Check for correct env keys in Command

Return an error if the key contains an ASCII equals sign (`=`) at the
non-first position.

Author: tbu-

src/libstd/process.rs

@@ -1374,6 +1374,27 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_empty_env_key_is_error() {
+        match env_cmd().env("", "value").spawn() {
+            Err(e) => assert_eq!(e.kind(), ErrorKind::InvalidInput),
+            Ok(_) => panic!(),
+        }
+    }
+
+    #[test]
+    fn test_interior_eq_in_env_key_is_error() {
+        match env_cmd().env("has-some-==s-inside", "value").spawn() {
+            Err(e) => assert_eq!(e.kind(), ErrorKind::InvalidInput),
+            Ok(_) => panic!(),
+        }
+    }
+
+    #[test]
+    fn test_leading_eq_key_is_no_error() {
+        env_cmd().env("=NAME", "value").output().unwrap();
+    }
+
     /// Test that process creation flags work by debugging a process.
     /// Other creation flags make it hard or impossible to detect
     /// behavioral changes in the process.

src/libstd/sys/unix/process/process_common.rs

@@ -53,6 +53,7 @@ pub struct Command {
     uid: Option<uid_t>,
     gid: Option<gid_t>,
     saw_nul: bool,
+    saw_malformed_env_key: bool,
     closures: Vec<Box<FnMut() -> io::Result<()> + Send + Sync>>,
     stdin: Option<Stdio>,
     stdout: Option<Stdio>,
@@ -102,6 +103,7 @@ impl Command {
             uid: None,
             gid: None,
             saw_nul: saw_nul,
+            saw_malformed_env_key: false,
             closures: Vec::new(),
             stdin: None,
             stdout: None,
@@ -127,7 +129,11 @@ impl Command {
             let mut map = HashMap::new();
             let mut envp = Vec::new();
             for (k, v) in env::vars_os() {
-                let s = pair_to_key(&k, &v, &mut self.saw_nul);
+                let mut saw_nul = false;
+                let mut saw_malformed_env_key = false;
+                let s = pair_to_key(&k, &v, &mut saw_nul, &mut saw_malformed_env_key);
+                assert!(!saw_nul);
+                assert!(!saw_malformed_env_key);
                 envp.push(s.as_ptr());
                 map.insert(k, (envp.len() - 1, s));
             }
@@ -139,7 +145,8 @@ impl Command {
     }
 
     pub fn env(&mut self, key: &OsStr, val: &OsStr) {
-        let new_key = pair_to_key(key, val, &mut self.saw_nul);
+        let new_key = pair_to_key(key, val, &mut self.saw_nul, &mut self.saw_malformed_env_key);
+
         let (map, envp) = self.init_env_map();
 
         // If `key` is already present then we just update `envp` in place
@@ -162,6 +169,8 @@ impl Command {
     }
 
     pub fn env_remove(&mut self, key: &OsStr) {
+        pair_to_key(key, OsStr::new(""), &mut self.saw_nul, &mut self.saw_malformed_env_key);
+
         let (map, envp) = self.init_env_map();
 
         // If we actually ended up removing a key, then we need to update the
@@ -193,9 +202,6 @@ impl Command {
         self.gid = Some(id);
     }
 
-    pub fn saw_nul(&self) -> bool {
-        self.saw_nul
-    }
     pub fn get_envp(&self) -> &Option<Vec<*const c_char>> {
         &self.envp
     }
@@ -237,6 +243,18 @@ impl Command {
         self.stderr = Some(stderr);
     }
 
+    pub fn check_malformed(&self) -> io::Result<()> {
+        if self.saw_nul {
+            return Err(io::Error::new(io::ErrorKind::InvalidInput,
+                                      "nul byte found in provided data"));
+        }
+        if self.saw_malformed_env_key {
+            return Err(io::Error::new(io::ErrorKind::InvalidInput,
+                                      "malformed env key in provided data"));
+        }
+        Ok(())
+    }
+
     pub fn setup_io(&self, default: Stdio, needs_stdin: bool)
                 -> io::Result<(StdioPipes, ChildPipes)> {
         let null = Stdio::Null;
@@ -261,6 +279,13 @@ impl Command {
     }
 }
 
+fn check_env_key(s: &OsStr, saw_malformed: &mut bool) {
+    let bytes = s.as_bytes();
+    if bytes.is_empty() || bytes[1..].contains(&b'=') {
+        *saw_malformed = true;
+    }
+}
+
 fn os2c(s: &OsStr, saw_nul: &mut bool) -> CString {
     CString::new(s.as_bytes()).unwrap_or_else(|_e| {
         *saw_nul = true;
@@ -325,15 +350,19 @@ impl ChildStdio {
     }
 }
 
-fn pair_to_key(key: &OsStr, value: &OsStr, saw_nul: &mut bool) -> CString {
+fn pair_to_key(key: &OsStr, value: &OsStr, saw_nul: &mut bool, saw_malformed: &mut bool)
+    -> CString
+{
+    check_env_key(key, saw_malformed);
+
     let (key, value) = (key.as_bytes(), value.as_bytes());
     let mut v = Vec::with_capacity(key.len() + value.len() + 1);
     v.extend(key);
     v.push(b'=');
     v.extend(value);
     CString::new(v).unwrap_or_else(|_e| {
         *saw_nul = true;
-        CString::new("foo=bar").unwrap()
+        CString::new("<ENV_WITH_NUL>").unwrap()
     })
 }
 

src/libstd/sys/unix/process/process_fuchsia.rs

@@ -23,10 +23,7 @@ use sys::process::process_common::*;
 impl Command {
     pub fn spawn(&mut self, default: Stdio, needs_stdin: bool)
                  -> io::Result<(Process, StdioPipes)> {
-        if self.saw_nul() {
-            return Err(io::Error::new(io::ErrorKind::InvalidInput,
-                                      "nul byte found in provided data"));
-        }
+        self.check_malformed()?;
 
         let (ours, theirs) = self.setup_io(default, needs_stdin)?;
 
@@ -36,9 +33,9 @@ impl Command {
     }
 
     pub fn exec(&mut self, default: Stdio) -> io::Error {
-        if self.saw_nul() {
-            return io::Error::new(io::ErrorKind::InvalidInput,
-                                  "nul byte found in provided data")
+        match self.check_malformed() {
+            Ok(()) => {},
+            Err(e) => return e,
         }
 
         match self.setup_io(default, true) {

src/libstd/sys/unix/process/process_unix.rs

@@ -27,10 +27,7 @@ impl Command {
 
         const CLOEXEC_MSG_FOOTER: &'static [u8] = b"NOEX";
 
-        if self.saw_nul() {
-            return Err(io::Error::new(ErrorKind::InvalidInput,
-                                      "nul byte found in provided data"));
-        }
+        self.check_malformed()?;
 
         let (ours, theirs) = self.setup_io(default, needs_stdin)?;
         let (input, output) = sys::pipe::anon_pipe()?;
@@ -100,9 +97,9 @@ impl Command {
     }
 
     pub fn exec(&mut self, default: Stdio) -> io::Error {
-        if self.saw_nul() {
-            return io::Error::new(ErrorKind::InvalidInput,
-                                  "nul byte found in provided data")
+        match self.check_malformed() {
+            Ok(()) => {},
+            Err(e) => return e,
         }
 
         match self.setup_io(default, true) {