Fail fast for Buffer with unsupported format #105

index.js

@@ -54,10 +54,15 @@ var Sharp = function(input) {
     this.options.fileIn = input;
   } else if (typeof input === 'object' && input instanceof Buffer) {
     // input=buffer
-    if (input.length > 0) {
+    if (
+      (input.length > 1) &&
+      (input[0] === 0xff && input[1] === 0xd8) || // JPEG
+      (input[0] === 0x89 && input[1] === 0x50) || // PNG
+      (input[0] === 0x52 && input[1] === 0x49) // WebP
+    ) {
       this.options.bufferIn = input;
     } else {
-      throw new Error('Buffer is empty');
+      throw new Error('Buffer contains an unsupported image format. JPEG, PNG and WebP are currently supported.');
     }
   } else {
     // input=stream

test/unit/io.js

@@ -189,22 +189,27 @@ describe('Input/output', function() {
   });
 
   it('Fail when input is empty Buffer', function(done) {
-    var fail = false;
+    var failed = true;
     try {
       sharp(new Buffer(0));
-      fail = true;
-    } catch (e) {}
-    assert(!fail);
+      failed = false;
+    } catch (err) {
+      assert(err instanceof Error);
+    }
+    assert(failed);
     done();
   });
 
   it('Fail when input is invalid Buffer', function(done) {
-    sharp(new Buffer([0x1, 0x2, 0x3, 0x4]))
-      .toBuffer(function (err) {
-        assert.ok(err);
-        assert.ok(err instanceof Error);
-        done();
-      });
+    var failed = true;
+    try {
+      sharp(new Buffer([0x1, 0x2, 0x3, 0x4]));
+      failed = false;
+    } catch (err) {
+      assert(err instanceof Error);
+    }
+    assert(failed);
+    done();
   });
 
   it('Promises/A+', function(done) {

test/unit/metadata.js

@@ -185,11 +185,4 @@ describe('Image metadata', function() {
     });
   });
 
-  it('Report an invalid image as an error', function(done) {
-    sharp(new Buffer([0x1, 0x2, 0x3, 0x4])).metadata(function (err, metadata) {
-      assert.ok(err);
-      assert.ok(err instanceof Error);
-      done();
-    });
-  });
 });