed();
     while (preg_match('/^#/', $line)) {
       $line = $this->nextLine();
     }
 
     if (strlen($message)) {
       // If we found a message during pre-parse steps, add it to the resulting
       // changes here.
       $change = $this->buildChange(null)
         ->setType(ArcanistDiffChangeType::TYPE_MESSAGE)
         ->setMetadata('message', $message);
     }
 
     do {
       $patterns = array(
         // This is a normal SVN text change, probably from "svn diff".
         '(?P<type>Index): (?P<cur>.+)',
         // This is an SVN text change, probably from "svnlook diff".
         '(?P<type>Modified|Added|Deleted|Copied): (?P<cur>.+)',
         // This is an SVN property change, probably from "svn diff".
         '(?P<type>Property changes on): (?P<cur>.+)',
         // This is a git commit message, probably from "git show".
         '(?P<type>commit) (?P<hash>[a-f0-9]+)(?: \(.*\))?',
         // This is a git diff, probably from "git show" or "git diff".
         // Note that the filenames may appear quoted.
         '(?P<type>diff --git) (?P<oldnew>.*)',
         // RCS Diff
         '(?P<type>rcsdiff -u) (?P<oldnew>.*)',
         // This is a unified diff, probably from "diff -u" or synthetic diffing.
         '(?P<type>---) (?P<old>.+)\s+\d{4}-\d{2}-\d{2}.*',
         '(?P<binary>Binary files|Files) '.
           '(?P<old>.+)\s+\d{4}-\d{2}-\d{2} and '.
           '(?P<new>.+)\s+\d{4}-\d{2}-\d{2} differ.*',
         // This is a normal Mercurial text change, probably from "hg diff". It
         // may have two "-r" blocks if it came from "hg diff -r x:y".
         '(?P<type>diff -r) (?P<hgrev>[a-f0-9]+) (?:-r [a-f0-9]+ )?(?P<cur>.+)',
       );
 
       $line = $this->getLineTrimmed();
       $match = null;
       $ok = $this->tryMatchHeader($patterns, $line, $match);
 
       $failed_parse = false;
       if (!$ok && $this->isFirstNonEmptyLine()) {
         // 'hg export' command creates so called "extended diff" that
         // contains some meta information and comment at the beginning
         // (isFirstNonEmptyLine() to check for beginning). Actual mercurial
         // code detects where comment ends and unified diff starts by
         // searching for "diff -r" or "diff --git" in the text.
         $this->saveLine();
         $line = $this->nextLineThatLooksLikeDiffStart();
         if (!$this->tryMatchHeader($patterns, $line, $match)) {
           // Restore line before guessing to display correct error.
           $this->restoreLine();
           $failed_parse = true;
         }
       } else if (!$ok) {
         $failed_parse = true;
       }
 
       if ($failed_parse) {
         $this->didFailParse(
           pht(
             "Expected a hunk header, like '%s' (svn), '%s' (svn properties), ".
             "'%s' (git show), '%s' (git diff), '%s' (unified diff), or ".
             "'%s' (hg diff or patch).",
             'Index: /path/to/file.ext',
             'Property changes on: /path/to/file.ext',
             'commit 59bcc3ad6775562f845953cf01624225',
             'diff --git',
             '--- filename',
             'diff -r'));
       }
 
       if (isset($match['type'])) {
         if ($match['type'] == 'diff --git') {
           $filename = self::extractGitCommonFilename($match['oldnew']);
           if ($filename !== null) {
             $match['old'] = $filename;
             $match['cur'] = $filename;
           }
         }
       }
 
       $change = $this->buildChange(idx($match, 'cur'));
 
       if (isset($match['old'])) {
         $change->setOldPath($match['old']);
       }
 
       if (isset($match['hash'])) {
         $change->setCommitHash($match['hash']);
       }
 
       if (isset($match['binary'])) {
         $change->setFileType(ArcanistDiffChangeType::FILE_BINARY);
         $line = $this->nextNonemptyLine();
         continue;
       }
 
       $line = $this->nextLine();
 
       switch ($match['type']) {
         case 'Index':
         case 'Modified':
         case 'Added':
         case 'Deleted':
         case 'Copied':
           $this->parseIndexHunk($change);
           break;
         case 'Property changes on':
           $this->parsePropertyHunk($change);
           break;
         case 'diff --git':
           $this->setIsGit(true);
           $this->parseIndexHunk($change);
           break;
         case 'commit':
           $this->setIsGit(true);
           $this->parseCommitMessage($change);
           break;
         case '---':
           $ok = preg_match(
             '@^(?:\+\+\+) (.*)\s+\d{4}-\d{2}-\d{2}.*$@',
             $line,
             $match);
           if (!$ok) {
             $this->didFailParse(pht(
               "Expected '%s' in unified diff.",
               '+++ filename'));
           }
           $change->setCurrentPath($match[1]);
           $line = $this->nextLine();
           $this->parseChangeset($change);
           break;
         case 'diff -r':
           $this->setIsMercurial(true);
           $this->parseIndexHunk($change);
           break;
         case 'rcsdiff -u':
           $this->isRCS = true;
           $this->parseIndexHunk($change);
           break;
         default:
           $this->didFailParse(pht('Unknown diff type.'));
           break;
       }
     } while ($this->getLine() !== null);
 
