Fix write() truncation with ext-uv and ext-eio (#76)

Author: danog

src/Driver/EioFilesystemDriver.php

@@ -346,7 +346,7 @@ public function read(string $path): string
 
     public function write(string $path, string $contents): void
     {
-        $flags = \EIO_O_RDWR | \EIO_O_CREAT;
+        $flags = \EIO_O_RDWR | \EIO_O_CREAT | \EIO_O_TRUNC;
         $mode = \EIO_S_IRUSR | \EIO_S_IWUSR | \EIO_S_IXUSR;
         $priority = \EIO_PRI_DEFAULT;
 

src/Driver/UvFilesystemDriver.php

@@ -418,7 +418,7 @@ public function read(string $path): string
 
     public function write(string $path, string $contents): void
     {
-        $flags = \UV::O_WRONLY | \UV::O_CREAT;
+        $flags = \UV::O_WRONLY | \UV::O_CREAT | \UV::O_TRUNC;
         $mode = \UV::S_IRWXU | \UV::S_IRUSR;
 
         $this->poll->listen();
@@ -454,8 +454,10 @@ private function parseMode(string $mode): int
         return match ($mode) {
             "r" => \UV::O_RDONLY,
             "r+" => \UV::O_RDWR,
-            "c", "w" => \UV::O_WRONLY | \UV::O_CREAT,
-            "c+", "w+" => \UV::O_RDWR | \UV::O_CREAT,
+            "c" => \UV::O_WRONLY | \UV::O_CREAT,
+            "w" => \UV::O_WRONLY | \UV::O_CREAT | \UV::O_TRUNC,
+            "c+" => \UV::O_RDWR | \UV::O_CREAT,
+            "w+" => \UV::O_RDWR | \UV::O_CREAT | \UV::O_TRUNC,
             "a" => \UV::O_WRONLY | \UV::O_CREAT | \UV::O_APPEND,
             "a+" => \UV::O_RDWR | \UV::O_CREAT | \UV::O_APPEND,
             "x" => \UV::O_WRONLY | \UV::O_CREAT | \UV::O_EXCL,

test/FileTest.php

@@ -4,6 +4,8 @@
 
 use Amp\ByteStream\ClosedException;
 use Amp\File;
+use Amp\File\Whence;
+
 use function Amp\async;
 
 abstract class FileTest extends FilesystemTest
@@ -25,6 +27,35 @@ public function testWrite(): void
         $this->assertSame("foobar", $contents);
 
         $handle->close();
+
+        $handle = $this->driver->openFile($path, "c+");
+        $handle->seek(0, Whence::End);
+        $this->assertSame(6, $handle->tell());
+
+        $handle->close();
+    }
+
+    public function testWriteTruncate(): void
+    {
+        $path = Fixture::path() . "/write";
+        $handle = $this->driver->openFile($path, "c+");
+        $this->assertSame(0, $handle->tell());
+
+        $handle->write("foo");
+        $handle->write("bar");
+        $handle->seek(0);
+        $contents = $handle->read();
+        $this->assertSame(6, $handle->tell());
+        $this->assertTrue($handle->eof());
+        $this->assertSame("foobar", $contents);
+
+        $handle->close();
+
+        $handle = $this->driver->openFile($path, "w+");
+        $handle->seek(0, Whence::End);
+        $this->assertSame(0, $handle->tell());
+
+        $handle->close();
     }
 
     public function testEmptyWrite(): void

test/FilesystemDriverTest.php

@@ -506,6 +506,27 @@ public function testTouch(): void
         $this->assertTrue($newStat["mtime"] > $oldStat["mtime"]);
     }
 
+    /**
+     * @group slow
+     */
+    public function testWrite(): void
+    {
+        $fixtureDir = Fixture::path();
+
+        $contents1 = "write test longer";
+        $contents2 = "write test";
+        $path = "{$fixtureDir}/write.txt";
+
+        $this->driver->write($path, $contents1);
+        $this->assertSame($contents1, $this->driver->read($path));
+
+        $this->driver->write($path, $contents2);
+        $this->assertSame($contents2, $this->driver->read($path));
+
+        $this->driver->write($path, $contents1);
+        $this->assertSame($contents1, $this->driver->read($path));
+    }
+
     public function testTouchFailsOnNonexistentPath(): void
     {
         $fixtureDir = Fixture::path();