Merge branch 'libc-scheme' into 'master'

add libc scheme for /dev/tty etc.

See merge request redox-os/relibc!443

src/platform/redox/libcscheme.rs

@@ -0,0 +1,49 @@
+use super::libredox;
+use crate::{c_str::CStr, header::stdlib::getenv, platform::types::*};
+use core::{ptr, slice};
+use syscall::{Error, Result, EINVAL, EIO, ENOENT};
+
+pub const LIBC_SCHEME: &'static str = "libc:";
+
+const ENV_MAX_LEN: i32 = i32::MAX;
+
+macro_rules! env_str {
+    ($lit:expr) => {
+        #[allow(unused_unsafe)]
+        {
+            let val_bytes = unsafe { getenv(concat!($lit, "\0").as_ptr() as *const c_char) };
+            if val_bytes != ptr::null_mut() {
+                if let Ok(val_str) = unsafe { CStr::from_ptr(val_bytes) }.to_str() {
+                    Some(val_str)
+                } else {
+                    None
+                }
+            } else {
+                None
+            }
+        }
+    };
+}
+
+pub fn open(path: &str, oflag: c_int, mode: mode_t) -> Result<usize> {
+    assert!(path.starts_with(LIBC_SCHEME));
+
+    let basename = match path.strip_prefix(LIBC_SCHEME) {
+        Some(path) => path.trim_start_matches('/').trim_end_matches('/'),
+        _ => return Err(Error::new(EIO)),
+    };
+
+    // Linux seems to allow you to read from or write to any of /dev/{stdin,stderr,stdout}
+    match basename {
+        "stderr" => syscall::dup(2, &[]),
+        "stdin" => syscall::dup(0, &[]),
+        "stdout" => syscall::dup(1, &[]),
+        "tty" => {
+            if let Some(tty) = env_str!("TTY") {
+                return libredox::open(tty, oflag, mode);
+            }
+            Err(Error::new(ENOENT))
+        }
+        _ => Err(Error::new(ENOENT)),
+    }
+}

src/platform/redox/mod.rs

@@ -42,6 +42,7 @@ mod clone;
 mod epoll;
 mod exec;
 mod extra;
+mod libcscheme;
 mod libredox;
 pub(crate) mod path;
 mod ptrace;
@@ -744,6 +745,10 @@ impl Pal for Sys {
     fn open(path: CStr, oflag: c_int, mode: mode_t) -> c_int {
         let path = path_from_c_str!(path);
 
+        if path.starts_with(libcscheme::LIBC_SCHEME) {
+            return e(libcscheme::open(path, oflag, mode)) as c_int;
+        }
+
         e(libredox::open(path, oflag, mode)) as c_int
     }