From fdeba57ceeb82e6ad551b3074325dd92da79af40 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Kr=C3=B6ning?=
 <martin.kroening@eonerc.rwth-aachen.de>
Date: Wed, 13 Nov 2024 12:10:41 +0100
Subject: [PATCH] feat: add `libc` feature for linking to the C library
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Signed-off-by: Martin Kröning <martin.kroening@eonerc.rwth-aachen.de>
---
 hermit/Cargo.toml |  2 ++
 hermit/build.rs   | 12 ++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/hermit/Cargo.toml b/hermit/Cargo.toml
index 383a3d26a..55d10ccb8 100644
--- a/hermit/Cargo.toml
+++ b/hermit/Cargo.toml
@@ -37,6 +37,7 @@ idle-poll = []
 # Build the kernel with function instrument code for mcount-based tracing
 instrument = []
 
+libc = []
 mmap = []
 pci = []
 pci-ids = ["pci"]
@@ -57,6 +58,7 @@ vga = []
 vsock = []
 
 [build-dependencies]
+cc = "1"
 flate2 = "1"
 ureq = "2.4"
 tar = "0.4"
diff --git a/hermit/build.rs b/hermit/build.rs
index 6a028ee28..cbe790856 100644
--- a/hermit/build.rs
+++ b/hermit/build.rs
@@ -18,6 +18,18 @@ fn main() {
 	let kernel_src = KernelSrc::local().unwrap_or_else(KernelSrc::download);
 
 	kernel_src.build();
+
+	if has_feature("libc") {
+		let libc = cc::Build::new()
+			.get_compiler()
+			.to_command()
+			.arg("-print-file-name=libc.a")
+			.output()
+			.unwrap()
+			.stdout;
+		let libc = str::from_utf8(&libc).unwrap().trim_ascii_end();
+		println!("cargo:rustc-link-lib=static:+verbatim={libc}");
+	}
 }
 
 struct KernelSrc {