     $this->didFinishParse();
 
     $this->loadSyntheticData();
 
     return $this->changes;
   }
 
   protected function tryMatchHeader($patterns, $line, &$match) {
     foreach ($patterns as $pattern) {
       if (preg_match('@^'.$pattern.'$@', $line, $match)) {
         return true;
       }
     }
     return false;
   }
 
   protected function parseCommitMessage(ArcanistDiffChange $change) {
     $change->setType(ArcanistDiffChangeType::TYPE_MESSAGE);
 
     $message = array();
 
     $line = $this->getLine();
     if (preg_match('/^Merge: /', $line)) {
       $this->nextLine();
     }
 
     $line = $this->getLine();
     if (!preg_match('/^Author: /', $line)) {
       $this->didFailParse(pht("Expected 'Author:'."));
     }
 
     $line = $this->nextLine();
     if (!preg_match('/^Date: /', $line)) {
       $this->didFailParse(pht("Expected 'Date:'."));
     }
 
     while (($line = $this->nextLineTrimmed()) !== null) {
       if (strlen($line) && $line[0] != ' ') {
         break;
       }
 
       // Strip leading spaces from Git commit messages. Note that empty lines
       // are represented as just "\n"; don't touch those.
       $message[] = preg_replace('/^    /', '', $this->getLine());
     }
 
     $message = rtrim(implode('', $message), "\r\n");
     $change->setMetadata('message', $message);
   }
 
   /**
    * Parse an SVN property change hunk. These hunks are ambiguous so just sort
    * of try to get it mostly right. It's entirely possible to foil this parser
    * (or any other parser) with a carefully constructed property change.
    */
   protected function parsePropertyHunk(ArcanistDiffChange $change) {
     $line = $this->getLineTrimmed();
     if (!preg_match('/^_+$/', $line)) {
       $this->didFailParse(pht("Expected '%s'.", '______________________'));
     }
 
     $line = $this->nextLine();
     while ($line !== null) {
       $done = preg_match('/^(Index|Property changes on):/', $line);
       if ($done) {
         break;
       }
 
       // NOTE: Before 1.5, SVN uses "Name". At 1.5 and later, SVN uses
       // "Modified", "Added" and "Deleted".
 
       $matches = null;
       $ok = preg_match(
         '/^(Name|Modified|Added|Deleted): (.*)$/',
         $line,
         $matches);
       if (!$ok) {
         $this->didFailParse(
           pht("Expected 'Name', 'Added', 'Deleted', or 'Modified'."));
       }
 
       $op = $matches[1];
       $prop = $matches[2];
 
       list($old, $new) = $this->parseSVNPropertyChange($op, $prop);
 
       if ($old !== null) {
         $change->setOldProperty($prop, $old);
       }
 
       if ($new !== null) {
         $change->setNewProperty($prop, $new);
       }
 
       $line = $this->getLine();
     }
   }
 
   private function parseSVNPropertyChange($op, $prop) {
     $old = array();
     $new = array();
 
     $target = null;
 
     $line = $this->nextLine();
     $prop_index = 2;
     while ($line !== null) {
       $done = preg_match(
         '/^(Modified|Added|Deleted|Index|Property changes on):/',
         $line);
       if ($done) {
         break;
       }
       $trimline = ltrim($line);
       if ($trimline && $trimline[0] == '#') {
         // in svn1.7, a line like ## -0,0 +1 ## is put between the Added: line
         // and the line with the property change. If we have such a line, we'll
         // just ignore it (:
         $line = $this->nextLine();
         $prop_index = 1;
         $trimline = ltrim($line);
       }
       if ($trimline && $trimline[0] == '+') {
         if ($op == 'Deleted') {
           $this->didFailParse(pht(
             'Unexpected "%s" section in property deletion.',
             '+'));
         }
         $target = 'new';
         $line = substr($trimline, $prop_index);
       } else if ($trimline && $trimline[0] == '-') {
         if ($op == 'Added') {
           $this->didFailParse(pht(
             'Unexpected "%s" section in property addition.',
             '-'));
         }
         $target = 'old';
         $line = substr($trimline, $prop_index);
       } else if (!strncmp($trimline, 'Merged', 6)) {
         if ($op == 'Added') {
           $target = 'new';
         } else {
           // These can appear on merges. No idea how to interpret this (unclear
           // what the old / new values are) and it's of dubious usefulness so
           // just throw it away until someone complains.
           $target = null;
         }
         $line = $trimline;
       }
 
       if ($target == 'new') {
         $new[] = $line;
       } else if ($target == 'old') {
         $old[] = $line;
       }
 
