From e60f6bd4ce831ced94fafeb527c429b6f88159ac Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Wed, 27 Mar 2019 20:45:56 +0100 Subject: [PATCH] Enable Rust code to call C++ Source objects --- nix-rust/src/lib.rs | 19 +++++++++++++++++-- src/nix/test.cc | 34 ++++++++++++++++++++++++++++------ 2 files changed, 45 insertions(+), 8 deletions(-) diff --git a/nix-rust/src/lib.rs b/nix-rust/src/lib.rs index abcb89055..799d52e31 100644 --- a/nix-rust/src/lib.rs +++ b/nix-rust/src/lib.rs @@ -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 { + 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(); diff --git a/src/nix/test.cc b/src/nix/test.cc index 70e0a903d..7f1f0d47a 100644 --- a/src/nix/test.cc +++ b/src/nix/test.cc @@ -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 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 struct Slice struct StringSlice : Slice { - 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 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 data) + { + auto n = ((nix::Source *) _this)->read(data.ptr, data.size); + return n; + } }; } extern "C" { - bool unpack_tarfile(rust::Slice 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) 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); } };