Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
C helper functions for wrapping and unwrapping Node Buffer instances as "pointers"
/*
* Helper functions for treating node Buffer instances as C "pointers".
*/
#include "v8.h"
#include "node_buffer.h"
/*
* Called when the "pointer" is garbage collected.
*/
inline static void wrap_pointer_cb(char *data, void *hint) {
//fprintf(stderr, "wrap_pointer_cb\n");
}
/*
* Wraps "ptr" into a new SlowBuffer instance with size "length".
*/
inline static v8::Handle<v8::Value> WrapPointer(void *ptr, size_t length) {
void *user_data = NULL;
node::Buffer *buf = node::Buffer::New((char *)ptr, length, wrap_pointer_cb, user_data);
return buf->handle_;
}
/*
* Wraps "ptr" into a new SlowBuffer instance with length 0.
*/
inline static v8::Handle<v8::Value> WrapPointer(void *ptr) {
return WrapPointer((char *)ptr, 0);
}
/*
* Unwraps Buffer instance "buffer" to a C `char *` with the offset specified.
*/
inline static char * UnwrapPointer(v8::Handle<v8::Value> buffer, int64_t offset) {
if (node::Buffer::HasInstance(buffer)) {
return node::Buffer::Data(buffer.As<v8::Object>()) + offset;
} else {
return NULL;
}
}
/*
* Unwraps Buffer instance "buffer" to a C `char *` (no offset applied).
*/
inline static char * UnwrapPointer(v8::Handle<v8::Value> buffer) {
if (node::Buffer::HasInstance(buffer)) {
return node::Buffer::Data(buffer.As<v8::Object>());
} else {
return NULL;
}
}
/**
* Templated version of UnwrapPointer that does a reinterpret_cast() on the
* pointer before returning it.
*/
template <typename Type>
inline static Type UnwrapPointer(v8::Handle<v8::Value> buffer) {
return reinterpret_cast<Type>(UnwrapPointer(buffer));
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment