Fix an issue where Herald may fail to extract content from an empty commit

Summary:
Ref T13667. The Herald "content added" rule (and other similar rules) do not correctly extract content from empty commits.

When we load an empty raw diff, return an empty changed content map.

Ref T13588. Also fix some PHP8.1 null/string stuff

Test Plan:
  - Ran "bin/repository reparse --publish <commit>", with an empty commit hash and a nonempty commit hash.
  - Reviewed Herald transcripts for general sanity.

Maniphest Tasks: T13667, T13588

Differential Revision: https://secure.phabricator.com/D21761

src/applications/diffusion/herald/HeraldCommitAdapter.php

@@ -267,6 +267,11 @@ final class HeraldCommitAdapter
 
     $raw = $diff_file->loadFileData();
 
+    // See T13667. This happens when a commit is empty and affects no files.
+    if (!strlen($raw)) {
+      return false;
+    }
+
     $parser = new ArcanistDiffParser();
     $changes = $parser->parseDiff($raw);
 
@@ -290,6 +295,10 @@ final class HeraldCommitAdapter
       }
     }
 
+    if ($this->commitDiff === false) {
+      return array();
+    }
+
     if ($this->commitDiff instanceof Exception) {
       $ex = $this->commitDiff;
       $ex_class = get_class($ex);

src/applications/diffusion/query/pathchange/DiffusionPathChangeQuery.php

@@ -88,7 +88,12 @@ final class DiffusionPathChangeQuery extends Phobject {
       $change->setFileType($raw_change['fileType']);
       $change->setCommitIdentifier($commit->getCommitIdentifier());
 
-      $change->setTargetPath(ltrim($raw_change['targetPathName'], '/'));
+      $target_path = $raw_change['targetPathName'];
+      if ($target_path !== null) {
+        $target_path = ltrim($target_path, '/');
+      }
+      $change->setTargetPath($target_path);
+
       $change->setTargetCommitIdentifier($raw_change['targetCommitIdentifier']);
 
       $id = $raw_change['pathID'];

src/applications/diffusion/request/DiffusionRequest.php

@@ -207,7 +207,7 @@ abstract class DiffusionRequest extends Phobject {
    */
   private function initializeFromDictionary(array $data) {
     $blob = idx($data, 'blob');
-    if (strlen($blob)) {
+    if (phutil_nonempty_string($blob)) {
       $blob = self::parseRequestBlob($blob, $this->supportsBranches());
       $data = $blob + $data;
     }
@@ -518,12 +518,14 @@ abstract class DiffusionRequest extends Phobject {
       $result['path'] = $blob;
     }
 
-    $parts = explode('/', $result['path']);
-    foreach ($parts as $part) {
-      // Prevent any hyjinx since we're ultimately shipping this to the
-      // filesystem under a lot of workflows.
-      if ($part == '..') {
-        throw new Exception(pht('Invalid path URI.'));
+    if ($result['path'] !== null) {
+      $parts = explode('/', $result['path']);
+      foreach ($parts as $part) {
+        // Prevent any hyjinx since we're ultimately shipping this to the
+        // filesystem under a lot of workflows.
+        if ($part == '..') {
+          throw new Exception(pht('Invalid path URI.'));
+        }
       }
     }
 

src/applications/macro/query/PhabricatorMacroQuery.php

@@ -128,7 +128,7 @@ final class PhabricatorMacroQuery
         $this->authorPHIDs);
     }
 
-    if (strlen($this->nameLike)) {
+    if (($this->nameLike !== null) && strlen($this->nameLike)) {
       $where[] = qsprintf(
         $conn,
         'm.name LIKE %~',
@@ -142,7 +142,7 @@ final class PhabricatorMacroQuery
         $this->names);
     }
 
-    if (strlen($this->namePrefix)) {
+    if (($this->namePrefix !== null) && strlen($this->namePrefix)) {
       $where[] = qsprintf(
         $conn,
         'm.name LIKE %>',

src/applications/passphrase/query/PassphraseCredentialQuery.php

@@ -148,7 +148,7 @@ final class PassphraseCredentialQuery
         (int)$this->allowConduit);
     }
 
