Simplify perror

Cargo.lock

@@ -445,8 +445,8 @@ name = "stdio"
 version = "0.1.0"
 dependencies = [
  "cbindgen 0.5.0",
+ "errno 0.1.0",
  "platform 0.1.0",
- "string 0.1.0",
  "va_list 0.1.0",
 ]
 

src/stdio/Cargo.toml

@@ -10,5 +10,4 @@ cbindgen = { path = "../../cbindgen" }
 [dependencies]
 platform = { path = "../platform" }
 va_list = { path = "../../va_list", features = ["no_std"] }
-string = { path = "../string" }
 errno = { path = "../errno"}

src/stdio/src/lib.rs

@@ -4,7 +4,6 @@
 
 extern crate platform;
 extern crate va_list as vl;
-extern crate string;
 extern crate errno;
 
 use core::str;
@@ -210,22 +209,14 @@ pub extern "C" fn pclose(stream: *mut FILE) -> c_int {
 
 #[no_mangle]
 pub unsafe extern "C" fn perror(s: *const c_char) {
-    let mut buf: [u8; 256] = [0; 256];
-
-    let mut sw = platform::StringWriter(buf.as_mut_ptr(), buf.len());
+    let s_str = str::from_utf8_unchecked(c_str(s));
 
+    let mut w = platform::FileWriter(2);
     if errno >= 0 && errno < STR_ERROR.len() as c_int {
-        sw.write_str(STR_ERROR[errno as usize]);
+        w.write_fmt(format_args!("{}: {}\n", s_str, STR_ERROR[errno as usize]));
     } else {
-        sw.write_fmt(format_args!("Unknown error {}", errno));
+        w.write_fmt(format_args!("{}: Unknown error {}\n", s_str, errno));
     }
-
-    let mut w = platform::FileWriter(2);
-    w.write_fmt(format_args!(
-        "{}: {}\n",
-        str::from_utf8_unchecked(c_str(s)),
-        str::from_utf8_unchecked(c_str(buf.as_mut_ptr() as *mut c_char))
-    ));
 }
 
 #[no_mangle]