Upgrade: Handle broken symlinks during file copies

src/wp-admin/includes/class-wp-filesystem-direct.php

@@ -334,6 +334,13 @@ public function copy( $source, $destination, $overwrite = false, $mode = false )
 			return false;
 		}
 
+		if ( $source === $destination ) {
+			return false;
+		}
+
+		if ( $overwrite && $this->exists( $destination ) && ! $this->delete( $destination ) ) {
+			return false;
+		}
 		$rtval = copy( $source, $destination );
 
 		if ( $mode ) {
@@ -444,7 +451,7 @@ public function delete( $file, $recursive = false, $type = false ) {
 	 * @return bool Whether $path exists or not.
 	 */
 	public function exists( $path ) {
-		return @file_exists( $path );
+		return @file_exists( $path ) || @is_link( $path );
 	}
 
 	/**
@@ -456,7 +463,7 @@ public function exists( $path ) {
 	 * @return bool Whether $file is a file.
 	 */
 	public function is_file( $file ) {
-		return @is_file( $file );
+		return @is_file( $file ) || @is_link( $file );
 	}
 
 	/**

src/wp-admin/includes/class-wp-filesystem-ftpext.php

@@ -402,6 +402,13 @@ public function copy( $source, $destination, $overwrite = false, $mode = false )
 			return false;
 		}
 
+		if ( $source === $destination ) {
+			return false;
+		}
+
+		if ( $overwrite && $this->exists( $destination ) && ! $this->delete( $destination ) ) {
+			return false;
+		}
 		$content = $this->get_contents( $source );
 
 		if ( false === $content ) {

src/wp-admin/includes/class-wp-filesystem-ftpsockets.php

@@ -409,6 +409,13 @@ public function copy( $source, $destination, $overwrite = false, $mode = false )
 			return false;
 		}
 
+		if ( $source === $destination ) {
+			return false;
+		}
+
+		if ( $overwrite && $this->exists( $destination ) && ! $this->delete( $destination ) ) {
+			return false;
+		}
 		$content = $this->get_contents( $source );
 
 		if ( false === $content ) {

src/wp-admin/includes/class-wp-filesystem-ssh2.php

@@ -547,6 +547,13 @@ public function copy( $source, $destination, $overwrite = false, $mode = false )
 			return false;
 		}
 
+		if ( $source === $destination ) {
+			return false;
+		}
+
+		if ( $overwrite && $this->exists( $destination ) && ! $this->delete( $destination ) ) {
+			return false;
+		}
 		$content = $this->get_contents( $source );
 
 		if ( false === $content ) {
@@ -635,7 +642,9 @@ public function delete( $file, $recursive = false, $type = false ) {
 	 * @return bool Whether $path exists or not.
 	 */
 	public function exists( $path ) {
-		return file_exists( $this->sftp_path( $path ) );
+		$path = $this->sftp_path( $path );
+
+		return file_exists( $path ) || is_link( $path );
 	}
 
 	/**
@@ -647,7 +656,9 @@ public function exists( $path ) {
 	 * @return bool Whether $file is a file.
 	 */
 	public function is_file( $file ) {
-		return is_file( $this->sftp_path( $file ) );
+		$file = $this->sftp_path( $file );
+
+		return is_file( $file ) || is_link( $file );
 	}
 
 	/**

tests/phpunit/tests/filesystem/wpFilesystemDirect/copy.php

@@ -66,7 +66,34 @@ public function test_should_not_overwrite_an_existing_file_when_overwriting_is_d
 	 * @ticket 57774
 	 */
 	public function test_should_not_overwrite_when_overwriting_is_enabled_and_source_and_destination_are_the_same() {
+
 		$source = self::$file_structure['test_dir']['path'] . 'a_file_that_exists.txt';
 		$this->assertFalse( self::$filesystem->copy( $source, $source, true ) );
 	}
+
+	/**
+	 * Tests that `WP_Filesystem_Direct::copy()` replaces a broken symlink when
+	 * overwriting is enabled.
+	 *
+	 * @ticket 46040
+	 */
+	public function test_should_replace_a_broken_symlink_when_overwriting_is_enabled() {
+		$source      = self::$file_structure['visible_file']['path'];
+		$destination = self::$file_structure['test_dir']['path'] . '.broken_symlink';
+
+		if ( ! function_exists( 'symlink' ) ) {
+			$this->markTestSkipped( 'The environment does not support creating symlinks.' );
+		}
+
+		$created = symlink( 'does-not-exist', $destination );
+		if ( ! $created ) {
+			$this->markTestSkipped( 'The environment does not support creating symlinks.' );
+		}
+
+		$this->assertTrue( self::$filesystem->exists( $destination ) );
+		$this->assertTrue( self::$filesystem->copy( $source, $destination, true ) );
+		$this->assertSame( file_get_contents( $source ), file_get_contents( $destination ) );
+
+		unlink( $destination );
+	}
 }