Don't assume that file binary exists on *nix OS

teohhanhui · teohhanhui · commit 8b1c6801fabe · 2018-04-12T15:38:16.000+02:00
Certain lightweight distributions such as Alpine Linux (popular for smaller Docker images) do not include it by default.
diff --git a/src/Symfony/Component/HttpFoundation/File/MimeType/FileBinaryMimeTypeGuesser.php b/src/Symfony/Component/HttpFoundation/File/MimeType/FileBinaryMimeTypeGuesser.php
@@ -43,7 +43,7 @@ public function __construct($cmd = 'file -b --mime %s 2>/dev/null')
      */
     public static function isSupported()
     {
-        return '\\' !== DIRECTORY_SEPARATOR && function_exists('passthru') && function_exists('escapeshellarg');
+        return '\\' !== DIRECTORY_SEPARATOR && function_exists('passthru') && function_exists('escapeshellarg') && static::hasFileBinary();
     }
 
     /**
@@ -82,4 +82,14 @@ public function guess($path)
 
         return $match[1];
     }
+
+    /**
+     * @return bool
+     */
+    private static function hasFileBinary()
+    {
+        static $exists;
+
+        return isset($exists) ? $exists : ($exists = null !== shell_exec('command -v file'));
+    }
 }

Original file line number	Diff line number	Diff line change
`@@ -43,7 +43,7 @@ public function __construct($cmd = 'file -b --mime %s 2>/dev/null')`
`43`	`43`	`*/`
`44`	`44`	`public static function isSupported()`
`45`	`45`	`{`
`46`		`- return '\\' !== DIRECTORY_SEPARATOR && function_exists('passthru') && function_exists('escapeshellarg');`
	`46`	`+ return '\\' !== DIRECTORY_SEPARATOR && function_exists('passthru') && function_exists('escapeshellarg') && static::hasFileBinary();`
`47`	`47`	`}`
`48`	`48`
`49`	`49`	`/**`
`@@ -82,4 +82,14 @@ public function guess($path)`
`82`	`82`
`83`	`83`	`return $match[1];`
`84`	`84`	`}`
	`85`	`+`
	`86`	`+ /**`
	`87`	`+ * @return bool`
	`88`	`+ */`
	`89`	`+ private static function hasFileBinary()`
	`90`	`+ {`
	`91`	`+ static $exists;`
	`92`	`+`
	`93`	`+ return isset($exists) ? $exists : ($exists = null !== shell_exec('command -v file'));`
	`94`	`+ }`
`85`	`95`	`}`