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authorJosh Steadmon <steadmon@google.com>2025-01-28 14:01:38 -0800
committerJunio C Hamano <gitster@pobox.com>2025-01-28 14:45:47 -0800
commite7f8bf125c078004232e254e71b97226c4fed81b (patch)
treebc14f55bd4768731a7e47ccb3b985edd8231fcf1 /contrib
parent3f8f2abe05c0aeb0ea60768d44a99261ed456d44 (diff)
downloadgit-e7f8bf125c078004232e254e71b97226c4fed81b.tar.gz
libgit-sys: introduce Rust wrapper for libgit.a
Introduce libgit-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 containing a more Rust-friendly interface will be added at `contrib/libgit-rs`. Symbols in libgit 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/libgit-rs/libgit-sys/libgitpub.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@google.com> Co-authored-by: Calvin Wan <calvinwan@google.com> Signed-off-by: Calvin Wan <calvinwan@google.com> Signed-off-by: Kyle Lippincott <spectral@google.com> Signed-off-by: Josh Steadmon <steadmon@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'contrib')
-rw-r--r--contrib/libgit-sys/Cargo.lock69
-rw-r--r--contrib/libgit-sys/Cargo.toml19
-rw-r--r--contrib/libgit-sys/README.md4
-rw-r--r--contrib/libgit-sys/build.rs35
-rw-r--r--contrib/libgit-sys/public_symbol_export.c23
-rw-r--r--contrib/libgit-sys/public_symbol_export.h8
-rw-r--r--contrib/libgit-sys/src/lib.rs46
7 files changed, 204 insertions, 0 deletions
diff --git a/contrib/libgit-sys/Cargo.lock b/contrib/libgit-sys/Cargo.lock
new file mode 100644
index 0000000000..427a4c66b7
--- /dev/null
+++ b/contrib/libgit-sys/Cargo.lock
@@ -0,0 +1,69 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "autocfg"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
+
+[[package]]
+name = "cc"
+version = "1.1.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "57b6a275aa2903740dc87da01c62040406b8812552e97129a63ea8850a17c6e6"
+dependencies = [
+ "shlex",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.158"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8adc4bb1803a324070e64a98ae98f38934d91957a99cfb3a43dcbc01bc56439"
+
+[[package]]
+name = "libgit-sys"
+version = "0.1.0"
+dependencies = [
+ "autocfg",
+ "libz-sys",
+ "make-cmd",
+]
+
+[[package]]
+name = "libz-sys"
+version = "1.1.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2d16453e800a8cf6dd2fc3eb4bc99b786a9b90c663b8559a5b1a041bf89e472"
+dependencies = [
+ "cc",
+ "libc",
+ "pkg-config",
+ "vcpkg",
+]
+
+[[package]]
+name = "make-cmd"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a8ca8afbe8af1785e09636acb5a41e08a765f5f0340568716c18a8700ba3c0d3"
+
+[[package]]
+name = "pkg-config"
+version = "0.3.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d231b230927b5e4ad203db57bbcbee2802f6bce620b1e4a9024a07d94e2907ec"
+
+[[package]]
+name = "shlex"
+version = "1.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
+
+[[package]]
+name = "vcpkg"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "accd4ea62f7bb7a82fe23066fb0957d48ef677f6eeb8215f372f52e48bb32426"
diff --git a/contrib/libgit-sys/Cargo.toml b/contrib/libgit-sys/Cargo.toml
new file mode 100644
index 0000000000..e0623022c3
--- /dev/null
+++ b/contrib/libgit-sys/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "libgit-sys"
+version = "0.1.0"
+edition = "2021"
+build = "build.rs"
+links = "gitpub"
+rust-version = "1.63" # TODO: Once we hit 1.84 or newer, we may want to remove Cargo.lock from
+ # version control. See https://lore.kernel.org/git/Z47jgK-oMjFRSslr@tapette.crustytoothpaste.net/
+description = "Native bindings to a portion of libgit"
+
+[lib]
+path = "src/lib.rs"
+
+[dependencies]
+libz-sys = "1.1.19"
+
+[build-dependencies]
+autocfg = "1.4.0"
+make-cmd = "0.1.0"
diff --git a/contrib/libgit-sys/README.md b/contrib/libgit-sys/README.md
new file mode 100644
index 0000000000..c061cfcaf5
--- /dev/null
+++ b/contrib/libgit-sys/README.md
@@ -0,0 +1,4 @@
+# libgit-sys
+
+A small proof-of-concept crate showing how to provide a Rust FFI to Git
+internals.
diff --git a/contrib/libgit-sys/build.rs b/contrib/libgit-sys/build.rs
new file mode 100644
index 0000000000..3ffd80ad91
--- /dev/null
+++ b/contrib/libgit-sys/build.rs
@@ -0,0 +1,35 @@
+use std::env;
+use std::path::PathBuf;
+
+pub fn main() -> std::io::Result<()> {
+ let ac = autocfg::new();
+ ac.emit_has_path("std::ffi::c_char");
+
+ 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 = make_cmd::gnu_make()
+ .env("DEVELOPER", "1")
+ .env_remove("PROFILE")
+ .current_dir(git_root.clone())
+ .args([
+ "INCLUDE_LIBGIT_RS=YesPlease",
+ "contrib/libgit-sys/libgitpub.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("libgitpub.a"), dst.join("libgitpub.a"))?;
+ println!("cargo:rustc-link-search=native={}", dst.display());
+ println!("cargo:rustc-link-lib=gitpub");
+ println!("cargo:rerun-if-changed={}", git_root.display());
+
+ Ok(())
+}
diff --git a/contrib/libgit-sys/public_symbol_export.c b/contrib/libgit-sys/public_symbol_export.c
new file mode 100644
index 0000000000..4c153c6f0d
--- /dev/null
+++ b/contrib/libgit-sys/public_symbol_export.c
@@ -0,0 +1,23 @@
+/*
+ * 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
+ * avoids conflicts with other libraries such as libgit2.
+ */
+
+#include "git-compat-util.h"
+#include "contrib/libgit-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/libgit-sys/public_symbol_export.h b/contrib/libgit-sys/public_symbol_export.h
new file mode 100644
index 0000000000..a3372f93fa
--- /dev/null
+++ b/contrib/libgit-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/libgit-sys/src/lib.rs b/contrib/libgit-sys/src/lib.rs
new file mode 100644
index 0000000000..d4853f3074
--- /dev/null
+++ b/contrib/libgit-sys/src/lib.rs
@@ -0,0 +1,46 @@
+#[cfg(has_std__ffi__c_char)]
+use std::ffi::c_char;
+
+#[cfg(not(has_std__ffi__c_char))]
+#[allow(non_camel_case_types)]
+pub type c_char = i8;
+
+extern crate libz_sys;
+
+extern "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
+ );
+ }
+}
generated by cgit 1.2.3-korg (git 2.43.0) at 2025-12-08 22:31:10 +0000