       $line = $this->nextLine();
     }
 
     $old = rtrim(implode('', $old));
     $new = rtrim(implode('', $new));
 
     if (!strlen($old)) {
       $old = null;
     }
 
     if (!strlen($new)) {
       $new = null;
     }
 
     return array($old, $new);
   }
 
   protected function setIsGit($git) {
     if ($this->isGit !== null && $this->isGit != $git) {
       throw new Exception(pht('Git status has changed!'));
     }
     $this->isGit = $git;
     return $this;
   }
 
   protected function getIsGit() {
     return $this->isGit;
   }
 
   public function setIsMercurial($is_mercurial) {
     $this->isMercurial = $is_mercurial;
     return $this;
   }
 
   public function getIsMercurial() {
     return $this->isMercurial;
   }
 
   protected function parseIndexHunk(ArcanistDiffChange $change) {
     $is_git = $this->getIsGit();
     $is_mercurial = $this->getIsMercurial();
     $is_svn = (!$is_git && !$is_mercurial);
 
     $move_source = null;
 
     $line = $this->getLine();
     if ($is_git) {
       do {
 
         $patterns = array(
           '(?P<new>new) file mode (?P<newmode>\d+)',
           '(?P<deleted>deleted) file mode (?P<oldmode>\d+)',
           // These occur when someone uses `chmod` on a file.
           'old mode (?P<oldmode>\d+)',
           'new mode (?P<newmode>\d+)',
           // These occur when you `mv` a file and git figures it out.
           'similarity index ',
           'rename from (?P<old>.*)',
           '(?P<move>rename) to (?P<cur>.*)',
           'copy from (?P<old>.*)',
           '(?P<copy>copy) to (?P<cur>.*)',
         );
 
         $ok = false;
         $match = null;
         foreach ($patterns as $pattern) {
           $ok = preg_match('@^'.$pattern.'@', $line, $match);
           if ($ok) {
             break;
           }
         }
 
         if (!$ok) {
           if ($line === null ||
               preg_match('/^(diff --git|commit) /', $line)) {
             // In this case, there are ONLY file mode changes, or this is a
             // pure move. If it's a move, flag these changesets so we can build
             // synthetic changes later, enabling us to show file contents in
             // Differential -- git only gives us a block like this:
             //
             //   diff --git a/README b/READYOU
             //   similarity index 100%
             //   rename from README
             //   rename to READYOU
             //
             // ...i.e., there is no associated diff.
 
             // This allows us to distinguish between property changes only
             // and actual moves. For property changes only, we can't currently
             // build a synthetic diff correctly, so just skip it.
             // TODO: Build synthetic diffs for property changes, too.
             if ($change->getType() != ArcanistDiffChangeType::TYPE_CHANGE) {
               $change->setNeedsSyntheticGitHunks(true);
               if ($move_source) {
                 $move_source->setNeedsSyntheticGitHunks(true);
               }
             }
             return;
           }
           break;
         }
 
         if (!empty($match['oldmode'])) {
           $change->setOldProperty('unix:filemode', $match['oldmode']);
         }
         if (!empty($match['newmode'])) {
           $change->setNewProperty('unix:filemode', $match['newmode']);
         }
 
         if (!empty($match['deleted'])) {
           $change->setType(ArcanistDiffChangeType::TYPE_DELETE);
         }
 
         if (!empty($match['new'])) {
           // If you replace a symlink with a normal file, git renders the change
           // as a "delete" of the symlink plus an "add" of the new file. We
           // prefer to represent this as a change.
           if ($change->getType() == ArcanistDiffChangeType::TYPE_DELETE) {
             $change->setType(ArcanistDiffChangeType::TYPE_CHANGE);
           } else {
             $change->setType(ArcanistDiffChangeType::TYPE_ADD);
           }
         }
 
         if (!empty($match['old'])) {
           $match['old'] = self::unescapeFilename($match['old']);
           $change->setOldPath($match['old']);
         }
 
         if (!empty($match['cur'])) {
           $match['cur'] = self::unescapeFilename($match['cur']);
           $change->setCurrentPath($match['cur']);
         }
 
         if (!empty($match['copy'])) {
           $change->setType(ArcanistDiffChangeType::TYPE_COPY_HERE);
           $old = $this->buildChange($change->getOldPath());
           $type = $old->getType();
 
           if ($type == ArcanistDiffChangeType::TYPE_MOVE_AWAY) {
             $old->setType(ArcanistDiffChangeType::TYPE_MULTICOPY);
           } else {
             $old->setType(ArcanistDiffChangeType::TYPE_COPY_AWAY);
           }
 
