subplotlib: Update runcmd for better PATH management

In preparation for supporting external environment inputs,
process PATH more effectively.

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

1 files changed, 32 insertions, 11 deletions

diff --git a/subplotlib/src/steplibrary/runcmd.rs b/subplotlib/src/steplibrary/runcmd.rs
index 02ec186..8aabffc 100644
--- a/subplotlib/src/steplibrary/runcmd.rs
+++ b/subplotlib/src/steplibrary/runcmd.rs
@@ -6,7 +6,8 @@ pub use super::datadir::Datadir;
 pub use crate::prelude::*;
 
 use std::collections::HashMap;
-use std::ffi::OsString;
+use std::env;
+use std::ffi::{OsStr, OsString};
 use std::io::Write;
 use std::path::PathBuf;
 use std::process::{Command, Stdio};
@@ -22,12 +23,24 @@ pub struct Runcmd {
     stderr: Vec<u8>,
 }
 
+#[cfg(not(windows))]
+static DEFAULT_PATHS: &[&str] = &["/usr/bin", "/bin"];
+
+// Note, this comes from https://www.computerhope.com/issues/ch000549.htm#defaultpath
+#[cfg(windows)]
+static DEFAULT_PATHS: &[&str] = &[
+    r"%SystemRoot%\system32",
+    r"%SystemRoot%",
+    r"%SystemRoot%\System32\Wbem",
+];
+
 impl ContextElement for Runcmd {
     fn scenario_starts(&mut self) -> StepResult {
         self.env.drain();
         self.paths.drain(..);
-        self.prepend_to_path("/usr/bin");
-        self.prepend_to_path("/bin");
+        self.env.insert("SHELL".into(), "/bin/sh".into());
+        self.env
+            .insert("PATH".into(), env::join_paths(DEFAULT_PATHS.iter())?);
         Ok(())
     }
 }
@@ -79,23 +92,31 @@ pub fn try_to_run(context: &ScenarioContext, argv0: &str, args: &str) {
     proc.args(&shell_words::split(args)?);
     proc.current_dir(&datadir);
     proc.env_clear();
-    proc.env("SHELL", "/bin/sh");
     proc.env("HOME", &datadir);
     proc.env("TMPDIR", &datadir);
-    let path = context.with(
-        |runcmd: &Runcmd| Ok(std::env::join_paths(runcmd.paths.iter().rev())?),
-        false,
-    )?;
-    proc.env("PATH", path);
-    context.with(
+    let curpath = context.with(
         |runcmd: &Runcmd| {
+            let mut curpath = None;
             for (k, v) in runcmd.env.iter() {
                 proc.env(k, v);
+                if k == "PATH" {
+                    curpath = Some(v.to_owned());
+                }
             }
-            Ok(())
+            Ok(curpath)
         },
         false,
     )?;
+    let path = context.with(
+        |runcmd: &Runcmd| {
+            Ok(env::join_paths(
+                env::split_paths(curpath.as_deref().unwrap_or_else(|| OsStr::new("")))
+                    .chain(runcmd.paths.iter().rev().map(PathBuf::from)),
+            )?)
+        },
+        false,
+    )?;
+    proc.env("PATH", path);
     proc.stdin(Stdio::null())
         .stdout(Stdio::piped())
         .stderr(Stdio::piped());