Rendering files from C++ Node.js addon - c++

Question

I would like to render files in node.js from C++ addon.
I want to apply some file processing and render the output to the browser via node.js
Here is my C++ Code
std::ifstream in(filename, std::ios::binary);
in.seekg (0, in.end);
int length = in.tellg();
in.seekg (0, in.beg);
char * buffer = new char [length];
in.read (buffer,length);
in.close();
return buffer;
Following is the V8 code to add bindings for node.js, here buffer is the output from the above c++ code.
Local<Function> cb = Local<Function>::Cast(args[1]);
const unsigned argc = 1;
Local<Value> argv[argc] = {Local<Value>::New(String::New(buffer))};
cb->Call(Context::GetCurrent()->Global(), argc, argv);
This code works well for normal text files. I'm getting problem when reading text files which are having unicode characters.
For eg,
Original text file
test start
Billél
last
When receiving in node, I will get
test start
Bill�l
last
Similarly when reading a jpg, png files the output file is different than the original file.
Please help.

Answer 1

I was having problems with this as well. I found an implementation in the V8 examples from Google. The example I found that properly handles UTF8 encoded files is found here:
https://code.google.com/p/v8/source/browse/trunk/samples/shell.cc#218
I adapted the source to this:
const char* ReadFile(const char* fileName, int* fileSize)
{
// reference to c-string version of file
char *fileBuffer = 0;
// attempt to open the file
FILE* fd = fopen(fileName, "rb");
// clear file size
*fileSize = 0;
// file was valid
if(fd != 0)
{
// get size of file
fseek(fd, 0, SEEK_END);
*fileSize = ftell(fd);
rewind(fd);
// allocate file buffer for file contents
fileBuffer = (char*)malloc(*fileSize + 1);
fileBuffer[*fileSize] = 0;
// copy file contents
for (int charCount = 0; charCount < *fileSize;)
{
int charRead = static_cast<int>(fread(&fileBuffer[charCount], 1, *fileSize - charCount, fd));
charCount += charRead;
}
// close the file
fclose(fd);
}
return fileBuffer;
}
Also, make sure when you create a V8 string that you create a String::Utf8Value.
String::Utf8Value v8Utf8String(...);
Then to use the String::Utf8Value as a char* use the following function:
https://code.google.com/p/v8/source/browse/trunk/samples/shell.cc#91