Fix expansion of ~ in path e nont in name

.github/workflows/rust.yml

@@ -0,0 +1,15 @@
+name: Rust
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build
+      run: cargo build --verbose
+    - name: Run tests
+      run: cargo test --verbose

src/lib.rs

@@ -2,67 +2,107 @@ extern crate libc;
 
 use libc::{c_char, c_int, size_t};
 
-extern
-{
-	//fn getpwuid_r(uid: uid_t, pwd: *mut libc::passwd, buf: *mut c_char, buflen: size_t, result: *mut *mut libc::passwd) -> c_int
-	fn getpwnam_r(name: *const c_char, pwd: *mut libc::passwd, buf: *mut c_char, buflen: size_t, result: *mut *mut libc::passwd) -> c_int;
+extern "C" {
+    //fn getpwuid_r(uid: uid_t, pwd: *mut libc::passwd, buf: *mut c_char, buflen: size_t, result: *mut *mut libc::passwd) -> c_int
+    fn getpwnam_r(
+        name: *const c_char,
+        pwd: *mut libc::passwd,
+        buf: *mut c_char,
+        buflen: size_t,
+        result: *mut *mut libc::passwd,
+    ) -> c_int;
 }
 
-fn write_user_home<W: std::io::Write>(mut writer: W, username: &[u8]) -> Result<usize, std::io::Error>
-{
-	let mut getpw_string_buf = [0; 4096];
-	let mut passwd: libc::passwd = unsafe {std::mem::zeroed()};
-	let mut passwd_out: *mut libc::passwd = std::ptr::null_mut();
-	let result = if username == &[]
-	{
-		let uid = unsafe {libc::getuid()};
-		unsafe {libc::getpwuid_r(uid, &mut passwd as *mut _,
-			getpw_string_buf.as_mut_ptr(), getpw_string_buf.len() as size_t,
-			&mut passwd_out as *mut _)}
-	}
-	else
-	{
-		let username = match std::ffi::CString::new(username)
-		{
-			Ok(un) => un,
-			Err(_) => return Err(std::io::Error::from_raw_os_error(libc::ENOENT)),
-		};
-		unsafe {getpwnam_r(username.as_ptr(), &mut passwd as *mut _,
-			getpw_string_buf.as_mut_ptr(), getpw_string_buf.len() as size_t,
-			&mut passwd_out as *mut _)}
-	};
-	if result == 0 {
-		writer.write(unsafe {std::ffi::CStr::from_ptr(passwd.pw_dir)}.to_bytes())
-	}
-	else
-	{
-		Err(std::io::Error::from_raw_os_error(result))
-	}
+fn write_user_home<W: std::io::Write>(
+    mut writer: W,
+    username: &[u8],
+) -> Result<usize, std::io::Error> {
+    let mut getpw_string_buf = [0; 4096];
+    let mut passwd: libc::passwd = unsafe { std::mem::zeroed() };
+    let mut passwd_out: *mut libc::passwd = std::ptr::null_mut();
+    let result = if username.is_empty() {
+        let uid = unsafe { libc::getuid() };
+        unsafe {
+            libc::getpwuid_r(
+                uid,
+                &mut passwd as *mut _,
+                getpw_string_buf.as_mut_ptr(),
+                getpw_string_buf.len() as size_t,
+                &mut passwd_out as *mut _,
+            )
+        }
+    } else {
+        let username = match std::ffi::CString::new(username) {
+            Ok(un) => un,
+            Err(_) => return Err(std::io::Error::from_raw_os_error(libc::ENOENT)),
+        };
+        unsafe {
+            getpwnam_r(
+                username.as_ptr(),
+                &mut passwd as *mut _,
+                getpw_string_buf.as_mut_ptr(),
+                getpw_string_buf.len() as size_t,
+                &mut passwd_out as *mut _,
+            )
+        }
+    };
+    if result == 0 {
+        writer.write(unsafe { std::ffi::CStr::from_ptr(passwd.pw_dir) }.to_bytes())
+    } else {
+        Err(std::io::Error::from_raw_os_error(result))
+    }
 }
 
 /// perform tilde-expansion, replacing an initial ~ or ~username with that username's home directory as determined by getpwnam
-pub fn tilde_expand(s: &[u8]) -> Vec<u8>
-{
-	let mut out = Vec::with_capacity(s.len());
-	/* if it starts with ~ and has no other tildes, tilde-expand it */
-	match s.first()
-	{
-		Some(&b'~') if s.iter().filter(|&&c| c==b'~').count() == 1 => {
-			let end = s.iter().position(|&c| c==b'/').unwrap_or(s.len());
-			let name = &s[1..end];
-			let _ = write_user_home(&mut out, name);
-			out.extend_from_slice(&s[end..]);
-		},
-		_ => out.extend_from_slice(s)
-	}
-	out
+pub fn tilde_expand(s: &[u8]) -> Vec<u8> {
+    let mut out = Vec::with_capacity(s.len());
+    /* if it starts with ~ and has no other tildes before /, tilde-expand it */
+    let maybe_name = if s.starts_with(b"~") {
+        let end = s.iter().position(|&c| b'/' == c).unwrap_or_else(|| s.len());
+        let name = &s[1..end];
+        let rest = &s[end..];
+        if name.contains(&b'~') {
+            None
+        } else {
+            Some((name, rest))
+        }
+    } else {
+        None
+    };
+    if let Some((name, rest)) = maybe_name {
+        let _ = write_user_home(&mut out, name);
+        out.extend_from_slice(rest);
+    } else {
+        out.extend_from_slice(s)
+    }
+    out
 }
 
 #[test]
-fn test()
-{
-	println!("{}", String::from_utf8_lossy(&*tilde_expand(b"~/user-test")));
-	println!("{}", String::from_utf8_lossy(&*tilde_expand(b"~root/root-test")));
-	println!("{}", String::from_utf8_lossy(&*tilde_expand(b"noexpand~/test")));
-	println!("{}", String::from_utf8_lossy(&*tilde_expand(b"~~/noexpand-test")));
+fn test_output_equals_bash() {
+    use std::process::Command;
+    fn bash(path: &[u8]) -> Vec<u8> {
+        Command::new("sh")
+            .arg("-c")
+            .arg(format!("echo -n {}", String::from_utf8_lossy(path)))
+            .output()
+            .expect("failed to execute process")
+            .stdout
+    }
+    fn check_output_equals(path: &[u8]) {
+        let internal = tilde_expand(path);
+        let reference = bash(path);
+        assert_eq!(
+            internal,
+            reference,
+            "'{}' differs from expected '{}'",
+            String::from_utf8_lossy(&internal),
+            String::from_utf8_lossy(&reference)
+        );
+    }
+    check_output_equals(b"~/user-test");
+    check_output_equals(b"~root/root-test");
+    check_output_equals(b"~root/root~test");
+    check_output_equals(b"noexpand~/test");
+    check_output_equals(b"~~/noexpand-test");
 }