Merge pull request #38 from xd009642/pidpath

pidpath implementation linux

Author: andrewdavidmackenzie

src/libproc/proc_pid.rs

@@ -3,6 +3,8 @@ extern crate libc;
 #[cfg(target_os = "linux")]
 use std::fs;
 #[cfg(target_os = "linux")]
+use std::ffi::CString;
+#[cfg(target_os = "linux")]
 use std::fs::File;
 #[cfg(target_os = "linux")]
 use std::io::{BufRead, BufReader};
@@ -11,6 +13,9 @@ use std::{mem, process};
 use std::path::PathBuf;
 use std::ptr;
 
+#[cfg(not(target_os = "macos"))]
+use libc::PATH_MAX;
+
 use libc::pid_t;
 
 use crate::libproc::bsd_info::BSDInfo;
@@ -19,7 +24,7 @@ use crate::libproc::task_info::{TaskAllInfo, TaskInfo};
 use crate::libproc::thread_info::ThreadInfo;
 use crate::libproc::work_queue_info::WorkQueueInfo;
 
-use self::libc::{c_int, c_void};
+use self::libc::{c_char, c_int, c_void, readlink};
 
 // Since we cannot access C macros for constants from Rust - I have had to redefine this, based on Apple's source code
 // See http://opensource.apple.com/source/Libc/Libc-594.9.4/darwin/libproc.c
@@ -282,7 +287,15 @@ pub fn pidpath(pid: i32) -> Result<String, String> {
 
 #[cfg(target_os = "linux")]
 pub fn pidpath(pid: i32) -> Result<String, String> {
-    unimplemented!()
+    let exe_path = CString::new(format!("/proc/{}/exe", pid)).unwrap();
+    let mut buf: Vec<u8> = Vec::with_capacity(PATH_MAX as usize - 1);
+    let buffer_ptr = buf.as_mut_ptr() as *mut c_char;
+    let buffer_size = buf.capacity();
+    let ret = unsafe {
+        readlink(exe_path.as_ptr(), buffer_ptr, buffer_size)
+    };
+
+    helpers::check_errno(ret as i32, &mut buf)
 }
 
 /// Returns the major and minor version numbers of the native librproc library being used
@@ -559,13 +572,18 @@ mod test {
         }
     }
 
-    #[cfg(target_os = "macos")]
+   // 
     #[test]
     // This checks that it cannot find the path of the process with pid -1 and returns correct error messaage
     fn pidpath_test_unknown_pid() {
+        #[cfg(target_os = "macos")]
+        let error_message = "No such process";
+        #[cfg(target_os = "linux")]
+        let error_message = "No such file or directory";
+
         match pidpath(-1) {
             Ok(path) => assert!(false, "It found the path of process Pwith ID = -1 (path = {}), that's not possible\n", path),
-            Err(message) => assert!(message.contains("No such process"))
+            Err(message) => assert!(message.contains(error_message)),
         }
     }
 
@@ -580,4 +598,4 @@ mod test {
     fn test_pidcwd_of_self() {
         assert_eq!(env::current_dir().unwrap(), pidcwd(process::id() as i32).unwrap());
     }
-}
+}