Introduce cgit-sys, 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. This library can be tested with `cargo test`. In later commits,
a higher-level library providing a more Rust-friendly interface will be
added at `contrib/cgit-rs`.
Symbols in cgit-sys 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/cgit-sys/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/cgit-sys/Cargo.lock | 7 ++++
contrib/cgit-rs/cgit-sys/Cargo.toml | 9 +++++
contrib/cgit-rs/cgit-sys/README.md | 15 +++++++
contrib/cgit-rs/cgit-sys/build.rs | 32 +++++++++++++++
.../cgit-rs/cgit-sys/public_symbol_export.c | 20 ++++++++++
.../cgit-rs/cgit-sys/public_symbol_export.h | 8 ++++
contrib/cgit-rs/cgit-sys/src/lib.rs | 40 +++++++++++++++++++
9 files changed, 145 insertions(+)
create mode 100644 contrib/cgit-rs/cgit-sys/Cargo.lock
create mode 100644 contrib/cgit-rs/cgit-sys/Cargo.toml
create mode 100644 contrib/cgit-rs/cgit-sys/README.md
create mode 100644 contrib/cgit-rs/cgit-sys/build.rs
create mode 100644 contrib/cgit-rs/cgit-sys/public_symbol_export.c
create mode 100644 contrib/cgit-rs/cgit-sys/public_symbol_export.h
create mode 100644 contrib/cgit-rs/cgit-sys/src/lib.rs
diff --git a/.gitignore b/.gitignore
index 8caf3700c2..567cc9888f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -248,3 +248,4 @@ Release/
/git.VC.db
*.dSYM
/contrib/buildsystems/out
+/contrib/cgit-rs/cgit-sys/target
diff --git a/Makefile b/Makefile
index 7caeb3c872..db8af99f20 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
@@ -2713,6 +2715,7 @@ OBJECTS += $(XDIFF_OBJS)
OBJECTS += $(FUZZ_OBJS)
OBJECTS += $(REFTABLE_OBJS) $(REFTABLE_TEST_OBJS)
OBJECTS += $(UNIT_TEST_OBJS)
+OBJECTS += contrib/cgit-rs/cgit-sys/public_symbol_export.o
ifndef NO_CURL
OBJECTS += http.o http-walker.o remote-curl.o
@@ -3720,6 +3723,7 @@ 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/cgit-sys/target
ifndef NO_PERL
$(RM) -r perl/build/
endif
@@ -3865,3 +3869,12 @@ $(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/cgit-sys/partial_symbol_export.o: contrib/cgit-rs/cgit-sys/public_symbol_export.o libgit.a reftable/libreftable.a xdiff/lib.a
+ $(LD) -r $^ -o $@
+
+contrib/cgit-rs/cgit-sys/hidden_symbol_export.o: contrib/cgit-rs/cgit-sys/partial_symbol_export.o
+ $(OBJCOPY) --localize-hidden $^ $@
+
+contrib/cgit-rs/cgit-sys/libcgit.a: contrib/cgit-rs/cgit-sys/hidden_symbol_export.o
+ $(AR) $(ARFLAGS) $@ $^
diff --git a/contrib/cgit-rs/cgit-sys/Cargo.lock b/contrib/cgit-rs/cgit-sys/Cargo.lock
new file mode 100644
index 0000000000..419a6d42f2
--- /dev/null
+++ b/contrib/cgit-rs/cgit-sys/Cargo.lock
@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "cgit-sys"
+version = "0.1.0"
diff --git a/contrib/cgit-rs/cgit-sys/Cargo.toml b/contrib/cgit-rs/cgit-sys/Cargo.toml
new file mode 100644
index 0000000000..e840f04024
--- /dev/null
+++ b/contrib/cgit-rs/cgit-sys/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "cgit-sys"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+links = "git"
+
+[lib]
+path = "src/lib.rs"
diff --git a/contrib/cgit-rs/cgit-sys/README.md b/contrib/cgit-rs/cgit-sys/README.md
new file mode 100644
index 0000000000..7a59602c30
--- /dev/null
+++ b/contrib/cgit-rs/cgit-sys/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/cgit-sys/build.rs b/contrib/cgit-rs/cgit-sys/build.rs
new file mode 100644
index 0000000000..e29d703870
--- /dev/null
+++ b/contrib/cgit-rs/cgit-sys/build.rs
@@ -0,0 +1,32 @@
+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([
+ "CFLAGS=-fvisibility=hidden",
+ "contrib/cgit-rs/cgit-sys/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.display());
+ println!("cargo::rustc-link-lib=cgit");
+ println!("cargo::rustc-link-lib=z");
+ println!("cargo::rerun-if-changed={}", git_root.display());
+
+ Ok(())
+}
diff --git a/contrib/cgit-rs/cgit-sys/public_symbol_export.c b/contrib/cgit-rs/cgit-sys/public_symbol_export.c
new file mode 100644
index 0000000000..deef4488c0
--- /dev/null
+++ b/contrib/cgit-rs/cgit-sys/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/cgit-sys/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/cgit-sys/public_symbol_export.h b/contrib/cgit-rs/cgit-sys/public_symbol_export.h
new file mode 100644
index 0000000000..a3372f93fa
--- /dev/null
+++ b/contrib/cgit-rs/cgit-sys/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/cgit-sys/src/lib.rs b/contrib/cgit-rs/cgit-sys/src/lib.rs
new file mode 100644
index 0000000000..bc33c6c498
--- /dev/null
+++ b/contrib/cgit-rs/cgit-sys/src/lib.rs
@@ -0,0 +1,40 @@
+use std::ffi::c_char;
+
+extern "C" {
+ // From version.c
+ pub fn libgit_user_agent() -> *const c_char;
+ pub fn libgit_user_agent_sanitized() -> *const c_char;
+}
+
+#[cfg(test)]
+mod tests {
+ use std::ffi::CStr;
+
+ use super::*;
+
+ #[test]
+ fn user_agent_starts_with_git() {
+ let c_str = unsafe { CStr::from_ptr(libgit_user_agent()) };
+ let agent = c_str
+ .to_str()
+ .expect("User agent contains invalid UTF-8 data");
+ assert!(
+ agent.starts_with("git/"),
+ r#"Expected user agent to start with "git/", got: {}"#,
+ agent
+ );
+ }
+
+ #[test]
+ fn sanitized_user_agent_starts_with_git() {
+ let c_str = unsafe { CStr::from_ptr(libgit_user_agent_sanitized()) };
+ let agent = c_str
+ .to_str()
+ .expect("Sanitized user agent contains invalid UTF-8 data");
+ assert!(
+ agent.starts_with("git/"),
+ r#"Expected user agent to start with "git/", got: {}"#,
+ agent
+ );
+ }
+}
--
2.46.0.76.ge559c4bf1a-goog
