add function to make env vars case-insensitive (#14390)

# Description

This PR adds a new function that allows one to get an env var
case-insensitively. I did this so we can hopefully stop having problems
when Windows has HKLM as path and HKCU as Path.

Instead of just changing every function that used the original one, I
chose the ones that I thought were specific to getting the path. I
didn't want to go all in and make every env get case insensitive, but
maybe we should? 🤷🏻‍♂️

closes #12676

# User-Facing Changes
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# Tests + Formatting
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crates/nu-cli/src/completions/command_completions.rs

@@ -41,8 +41,7 @@ impl CommandCompletion {
     ) -> HashMap<String, SemanticSuggestion> {
         let mut suggs = HashMap::new();
 
-        // os agnostic way to get the PATH env var
-        let paths = working_set.permanent_state.get_path_env_var();
+        let paths = working_set.permanent_state.get_env_var_insensitive("path");
 
         if let Some(paths) = paths {
             if let Ok(paths) = paths.as_list() {

crates/nu-cli/tests/completions/mod.rs

@@ -1759,13 +1759,3 @@ fn alias_offset_bug_7754() {
     // This crashes before PR #7756
     let _suggestions = completer.complete("ll -a | c", 9);
 }
-
-#[test]
-fn get_path_env_var_8003() {
-    // Create a new engine
-    let (_, _, engine, _) = new_engine();
-    // Get the path env var in a platform agnostic way
-    let the_path = engine.get_path_env_var();
-    // Make sure it's not empty
-    assert!(the_path.is_some());
-}

crates/nu-engine/src/env.rs

@@ -11,13 +11,6 @@ use std::{
     sync::Arc,
 };
 
-#[cfg(windows)]
-const ENV_PATH_NAME: &str = "Path";
-#[cfg(windows)]
-const ENV_PATH_NAME_SECONDARY: &str = "PATH";
-#[cfg(not(windows))]
-const ENV_PATH_NAME: &str = "PATH";
-
 const ENV_CONVERSIONS: &str = "ENV_CONVERSIONS";
 
 enum ConversionResult {
@@ -53,14 +46,14 @@ pub fn convert_env_values(engine_state: &mut EngineState, stack: &Stack) -> Resu
 
     #[cfg(not(windows))]
     {
-        error = error.or_else(|| ensure_path(&mut new_scope, ENV_PATH_NAME));
+        error = error.or_else(|| ensure_path(&mut new_scope, "PATH"));
     }
 
     #[cfg(windows)]
     {
-        let first_result = ensure_path(&mut new_scope, ENV_PATH_NAME);
+        let first_result = ensure_path(&mut new_scope, "Path");
         if first_result.is_some() {
-            let second_result = ensure_path(&mut new_scope, ENV_PATH_NAME_SECONDARY);
+            let second_result = ensure_path(&mut new_scope, "PATH");
 
             if second_result.is_some() {
                 error = error.or(first_result);
@@ -107,7 +100,7 @@ pub fn env_to_string(
         ConversionResult::CellPathError => match value.coerce_string() {
             Ok(s) => Ok(s),
             Err(_) => {
-                if env_name == ENV_PATH_NAME {
+                if env_name.to_lowercase() == "path" {
                     // Try to convert PATH/Path list to a string
                     match value {
                         Value::List { vals, .. } => {
@@ -216,31 +209,21 @@ pub fn current_dir_const(working_set: &StateWorkingSet) -> Result<PathBuf, Shell
 }
 
 /// Get the contents of path environment variable as a list of strings
-///
-/// On non-Windows: It will fetch PATH
-/// On Windows: It will try to fetch Path first but if not present, try PATH
 pub fn path_str(
     engine_state: &EngineState,
     stack: &Stack,
     span: Span,
 ) -> Result<String, ShellError> {
-    let (pathname, pathval) = match stack.get_env_var(engine_state, ENV_PATH_NAME) {
-        Some(v) => Ok((ENV_PATH_NAME, v)),
-        None => {
-            #[cfg(windows)]
-            match stack.get_env_var(engine_state, ENV_PATH_NAME_SECONDARY) {
-                Some(v) => Ok((ENV_PATH_NAME_SECONDARY, v)),
-                None => Err(ShellError::EnvVarNotFoundAtRuntime {
-                    envvar_name: ENV_PATH_NAME_SECONDARY.to_string(),
-                    span,
-                }),
-            }
-            #[cfg(not(windows))]
-            Err(ShellError::EnvVarNotFoundAtRuntime {
-                envvar_name: ENV_PATH_NAME.to_string(),
-                span,
-            })
-        }
+    let (pathname, pathval) = match stack.get_env_var_insensitive(engine_state, "path") {
+        Some(v) => Ok((if cfg!(windows) { "Path" } else { "PATH" }, v)),
+        None => Err(ShellError::EnvVarNotFoundAtRuntime {
+            envvar_name: if cfg!(windows) {
+                "Path".to_string()
+            } else {
+                "PATH".to_string()
+            },
+            span,
+        }),
     }?;
 
     env_to_string(pathname, pathval, engine_state, stack)

crates/nu-plugin-engine/src/context.rs

@@ -126,7 +126,7 @@ impl<'a> PluginExecutionContext for PluginExecutionCommandContext<'a> {
     }
 
