copy strerror implementation into perror

src/stdio/Cargo.toml

@@ -11,3 +11,4 @@ cbindgen = { path = "../../cbindgen" }
 platform = { path = "../platform" }
 va_list = { path = "../../va_list", features = ["no_std"] }
 string = { path = "../string" }
+errno = { path = "../errno"}

src/stdio/src/lib.rs

@@ -5,12 +5,15 @@
 extern crate platform;
 extern crate va_list as vl;
 extern crate string;
+extern crate errno;
 
 use core::str;
 use core::fmt::Write;
 
 use platform::types::*;
 use platform::c_str;
+use platform::errno;
+use errno::STR_ERROR;
 use vl::VaList as va_list;
 
 mod printf;
@@ -207,12 +210,21 @@ pub extern "C" fn pclose(stream: *mut FILE) -> c_int {
 
 #[no_mangle]
 pub unsafe extern "C" fn perror(s: *const c_char) {
-    let strerror = string::strerror(platform::errno);
+    let mut buf: [u8; 256] = [0; 256];
+
+    let mut sw = platform::StringWriter(buf.as_mut_ptr(), buf.len());
+
+    if errno >= 0 && errno < STR_ERROR.len() as c_int {
+        sw.write_str(STR_ERROR[errno as usize]);
+    } else {
+        sw.write_fmt(format_args!("Unknown error {}", 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(strerror))
+        str::from_utf8_unchecked(c_str(buf.as_mut_ptr() as *mut c_char))
     ));
 }