Make "arc download" use "file.search" if available

Summary: Fixes T8348. Just use normal HTTP GET to download files if the server is sufficiently modern.

Test Plan: Downloaded various files with `--as`, `--show`, large files, small files, old server, new server.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T8348

Differential Revision: https://secure.phabricator.com/D17614

src/workflow/ArcanistDownloadWorkflow.php

@@ -79,6 +79,163 @@ EOTEXT
   public function run() {
     $conduit = $this->getConduit();
 
+    $id = $this->id;
+    $display_name = 'F'.$id;
+    $is_show = $this->show;
+    $save_as = $this->saveAs;
+
+    try {
+      $file = $conduit->callMethodSynchronous(
+        'file.search',
+        array(
+          'constraints' => array(
+            'ids' => array($id),
+          ),
+        ));
+
+      $data = $file['data'];
+      if (!$data) {
+        throw new ArcanistUsageException(
+          pht(
+            'File "%s" is not a valid file, or not visible.',
+            $display_name));
+      }
+
+      $file = head($data);
+      $data_uri = idxv($file, array('fields', 'dataURI'));
+
+      if ($data_uri === null) {
+        throw new ArcanistUsageException(
+          pht(
+            'File "%s" can not be downloaded.',
+            $display_name));
+      }
+
+      if ($is_show) {
+        // Skip all the file path stuff if we're just going to echo the
+        // file contents.
+      } else {
+        if ($save_as !== null) {
+          $path = Filesystem::resolvePath($save_as);
+
+          $try_unique = false;
+        } else {
+          $path = idxv($file, array('fields', 'name'), $display_name);
+          $path = basename($path);
+          $path = Filesystem::resolvePath($path);
+
+          $try_unique = true;
+        }
+
+        if ($try_unique) {
+          $path = Filesystem::writeUniqueFile($path, '');
+        } else {
+          if (Filesystem::pathExists($path)) {
+            throw new ArcanistUsageException(
+              pht(
+                'File "%s" already exists.',
+                $save_as));
+          }
+
+          Filesystem::writeFile($path, '');
+        }
+
+        $display_path = Filesystem::readablePath($path);
+      }
+
+      $size = idxv($file, array('fields', 'size'), 0);
+
+      if ($is_show) {
+        $file_handle = null;
+      } else {
+        $file_handle = fopen($path, 'ab+');
+        if ($file_handle === false) {
+          throw new Exception(
+            pht(
+              'Failed to open file "%s" for writing.',
+              $path));
+        }
+
+        $this->writeInfo(
+          pht('DATA'),
+          pht(
+            'Downloading "%s" (%s byte(s))...',
+            $display_name,
+            new PhutilNumber($size)));
+      }
+
+      $future = new HTTPSFuture($data_uri);
+
+      // For small files, don't bother drawing a progress bar.
+      $minimum_bar_bytes = (1024 * 1024 * 4);
+
+      if ($is_show || ($size < $minimum_bar_bytes)) {
+        $bar = null;
+      } else {
+        $bar = id(new PhutilConsoleProgressBar())
+          ->setTotal($size);
+      }
+
+      // TODO: We should stream responses to disk, but cURL gives us the raw
+      // HTTP response data and BaseHTTPFuture can not currently parse it in
+      // a stream-oriented way. Until this is resolved, buffer the file data
+      // in memory and write it to disk in one shot.
+
+      list($status, $data) = $future->resolve();
+      if ($status->getStatusCode() !== 200) {
+        throw new Exception(
+          pht(
+            'Got HTTP %d status response, expected HTTP 200.',
+            $status));
+      }
+
+      if (strlen($data)) {
+        if ($is_show) {
+          echo $data;
+        } else {
+          $ok = fwrite($file_handle, $data);
+          if ($ok === false) {
+            throw new Exception(
+              pht(
+                'Failed to write file data to "%s".',
+                $path));
+          }
+        }
+      }
+
+      if ($bar) {
+        $bar->update(strlen($data));
+      }
+
+      if ($bar) {
+        $bar->done();
+      }
+
+      if ($file_handle) {
+        $ok = fclose($file_handle);
+        if ($ok === false) {
+          throw new Exception(
+            pht(
+              'Failed to close file handle for "%s".',
+              $path));
+        }
+      }
+
+      if (!$is_show) {
+        $this->writeOkay(
+          pht('DONE'),
+          pht(
+            'Saved "%s" as "%s".',
+            $display_name,
+            $display_path));
+      }
+
+      return 0;
+    } catch (Exception $ex) {
+      // If we fail for any reason, fall back to the older mechanism using
+      // "file.info" and "file.download".
+    }
+
     $this->writeStatusMessage(pht('Getting file information...')."\n");
     $info = $conduit->callMethodSynchronous(
       'file.info',