722040 - jsctypes is not able to deal with binary/blob strings

Status: UNCONFIRMED

(Core :: js-ctypes, enhancement)

Description

[Emmanuel Engelhart]

I want to use jsctypes in a js protocol component (@mozilla.org/network/protocol;1?name=).

For this reasons I need to deal with binary strings which are coming from the C/C++ code as char** (or ctypes.char.ptr given by address as parameter).

Unfortunately the CData readString() method is unadapted (UTF8 and null terminated assumptions) and there is no method to access quickly the underlying byte buffer. So, I have found no efficient way to access the data.

It would be great to modify readString() to allow that or do build a method like data([length]).

Comment 1

[David Teller [:Yoric] - still alive but not very active]

I need something along these lines for reading Unicode from files by chunks. Emmanuel, what do you think of merging this bug with bug 552551?

Comment 2

[David Teller [:Yoric] - still alive but not very active]

Emmanuel, actually, on second thought, I am not sure of how this relates to readString. Doesn't casting your ctypes.char.ptr to an array do what you need?

Comment 3

[Jeff]

I have tried to cast the char.ptr to a uint8 array and it still crashes when accessing the individual elements is there no way to get binary data?

Heres my testing code
var teststring = lib.declare("teststring",
                               ctypes.default_abi, //ctypes.stdcall_abi, // call ABI
                               ctypes.int64_t, // return type
							   ctypes.int32_t.ptr,       // buffer size
                               ctypes.char.ptr  //ctypes.char.ptr.array()        // Buffer
                               );

var bufferSize = new ctypes.int32_t(10).address();
var buffer = new ctypes.char();
var bufferPtr = buffer.address();
var ret = teststring(bufferSize, bufferPtr);

var hold = ctypes.cast( bufferPtr, ctypes.ArrayType(ctypes.uint8_t, parseInt(bufferSize.contents)).ptr );
console.error("Hold array length: "+hold.contents.length);
var output = "";
for(var i=0; i<bufferSize.contents; i++){
	output+=""+hold.contents[i];
}
console.error("Output: "+output);

Comment 4

[Jeff]

I can go directly to a Uint8Array with this
var byteArray = new Uint8Array(buffer);
I think I was trying to hard with the ctypes casting lol