Fix Diffusion rendering of SVN files which did not change

Summary:
Share code with the new PhabricatorDifferenceEngine, which handles diffs with no
changes correctly.

(This isn't the same issue as file moves, but I ran into it while generating a
repro case.)

Test Plan: Previously, changes which didn't change file content (e.g., property
changes) would throw. Now they work.
Reviewed By: tuomaspelkonen
Reviewers: tuomaspelkonen, jungejason, aran
CC: aran, epriestley, tuomaspelkonen
Differential Revision: 698

Author: epriestley

src/applications/diffusion/query/diff/svn/DiffusionSvnDiffQuery.php

@@ -90,24 +90,17 @@ protected function executeQuery() {
     $futures = array_filter($futures);
 
     foreach (Futures($futures) as $key => $future) {
-      $futures[$key] = $future->resolvex();
+      list($stdout) = $future->resolvex();
+      $futures[$key] = $stdout;
     }
 
     $old_data = idx($futures, 'old', '');
     $new_data = idx($futures, 'new', '');
 
-    $old_tmp = new TempFile();
-    $new_tmp = new TempFile();
-
-    Filesystem::writeFile($old_tmp, $old_data);
-    Filesystem::writeFile($new_tmp, $new_data);
-
-    list($err, $raw_diff) = exec_manual(
-      'diff -L %s -L %s -U65535 %s %s',
-      nonempty($old_name, '/dev/universe').' 9999-99-99',
-      nonempty($new_name, '/dev/universe').' 9999-99-99',
-      $old_tmp,
-      $new_tmp);
+    $engine = new PhabricatorDifferenceEngine();
+    $engine->setOldName($old_name);
+    $engine->setNewName($new_name);
+    $raw_diff = $engine->generateRawDiffFromFileContent($old_data, $new_data);
 
     $parser = new ArcanistDiffParser();
     $parser->setDetectBinaryFiles(true);

src/applications/diffusion/query/diff/svn/__init__.php

@@ -13,9 +13,8 @@
 phutil_require_module('phabricator', 'applications/diffusion/data/pathchange');
 phutil_require_module('phabricator', 'applications/diffusion/query/diff/base');
 phutil_require_module('phabricator', 'applications/diffusion/query/pathchange/base');
+phutil_require_module('phabricator', 'infrastructure/diff/engine');
 
-phutil_require_module('phutil', 'filesystem');
-phutil_require_module('phutil', 'filesystem/tempfile');
 phutil_require_module('phutil', 'future');
 phutil_require_module('phutil', 'future/exec');
 phutil_require_module('phutil', 'utils');

src/infrastructure/diff/engine/PhabricatorDifferenceEngine.php

@@ -25,7 +25,10 @@
  */
 final class PhabricatorDifferenceEngine {
 
+
   private $ignoreWhitespace;
+  private $oldName;
+  private $newName;
 
 
 /* -(  Configuring the Engine  )--------------------------------------------- */
@@ -44,20 +47,46 @@ public function setIgnoreWhitespace($ignore_whitespace) {
   }
 
 
+  /**
+   * Set the name to identify the old file with. Primarily cosmetic.
+   *
+   * @param  string Old file name.
+   * @return this
+   * @task config
+   */
+  public function setOldName($old_name) {
+    $this->oldName = $old_name;
+    return $this;
+  }
+
+
+  /**
+   * Set the name to identify the new file with. Primarily cosmetic.
+   *
+   * @param  string New file name.
+   * @return this
+   * @task config
+   */
+  public function setNewName($new_name) {
+    $this->newName = $new_name;
+    return $this;
+  }
+
+
 /* -(  Generating Diffs  )--------------------------------------------------- */
 
 
   /**
-   * Generate an @{class:DifferentialChangeset} from two raw files. This is
-   * principally useful because you can feed the output to
-   * @{class:DifferentialChangesetParser} in order to render it.
+   * Generate a raw diff from two raw files. This is a lower-level API than
+   * @{method:generateChangesetFromFileContent}, but may be useful if you need
+   * to use a custom parser configuration, as with Diffusion.
    *
    * @param string Entire previous file content.
    * @param string Entire current file content.
-   * @return @{class:DifferentialChangeset} Synthetic changeset.
+   * @return string Raw diff between the two files.
    * @task diff
    */
-  public function generateChangesetFromFileContent($old, $new) {
+  public function generateRawDiffFromFileContent($old, $new) {
 
     $options = array();
     if ($this->ignoreWhitespace) {
@@ -67,6 +96,14 @@ public function generateChangesetFromFileContent($old, $new) {
     // Generate diffs with full context.
     $options[] = '-U65535';
 
+    $old_name = nonempty($this->oldName, '/dev/universe').' 9999-99-99';
+    $new_name = nonempty($this->newName, '/dev/universe').' 9999-99-99';
+
+    $options[] = '-L';
+    $options[] = $old_name;
+    $options[] = '-L';
+    $options[] = $new_name;
+
     $old_tmp = new TempFile();
     $new_tmp = new TempFile();
 
@@ -78,13 +115,14 @@ public function generateChangesetFromFileContent($old, $new) {
       $old_tmp,
       $new_tmp);
 
-    if (!strlen($diff)) {
+    if (!$err) {
       // This indicates that the two files are the same (or, possibly, the
       // same modulo whitespace differences, which is why we can't do this
       // check trivially before running `diff`). Build a synthetic, changeless
       // diff so that we can still render the raw, unchanged file instead of
       // being forced to just say "this file didn't change" since we don't have
       // the content.
+
       $entire_file = explode("\n", $old);
       foreach ($entire_file as $k => $line) {
         $entire_file[$k] = ' '.$line;
@@ -93,12 +131,29 @@ public function generateChangesetFromFileContent($old, $new) {
       $entire_file = implode("\n", $entire_file);
 
       // This is a bit hacky but the diff parser can handle it.
-      $diff = "--- ignored 9999-99-99\n".
-              "+++ ignored 9999-99-99\n".
+      $diff = "--- {$old_name}\n".
+              "+++ {$new_name}\n".
               "@@ -1,{$len} +1,{$len} @@\n".
               $entire_file."\n";
     }
 
+    return $diff;
+  }
+
+
+  /**
+   * Generate an @{class:DifferentialChangeset} from two raw files. This is
+   * principally useful because you can feed the output to
+   * @{class:DifferentialChangesetParser} in order to render it.
+   *
+   * @param string Entire previous file content.
+   * @param string Entire current file content.
+   * @return @{class:DifferentialChangeset} Synthetic changeset.
+   * @task diff
+   */
+  public function generateChangesetFromFileContent($old, $new) {
+    $diff = $this->generateRawDiffFromFileContent($old, $new);
+
     $changes = id(new ArcanistDiffParser())->parseDiff($diff);
     $diff = DifferentialDiff::newFromRawChanges($changes);
     return head($diff->getChangesets());