           $old->addAwayPath($change->getCurrentPath());
         }
 
         if (!empty($match['move'])) {
           $change->setType(ArcanistDiffChangeType::TYPE_MOVE_HERE);
           $old = $this->buildChange($change->getOldPath());
           $type = $old->getType();
 
           if ($type == ArcanistDiffChangeType::TYPE_MULTICOPY) {
             // Great, no change.
           } else if ($type == ArcanistDiffChangeType::TYPE_MOVE_AWAY) {
             $old->setType(ArcanistDiffChangeType::TYPE_MULTICOPY);
           } else if ($type == ArcanistDiffChangeType::TYPE_COPY_AWAY) {
             $old->setType(ArcanistDiffChangeType::TYPE_MULTICOPY);
           } else {
             $old->setType(ArcanistDiffChangeType::TYPE_MOVE_AWAY);
           }
 
           // We'll reference this above.
           $move_source = $old;
 
           $old->addAwayPath($change->getCurrentPath());
         }
 
         $line = $this->nextNonemptyLine();
       } while (true);
     }
 
     $line = $this->getLine();
 
     if ($is_svn) {
       $ok = preg_match('/^=+\s*$/', $line);
       if (!$ok) {
         $this->didFailParse(pht(
           "Expected '%s' divider line.",
           '======================='));
       } else {
         // Adding an empty file in SVN can produce an empty line here.
         $line = $this->nextNonemptyLine();
       }
     } else if ($is_git) {
       $ok = preg_match('/^index .*$/', $line);
       if (!$ok) {
         // TODO: "hg diff -g" diffs ("mercurial git-style diffs") do not include
         // this line, so we can't parse them if we fail on it. Maybe introduce
         // a flag saying "parse this diff using relaxed git-style diff rules"?
 
         // $this->didFailParse("Expected 'index af23f...a98bc' header line.");
       } else {
         // NOTE: In the git case, where this patch is the last change in the
         // file, we may have a final terminal newline. Skip over it so that
         // we'll hit the '$line === null' block below. This is covered by the
         // 'git-empty-file.gitdiff' test case.
         $line = $this->nextNonemptyLine();
       }
     }
 
     // If there are files with only whitespace changes and -b or -w are
     // supplied as command-line flags to `diff', svn and git both produce
     // changes without any body.
     if ($line === null ||
         preg_match(
           '/^(Index:|Property changes on:|diff --git|commit) /',
           $line)) {
       return;
     }
 
     $is_binary_add = preg_match(
       '/^Cannot display: file marked as a binary type\.$/',
       rtrim($line));
     if ($is_binary_add) {
       $this->nextLine(); // Cannot display: file marked as a binary type.
       $this->nextNonemptyLine(); // svn:mime-type = application/octet-stream
       $this->markBinary($change);
       return;
     }
 
     // We can get this in git, or in SVN when a file exists in the repository
     // WITHOUT a binary mime-type and is changed and given a binary mime-type.
     $is_binary_diff = preg_match(
       '/^(Binary files|Files) .* and .* differ$/',
       rtrim($line));
     if ($is_binary_diff) {
       $this->nextNonemptyLine(); // Binary files x and y differ
       $this->markBinary($change);
       return;
     }
 
     // This occurs under "hg diff --git" when a binary file is removed. See
     // test case "hg-binary-delete.hgdiff". (I believe it never occurs under
     // git, which reports the "files X and /dev/null differ" string above. Git
     // can not apply these patches.)
     $is_hg_binary_delete = preg_match(
       '/^Binary file .* has changed$/',
       rtrim($line));
     if ($is_hg_binary_delete) {
       $this->nextNonemptyLine();
       $this->markBinary($change);
       return;
     }
 
     // With "git diff --binary" (not a normal mode, but one users may explicitly
     // invoke and then, e.g., copy-paste into the web console) or "hg diff
     // --git" (normal under hg workflows), we may encounter a literal binary
     // patch.
     $is_git_binary_patch = preg_match(
       '/^GIT binary patch$/',
       rtrim($line));
     if ($is_git_binary_patch) {
       $this->nextLine();
       $this->parseGitBinaryPatch();
       $line = $this->getLine();
       if (preg_match('/^literal/', $line)) {
         // We may have old/new binaries (change) or just a new binary (hg add).
         // If there are two blocks, parse both.
         $this->parseGitBinaryPatch();
       }
       $this->markBinary($change);
       return;
     }
 
     if ($is_git) {
       // "git diff -b" ignores whitespace, but has an empty hunk target
       if (preg_match('@^diff --git .*$@', $line)) {
         $this->nextLine();
         return null;
       }
     }
 
     if ($this->isRCS) {
       // Skip the RCS headers.
       $this->nextLine();
       $this->nextLine();
       $this->nextLine();
     }
 
