Changeset 49174

Timestamp:

10/16/2020 10:46:58 AM (4 years ago)

Author:

mikeschroder

Message:

Media: Work around use-cropbox bug in Ghostscript 8.70

Wraps Imagick::readImage() for PDFs with exception handling, trying again without use-cropbox if this fails.

Introduces WP_Image_Editor_Imagick::pdf_load_source().

Works around a known issue in Ghostscript 8.70 (fixed in 8.71) that results in a stack underflow.
While it only affects this version, it remains a common version found on hosts, and prevented some PDF thumbnails from being generated.

See this Ghostscript bug for more details: ​https://bugs.ghostscript.com/show_bug.cgi?id=690676

Props azaozz, joseaneto, cranewest, dantahoua, n5hzr, mikeschroder.
Fixes #48853.

File:

• trunk/src/wp-includes/class-wp-image-editor-imagick.php (modified) (3 diffs)

trunk/src/wp-includes/class-wp-image-editor-imagick.php

@@ -141 +141 @@
             $this->image    = new Imagick();
             $file_extension = strtolower( pathinfo( $this->file, PATHINFO_EXTENSION ) );
-            $filename       = $this->file;
 
             if ( 'pdf' === $file_extension ) {
-                $filename = $this->pdf_setup();
-            }
-
-            // Reading image after Imagick instantiation because `setResolution`
-            // only applies correctly before the image is read.
-            $this->image->readImage( $filename );
+                $pdf_loaded = $this->pdf_load_source();
+
+                if ( is_wp_error( $pdf_loaded ) ) {
+                    return $pdf_loaded;
+                }
+            } else {
+                $this->image->readImage( $this->file );
+            }
 
             if ( ! $this->image->valid() ) {
@@ -166 +167 @@
 
         $updated_size = $this->update_size();
+
         if ( is_wp_error( $updated_size ) ) {
             return $updated_size;
@@ -796 +798 @@
             $this->image->setResolution( 128, 128 );
 
+            // Only load the first page.
+            return $this->file . '[0]';
+        } catch ( Exception $e ) {
+            return new WP_Error( 'pdf_setup_failed', $e->getMessage(), $this->file );
+        }
+    }
+
+    /**
+     * Load the image produced by Ghostscript.
+     *
+     * Includes a workaround for a bug in Ghostscript 8.70 that prevents processing of some PDF files
+     * when `use-cropbox` is set.
+     *
+     * @since 5.6
+     *
+     * @return true|WP_error
+     */
+    protected function pdf_load_source() {
+        $filename = $this->pdf_setup();
+
+        if ( is_wp_error( $filename ) ) {
+            return $filename;
+        }
+
+        try {
             // When generating thumbnails from cropped PDF pages, Imagemagick uses the uncropped
             // area (resulting in unnecessary whitespace) unless the following option is set.
             $this->image->setOption( 'pdf:use-cropbox', true );
 
-            // Only load the first page.
-            return $this->file . '[0]';
-        } catch ( Exception $e ) {
-            return new WP_Error( 'pdf_setup_failed', $e->getMessage(), $this->file );
-        }
+            // Reading image after Imagick instantiation because `setResolution`
+            // only applies correctly before the image is read.
+            $this->image->readImage( $filename );
+        } catch ( Exception $e ) {
+            // Attempt to run `gs` without the `use-cropbox` option. See #48853.
+            $this->image->setOption( 'pdf:use-cropbox', false );
+
+            $this->image->readImage( $filename );
+        }
+
+        return true;
     }