add support for special env vars

2 files changed, 25 insertions, 2 deletions

diff --git a/src/env.rs b/src/env.rs
index 94ccaf1..e6cbe9c 100644
--- a/src/env.rs
+++ b/src/env.rs
@@ -87,12 +87,12 @@ impl Env {
 
     pub fn var(&self, k: &str) -> String {
         match self {
-            Self::V0(env) => {
+            Self::V0(env) => self.special_var(k).unwrap_or_else(|| {
                 env.vars.get(std::ffi::OsStr::new(k)).map_or_else(
                     || "".to_string(),
                     |v| v.to_str().unwrap().to_string(),
                 )
-            }
+            }),
         }
     }
 
@@ -118,6 +118,25 @@ impl Env {
     pub fn from_bytes(bytes: &[u8]) -> Self {
         bincode::deserialize(bytes).unwrap()
     }
+
+    fn special_var(&self, k: &str) -> Option<String> {
+        match self {
+            Self::V0(env) => Some(match k {
+                "$" => crate::info::pid(),
+                "?" => {
+                    let status = env.latest_status;
+                    status
+                        .signal()
+                        .map_or_else(
+                            || status.code().unwrap(),
+                            |signal| signal + 128,
+                        )
+                        .to_string()
+                }
+                _ => return None,
+            }),
+        }
+    }
 }
 
 #[allow(clippy::trivially_copy_pass_by_ref)]
diff --git a/src/info.rs b/src/info.rs
index e441b16..bd94205 100644
--- a/src/info.rs
+++ b/src/info.rs
@@ -29,6 +29,10 @@ pub fn time(offset: time::UtcOffset) -> anyhow::Result<String> {
     ))
 }
 
+pub fn pid() -> String {
+    nix::unistd::getpid().to_string()
+}
+
 // the time crate is currently unable to get the local offset on unix due to
 // soundness concerns, so we have to do it manually/:
 //