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buffer: let WriteFloatGeneric silently drop values #3767

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buffer: let WriteFloatGeneric silently drop values #3767

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8 changes: 5 additions & 3 deletions src/node_buffer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -735,7 +735,9 @@ uint32_t WriteFloatGeneric(const FunctionCallbackInfo<Value>& args) {

T val = args[1]->NumberValue();
uint32_t offset = args[2]->Uint32Value();
CHECK_LE(offset + sizeof(T), ts_obj_length);
size_t memcpy_num = sizeof(T);
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Just curious, why initialize memcpy_num to sizeof(T)?

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Just a coding style thing, it is the same as,

  if (offset + sizeof(T) > ts_obj_length)
    memcpy_num = ts_obj_length - offset;
  else
    memcpy_num = sizeof(T);

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ah I see. was focused on that memcpy_num = sizeof(T) was set then immediately after there's a check sizeof(T) in the conditional. nm it then. :)

if (offset + sizeof(T) > ts_obj_length)
memcpy_num = ts_obj_length - offset;

union NoAlias {
T val;
Expand All @@ -746,8 +748,8 @@ uint32_t WriteFloatGeneric(const FunctionCallbackInfo<Value>& args) {
char* ptr = static_cast<char*>(ts_obj_data) + offset;
if (endianness != GetEndianness())
Swizzle(na.bytes, sizeof(na.bytes));
memcpy(ptr, na.bytes, sizeof(na.bytes));
return offset + sizeof(na.bytes);
memcpy(ptr, na.bytes, memcpy_num);
return offset + memcpy_num;
}


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7 changes: 7 additions & 0 deletions test/parallel/test-buffer-arraybuffer.js
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Expand Up @@ -44,3 +44,10 @@ assert.throws(function() {
AB.prototype.__proto__ = ArrayBuffer.prototype;
new Buffer(new AB());
}, TypeError);

// write{Double,Float}{LE,BE} with noAssert should not crash, cf. #3766
var b = new Buffer(1);
b.writeFloatLE(11.11, 0, true);
b.writeFloatBE(11.11, 0, true);
b.writeDoubleLE(11.11, 0, true);
b.writeDoubleBE(11.11, 0, true);