Fix reading of small SVG images to determine dimensions

ampproject · Jan 11, 2019 · 7528117 · 7528117
1 parent d04af55
commit 7528117
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Showing 2 changed files with 17 additions and 10 deletions.
diff --git a/third_party/fasterimage/ImageParser.php b/third_party/fasterimage/ImageParser.php
@@ -136,7 +136,7 @@ public function parseType()
                     return $this->type = 'tiff';
                 default:
                     $this->stream->resetPointer();
-                    $markup = $this->stream->read( 1024 );
+                    $markup = $this->stream->read( 1024, false );
                     if ( false !== strpos( $markup, '<svg' ) ) {
                         $this->type = 'svg';
                     } else {
@@ -361,7 +361,7 @@ protected function parseSizeForWebp()
     protected function parseSizeForSvg()
     {
         $this->stream->resetPointer();
-        $markup = $this->stream->read( 1024 );
+        $markup = $this->stream->read( 1024, false );
         if ( ! preg_match( '#<svg.*?>#s', $markup, $matches ) ) {
             return null;
         }

diff --git a/third_party/fasterimage/Stream/Stream.php b/third_party/fasterimage/Stream/Stream.php
@@ -25,14 +25,15 @@ class Stream implements StreamableInterface
     /**
      * Get characters from the string but don't move the pointer
      *
-     * @param $characters
+     * @param int $characters Number of characters to read. If -1 then it will read until the end.
+     * @param bool $check_length Throw exception if there are not enough bytes left in the stream.
      *
      * @return string
      * @throws StreamBufferTooSmallException
      */
-    public function peek($characters)
+    public function peek($characters, $check_length=true)
     {
-        if ( strlen($this->stream_string) < $this->strpos + $characters ) {
+        if ( $check_length && strlen($this->stream_string) < $this->strpos + $characters ) {
             throw new StreamBufferTooSmallException('Not enough of the stream available.');
         }
 
@@ -42,16 +43,22 @@ public function peek($characters)
     /**
      * Get Characters from the string
      *
-     * @param $characters
+     * @param int  $characters   Number of characters to read.
+     * @param bool $check_length Throw exception if there are not enough bytes left in the stream.
      *
      * @return string
      * @throws StreamBufferTooSmallException
      */
-    public function read($characters)
+    public function read($characters, $check_length=true)
     {
-        $result = $this->peek($characters);
+        $size   = strlen($this->stream_string);
+        $result = $this->peek($characters, $check_length);
 
-        $this->strpos += $characters;
+        if ( strlen( $result ) + $characters > $size ) {
+            $this->strpos = $size;
+        } else {
+            $this->strpos += $characters;
+        }
 
         return $result;
     }
@@ -75,4 +82,4 @@ public function write($string)
     {
         $this->stream_string .= $string;
     }
-}
+}