library/std/src/sys_common/process.rs

   1 #![allow(dead_code)]
   2 #![unstable(feature = "process_internals", issue = "none")]
   3
   4 use crate::collections::BTreeMap;
   5 use crate::env;
   6 use crate::ffi::{OsStr, OsString};
   7 use crate::sys::process::EnvKey;
   8
   9 // Stores a set of changes to an environment
  10 #[derive(Clone, Debug)]
  11 pub struct CommandEnv {
  12     clear: bool,
  13     saw_path: bool,
  14     vars: BTreeMap<EnvKey, Option<OsString>>,
  15 }
  16
  17 impl Default for CommandEnv {
  18     fn default() -> Self {
  19         CommandEnv { clear: false, saw_path: false, vars: Default::default() }
  20     }
  21 }
  22
  23 impl CommandEnv {
  24     // Capture the current environment with these changes applied
  25     pub fn capture(&self) -> BTreeMap<EnvKey, OsString> {
  26         let mut result = BTreeMap::<EnvKey, OsString>::new();
  27         if !self.clear {
  28             for (k, v) in env::vars_os() {
  29                 result.insert(k.into(), v);
  30             }
  31         }
  32         for (k, maybe_v) in &self.vars {
  33             if let &Some(ref v) = maybe_v {
  34                 result.insert(k.clone(), v.clone());
  35             } else {
  36                 result.remove(k);
  37             }
  38         }
  39         result
  40     }
  41
  42     // Apply these changes directly to the current environment
  43     pub fn apply(&self) {
  44         if self.clear {
  45             for (k, _) in env::vars_os() {
  46                 env::remove_var(k);
  47             }
  48         }
  49         for (key, maybe_val) in self.vars.iter() {
  50             if let Some(ref val) = maybe_val {
  51                 env::set_var(key, val);
  52             } else {
  53                 env::remove_var(key);
  54             }
  55         }
  56     }
  57
  58     pub fn is_unchanged(&self) -> bool {
  59         !self.clear && self.vars.is_empty()
  60     }
  61
  62     pub fn capture_if_changed(&self) -> Option<BTreeMap<EnvKey, OsString>> {
  63         if self.is_unchanged() { None } else { Some(self.capture()) }
  64     }
  65
  66     // The following functions build up changes
  67     pub fn set(&mut self, key: &OsStr, value: &OsStr) {
  68         let key = EnvKey::from(key);
  69         self.maybe_saw_path(&key);
  70         self.vars.insert(key, Some(value.to_owned()));
  71     }
  72
  73     pub fn remove(&mut self, key: &OsStr) {
  74         let key = EnvKey::from(key);
  75         self.maybe_saw_path(&key);
  76         if self.clear {
  77             self.vars.remove(&key);
  78         } else {
  79             self.vars.insert(key, None);
  80         }
  81     }
  82
  83     pub fn clear(&mut self) {
  84         self.clear = true;
  85         self.vars.clear();
  86     }
  87
  88     pub fn have_changed_path(&self) -> bool {
  89         self.saw_path || self.clear
  90     }
  91
  92     fn maybe_saw_path(&mut self, key: &EnvKey) {
  93         if !self.saw_path && key == "PATH" {
  94             self.saw_path = true;
  95         }
  96     }
  97
  98     pub fn iter(&self) -> CommandEnvs<'_> {
  99         let iter = self.vars.iter();
 100         CommandEnvs { iter }
 101     }
 102 }
 103
 104 /// An iterator over the command environment variables.
 105 ///
 106 /// This struct is created by
 107 /// [`Command::get_envs`][crate::process::Command::get_envs]. See its
 108 /// documentation for more.
 109 #[unstable(feature = "command_access", issue = "44434")]
 110 #[derive(Debug)]
 111 pub struct CommandEnvs<'a> {
 112     iter: crate::collections::btree_map::Iter<'a, EnvKey, Option<OsString>>,
 113 }
 114
 115 #[unstable(feature = "command_access", issue = "44434")]
 116 impl<'a> Iterator for CommandEnvs<'a> {
 117     type Item = (&'a OsStr, Option<&'a OsStr>);
 118     fn next(&mut self) -> Option<Self::Item> {
 119         self.iter.next().map(|(key, value)| (key.as_ref(), value.as_deref()))
 120     }
 121     fn size_hint(&self) -> (usize, Option<usize>) {
 122         self.iter.size_hint()
 123     }
 124 }
 125
 126 #[unstable(feature = "command_access", issue = "44434")]
 127 impl<'a> ExactSizeIterator for CommandEnvs<'a> {
 128     fn len(&self) -> usize {
 129         self.iter.len()
 130     }
 131     fn is_empty(&self) -> bool {
 132         self.iter.is_empty()
 133     }
 134 }