Merge #1278

1278: Allow both &[CString] and &[&CStr] for sequence args in unistd r=asomers a=youknowone

I am new to this project, so I wonder this kind of change is acceptable for the project or not.

I agree taking `&[&CStr]` is the ideal way for the functions. But unfortunately, when users generate `CString`s from `&str`,  they may get `&[CString]` rather than `&[&CStr]`
Unlike single `CString` to `&CStr` argument, there is no easy way to convert `&[CString]` to `&[&CStr]` without creating new vector.

By changing the type from `&[&CStr]` to `&[AsRef<CStr>]`, the args now can take both `&[CString]` and `&[&CStr]` without changing that much from nix.

Co-authored-by: Jeong YunWon <[email protected]>

Author: bors[bot]

CHANGELOG.md

@@ -8,6 +8,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 (#[1289](https://github.com/nix-rust/nix/pull/1289))
 ### Added
 ### Changed
+- Changed unistd::{execv,execve,execvp,execvpe,fexecve,execveat} to take both `&[&CStr]` and `&[CString]` as its list argument(s).
+  (#[1278](https://github.com/nix-rust/nix/pull/1278))
 ### Fixed
 ### Removed
 

src/unistd.rs

@@ -12,9 +12,9 @@ use libc::{self, c_char, c_void, c_int, c_long, c_uint, size_t, pid_t, off_t,
            uid_t, gid_t, mode_t, PATH_MAX};
 use std::{fmt, mem, ptr};
 use std::convert::Infallible;
-use std::ffi::{CStr, OsString};
+use std::ffi::{CStr, CString, OsString};
 #[cfg(not(target_os = "redox"))]
-use std::ffi::{CString, OsStr};
+use std::ffi::{OsStr};
 use std::os::unix::ffi::OsStringExt;
 #[cfg(not(target_os = "redox"))]
 use std::os::unix::ffi::OsStrExt;
@@ -715,9 +715,9 @@ pub fn fchownat<P: ?Sized + NixPath>(
     Errno::result(res).map(drop)
 }
 
-fn to_exec_array(args: &[&CStr]) -> Vec<*const c_char> {
+fn to_exec_array<S: AsRef<CStr>>(args: &[S]) -> Vec<*const c_char> {
     use std::iter::once;
-    args.iter().map(|s| s.as_ptr()).chain(once(ptr::null())).collect()
+    args.iter().map(|s| s.as_ref().as_ptr()).chain(once(ptr::null())).collect()
 }
 
 /// Replace the current process image with a new one (see
@@ -727,7 +727,7 @@ fn to_exec_array(args: &[&CStr]) -> Vec<*const c_char> {
 /// performs the same action but does not allow for customization of the
 /// environment for the new process.
 #[inline]
-pub fn execv(path: &CStr, argv: &[&CStr]) -> Result<Infallible> {
+pub fn execv<S: AsRef<CStr>>(path: &CStr, argv: &[S]) -> Result<Infallible> {
     let args_p = to_exec_array(argv);
 
     unsafe {
@@ -751,7 +751,7 @@ pub fn execv(path: &CStr, argv: &[&CStr]) -> Result<Infallible> {
 /// in the `args` list is an argument to the new process. Each element in the
 /// `env` list should be a string in the form "key=value".
 #[inline]
-pub fn execve(path: &CStr, args: &[&CStr], env: &[&CStr]) -> Result<Infallible> {
+pub fn execve<SA: AsRef<CStr>, SE: AsRef<CStr>>(path: &CStr, args: &[SA], env: &[SE]) -> Result<Infallible> {
     let args_p = to_exec_array(args);
     let env_p = to_exec_array(env);
 
@@ -772,7 +772,7 @@ pub fn execve(path: &CStr, args: &[&CStr], env: &[&CStr]) -> Result<Infallible>
 /// would not work if "bash" was specified for the path argument, but `execvp`
 /// would assuming that a bash executable was on the system `PATH`.
 #[inline]
-pub fn execvp(filename: &CStr, args: &[&CStr]) -> Result<Infallible> {
+pub fn execvp<S: AsRef<CStr>>(filename: &CStr, args: &[S]) -> Result<Infallible> {
     let args_p = to_exec_array(args);
 
     unsafe {
@@ -792,7 +792,7 @@ pub fn execvp(filename: &CStr, args: &[&CStr]) -> Result<Infallible> {
 #[cfg(any(target_os = "haiku",
           target_os = "linux",
           target_os = "openbsd"))]
-pub fn execvpe(filename: &CStr, args: &[&CStr], env: &[&CStr]) -> Result<Infallible> {
+pub fn execvpe<SA: AsRef<CStr>, SE: AsRef<CStr>>(filename: &CStr, args: &[SA], env: &[SE]) -> Result<Infallible> {
     let args_p = to_exec_array(args);
     let env_p = to_exec_array(env);
 