-    if (strlen($this->nameContains)) {
+    if (phutil_nonempty_string($this->nameContains)) {
       $where[] = qsprintf(
         $conn,
         'LOWER(c.name) LIKE %~',

src/applications/repository/query/PhabricatorRepositoryQuery.php

@@ -633,7 +633,7 @@ final class PhabricatorRepositoryQuery
         $this->uuids);
     }
 
-    if (strlen($this->datasourceQuery)) {
+    if (phutil_nonempty_string($this->datasourceQuery)) {
       // This handles having "rP" match callsigns starting with "P...".
       $query = trim($this->datasourceQuery);
       if (preg_match('/^r/', $query)) {

src/applications/repository/storage/PhabricatorRepository.php

@@ -281,9 +281,11 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
 
   public function getSubversionBaseURI($commit = null) {
     $subpath = $this->getDetail('svn-subpath');
-    if (!strlen($subpath)) {
+
+    if (!phutil_nonempty_string($subpath)) {
       $subpath = null;
     }
+
     return $this->getSubversionPathURI($subpath, $commit);
   }
 
@@ -301,7 +303,7 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
 
     $uri = rtrim($uri, '/');
 
-    if (strlen($path)) {
+    if (phutil_nonempty_string($path)) {
       $path = rawurlencode($path);
       $path = str_replace('%2F', '/', $path);
       $uri = $uri.'/'.ltrim($path, '/');
@@ -574,12 +576,12 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
 
   public function getURI() {
     $short_name = $this->getRepositorySlug();
-    if (strlen($short_name)) {
+    if (phutil_nonempty_string($short_name)) {
       return "/source/{$short_name}/";
     }
 
     $callsign = $this->getCallsign();
-    if (strlen($callsign)) {
+    if (phutil_nonempty_string($callsign)) {
       return "/diffusion/{$callsign}/";
     }
 
@@ -593,7 +595,7 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
 
   public function getCommitURI($identifier) {
     $callsign = $this->getCallsign();
-    if (strlen($callsign)) {
+    if (phutil_nonempty_string($callsign)) {
       return "/r{$callsign}{$identifier}";
     }
 
@@ -736,25 +738,25 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
       return $this->getCommitURI($commit);
     }
 
-    if (strlen($path)) {
+    if (phutil_nonempty_string($path)) {
       $path = ltrim($path, '/');
       $path = str_replace(array(';', '$'), array(';;', '$$'), $path);
       $path = phutil_escape_uri($path);
     }
 
     $raw_branch = $branch;
-    if (strlen($branch)) {
+    if (phutil_nonempty_string($branch)) {
       $branch = phutil_escape_uri_path_component($branch);
       $path = "{$branch}/{$path}";
     }
 
     $raw_commit = $commit;
-    if (strlen($commit)) {
+    if (phutil_nonempty_string($commit)) {
       $commit = str_replace('$', '$$', $commit);
       $commit = ';'.phutil_escape_uri($commit);
     }
 
-    if (strlen($line)) {
+    if (phutil_nonempty_string($line)) {
       $line = '$'.phutil_escape_uri($line);
     }
 
@@ -862,7 +864,7 @@ final class PhabricatorRepository extends PhabricatorRepositoryDAO
 
   public function getDefaultBranch() {
     $default = $this->getDetail('default-branch');
-    if (strlen($default)) {
+    if (phutil_nonempty_string($default)) {
       return $default;
     }
 

src/infrastructure/markup/PhabricatorMarkupEngine.php

@@ -583,6 +583,14 @@ final class PhabricatorMarkupEngine extends Phobject {
     $engine->setConfig('viewer', $viewer);
 
     foreach ($content_blocks as $content_block) {
+      if ($content_block === null) {
+        continue;
+      }
+
+      if (!strlen($content_block)) {
+        continue;
+      }
+
       $engine->markupText($content_block);
       $phids = $engine->getTextMetadata(
         PhabricatorMentionRemarkupRule::KEY_MENTIONED,

src/infrastructure/markup/render.php

@@ -105,6 +105,10 @@ function phutil_tag_div($class, $content = null) {
 }
 
 function phutil_escape_html($string) {
+  if ($string === null) {
+    return '';
+  }
+
   if ($string instanceof PhutilSafeHTML) {
     return $string;
   } else if ($string instanceof PhutilSafeHTMLProducerInterface) {