process.rs.html -- source
Description: Source to the Rust file `src/libstd/sys_common/process.rs`.
Keywords: rust, rustlang, rust-lang

      1
      2
      3
      4
      5
      6
      7
      8
      9
     10
     11
     12
     13
     14
     15
     16
     17
     18
     19
     20
     21
     22
     23
     24
     25
     26
     27
     28
     29
     30
     31
     32
     33
     34
     35
     36
     37
     38
     39
     40
     41
     42
     43
     44
     45
     46
     47
     48
     49
     50
     51
     52
     53
     54
     55
     56
     57
     58
     59
     60
     61
     62
     63
     64
     65
     66
     67
     68
     69
     70
     71
     72
     73
     74
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103

    #![allow(dead_code)]
    #![unstable(feature = "process_internals", issue = "0")]

    use crate::collections::BTreeMap;
    use crate::env;
    use crate::ffi::{OsStr, OsString};
    use crate::sys::process::EnvKey;

    // Stores a set of changes to an environment
    #[derive(Clone, Debug)]
    pub struct CommandEnv {
        clear: bool,
        saw_path: bool,
        vars: BTreeMap<EnvKey, Option<OsString>>
    }

    impl Default for CommandEnv {
        fn default() -> Self {
            CommandEnv {
                clear: false,
                saw_path: false,
                vars: Default::default()
            }
        }
    }

    impl CommandEnv {
        // Capture the current environment with these changes applied
        pub fn capture(&self) -> BTreeMap<EnvKey, OsString> {
            let mut result = BTreeMap::<EnvKey, OsString>::new();
            if !self.clear {
                for (k, v) in env::vars_os() {
                    result.insert(k.into(), v);
                }
            }
            for (k, maybe_v) in &self.vars {
                if let &Some(ref v) = maybe_v {
                    result.insert(k.clone(), v.clone());
                } else {
                    result.remove(k);
                }
            }
            result
        }

        // Apply these changes directly to the current environment
        pub fn apply(&self) {
            if self.clear {
                for (k, _) in env::vars_os() {
                    env::remove_var(k);
                }
            }
            for (key, maybe_val) in self.vars.iter() {
                if let &Some(ref val) = maybe_val {
                    env::set_var(key, val);
                } else {
                    env::remove_var(key);
                }
            }
        }

        pub fn is_unchanged(&self) -> bool {
            !self.clear && self.vars.is_empty()
        }

        pub fn capture_if_changed(&self) -> Option<BTreeMap<EnvKey, OsString>> {
            if self.is_unchanged() {
                None
            } else {
                Some(self.capture())
            }
        }

        // The following functions build up changes
        pub fn set(&mut self, key: &OsStr, value: &OsStr) {
            self.maybe_saw_path(&key);
            self.vars.insert(key.to_owned().into(), Some(value.to_owned()));
        }

        pub fn remove(&mut self, key: &OsStr) {
            self.maybe_saw_path(&key);
            if self.clear {
                self.vars.remove(key);
            } else {
                self.vars.insert(key.to_owned().into(), None);
            }
        }

        pub fn clear(&mut self) {
            self.clear = true;
            self.vars.clear();
        }

        pub fn have_changed_path(&self) -> bool {
            self.saw_path || self.clear
        }

        fn maybe_saw_path(&mut self, key: &OsStr) {
            if !self.saw_path && key == "PATH" {
                self.saw_path = true;
            }
        }
    }