@@ -820,7 +820,7 @@ pub fn execvpe(filename: &CStr, args: &[&CStr], env: &[&CStr]) -> Result<Infalli
           target_os = "linux",
           target_os = "freebsd"))]
 #[inline]
-pub fn fexecve(fd: RawFd, args: &[&CStr], env: &[&CStr]) -> Result<Infallible> {
+pub fn fexecve<SA: AsRef<CStr> ,SE: AsRef<CStr>>(fd: RawFd, args: &[SA], env: &[SE]) -> Result<Infallible> {
     let args_p = to_exec_array(args);
     let env_p = to_exec_array(env);
 
@@ -843,8 +843,8 @@ pub fn fexecve(fd: RawFd, args: &[&CStr], env: &[&CStr]) -> Result<Infallible> {
 /// is referenced as a file descriptor to the base directory plus a path.
 #[cfg(any(target_os = "android", target_os = "linux"))]
 #[inline]
-pub fn execveat(dirfd: RawFd, pathname: &CStr, args: &[&CStr],
-                env: &[&CStr], flags: super::fcntl::AtFlags) -> Result<Infallible> {
+pub fn execveat<SA: AsRef<CStr>,SE: AsRef<CStr>>(dirfd: RawFd, pathname: &CStr, args: &[SA],
+                env: &[SE], flags: super::fcntl::AtFlags) -> Result<Infallible> {
     let args_p = to_exec_array(args);
     let env_p = to_exec_array(env);
 

test/test_unistd.rs

@@ -256,8 +256,38 @@ fn test_initgroups() {
 #[cfg(not(target_os = "redox"))]
 macro_rules! execve_test_factory(
     ($test_name:ident, $syscall:ident, $exe: expr $(, $pathname:expr, $flags:expr)*) => (
-    #[test]
-    fn $test_name() {
+
+    #[cfg(test)]
+    mod $test_name {
+    use super::*;
+
+    fn syscall_cstr_ref() -> Result<std::convert::Infallible, nix::Error> {
+        $syscall(
+            $exe,
+            $(CString::new($pathname).unwrap().as_c_str(), )*
+            &[CString::new(b"".as_ref()).unwrap().as_c_str(),
+              CString::new(b"-c".as_ref()).unwrap().as_c_str(),
+              CString::new(b"echo nix!!! && echo foo=$foo && echo baz=$baz"
+                           .as_ref()).unwrap().as_c_str()],
+            &[CString::new(b"foo=bar".as_ref()).unwrap().as_c_str(),
+              CString::new(b"baz=quux".as_ref()).unwrap().as_c_str()]
+            $(, $flags)*)
+    }
+
+    fn syscall_cstring() -> Result<std::convert::Infallible, nix::Error> {
+        $syscall(
+            $exe,
+            $(CString::new($pathname).unwrap().as_c_str(), )*
+            &[CString::new(b"".as_ref()).unwrap(),
+              CString::new(b"-c".as_ref()).unwrap(),
+              CString::new(b"echo nix!!! && echo foo=$foo && echo baz=$baz"
+                           .as_ref()).unwrap()],
+            &[CString::new(b"foo=bar".as_ref()).unwrap(),
+              CString::new(b"baz=quux".as_ref()).unwrap()]
+            $(, $flags)*)
+    }
+
+    fn common_test(syscall: fn() -> Result<std::convert::Infallible, nix::Error>) {
         if "execveat" == stringify!($syscall) {
             // Though undocumented, Docker's default seccomp profile seems to
             // block this syscall.  https://github.com/nix-rust/nix/issues/1122
@@ -276,16 +306,7 @@ macro_rules! execve_test_factory(
             Child => {
                 // Make `writer` be the stdout of the new process.
                 dup2(writer, 1).unwrap();
-                let r = $syscall(
-                    $exe,
-                    $(CString::new($pathname).unwrap().as_c_str(), )*
-                    &[CString::new(b"".as_ref()).unwrap().as_c_str(),
-                      CString::new(b"-c".as_ref()).unwrap().as_c_str(),
-                      CString::new(b"echo nix!!! && echo foo=$foo && echo baz=$baz"
-                                   .as_ref()).unwrap().as_c_str()],
-                    &[CString::new(b"foo=bar".as_ref()).unwrap().as_c_str(),
-                      CString::new(b"baz=quux".as_ref()).unwrap().as_c_str()]
-                    $(, $flags)*);
+                let r = syscall();
                 let _ = std::io::stderr()
                     .write_all(format!("{:?}", r).as_bytes());
                 // Should only get here in event of error
@@ -307,6 +328,18 @@ macro_rules! execve_test_factory(
             }
         }
     }
+
+    #[test]
+    fn test_cstr_ref() {
+        common_test(syscall_cstr_ref);
+    }
+
+    #[test]
+    fn test_cstring() {
+        common_test(syscall_cstring);
+    }
+    }
+
     )
 );