Expose PamEnvList and PamEnvIter API

CHANGELOG.md

@@ -12,6 +12,12 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 -->
 
 ## [Unreleased]
+### Added
+- Add API for interacting with the PAM environment (needs some more tests)
+  - Add `Authenticator::environment` function.
+  - Add `PamEnvIter` struct
+  - Add `PamEnvList::iter` function to iterate over the `&CStr`'s in the environment list.
+  - Add implementation of `FusedIterator` for `PamEnvIter`
 ### Changed
 - Move CI to azure pipelines (and remove `.travis.yml`)
 
@@ -20,6 +26,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Changed
 - Change `Authenticator::get_handler` to `Authenticator::handler_mut` and add `Authenticator::handler` for immutable access to the handler
+- Change `PamEnvList` to public and re-export env module at library root
 
 ## [0.7.0] - 2019-02-07
 ### Added

src/authenticator.rs

@@ -6,7 +6,7 @@ use users;
 
 use std::{env, ptr};
 
-use crate::{env::get_pam_env, ffi, Converse, PamError, PamResult, PasswordConv};
+use crate::{env::get_pam_env, env::PamEnvList, ffi, Converse, PamError, PamResult, PasswordConv};
 
 /// Main struct to authenticate a user
 ///
@@ -73,6 +73,10 @@ impl<'a, C: Converse> Authenticator<'a, C> {
         }
     }
 
+    pub fn environment(&mut self) -> Option<PamEnvList> {
+        get_pam_env(self.handle)
+    }
+
     /// Mutable access to the conversation handler of this Authenticator
     pub fn handler_mut(&mut self) -> &mut C {
         &mut *self.converse
@@ -135,10 +139,14 @@ impl<'a, C: Converse> Authenticator<'a, C> {
         use users::os::unix::UserExt;
 
         // Set PAM environment in the local process
-        if let Some(mut env_list) = get_pam_env(self.handle) {
-            let env = env_list.to_vec();
-            for (key, value) in env {
-                env::set_var(&key, &value);
+        if let Some(env) = self.environment() {
+            for name_value in env.iter() {
+                let split = name_value.to_string_lossy();
+                let mut split = split.splitn(2, '=');
+
+                if let (Some(key), Some(value)) = (split.next(), split.next()) {
+                    env::set_var(&key, &value);
+                }
             }
         }
 

src/env.rs

@@ -1,13 +1,20 @@
 use libc::{c_char, free};
 use pam_sys::{getenvlist, raw, PamHandle};
 
+use core::iter::FusedIterator;
 use std::ffi::CStr;
 
 pub struct PamEnvList {
     ptr: *const *const c_char,
 }
 
-pub fn get_pam_env(handle: &mut PamHandle) -> Option<PamEnvList> {
+pub struct PamEnvIter<'a> {
+    envs: &'a PamEnvList,
+    idx: isize,
+    ended: bool,
+}
+
+pub(crate) fn get_pam_env(handle: &mut PamHandle) -> Option<PamEnvList> {
     let env = getenvlist(handle);
     if !env.is_null() {
         Some(PamEnvList { ptr: env })
@@ -17,32 +24,41 @@ pub fn get_pam_env(handle: &mut PamHandle) -> Option<PamEnvList> {
 }
 
 impl PamEnvList {
-    pub fn to_vec(&mut self) -> Vec<(String, String)> {
-        let mut vec = Vec::new();
-
-        let mut idx = 0;
-        loop {
-            let env_ptr: *const *const c_char = unsafe { self.ptr.offset(idx) };
-            if unsafe { !(*env_ptr).is_null() } {
-                idx += 1;
-
-                let env = unsafe { CStr::from_ptr(*env_ptr) }.to_string_lossy();
-                let split: Vec<_> = env.splitn(2, '=').collect();
-
-                if split.len() == 2 {
-                    // Only add valid env vars (contain at least one '=')
-                    vec.push((split[0].into(), split[1].into()));
-                }
-            } else {
-                // Reached the end of the env array -> break out of the loop
-                break;
-            }
+    pub fn iter(&self) -> PamEnvIter {
+        PamEnvIter {
+            envs: self,
+            idx: 0,
+            ended: false,
+        }
+    }
+
+    pub fn as_ptr(&self) -> *const *const c_char {
+        self.ptr
+    }
+}
+
+impl<'a> Iterator for PamEnvIter<'a> {
+    type Item = &'a CStr;
+
+    fn next(&mut self) -> Option<&'a CStr> {
+        if self.ended {
+            return None;
         }
 
-        vec
+        let env_ptr = unsafe { self.envs.ptr.offset(self.idx) };
+        self.idx += 1;
+
+        if env_ptr.is_null() || unsafe { (*env_ptr).is_null() } {
+            self.ended = true;
+            None
+        } else {
+            Some(unsafe { CStr::from_ptr(*env_ptr) })
+        }
     }
 }
 
+impl FusedIterator for PamEnvIter<'_> {}
+
 #[cfg(target_os = "linux")]
 impl Drop for PamEnvList {
     fn drop(&mut self) {

src/lib.rs

@@ -8,6 +8,7 @@ use pam_sys::PamReturnCode;
 use std::ffi::{CStr, CString};
 
 pub use crate::authenticator::*;
+pub use crate::env::*;
 
 pub struct PamError(PamReturnCode);
 pub type PamResult<T> = std::result::Result<T, PamError>;