     fn get_env_var(&self, name: &str) -> Result<Option<&Value>, ShellError> {
-        Ok(self.stack.get_env_var(&self.engine_state, name))
+        Ok(self.stack.get_env_var_insensitive(&self.engine_state, name))
     }
 
     fn get_env_vars(&self) -> Result<HashMap<String, Value>, ShellError> {

crates/nu-protocol/src/engine/engine_state.rs

@@ -14,6 +14,7 @@ use crate::{
 use fancy_regex::Regex;
 use lru::LruCache;
 use nu_path::AbsolutePathBuf;
+use nu_utils::IgnoreCaseExt;
 use std::{
     collections::HashMap,
     num::NonZeroUsize,
@@ -465,20 +466,12 @@ impl EngineState {
         None
     }
 
-    // Get the path environment variable in a platform agnostic way
-    pub fn get_path_env_var(&self) -> Option<&Value> {
-        let env_path_name_windows: &str = "Path";
-        let env_path_name_nix: &str = "PATH";
-
+    pub fn get_env_var_insensitive(&self, name: &str) -> Option<&Value> {
         for overlay_id in self.scope.active_overlays.iter().rev() {
             let overlay_name = String::from_utf8_lossy(self.get_overlay_name(*overlay_id));
             if let Some(env_vars) = self.env_vars.get(overlay_name.as_ref()) {
-                if let Some(val) = env_vars.get(env_path_name_nix) {
-                    return Some(val);
-                } else if let Some(val) = env_vars.get(env_path_name_windows) {
-                    return Some(val);
-                } else {
-                    return None;
+                if let Some(v) = env_vars.iter().find(|(k, _)| k.eq_ignore_case(name)) {
+                    return Some(v.1);
                 }
             }
         }

crates/nu-protocol/src/engine/stack.rs

@@ -5,6 +5,7 @@ use crate::{
     },
     Config, IntoValue, OutDest, ShellError, Span, Value, VarId, ENV_VARIABLE_ID, NU_VARIABLE_ID,
 };
+use nu_utils::IgnoreCaseExt;
 use std::{
     collections::{HashMap, HashSet},
     fs::File,
@@ -494,6 +495,40 @@ impl Stack {
         None
     }
 
+    // Case-Insensitive version of get_env_var
+    pub fn get_env_var_insensitive<'a>(
+        &'a self,
+        engine_state: &'a EngineState,
+        name: &str,
+    ) -> Option<&'a Value> {
+        for scope in self.env_vars.iter().rev() {
+            for active_overlay in self.active_overlays.iter().rev() {
+                if let Some(env_vars) = scope.get(active_overlay) {
+                    if let Some(v) = env_vars.iter().find(|(k, _)| k.eq_ignore_case(name)) {
+                        return Some(v.1);
+                    }
+                }
+            }
+        }
+
+        for active_overlay in self.active_overlays.iter().rev() {
+            let is_hidden = if let Some(env_hidden) = self.env_hidden.get(active_overlay) {
+                env_hidden.iter().any(|k| k.eq_ignore_case(name))
+            } else {
+                false
+            };
+
+            if !is_hidden {
+                if let Some(env_vars) = engine_state.env_vars.get(active_overlay) {
+                    if let Some(v) = env_vars.iter().find(|(k, _)| k.eq_ignore_case(name)) {
+                        return Some(v.1);
+                    }
+                }
+            }
+        }
+        None
+    }
+
     pub fn has_env_var(&self, engine_state: &EngineState, name: &str) -> bool {
         for scope in self.env_vars.iter().rev() {
             for active_overlay in self.active_overlays.iter().rev() {

crates/nu-protocol/tests/test_value.rs

@@ -1,4 +1,7 @@
-use nu_protocol::{Config, Span, Value};
+use nu_protocol::{
+    engine::{EngineState, Stack},
+    Config, Span, Value,
+};
 use rstest::rstest;
 
 #[test]
@@ -46,3 +49,27 @@ fn test_duration_to_string(#[case] in_ns: i64, #[case] expected: &str) {
         "expected != observed"
     );
 }
+
+#[test]
+fn test_case_insensitive_env_var() {
+    let mut engine_state = EngineState::new();
+    let stack = Stack::new();
+
+    for (name, value) in std::env::vars() {
+        engine_state.add_env_var(name, Value::test_string(value));
+    }
+
+    let path_lower = engine_state.get_env_var_insensitive("path");
+    let path_upper = engine_state.get_env_var_insensitive("PATH");
+    let path_mixed = engine_state.get_env_var_insensitive("PaTh");
+
+    assert_eq!(path_lower, path_upper);
+    assert_eq!(path_lower, path_mixed);
+
+    let stack_path_lower = stack.get_env_var_insensitive(&engine_state, "path");
+    let stack_path_upper = stack.get_env_var_insensitive(&engine_state, "PATH");
+    let stack_path_mixed = stack.get_env_var_insensitive(&engine_state, "PaTh");
+
+    assert_eq!(stack_path_lower, stack_path_upper);
+    assert_eq!(stack_path_lower, stack_path_mixed);
+}