can now build without git command or .git directory

1 files changed, 17 insertions, 16 deletions

diff --git a/build.rs b/build.rs
index 63677f7..78068b8 100644
--- a/build.rs
+++ b/build.rs
@@ -1,19 +1,19 @@
 use std::process::Command;
 
-fn git(args: &[&str]) -> String {
+fn git(args: &[&str]) -> Option<String> {
     let output = Command::new("git")
         .args(args)
         .output()
-        .expect("failed to execute git");
+        .ok()?;
 
     if !output.status.success() {
-        panic!("git command failed: git {}", args.join(" "));
+        return None;
     }
 
-    String::from_utf8(output.stdout)
+    Some(String::from_utf8(output.stdout)
         .expect("git output not utf8")
         .trim()
-        .to_string()
+        .to_string())
 }
 
 fn main() {
@@ -21,21 +21,22 @@ fn main() {
     println!("cargo:rerun-if-changed=.git/HEAD");
     println!("cargo:rerun-if-changed=.git/refs");
 
-    let git_hash = git(&["rev-parse", "HEAD"]);
-    let git_hash_short = git(&["rev-parse", "--short", "HEAD"]);
+    if let Some(git_hash) = git(&["rev-parse", "HEAD"]) {
+        println!("cargo:rustc-env=GIT_HASH={git_hash}");
+    }
 
-    let git_dirty = {
-        let status = Command::new("git")
-            .args(["diff", "--quiet"])
-            .status()
-            .expect("failed to check git dirty state");
+    if let Some(git_hash_short) = git(&["rev-parse", "--short", "HEAD"]) {
+        println!("cargo:rustc-env=GIT_HASH_SHORT={git_hash_short}");
+    }
 
-        !status.success()
-    };
+    let git_dirty = Command::new("git")
+        .args(["diff-index", "--quiet", "HEAD", "--"])
+        .status()
+        .map(|s| !s.success())
+        .unwrap_or(false);
 
-    println!("cargo:rustc-env=GIT_HASH={git_hash}");
-    println!("cargo:rustc-env=GIT_HASH_SHORT={git_hash_short}");
     if git_dirty {
         println!("cargo:rustc-env=GIT_DIRTY=1");
     }
 }
+