Strip trailing newline

src/main.rs

@@ -11,26 +11,7 @@ use std::{
 };
 
 fn main() {
-    let mut child_env = vec![];
+    let child_env = build_env();
-    for (key, value) in env::vars_os() {
-        let key_bytes: Vec<_> = key.as_bytes().into();
-        if key_bytes.ends_with(b"_FILE") && !value.is_empty() {
-            match fs::read(&value) {
-                Ok(content) => {
-                    let key = OsString::from_vec(key_bytes[0..key_bytes.len() - 5].to_owned());
-                    child_env.push((key, OsString::from_vec(content)));
-                }
-                Err(error) => {
-                    panic!(
-                        "failed to read contents of {value:?} (specified by ${}): {error:?}",
-                        key.to_string_lossy()
-                    )
-                }
-            }
-        } else {
-            child_env.push((key, value))
-        }
-    }
     let mut args = env::args().skip(1);
     if let Some(cmd) = args.next() {
         let collected: Vec<_> = args.collect();
@@ -45,3 +26,40 @@ fn main() {
         panic!("no command given");
     }
 }
+
+fn build_env() -> Vec<(OsString, OsString)> {
+    let mut child_env = vec![];
+    for (key, value) in env::vars_os() {
+        let key_bytes: Vec<_> = key.as_bytes().into();
+        if key_bytes.ends_with(b"_FILE") && !value.is_empty() {
+            match fs::read(&value) {
+                Ok(content) => {
+                    let key = OsString::from_vec(key_bytes[0..key_bytes.len() - 5].to_owned());
+                    child_env.push((key, OsString::from_vec(strip_trailing_newline(&content).to_owned())));
+                }
+                Err(error) => {
+                    panic!(
+                        "failed to read contents of {value:?} (specified by ${}): {error:?}",
+                        key.to_string_lossy()
+                    )
+                }
+            }
+        } else {
+            child_env.push((key, value))
+        }
+    }
+    child_env
+}
+
+fn strip_trailing_newline(content: &[u8]) -> &[u8] {
+    let len = content.len();
+    if content[len - 1] == b'\n' {
+        if content[len - 2] == b'\r' {
+            &content[0..len - 2]
+        } else {
+            &content[0..len - 1]
+        }
+    } else {
+        content
+    }
+}