From 2acae17fc235dce288c186d04b4f0750bdecc198 Mon Sep 17 00:00:00 2001
From: Jonas Maier <jonas@x77.dev>
Date: Thu, 14 May 2026 17:12:18 +0200
Subject: automatically set XDG_ variables for child processes

---
 src/basedir.rs | 12 +++++++++---
 src/run/var.rs | 19 +++++++++++++++++--
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/basedir.rs b/src/basedir.rs
index d2ede87..3589b71 100644
--- a/src/basedir.rs
+++ b/src/basedir.rs
@@ -14,30 +14,36 @@ pub fn home() -> PathBuf {
 pub mod xdg {
     use super::*;
 
+    pub const DATA_HOME: &str = "XDG_DATA_HOME";
+
     /// $XDG_DATA_HOME defines the base directory relative to which user-specific data files should be stored.
     /// If $XDG_DATA_HOME is either not set or empty, a default equal to $HOME/.local/share should be used.
     pub fn data_home() -> PathBuf {
-        if let Some(dir) = env::var_os("XDG_DATA_HOME") {
+        if let Some(dir) = env::var_os(DATA_HOME) {
             PathBuf::from(dir)
         } else {
             home().join(".local/share")
         }
     }
 
+    pub const CONFIG_HOME: &str = "XDG_CONFIG_HOME";
+
     /// $XDG_CONFIG_HOME defines the base directory relative to which user-specific configuration files should be stored.
     /// If $XDG_CONFIG_HOME is either not set or empty, a default equal to $HOME/.config should be used.
     pub fn config_home() -> PathBuf {
-        if let Some(dir) = env::var_os("XDG_CONFIG_HOME") {
+        if let Some(dir) = env::var_os(CONFIG_HOME) {
             PathBuf::from(dir)
         } else {
             home().join(".config")
         }
     }
 
+    pub const STATE_HOME: &str = "XDG_STATE_HOME";
+
     /// $XDG_STATE_HOME defines the base directory relative to which user-specific state files should be stored.
     /// If $XDG_STATE_HOME is either not set or empty, a default equal to $HOME/.local/state should be used.
     pub fn state_home() -> PathBuf {
-        if let Some(dir) = env::var_os("XDG_STATE_HOME") {
+        if let Some(dir) = env::var_os(STATE_HOME) {
             PathBuf::from(dir)
         } else {
             home().join(".local/state")
diff --git a/src/run/var.rs b/src/run/var.rs
index d3e98f4..8e22f5c 100644
--- a/src/run/var.rs
+++ b/src/run/var.rs
@@ -1,5 +1,6 @@
 use std::borrow::Cow;
 use std::collections::{HashMap, HashSet};
+use std::os::unix::ffi::OsStrExt;
 use std::sync::LazyLock;
 use std::time::Instant;
 
@@ -19,7 +20,10 @@ impl Vars {
         magic: HashMap<BString, fn() -> BString>,
     ) -> Self {
         for (var, val) in std::env::vars_os() {
-            simple.insert(var.into_encoded_bytes(), val.into_encoded_bytes());
+            // explicitly added variables get priority.
+            if !simple.contains_key(var.as_bytes()) {
+                simple.insert(var.into_encoded_bytes(), val.into_encoded_bytes());
+            }
         }
         let all = simple
             .keys()
@@ -87,10 +91,15 @@ macro_rules! map {
 
 impl Default for Vars {
     fn default() -> Self {
+        use crate::basedir::xdg;
+
         let simple = map! {
             b"PISH_VERSION" => crate::consts::PISH_VERSION.as_bytes().to_vec(),
             b"PISH_COMMIT" => crate::consts::PISH_COMMIT.as_bytes().to_vec(),
             b"PISH_DIRTY" => vec![crate::consts::PISH_DIRTY as u8 + b'0'],
+            xdg::DATA_HOME => xdg::data_home().as_os_str().as_bytes().to_vec(),
+            xdg::STATE_HOME => xdg::state_home().as_os_str().as_bytes().to_vec(),
+            xdg::CONFIG_HOME => xdg::config_home().as_os_str().as_bytes().to_vec(),
         };
 
         let magic = map! {
@@ -101,7 +110,13 @@ impl Default for Vars {
         // call it once such that lazylock gets initialized
         seconds_since_startup();
 
-        Self::new(simple, magic)
+        let mut this = Self::new(simple.clone(), magic);
+        for var in simple.keys() {
+            if var.starts_with(b"XDG_") {
+                this.allow_export(var, true);
+            }
+        }
+        this
     }
 }
 
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