1 files changed, 54 insertions, 9 deletions

diff --git a/vendor/libgit2-sys/build.rs b/vendor/libgit2-sys/build.rs
index 24df572ef..b49700583 100644
--- a/vendor/libgit2-sys/build.rs
+++ b/vendor/libgit2-sys/build.rs
@@ -4,22 +4,55 @@ use std::io;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
+/// Tries to use system libgit2 and emits necessary build script instructions.
+fn try_system_libgit2() -> Result<pkg_config::Library, pkg_config::Error> {
+    let mut cfg = pkg_config::Config::new();
+    match cfg.range_version("1.7.1".."1.8.0").probe("libgit2") {
+        Ok(lib) => {
+            for include in &lib.include_paths {
+                println!("cargo:root={}", include.display());
+            }
+            Ok(lib)
+        }
+        Err(e) => {
+            println!("cargo:warning=failed to probe system libgit2: {e}");
+            Err(e)
+        }
+    }
+}
+
 fn main() {
     let https = env::var("CARGO_FEATURE_HTTPS").is_ok();
     let ssh = env::var("CARGO_FEATURE_SSH").is_ok();
     let vendored = env::var("CARGO_FEATURE_VENDORED").is_ok();
     let zlib_ng_compat = env::var("CARGO_FEATURE_ZLIB_NG_COMPAT").is_ok();
 
+    // Specify `LIBGIT2_NO_VENDOR` to force to use system libgit2.
+    // Due to the additive nature of Cargo features, if some crate in the
+    // dependency graph activates `vendored` feature, there is no way to revert
+    // it back. This env var serves as a workaround for this purpose.
+    println!("cargo:rerun-if-env-changed=LIBGIT2_NO_VENDOR");
+    let forced_no_vendor = env::var_os("LIBGIT2_NO_VENDOR").map_or(false, |s| s != "0");
+
+    if forced_no_vendor {
+        if try_system_libgit2().is_err() {
+            panic!(
+                "\
+The environment variable `LIBGIT2_NO_VENDOR` has been set but no compatible system libgit2 could be found.
+The build is now aborting. To disable, unset the variable or use `LIBGIT2_NO_VENDOR=0`.
+",
+            );
+        }
+
+        // We've reached here, implying we're using system libgit2.
+        return;
+    }
+
     // To use zlib-ng in zlib-compat mode, we have to build libgit2 ourselves.
     let try_to_use_system_libgit2 = !vendored && !zlib_ng_compat;
-    if try_to_use_system_libgit2 {
-        let mut cfg = pkg_config::Config::new();
-        if let Ok(lib) = cfg.range_version("1.6.4".."1.7.0").probe("libgit2") {
-            for include in &lib.include_paths {
-                println!("cargo:root={}", include.display());
-            }
-            return;
-        }
+    if try_to_use_system_libgit2 && try_system_libgit2().is_ok() {
+        // using system libgit2 has worked
+        return;
     }
 
     println!("cargo:rustc-cfg=libgit2_vendored");
@@ -49,7 +82,6 @@ fn main() {
     // Include all cross-platform C files
     add_c_files(&mut cfg, "libgit2/src/libgit2");
     add_c_files(&mut cfg, "libgit2/src/util");
-    add_c_files(&mut cfg, "libgit2/src/libgit2/xdiff");
 
     // These are activated by features, but they're all unconditionally always
     // compiled apparently and have internal #define's to make sure they're
@@ -61,6 +93,10 @@ fn main() {
     cfg.include("libgit2/deps/http-parser")
         .file("libgit2/deps/http-parser/http_parser.c");
 
+    // external/system xdiff is not yet supported
+    cfg.include("libgit2/deps/xdiff");
+    add_c_files(&mut cfg, "libgit2/deps/xdiff");
+
     // Use the included PCRE regex backend.
     //
     // Ideally these defines would be specific to the pcre files (or placed in
@@ -119,6 +155,14 @@ fn main() {
         features.push_str("#define GIT_USE_NSEC 1\n");
     }
 
+    if windows {
+        features.push_str("#define GIT_IO_WSAPOLL 1\n");
+    } else {
+        // Should we fallback to `select` as more systems have that?
+        features.push_str("#define GIT_IO_POLL 1\n");
+        features.push_str("#define GIT_IO_SELECT 1\n");
+    }
+
     if target.contains("apple") {
         features.push_str("#define GIT_USE_STAT_MTIMESPEC 1\n");
     } else {
@@ -199,6 +243,7 @@ fn main() {
         println!("cargo:rustc-link-lib=rpcrt4");
         println!("cargo:rustc-link-lib=ole32");
         println!("cargo:rustc-link-lib=crypt32");
+        println!("cargo:rustc-link-lib=secur32");
     }
 
     if target.contains("apple") {