From 04e3680d1c39b1b08f331f54cd3388f694c19d41 Mon Sep 17 00:00:00 2001
From: Joe McGill <joemcgill@git.wordpress.org>
Date: Sun, 9 Apr 2017 22:43:04 +0000
Subject: [PATCH] Media: Improve handling of non-image files in
 wp_get_image_mime.

This prevents non-image fileypes from returning a mime type of
"application/octet-stream" when `exif_imagetype()` returns `false`.

Props blobfolio.
Fixes #40017.


git-svn-id: https://develop.svn.wordpress.org/trunk@40397 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/functions.php     |  3 +-
 tests/phpunit/tests/functions.php | 47 +++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index ee214e923a..966dcd8265 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -2367,7 +2367,8 @@ function wp_get_image_mime( $file ) {
 	 */
 	try {
 		if ( is_callable( 'exif_imagetype' ) ) {
-			$mime = image_type_to_mime_type( exif_imagetype( $file ) );
+			$imagetype = exif_imagetype( $file );
+			$mime = ( $imagetype ) ? image_type_to_mime_type( $imagetype ) : false;
 		} elseif ( function_exists( 'getimagesize' ) ) {
 			$imagesize = getimagesize( $file );
 			$mime = ( isset( $imagesize['mime'] ) ) ? $imagesize['mime'] : false;
diff --git a/tests/phpunit/tests/functions.php b/tests/phpunit/tests/functions.php
index a3aba79c44..47704f8036 100644
--- a/tests/phpunit/tests/functions.php
+++ b/tests/phpunit/tests/functions.php
@@ -915,6 +915,18 @@ class Tests_Functions extends WP_UnitTestCase {
 		$this->assertEquals( $uuids, $unique_uuids );
 	}
 
+	/**
+	 * @ticket 40017
+	 * @dataProvider _wp_get_image_mime
+	 */
+	public function test_wp_get_image_mime( $file, $expected ) {
+		if ( ! is_callable( 'exif_imagetype' ) && ! function_exists( 'getimagesize' ) ) {
+			$this->markTestSkipped( 'The exif PHP extension is not loaded.' );
+		}
+
+		$this->assertEquals( $expected, wp_get_image_mime( $file ) );
+	}
+
 	/**
 	 * @ticket 39550
 	 * @dataProvider _wp_check_filetype_and_ext_data
@@ -993,6 +1005,41 @@ class Tests_Functions extends WP_UnitTestCase {
 		return $mimes;
 	}
 
+	/**
+	 * Data profider for test_wp_get_image_mime();
+	 */
+	public function _wp_get_image_mime() {
+		$data = array(
+			// Standard JPEG.
+			array(
+				DIR_TESTDATA . '/images/test-image.jpg',
+				'image/jpeg',
+			),
+			// Standard GIF.
+			array(
+				DIR_TESTDATA . '/images/test-image.gif',
+				'image/gif',
+			),
+			// Standard PNG.
+			array(
+				DIR_TESTDATA . '/images/test-image.png',
+				'image/png',
+			),
+			// Image with wrong extension.
+			array(
+				DIR_TESTDATA . '/images/test-image-mime-jpg.png',
+				'image/jpeg',
+			),
+			// Not an image.
+			array(
+				DIR_TESTDATA . '/uploads/dashicons.woff',
+				false,
+			),
+		);
+
+		return $data;
+	}
+
 	public function _wp_check_filetype_and_ext_data() {
 		$data = array(
 			// Standard image.