     $old_file = $this->parseHunkTarget();
     $new_file = $this->parseHunkTarget();
 
     if ($this->isRCS) {
       $change->setCurrentPath($new_file);
     }
 
     $change->setOldPath($old_file);
 
     $this->parseChangeset($change);
   }
 
   private function parseGitBinaryPatch() {
 
     // TODO: We could decode the patches, but it's a giant mess so don't bother
     // for now. We'll pick up the data from the working copy in the common
     // case ("arc diff").
 
     $line = $this->getLine();
     if (!preg_match('/^literal /', $line)) {
       $this->didFailParse(
         pht("Expected '%s' to start git binary patch.", 'literal NNNN'));
     }
     do {
       $line = $this->nextLineTrimmed();
       if ($line === '' || $line === null) {
         // Some versions of Mercurial apparently omit the terminal newline,
         // although it's unclear if Git will ever do this. In either case,
         // rely on the base85 check for sanity.
         $this->nextNonemptyLine();
         return;
       } else if (!preg_match('/^[a-zA-Z]/', $line)) {
         $this->didFailParse(
           pht('Expected base85 line length character (a-zA-Z).'));
       }
     } while (true);
   }
 
   protected function parseHunkTarget() {
     $line = $this->getLine();
     $matches = null;
 
     $remainder = '(?:\s*\(.*\))?';
     if ($this->getIsMercurial()) {
       // Something like "Fri Aug 26 01:20:50 2005 -0700", don't bother trying
       // to parse it.
       $remainder = '\t.*';
     } else if ($this->isRCS) {
       $remainder = '\s.*';
     } else if ($this->getIsGit()) {
       // When filenames contain spaces, Git terminates this line with a tab.
       // Normally, the tab is not present. If there's a tab, ignore it.
       $remainder = '(?:\t.*)?';
     }
 
     $ok = preg_match(
       '@^[-+]{3} (?:[ab]/)?(?P<path>.*?)'.$remainder.'$@',
       $line,
       $matches);
 
     if (!$ok) {
       $this->didFailParse(
         pht(
           "Expected hunk target '%s'.",
           '+++ path/to/file.ext (revision N)'));
     }
 
     $this->nextLine();
     return $matches['path'];
   }
 
   protected function markBinary(ArcanistDiffChange $change) {
     $change->setFileType(ArcanistDiffChangeType::FILE_BINARY);
     return $this;
   }
 
   protected function parseChangeset(ArcanistDiffChange $change) {
     // If a diff includes two sets of changes to the same file, let the
     // second one win. In particular, this occurs when adding subdirectories
     // in Subversion that contain files: the file text will be present in
     // both the directory diff and the file diff. See T5555. Dropping the
     // hunks lets whichever one shows up later win instead of showing changes
     // twice.
     $change->dropHunks();
 
     $all_changes = array();
     do {
       $hunk = new ArcanistDiffHunk();
       $line = $this->getLineTrimmed();
       $real = array();
 
       // In the case where only one line is changed, the length is omitted.
       // The final group is for git, which appends a guess at the function
       // context to the diff.
       $matches = null;
       $ok = preg_match(
         '/^@@ -(\d+)(?:,(\d+))? \+(\d+)(?:,(\d+))? @@(?: .*?)?$/U',
         $line,
         $matches);
 
       if (!$ok) {
         // It's possible we hit the style of an svn1.7 property change.
         // This is a 4-line Index block, followed by an empty line, followed
         // by a "Property changes on:" section similar to svn1.6.
         if ($line == '') {
           $line = $this->nextNonemptyLine();
           $ok = preg_match('/^Property changes on:/', $line);
           if (!$ok) {
             $this->didFailParse(pht('Confused by empty line'));
           }
           $line = $this->nextLine();
           return $this->parsePropertyHunk($change);
         }
         $this->didFailParse(pht(
           "Expected hunk header '%s'.",
           '@@ -NN,NN +NN,NN @@'));
       }
 
       $hunk->setOldOffset($matches[1]);
       $hunk->setNewOffset($matches[3]);
 
       // Cover for the cases where length wasn't present (implying one line).
       $old_len = idx($matches, 2);
       if (!strlen($old_len)) {
         $old_len = 1;
       }
       $new_len = idx($matches, 4);
       if (!strlen($new_len)) {
         $new_len = 1;
       }
 
       $hunk->setOldLength($old_len);
       $hunk->setNewLength($new_len);
 
       $add = 0;
       $del = 0;
 
