Hardening of SimpleFile getContent

if file_get_contents fails remove the file. And traverse up the tree
checking if the other folders are there.

Signed-off-by: Roeland Jago Douma <roeland@famdouma.nl>

lib/private/Files/SimpleFS/SimpleFile.php

@@ -23,6 +23,7 @@
 namespace OC\Files\SimpleFS;
 
 use OCP\Files\File;
+use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
 use OCP\Files\SimpleFS\ISimpleFile;
 
@@ -79,10 +80,18 @@ class SimpleFile implements ISimpleFile  {
 	/**
 	 * Get the content
 	 *
+	 * @throws NotPermittedException
+	 * @throws NotFoundException
 	 * @return string
 	 */
 	public function getContent() {
-		return $this->file->getContent();
+		$result = $this->file->getContent();
+
+		if ($result === false) {
+			$this->checkFile();
+		}
+
+		return $result;
 	}
 
 	/**
@@ -95,6 +104,31 @@ class SimpleFile implements ISimpleFile  {
 		$this->file->putContent($data);
 	}
 
+	/**
+	 * Sometimes there are some issues with the AppData. Most of them are from
+	 * user error. But we should handle them gracefull anyway.
+	 *
+	 * If for some reason the current file can't be found. We remove it.
+	 * Then traverse up and check all folders if they exists. This so that the
+	 * next request will have a valid appdata structure again.
+	 *
+	 * @throws NotFoundException
+	 */
+	private function checkFile() {
+		$cur = $this->file;
+
+		while ($cur->stat() === false) {
+			$parent = $cur->getParent();
+			$cur->delete();
+			$cur = $parent;
+		}
+
+		if ($cur !== $this->file) {
+			throw new NotFoundException('File does not exist');
+		}
+	}
+
+
 	/**
 	 * Delete the file
 	 *

lib/public/Files/SimpleFS/ISimpleFile.php

@@ -22,6 +22,7 @@
  */
 namespace OCP\Files\SimpleFS;
 
+use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
 
 /**
@@ -67,6 +68,8 @@ interface ISimpleFile {
 	/**
 	 * Get the content
 	 *
+	 * @throws NotPermittedException
+	 * @throws NotFoundException
 	 * @return string
 	 * @since 11.0.0
 	 */

tests/lib/Files/SimpleFS/SimpleFileTest.php

@@ -24,6 +24,9 @@ namespace Test\File\SimpleFS;
 
 use OC\Files\SimpleFS\SimpleFile;
 use OCP\Files\File;
+use OCP\Files\Folder;
+use OCP\Files\NotFoundException;
+use OCP\Files\NotPermittedException;
 
 class SimpleFileTest extends \Test\TestCase  {
 	/** @var File|\PHPUnit_Framework_MockObject_MockObject */
@@ -101,4 +104,23 @@ class SimpleFileTest extends \Test\TestCase  {
 
 		$this->assertEquals('app/awesome', $this->simpleFile->getMimeType());
 	}
+
+	public function testGetContentInvalidAppData() {
+		$this->file->method('getContent')
+			->willReturn(false);
+		$this->file->method('stat')->willReturn(false);
+
+		$parent = $this->createMock(Folder::class);
+		$parent->method('stat')->willReturn(false);
+
+		$root = $this->createMock(Folder::class);
+		$root->method('stat')->willReturn([]);
+
+		$this->file->method('getParent')->willReturn($parent);
+		$parent->method('getParent')->willReturn($root);
+
+		$this->expectException(NotFoundException::class);
+
+		$this->simpleFile->getContent();
+	}
 }