Introduce cgit-rs, a Rust wrapper crate that allows Rust code to call functions in libgit.a. This initial patch defines build rules and an interface that exposes user agent string getter functions as a proof of concept. A proof-of-concept library consumer is provided in contrib/cgit-rs/src/main.rs. This executable can be run with `cargo run` Symbols in cgit can collide with symbols from other libraries such as libgit2. We avoid this by first exposing library symbols in public_symbol_export.[ch]. These symbols are prepended with "libgit_" to avoid collisions and set to visible using a visibility pragma. In build.rs, Rust builds contrib/cgit-rs/libcgit.a, which also contains libgit.a and other dependent libraries, with -fvisibility=hidden to hide all symbols within those libraries that haven't been exposed with a visibility pragma. Co-authored-by: Kyle Lippincott <spectral@xxxxxxxxxx> Co-authored-by: Calvin Wan <calvinwan@xxxxxxxxxx> Co-authored-by: Josh Steadmon <steadmon@xxxxxxxxxx> Signed-off-by: Calvin Wan <calvinwan@xxxxxxxxxx> Signed-off-by: Kyle Lippincott <spectral@xxxxxxxxxx> Signed-off-by: Josh Steadmon <steadmon@xxxxxxxxxx> --- .gitignore | 1 + Makefile | 13 ++++++++++ contrib/cgit-rs/Cargo.lock | 16 +++++++++++++ contrib/cgit-rs/Cargo.toml | 16 +++++++++++++ contrib/cgit-rs/README.md | 15 ++++++++++++ contrib/cgit-rs/build.rs | 33 ++++++++++++++++++++++++++ contrib/cgit-rs/public_symbol_export.c | 20 ++++++++++++++++ contrib/cgit-rs/public_symbol_export.h | 8 +++++++ contrib/cgit-rs/src/lib.rs | 7 ++++++ contrib/cgit-rs/src/main.rs | 10 ++++++++ 10 files changed, 139 insertions(+) create mode 100644 contrib/cgit-rs/Cargo.lock create mode 100644 contrib/cgit-rs/Cargo.toml create mode 100644 contrib/cgit-rs/README.md create mode 100644 contrib/cgit-rs/build.rs create mode 100644 contrib/cgit-rs/public_symbol_export.c create mode 100644 contrib/cgit-rs/public_symbol_export.h create mode 100644 contrib/cgit-rs/src/lib.rs create mode 100644 contrib/cgit-rs/src/main.rs diff --git a/.gitignore b/.gitignore index 8caf3700c2..7031012330 100644 --- a/.gitignore +++ b/.gitignore @@ -248,3 +248,4 @@ Release/ /git.VC.db *.dSYM /contrib/buildsystems/out +/contrib/cgit-rs/target diff --git a/Makefile b/Makefile index 1cac51a4f7..fcd06af123 100644 --- a/Makefile +++ b/Makefile @@ -653,6 +653,8 @@ CURL_CONFIG = curl-config GCOV = gcov STRIP = strip SPATCH = spatch +LD = ld +OBJCOPY = objcopy export TCL_PATH TCLTK_PATH @@ -2712,6 +2714,7 @@ OBJECTS += $(XDIFF_OBJS) OBJECTS += $(FUZZ_OBJS) OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS) OBJECTS += $(UNIT_TEST_OBJS) +OBJECTS += contrib/cgit-rs/public_symbol_export.o ifndef NO_CURL OBJECTS += http.o http-walker.o remote-curl.o @@ -3719,6 +3722,7 @@ clean: profile-clean coverage-clean cocciclean $(RM) $(htmldocs).tar.gz $(manpages).tar.gz $(MAKE) -C Documentation/ clean $(RM) Documentation/GIT-EXCLUDED-PROGRAMS + $(RM) -r contrib/cgit-rs/target ifndef NO_PERL $(RM) -r perl/build/ endif @@ -3864,3 +3868,12 @@ $(UNIT_TEST_PROGS): $(UNIT_TEST_BIN)/%$X: $(UNIT_TEST_DIR)/%.o \ build-unit-tests: $(UNIT_TEST_PROGS) unit-tests: $(UNIT_TEST_PROGS) t/helper/test-tool$X $(MAKE) -C t/ unit-tests + +contrib/cgit-rs/partial_symbol_export.o: contrib/cgit-rs/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a + $(LD) -r $^ -o $@ + +contrib/cgit-rs/hidden_symbol_export.o: contrib/cgit-rs/partial_symbol_export.o + $(OBJCOPY) --localize-hidden $^ $@ + +contrib/cgit-rs/libcgit.a: contrib/cgit-rs/hidden_symbol_export.o + $(AR) $(ARFLAGS) $@ $^ diff --git a/contrib/cgit-rs/Cargo.lock b/contrib/cgit-rs/Cargo.lock new file mode 100644 index 0000000000..f50c593995 --- /dev/null +++ b/contrib/cgit-rs/Cargo.lock @@ -0,0 +1,16 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +version = 3 + +[[package]] +name = "cgit" +version = "0.1.0" +dependencies = [ + "libc", +] + +[[package]] +name = "libc" +version = "0.2.155" +source = "registry+https://github.com/rust-lang/crates.io-index"; +checksum = "97b3888a4aecf77e811145cadf6eef5901f4782c53886191b2f693f24761847c" diff --git a/contrib/cgit-rs/Cargo.toml b/contrib/cgit-rs/Cargo.toml new file mode 100644 index 0000000000..7b55e6f3e1 --- /dev/null +++ b/contrib/cgit-rs/Cargo.toml @@ -0,0 +1,16 @@ +[package] +name = "cgit" +version = "0.1.0" +edition = "2021" +build = "build.rs" +links = "git" + +[[bin]] +name = "cgit-test" +path = "src/main.rs" + +[lib] +path = "src/lib.rs" + +[dependencies] +libc = "0.2.155" diff --git a/contrib/cgit-rs/README.md b/contrib/cgit-rs/README.md new file mode 100644 index 0000000000..7a59602c30 --- /dev/null +++ b/contrib/cgit-rs/README.md @@ -0,0 +1,15 @@ +# cgit-info + +A small hacky proof-of-concept showing how to provide a Rust FFI for the Git +library. + +## Building + +`cargo build` automatically builds and picks up on changes made to both +the Rust wrapper and git.git code so there is no need to run `make` +beforehand. + +## Running + +Assuming you don't make any changes to the Git source, you can just work from +`contrib/cgit-rs` and use `cargo build` or `cargo run` as usual. diff --git a/contrib/cgit-rs/build.rs b/contrib/cgit-rs/build.rs new file mode 100644 index 0000000000..0c1ec06737 --- /dev/null +++ b/contrib/cgit-rs/build.rs @@ -0,0 +1,33 @@ +use std::env; +use std::path::PathBuf; + +pub fn main() -> std::io::Result<()> { + let crate_root = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap()); + let git_root = crate_root.join("../.."); + let dst = PathBuf::from(env::var_os("OUT_DIR").unwrap()); + + let make_output = std::process::Command::new("make") + .env_remove("PROFILE") + .current_dir(git_root.clone()) + .args(&[ + "CC=clang", + "CFLAGS=-fvisibility=hidden", + "contrib/cgit-rs/libcgit.a" + ]) + .output() + .expect("Make failed to run"); + if !make_output.status.success() { + panic!( + "Make failed:\n stdout = {}\n stderr = {}\n", + String::from_utf8(make_output.stdout).unwrap(), + String::from_utf8(make_output.stderr).unwrap() + ); + } + std::fs::copy(crate_root.join("libcgit.a"), dst.join("libcgit.a"))?; + println!("cargo::rustc-link-search=native={}", dst.into_os_string().into_string().unwrap()); + println!("cargo::rustc-link-lib=cgit"); + println!("cargo::rustc-link-lib=z"); + println!("cargo::rerun-if-changed={}", git_root.into_os_string().into_string().unwrap()); + + Ok(()) +} diff --git a/contrib/cgit-rs/public_symbol_export.c b/contrib/cgit-rs/public_symbol_export.c new file mode 100644 index 0000000000..3d1cd6cc4f --- /dev/null +++ b/contrib/cgit-rs/public_symbol_export.c @@ -0,0 +1,20 @@ +// Shim to publicly export Git symbols. These must be renamed so that the +// original symbols can be hidden. Renaming these with a "libgit_" prefix also +// avoid conflicts with other libraries such as libgit2. + +#include "contrib/cgit-rs/public_symbol_export.h" +#include "version.h" + +#pragma GCC visibility push(default) + +const char *libgit_user_agent(void) +{ + return git_user_agent(); +} + +const char *libgit_user_agent_sanitized(void) +{ + return git_user_agent_sanitized(); +} + +#pragma GCC visibility pop diff --git a/contrib/cgit-rs/public_symbol_export.h b/contrib/cgit-rs/public_symbol_export.h new file mode 100644 index 0000000000..a3372f93fa --- /dev/null +++ b/contrib/cgit-rs/public_symbol_export.h @@ -0,0 +1,8 @@ +#ifndef PUBLIC_SYMBOL_EXPORT_H +#define PUBLIC_SYMBOL_EXPORT_H + +const char *libgit_user_agent(void); + +const char *libgit_user_agent_sanitized(void); + +#endif /* PUBLIC_SYMBOL_EXPORT_H */ diff --git a/contrib/cgit-rs/src/lib.rs b/contrib/cgit-rs/src/lib.rs new file mode 100644 index 0000000000..dc46e7ff42 --- /dev/null +++ b/contrib/cgit-rs/src/lib.rs @@ -0,0 +1,7 @@ +use libc::c_char; + +extern "C" { + // From version.c + pub fn libgit_user_agent() -> *const c_char; + pub fn libgit_user_agent_sanitized() -> *const c_char; +} diff --git a/contrib/cgit-rs/src/main.rs b/contrib/cgit-rs/src/main.rs new file mode 100644 index 0000000000..1794e3f43e --- /dev/null +++ b/contrib/cgit-rs/src/main.rs @@ -0,0 +1,10 @@ +use std::ffi::CStr; + +fn main() { + println!("Let's print some strings provided by Git"); + let c_buf = unsafe { cgit::libgit_user_agent() }; + let c_str = unsafe { CStr::from_ptr(c_buf) }; + println!("git_user_agent() = {:?}", c_str); + println!("git_user_agent_sanitized() = {:?}", + unsafe { CStr::from_ptr(cgit::libgit_user_agent_sanitized()) }); +} -- 2.46.0.rc2.264.g509ed76dc8-goog
