Enable Rust code to call C++ Source objects

This commit is contained in:
Eelco Dolstra 2019-03-27 20:45:56 +01:00
parent 11da5b2816
commit e60f6bd4ce
2 changed files with 45 additions and 8 deletions

View file

@ -7,13 +7,28 @@ use std::os::unix::fs::OpenOptionsExt;
use std::path::Path;
use tar::Archive;
/// A wrapper around Nix's Source class that provides the Read trait.
#[repr(C)]
pub struct Source {
fun: extern "C" fn(this: *mut libc::c_void, data: &mut [u8]) -> usize,
this: *mut libc::c_void,
}
impl std::io::Read for Source {
fn read(&mut self, buf: &mut [u8]) -> std::result::Result<usize, std::io::Error> {
let n = (self.fun)(self.this, buf);
assert!(n <= buf.len());
Ok(n)
}
}
#[no_mangle]
pub extern "C" fn unpack_tarfile(data: &[u8], dest_dir: &str) -> bool {
pub extern "C" fn unpack_tarfile(source: Source, dest_dir: &str) -> bool {
// FIXME: handle errors.
let dest_dir = Path::new(dest_dir);
let mut tar = Archive::new(data);
let mut tar = Archive::new(source);
for file in tar.entries().unwrap() {
let mut file = file.unwrap();

View file

@ -1,6 +1,7 @@
#include "command.hh"
#include "store-api.hh"
#include "common-args.hh"
#include "compression.hh"
using namespace nix;
@ -10,10 +11,10 @@ namespace rust {
// evil...
template<typename T> struct Slice
{
const T * ptr;
T * ptr;
size_t size;
Slice(const T * ptr, size_t size) : ptr(ptr), size(size)
Slice(T * ptr, size_t size) : ptr(ptr), size(size)
{
assert(ptr);
}
@ -21,13 +22,30 @@ template<typename T> struct Slice
struct StringSlice : Slice<char>
{
StringSlice(const std::string & s): Slice(s.data(), s.size()) { }
StringSlice(const std::string & s): Slice((char *) s.data(), s.size()) {}
};
struct Source
{
size_t (*fun)(void * source_this, rust::Slice<uint8_t> data);
nix::Source * _this;
Source(nix::Source & _this)
: fun(sourceWrapper), _this(&_this)
{}
// FIXME: how to propagate exceptions?
static size_t sourceWrapper(void * _this, rust::Slice<uint8_t> data)
{
auto n = ((nix::Source *) _this)->read(data.ptr, data.size);
return n;
}
};
}
extern "C" {
bool unpack_tarfile(rust::Slice<uint8_t> data, rust::StringSlice dest_dir);
bool unpack_tarfile(rust::Source source, rust::StringSlice dest_dir);
}
struct CmdTest : StoreCommand
@ -48,13 +66,17 @@ struct CmdTest : StoreCommand
void run(ref<Store> store) override
{
auto data = readFile("./nix-2.2.tar");
auto source = sinkToSource([&](Sink & sink) {
auto decompressor = makeDecompressionSink("bzip2", sink);
readFile("./nix-2.2.tar.bz2", *decompressor);
decompressor->finish();
});
std::string destDir = "./dest";
deletePath(destDir);
unpack_tarfile({(uint8_t*) data.data(), data.size()}, destDir);
unpack_tarfile(*source, destDir);
}
};