buffer: fix usage of kMaxLength

Starting in V8 v4.3 the maximum array index of a typed array is the same
as the largest Smi supported on a given architecture. To compensate for
these differences export kMaxLength from the buffer module with the
correct size for the given architecture.

PR-URL: https://github.com/nodejs/io.js/pull/2003
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>

lib/fs.js

@@ -20,7 +20,7 @@ const Readable = Stream.Readable;
 const Writable = Stream.Writable;
 
 const kMinPoolSpace = 128;
-const kMaxLength = process.binding('smalloc').kMaxLength;
+const kMaxLength = require('buffer').kMaxLength;
 
 const O_APPEND = constants.O_APPEND || 0;
 const O_CREAT = constants.O_CREAT || 0;

lib/internal/buffer_new.js

@@ -6,6 +6,7 @@ const internalUtil = require('internal/util');
 exports.Buffer = Buffer;
 exports.SlowBuffer = SlowBuffer;
 exports.INSPECT_MAX_BYTES = 50;
+exports.kMaxLength = binding.kMaxLength;
 
 
 Buffer.poolSize = 8 * 1024;

lib/internal/buffer_old.js

@@ -11,6 +11,7 @@ const kMaxLength = smalloc.kMaxLength;
 exports.Buffer = Buffer;
 exports.SlowBuffer = SlowBuffer;
 exports.INSPECT_MAX_BYTES = 50;
+exports.kMaxLength = binding.kMaxLength;
 
 
 Buffer.poolSize = 8 * 1024;

lib/zlib.js

@@ -5,7 +5,7 @@ const Transform = require('_stream_transform');
 const binding = process.binding('zlib');
 const util = require('util');
 const assert = require('assert').ok;
-const kMaxLength = process.binding('smalloc').kMaxLength;
+const kMaxLength = require('buffer').kMaxLength;
 const kRangeErrorMessage = 'Cannot create final Buffer. ' +
     'It would be larger than 0x' + kMaxLength.toString(16) + ' bytes.';
 

src/node_buffer.cc

@@ -71,6 +71,7 @@ using v8::FunctionCallbackInfo;
 using v8::FunctionTemplate;
 using v8::Handle;
 using v8::HandleScope;
+using v8::Integer;
 using v8::Isolate;
 using v8::Local;
 using v8::Maybe;
@@ -1188,6 +1189,16 @@ void Initialize(Handle<Object> target,
   env->SetMethod(target, "writeDoubleLE", WriteDoubleLE);
   env->SetMethod(target, "writeFloatBE", WriteFloatBE);
   env->SetMethod(target, "writeFloatLE", WriteFloatLE);
+
+  uint32_t kMaxLength;
+  if (sizeof(int32_t) == sizeof(intptr_t) || using_old_buffer) {
+    kMaxLength = 0x3fffffff;
+  } else {
+    kMaxLength = 0x7fffffff;
+  }
+  target->Set(env->context(),
+              FIXED_ONE_BYTE_STRING(env->isolate(), "kMaxLength"),
+              Integer::NewFromUnsigned(env->isolate(), kMaxLength)).FromJust();
 }
 
 

test/parallel/test-regress-GH-io-1811.js

@@ -2,12 +2,13 @@
 
 const assert = require('assert');
 
-// Change kMaxLength for zlib to trigger the error
-// without having to allocate 1GB of buffers
-const smalloc = process.binding('smalloc');
-smalloc.kMaxLength = 128;
+// Change kMaxLength for zlib to trigger the error without having to allocate
+// large Buffers.
+const buffer = require('buffer');
+const oldkMaxLength = buffer.kMaxLength;
+buffer.kMaxLength = 128;
 const zlib = require('zlib');
-smalloc.kMaxLength = 0x3fffffff;
+buffer.kMaxLength = oldkMaxLength;
 
 const encoded = new Buffer('H4sIAAAAAAAAA0tMHFgAAIw2K/GAAAAA', 'base64');