Added parser for /proc/<pid>/environ

Author: mexus

README.md

@@ -15,6 +15,7 @@ currently the following interfaces are provided:
 
 * `/proc/loadavg`
 * `/proc/<pid>/cwd`
+* `/proc/<pid>/environ`
 * `/proc/<pid>/limits`
 * `/proc/<pid>/mountinfo`
 * `/proc/<pid>/stat`

src/pid/environ.rs

@@ -0,0 +1,78 @@
+//! Process initial environment from `/proc/[pid]/environ`.
+
+use std::ffi::{OsStr, OsString};
+use std::fs::File;
+use std::io::{Result, Read};
+use std::os::unix::ffi::OsStrExt;
+use std::path::Path;
+
+use parsers::map_result;
+use nom::IResult;
+
+use libc::pid_t;
+
+/// A list of environment variables and their values.
+pub type Environ = Vec<(OsString, OsString)>;
+
+/// Parses the provided buffer.
+fn parse_environ(input: &[u8]) -> IResult<&[u8], Environ> {
+    // Parse 'key=value" pair.
+    named!(
+        pair<&[u8], (&[u8], &[u8])>,
+        tuple!(take_until_and_consume!("="), take_until!("\0"))
+    );
+    // Parse (key=value\0) list.
+    named!(
+        multi<&[u8],Vec<(&[u8], &[u8])> >,
+        terminated!(
+            separated_list!(tag!("\0"), pair),
+            tag!("\0")
+        )
+    );
+    multi(input).map(|r| {
+        r.into_iter()
+            .map(|(x, y)| {
+                (
+                    OsString::from(OsStr::from_bytes(x)),
+                    OsString::from(OsStr::from_bytes(y)),
+                )
+            })
+            .collect()
+    })
+}
+
+#[test]
+fn test_parse() {
+    use nom::IResult::Done;
+    let res = parse_environ(&b"key1=val1\0key2=val2\0"[..]);
+    let reference: Environ = vec![
+        ("key1".into(), "val1".into()),
+        ("key2".into(), "val2".into()),
+    ];
+    assert_eq!(res, Done(&b""[..], reference));
+}
+
+/// Parses the provided environ file.
+fn environ_path<P: AsRef<Path>>(path: P) -> Result<Environ> {
+    let mut buf = Vec::new();
+    if File::open(path)?.read_to_end(&mut buf)? == 0 {
+        // Don't attempt to parse an empty file.
+        return Ok(Default::default());
+    }
+    map_result(parse_environ(&buf))
+}
+
+/// Returns initial environment for the process with the provided pid as key-value pairs.
+pub fn environ(pid: pid_t) -> Result<Environ> {
+    environ_path(format!("/proc/{}/environ", pid))
+}
+
+/// Returns initial environment for the current process as key-value pairs.
+pub fn environ_self() -> Result<Environ> {
+    environ_path("/proc/self/environ")
+}
+
+#[test]
+fn test_environ() {
+    assert!(environ_self().is_ok());
+}

src/pid/mod.rs

@@ -6,13 +6,15 @@ mod mountinfo;
 mod stat;
 mod statm;
 mod status;
+mod environ;
 
 pub use pid::cwd::{cwd, cwd_self};
 pub use pid::limits::{Limit, Limits, limits, limits_self};
 pub use pid::mountinfo::{Mountinfo, mountinfo, mountinfo_self};
 pub use pid::statm::{Statm, statm, statm_self};
 pub use pid::status::{SeccompMode, Status, status, status_self};
 pub use pid::stat::{Stat, stat, stat_self};
+pub use pid::environ::{Environ, environ, environ_self};
 
 /// The state of a process.
 #[derive(Debug, PartialEq, Eq, Hash)]