MDL-70631 files: Fix performance of zip_packer::extract_to_pathname()

The original implementation was based on ZipArchive::getStream() which
turns out to be very slow and if the archive contains many files, the
unzipping performance is very slow.

The patch changes the implementation to use ZipArchive::extractTo()
unless the extracted entry path contains a folder name ending with dot
(such as some/path./to/file.txt). There is a known upstream bug in the
PHP ZIP extension #77214 (also #74619 and #69477) so that we fall back
to keep using the stream in those cases.

lib/filestorage/tests/zip_packer_test.php

@@ -254,6 +254,55 @@ public function test_extract_to_pathname() {
         }
     }
 
+    /**
+     * Test functionality of {@see zip_packer} for entries with folders ending with dots.
+     *
+     * @link https://bugs.php.net/bug.php?id=77214
+     */
+    public function test_zip_entry_path_having_folder_ending_with_dot() {
+        $this->resetAfterTest(false);
+
+        $packer = get_file_packer('application/zip');
+        $tmp = make_request_directory();
+        $now = time();
+
+        // Create a test archive containing a folder ending with dot.
+        $zippath = $tmp . '/test_archive.zip';
+        $zipcontents = [
+            'HOW.TO' => ['Just run tests.'],
+            'README.' => ['This is a test ZIP file'],
+            './Current time' => [$now],
+            'Data/sub1./sub2/1221' => ['1221'],
+            'Data/sub1./sub2./Příliš žluťoučký kůň úpěl Ďábelské Ódy.txt' => [''],
+        ];
+
+        // Check that the archive can be created.
+        $result = $packer->archive_to_pathname($zipcontents, $zippath, false);
+        $this->assertTrue($result);
+
+        // Check list of files.
+        $listfiles = $packer->list_files($zippath);
+        $this->assertEquals(count($zipcontents), count($listfiles));
+
+        foreach ($listfiles as $fileinfo) {
+            $this->assertSame($fileinfo->pathname, $fileinfo->original_pathname);
+            $this->assertArrayHasKey($fileinfo->pathname, $zipcontents);
+        }
+
+        // Check actual extracting.
+        $targetpath = $tmp . '/target';
+        check_dir_exists($targetpath);
+        $result = $packer->extract_to_pathname($zippath, $targetpath, null, null, true);
+
+        $this->assertTrue($result);
+
+        foreach ($zipcontents as $filename => $filecontents) {
+            $filecontents = reset($filecontents);
+            $this->assertTrue(is_readable($targetpath . '/' . $filename));
+            $this->assertEquals($filecontents, file_get_contents($targetpath . '/' . $filename));
+        }
+    }
+
     /**
      * @depends test_archive_to_storage
      */

lib/filestorage/zip_archive.php

@@ -254,6 +254,28 @@ public function get_stream($index) {
         return $this->za->getStream($name);
     }
 
+    /**
+     * Extract the archive contents to the given location.
+     *
+     * @param string $destination Path to the location where to extract the files.
+     * @param int $index Index of the archive entry.
+     * @return bool true on success or false on failure
+     */
+    public function extract_to($destination, $index) {
+
+        if (!isset($this->za)) {
+            return false;
+        }
+
+        $name = $this->za->getNameIndex($index);
+
+        if ($name === false) {
+            return false;
+        }
+
+        return $this->za->extractTo($destination, $name);
+    }
+
     /**
      * Returns file information.
      *

lib/filestorage/zip_packer.php

@@ -341,33 +341,58 @@ public function extract_to_pathname($archivefile, $pathname,
             }
 
             $newfile = "$newdir/$filename";
-            if (!$fp = fopen($newfile, 'wb')) {
-                $processed[$name] = 'Can not write target file'; // TODO: localise
-                $success = false;
-                continue;
+
+            if (strpos($newfile, './') > 1) {
+                // The path to the entry contains a directory ending with dot. We cannot use extract_to() due to
+                // upstream PHP bugs #69477, #74619 and #77214. Extract the file from its stream which is slower but
+                // should work even in this case.
+                if (!$fp = fopen($newfile, 'wb')) {
+                    $processed[$name] = 'Can not write target file'; // TODO: localise.
+                    $success = false;
+                    continue;
+                }
+
+                if (!$fz = $ziparch->get_stream($info->index)) {
+                    $processed[$name] = 'Can not read file from zip archive'; // TODO: localise.
+                    $success = false;
+                    fclose($fp);
+                    continue;
+                }
+
+                while (!feof($fz)) {
+                    $content = fread($fz, 262143);
+                    fwrite($fp, $content);
+                }
+
+                fclose($fz);
+                fclose($fp);
+
+            } else {
+                if (!$fz = $ziparch->extract_to($pathname, $info->index)) {
+                    $processed[$name] = 'Can not read file from zip archive'; // TODO: localise.
+                    $success = false;
+                    continue;
+                }
             }
-            if (!$fz = $ziparch->get_stream($info->index)) {
-                $processed[$name] = 'Can not read file from zip archive'; // TODO: localise
+
+            // Check that the file was correctly created in the destination.
+            if (!file_exists($newfile)) {
+                $processed[$name] = 'Unknown error during zip extraction (file not created).'; // TODO: localise.
                 $success = false;
-                fclose($fp);
                 continue;
             }
 
-            while (!feof($fz)) {
-                $content = fread($fz, 262143);
-                fwrite($fp, $content);
-            }
-            fclose($fz);
-            fclose($fp);
+            // Check that the size of extracted file matches the expectation.
             if (filesize($newfile) !== $size) {
-                $processed[$name] = 'Unknown error during zip extraction'; // TODO: localise
+                $processed[$name] = 'Unknown error during zip extraction (file size mismatch).'; // TODO: localise.
                 $success = false;
-                // something went wrong :-(
                 @unlink($newfile);
                 continue;
             }
+
             $processed[$name] = true;
         }
+
         $ziparch->close();
 
         if ($returnbool) {