       $hit_next_hunk = false;
       while ((($line = $this->nextLine()) !== null)) {
         if (strlen(rtrim($line, "\r\n"))) {
           $char = $line[0];
         } else {
           // Normally, we do not encouter empty lines in diffs, because
           // unchanged lines have an initial space. However, in Git, with
           // the option `diff.suppress-blank-empty` set, unchanged blank lines
           // emit as completely empty. If we encounter a completely empty line,
           // treat it as a ' ' (i.e., unchanged empty line) line.
           $char = ' ';
         }
         switch ($char) {
           case '\\':
             if (!preg_match('@\\ No newline at end of file@', $line)) {
               $this->didFailParse(
                 pht("Expected '\ No newline at end of file'."));
             }
             if ($new_len) {
               $real[] = $line;
               $hunk->setIsMissingOldNewline(true);
             } else {
               $real[] = $line;
               $hunk->setIsMissingNewNewline(true);
             }
             if (!$new_len) {
               break 2;
             }
             break;
           case '+':
             ++$add;
             --$new_len;
             $real[] = $line;
             break;
           case '-':
             if (!$old_len) {
               // In this case, we've hit "---" from a new file. So don't
               // advance the line cursor.
               $hit_next_hunk = true;
               break 2;
             }
             ++$del;
             --$old_len;
             $real[] = $line;
             break;
           case ' ':
             if (!$old_len && !$new_len) {
               break 2;
             }
             --$old_len;
             --$new_len;
             $real[] = $line;
             break;
           default:
             // We hit something, likely another hunk.
             $hit_next_hunk = true;
             break 2;
         }
       }
 
       if ($old_len || $new_len) {
         $this->didFailParse(pht('Found the wrong number of hunk lines.'));
       }
 
       $corpus = implode('', $real);
 
       $is_binary = false;
       if ($this->detectBinaryFiles) {
         $is_binary = !phutil_is_utf8($corpus);
         $try_encoding = $this->tryEncoding;
 
         if ($is_binary && $try_encoding) {
           $is_binary = ArcanistDiffUtils::isHeuristicBinaryFile($corpus);
           if (!$is_binary) {
             $corpus = phutil_utf8_convert($corpus, 'UTF-8', $try_encoding);
             if (!phutil_is_utf8($corpus)) {
               throw new Exception(
                 pht(
                   "Failed to convert a hunk from '%s' to UTF-8. ".
                   "Check that the specified encoding is correct.",
                   $try_encoding));
             }
           }
         }
 
       }
 
       if ($is_binary) {
         // SVN happily treats binary files which aren't marked with the right
         // mime type as text files. Detect that junk here and mark the file
         // binary. We'll catch stuff with unicode too, but that's verboten
         // anyway. If there are too many false positives with this we might
         // need to make it threshold-triggered instead of triggering on any
         // unprintable byte.
         $change->setFileType(ArcanistDiffChangeType::FILE_BINARY);
       } else {
         $hunk->setCorpus($corpus);
         $hunk->setAddLines($add);
         $hunk->setDelLines($del);
         $change->addHunk($hunk);
       }
 
       if (!$hit_next_hunk) {
         $line = $this->nextNonemptyLine();
       }
 
     } while (preg_match('/^@@ /', $line));
   }
 
   protected function buildChange($path = null) {
     $change = null;
     if ($path !== null) {
       if (!empty($this->changes[$path])) {
         return $this->changes[$path];
       }
     }
 
     if ($this->forcePath) {
       return $this->changes[$this->forcePath];
     }
 
     $change = new ArcanistDiffChange();
     if ($path !== null) {
       $change->setCurrentPath($path);
       $this->changes[$path] = $change;
     } else {
       $this->changes[] = $change;
     }
 
     return $change;
   }
 
   protected function didStartParse($text) {
     $this->rawDiff = $text;
 
     // Eat leading whitespace. This may happen if the first change in the diff
     // is an SVN property change.
     $text = ltrim($text);
 
     // Try to strip ANSI color codes from colorized diffs. ANSI color codes
     // might be present in two cases:
     //
     //   - You piped a colorized diff into 'arc --raw' or similar (normally
     //     we're able to disable colorization on diffs we control the generation
     //     of).
     //   - You're diffing a file which actually contains ANSI color codes.
     //
     // The former is vastly more likely, but we try to distinguish between the
     // two cases by testing for a color code at the beginning of a line. If
     // we find one, we know it's a colorized diff (since the beginning of the
     // line should be "+", "-" or " " if the code is in the diff text).
     //
     // While it's possible a diff might be colorized and fail this test, it's
     // unlikely, and it covers hg's color extension which seems to be the most
     // stubborn about colorizing text despite stdout not being a TTY.
     //
     // We might incorrectly strip color codes from a colorized diff of a text
     // file with color codes inside it, but this case is stupid and pathological
     // and you've dug your own grave.
 
