1 files changed, 29 insertions, 0 deletions
diff --git a/build.rs b/build.rs
index be96e83b68..8452940074 100644
--- a/build.rs
+++ b/build.rs
@@ -16,6 +16,12 @@ fn main() {
         );
     }
 
+    if std::env::var("LIBC_CI").is_ok() {
+        if let Some(12) = which_freebsd() {
+            println!("cargo:rustc-cfg=freebsd12");
+        }
+    }
+
     // Rust >= 1.15 supports private module use:
     if rustc_minor_ver >= 15 || rustc_dep_of_std {
         println!("cargo:rustc-cfg=libc_priv_mod_use");
@@ -70,3 +76,26 @@ fn rustc_minor_version() -> Option<u32> {
 
     otry!(pieces.next()).parse().ok()
 }
+
+fn which_freebsd() -> Option<i32> {
+    let output = std::process::Command::new("freebsd-version").output().ok();
+    if output.is_none() {
+        return None;
+    }
+    let output = output.unwrap();
+    if !output.status.success() {
+        return None;
+    }
+
+    let stdout = String::from_utf8(output.stdout).ok();
+    if stdout.is_none() {
+        return None;
+    }
+    let stdout = stdout.unwrap();
+
+    match &stdout {
+        s if s.starts_with("11") => Some(11),
+        s if s.starts_with("12") => Some(12),
+        _ => None,
+    }
+}