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 +1,63 @@
+//! Process initial environment from `/proc/[pid]/environ`.
+
+use std::collections::BTreeMap;
+use std::fs::{File, metadata};
+use std::io::{Result, Read};
+use std::path::Path;
+
+use parsers::map_result;
+use nom::IResult;
+
+use libc::pid_t;
+
+/// Parses the provided buffer.
+fn parse_environ(input: &[u8]) -> IResult<&[u8], BTreeMap<Vec<u8>, Vec<u8>>> {
+    // 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)| (x.to_vec(), y.to_vec()))
+            .collect()
+    })
+}
+
+#[test]
+fn test_parse() {
+    use nom::IResult::Done;
+    let res = parse_environ(&b"key1=val1\0key2=val2\0"[..]);
+    let reference = vec![
+        (b"key1".to_vec(), b"val1".to_vec()),
+        (b"key2".to_vec(), b"val2".to_vec()),
+    ];
+    assert_eq!(res, Done(&b""[..], reference.into_iter().collect()));
+}
+
+/// Parses the provided environ file.
+fn environ_path<P: AsRef<Path>>(path: P) -> Result<BTreeMap<Vec<u8>, Vec<u8>>> {
+    let file_size = metadata(&path)?.len();
+    let mut buf = vec![0u8; file_size as usize];
+    File::open(path)?.read_exact(&mut buf)?;
+    map_result(parse_environ(&buf))
+}
+
+/// Returns initial environment for the process with the provided pid in the form of 'key' =>
+/// 'value' BTreeMap.
+pub fn environ(pid: pid_t) -> Result<BTreeMap<Vec<u8>, Vec<u8>>> {
+    environ_path(format!("/proc/{}/environ", pid))
+}
+
+/// Returns initial environment for the current process in the form of 'key' => 'value' BTreeMap.
+pub fn environ_self() -> Result<BTreeMap<Vec<u8>, Vec<u8>>> {
+    environ_path("/proc/self/environ")
+}

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_self};
 
 /// The state of a process.
 #[derive(Debug, PartialEq, Eq, Hash)]