     $ansi_color_pattern = '\x1B\[[\d;]*m';
     if (preg_match('/^'.$ansi_color_pattern.'/m', $text)) {
       $text = preg_replace('/'.$ansi_color_pattern.'/', '', $text);
     }
 
     $this->text = phutil_split_lines($text);
     $this->line = 0;
   }
 
   protected function getLine() {
     if ($this->text === null) {
       throw new Exception(pht('Not parsing!'));
     }
     if (isset($this->text[$this->line])) {
       return $this->text[$this->line];
     }
     return null;
   }
 
   protected function getLineTrimmed() {
     $line = $this->getLine();
     if ($line !== null) {
       $line = trim($line, "\r\n");
     }
     return $line;
   }
 
   protected function nextLine() {
     $this->line++;
     return $this->getLine();
   }
 
   protected function nextLineTrimmed() {
     $line = $this->nextLine();
     if ($line !== null) {
       $line = trim($line, "\r\n");
     }
     return $line;
   }
 
   protected function nextNonemptyLine() {
     while (($line = $this->nextLine()) !== null) {
       if (strlen(trim($line)) !== 0) {
         break;
       }
     }
     return $this->getLine();
   }
 
   protected function nextLineThatLooksLikeDiffStart() {
     while (($line = $this->nextLine()) !== null) {
       if (preg_match('/^\s*diff\s+-(?:r|-git)/', $line)) {
         break;
       }
     }
     return $this->getLine();
   }
 
   protected function saveLine() {
     $this->lineSaved = $this->line;
   }
 
   protected function restoreLine() {
     $this->line = $this->lineSaved;
   }
 
   protected function isFirstNonEmptyLine() {
     $len = count($this->text);
     for ($ii = 0; $ii < $len; $ii++) {
       $line = $this->text[$ii];
 
       if (!strlen(trim($line))) {
         // This line is empty, skip it.
         continue;
       }
 
       if (preg_match('/^#/', $line)) {
         // This line is a comment, skip it.
         continue;
       }
 
       return ($ii == $this->line);
     }
 
     // Entire file is empty.
     return false;
   }
 
   protected function didFinishParse() {
     $this->text = null;
   }
 
   public function setWriteDiffOnFailure($write) {
     $this->writeDiffOnFailure = $write;
     return $this;
   }
 
   protected function didFailParse($message) {
     $context = 5;
     $min = max(0, $this->line - $context);
     $max = min($this->line + $context, count($this->text) - 1);
 
     $context = '';
     for ($ii = $min; $ii <= $max; $ii++) {
       $context .= sprintf(
         '%8.8s %6.6s   %s',
         ($ii == $this->line) ? '>>>  ' : '',
         $ii + 1,
         $this->text[$ii]);
     }
 
     $out = array();
     $out[] = pht('Diff Parse Exception: %s', $message);
 
     if ($this->writeDiffOnFailure) {
       $temp = new TempFile();
       $temp->setPreserveFile(true);
 
       Filesystem::writeFile($temp, $this->rawDiff);
       $out[] = pht('Raw input file was written to: %s', $temp);
     }
 
     $out[] = $context;
     $out = implode("\n\n", $out);
 
     throw new Exception($out);
   }
 
   /**
    * Unescape escaped filenames, e.g. from "git diff".
    */
   private static function unescapeFilename($name) {
     if (preg_match('/^".+"$/', $name)) {
       return stripcslashes(substr($name, 1, -1));
     } else {
       return $name;
     }
   }
 
   private function loadSyntheticData() {
     if (!$this->changes) {
       return;
     }
 
     $repository_api = $this->repositoryAPI;
     if (!$repository_api) {
       return;
     }
 
     $imagechanges = array();
 
     $changes = $this->changes;
     foreach ($changes as $change) {
       $path = $change->getCurrentPath();
 
       // Certain types of changes (moves and copies) don't contain change data
       // when expressed in raw "git diff" form. Augment any such diffs with
       // textual data.
       if ($change->getNeedsSyntheticGitHunks() &&
           ($repository_api instanceof ArcanistGitAPI)) {
         $diff = $repository_api->getRawDiffText($path, $moves = false);
 
         // NOTE: We're reusing the parser and it doesn't reset change state
         // between parses because there's an oddball SVN workflow in Phabricator
         // which relies on being able to inject changes.
         // TODO: Fix this.
         $parser = clone $this;
         $parser->setChanges(array());
         $raw_changes = $parser->parseDiff($diff);
 
         foreach ($raw_changes as $raw_change) {
           if ($raw_change->getCurrentPath() == $path) {
             $change->setFileType($raw_change->getFileType());
             foreach ($raw_change->getHunks() as $hunk) {
               // Git thinks that this file has been added. But we know that it
               // has been moved or copied without a change.
               $hunk->setCorpus(
                 preg_replace('/^\+/m', ' ', $hunk->getCorpus()));
               $change->addHunk($hunk);
             }
             break;
           }
         }
 
         $change->setNeedsSyntheticGitHunks(false);
       }
 
       if ($change->getFileType() != ArcanistDiffChangeType::FILE_BINARY &&
           $change->getFileType() != ArcanistDiffChangeType::FILE_IMAGE) {
         continue;
       }
 
       $imagechanges[$path] = $change;
     }
 
     // Fetch the actual file contents in batches so repositories
     // that have slow random file accesses (i.e. mercurial) can
     // optimize the retrieval.
     $paths = array_keys($imagechanges);
 
     $filedata = $repository_api->getBulkOriginalFileData($paths);
     foreach ($filedata as $path => $data) {
       $imagechanges[$path]->setOriginalFileData($data);
     }
 
     $filedata = $repository_api->getBulkCurrentFileData($paths);
     foreach ($filedata as $path => $data) {
       $imagechanges[$path]->setCurrentFileData($data);
     }
 
     $this->changes = $changes;
   }
 
 
   /**
-   * Split the paths on a "diff --git" line into old and new paths. This
-   * is difficult because they may be ambiguous if the files contain spaces.
+   * Extracts the common filename from two strings with differing path
+   * prefixes as found after `diff --git`.  These strings may be
+   * quoted; if so, the filename is returned unescaped.  The prefixes
+   * default to "a/" and "b/", but may be any string -- or may be
+   * entierly absent.  This function may return "null" if the hunk
+   * represents a file move or copy, and with pathological renames may
+   * return an incorrect value.  Such cases are expected to be
+   * recovered by later rename detection codepaths.
    *
    * @param string Text from a diff line after "diff --git ".
-   * @return pair<string, string> Old and new paths.
+   * @return string Filename being altered, or null for a rename.
    */
   public static function extractGitCommonFilename($paths) {
     $matches = null;
     $paths = rtrim($paths, "\r\n");
 
     // Try the exact same string twice in a row separated by a
     // space, with an optional prefix.  This can hit a false
     // positive for moves from files like "old file old" to "file",
     // but such a cases will be caught by the "rename from" /
     // "rename to" lines.
     $prefix = '(?:[^/]+/)?';
     $pattern =
              "@^(?P<old>(?P<oldq>\"?){$prefix}(?P<common>.+)\\k<oldq>)"
              ." "
              ."(?P<new>(?P<newq>\"?){$prefix}\\k<common>\\k<newq>)$@";
 
     if (!preg_match($pattern, $paths, $matches)) {
       // A rename or some form; return null for now, and let the
       // "rename from" / "rename to" lines fix it up.
       return null;
     }
 
     // Use the common subpart.  There may be ambiguity here: "src/file
     // dst/file" may _either_ be a prefix-less move, or a change with
     // two custom prefixes.  We assume it is the latter; if it is a
     // rename, diff parsing will update based on the "rename from" /
     // "rename to" lines.
 
     // This re-assembles with the differing prefixes removed, but the
     // quoting from the original.  Necessary so we know if we should
     // unescape characters from the common string.
     $new = $matches['newq'].$matches['common'].$matches['newq'];
     $new = self::unescapeFilename($new);
 
     return $new;
   }
 
 
   /**
    * Strip the header and footer off a `git-format-patch` diff.
    *
    * Returns a parseable normal diff and a textual commit message.
    */
   private function stripGitFormatPatch($diff) {
     // We can parse this by splitting it into two pieces over and over again
     // along different section dividers:
     //
     //   1. Mail headers.
     //   2. ("\n\n")
     //   3. Mail body.
     //   4. ("---")
     //   5. Diff stat section.
     //   6. ("\n\n")
     //   7. Actual diff body.
     //   8. ("--")
     //   9. Patch footer.
 
     list($head, $tail) = preg_split('/^---$/m', $diff, 2);
     list($mail_headers, $mail_body) = explode("\n\n", $head, 2);
     list($body, $foot) = preg_split('/^-- ?$/m', $tail, 2);
     list($stat, $diff) = explode("\n\n", $body, 2);
 
     // Rebuild the commit message by putting the subject line back on top of it,
     // if we can find one.
     $matches = null;
     $pattern = '/^Subject: (?:\[PATCH\] )?(.*)$/mi';
     if (preg_match($pattern, $mail_headers, $matches)) {
       $mail_body = $matches[1]."\n\n".$mail_body;
       $mail_body = rtrim($mail_body);
     }
 
     return array($mail_body, $diff);
   }
 
 }