Merge pull request #122 from Arcterus/qsort

Fix a bug in printf()

src/platform/src/lib.rs

@@ -58,6 +58,30 @@ pub unsafe fn cstr_from_bytes_with_nul_unchecked(bytes: &[u8]) -> *const c_char
     &*(bytes as *const [u8] as *const c_char)
 }
 
+// NOTE: defined here rather than in string because memcpy() is useful in multiple crates
+pub unsafe fn memcpy(s1: *mut c_void, s2: *const c_void, n: usize) -> *mut c_void {
+    let mut i = 0;
+    while i + 7 < n {
+        *(s1.offset(i as isize) as *mut u64) = *(s2.offset(i as isize) as *const u64);
+        i += 8;
+    }
+    while i < n {
+        *(s1 as *mut u8).offset(i as isize) = *(s2 as *const u8).offset(i as isize);
+        i += 1;
+    }
+    s1
+}
+
+pub trait Write: fmt::Write {
+    fn write_u8(&mut self, byte: u8) -> fmt::Result;
+}
+
+impl<'a, W: Write> Write for &'a mut W {
+    fn write_u8(&mut self, byte: u8) -> fmt::Result {
+        (**self).write_u8(byte)
+    }
+}
+
 pub struct FileWriter(pub c_int);
 
 impl FileWriter {
@@ -73,6 +97,13 @@ impl fmt::Write for FileWriter {
     }
 }
 
+impl Write for FileWriter {
+    fn write_u8(&mut self, byte: u8) -> fmt::Result {
+        self.write(&[byte]);
+        Ok(())
+    }
+}
+
 pub struct FileReader(pub c_int);
 
 impl FileReader {
@@ -85,21 +116,19 @@ pub struct StringWriter(pub *mut u8, pub usize);
 
 impl StringWriter {
     pub unsafe fn write(&mut self, buf: &[u8]) {
-        for &b in buf.iter() {
-            if self.1 == 0 {
-                break;
-            } else if self.1 == 1 {
-                *self.0 = b'\0';
-            } else {
-                *self.0 = b;
-            }
+        if self.1 > 0 {
+            let copy_size = buf.len().min(self.1 - 1);
+            memcpy(
+                self.0 as *mut c_void,
+                buf.as_ptr() as *const c_void,
+                copy_size,
+            );
+            *self.0.offset(copy_size as isize) = b'\0';
 
-            self.0 = self.0.offset(1);
-            self.1 -= 1;
-
-            if self.1 > 0 {
-                *self.0 = b'\0';
-            }
+            // XXX: i believe this correctly mimics the behavior from before, but it seems
+            //      incorrect (the next write will write after the NUL)
+            self.0 = self.0.offset(copy_size as isize + 1);
+            self.1 -= copy_size + 1;
         }
     }
 }
@@ -111,15 +140,24 @@ impl fmt::Write for StringWriter {
     }
 }
 
+impl Write for StringWriter {
+    fn write_u8(&mut self, byte: u8) -> fmt::Result {
+        unsafe { self.write(&[byte]) };
+        Ok(())
+    }
+}
+
 pub struct UnsafeStringWriter(pub *mut u8);
 
 impl UnsafeStringWriter {
     pub unsafe fn write(&mut self, buf: &[u8]) {
-        for &b in buf.iter() {
-            *self.0 = b;
-            self.0 = self.0.offset(1);
-            *self.0 = b'\0';
-        }
+        memcpy(
+            self.0 as *mut c_void,
+            buf.as_ptr() as *const c_void,
+            buf.len(),
+        );
+        *self.0.offset(buf.len() as isize) = b'\0';
+        self.0 = self.0.offset(buf.len() as isize);
     }
 }
 
@@ -129,3 +167,10 @@ impl fmt::Write for UnsafeStringWriter {
         Ok(())
     }
 }
+
+impl Write for UnsafeStringWriter {
+    fn write_u8(&mut self, byte: u8) -> fmt::Result {
+        unsafe { self.write(&[byte]) };
+        Ok(())
+    }
+}

src/stdio/src/lib.rs

@@ -11,11 +11,12 @@ extern crate va_list as vl;
 
 use core::str;
 use core::ptr;
-use core::fmt::{Error, Result, Write};
+use core::fmt::{self, Error, Result};
+use core::fmt::Write as WriteFmt;
 use core::sync::atomic::{AtomicBool, Ordering};
 
 use platform::types::*;
-use platform::{c_str, errno};
+use platform::{c_str, errno, Write};
 use errno::STR_ERROR;
 use vl::VaList as va_list;
 
@@ -164,7 +165,7 @@ impl FILE {
         unsafe { platform::lseek(self.fd, off, whence) }
     }
 }
-impl Write for FILE {
+impl fmt::Write for FILE {
     fn write_str(&mut self, s: &str) -> Result {
         let s = s.as_bytes();
         if self.write(s) != s.len() {
@@ -174,6 +175,15 @@ impl Write for FILE {
         }
     }
 }
+impl Write for FILE {
+    fn write_u8(&mut self, byte: u8) -> Result {
+        if self.write(&[byte]) != 1 {
+            Err(Error)
+        } else {
+            Ok(())
+        }
+    }
+}
 
 /// Clears EOF and ERR indicators on a stream
 #[no_mangle]
@@ -872,10 +882,3 @@ pub unsafe extern "C" fn vsnprintf(
 pub unsafe extern "C" fn vsprintf(s: *mut c_char, format: *const c_char, ap: va_list) -> c_int {
     printf::printf(&mut platform::UnsafeStringWriter(s as *mut u8), format, ap)
 }
-
-/*
-#[no_mangle]
-pub extern "C" fn func(args) -> c_int {
-    unimplemented!();
-}
-*/

src/stdio/src/printf.rs

@@ -1,19 +1,18 @@
 use core::{fmt, slice, str};
 
+use platform::{self, Write};
 use platform::types::*;
 use vl::VaList;
 
-pub unsafe fn printf<W: fmt::Write>(mut w: W, format: *const c_char, mut ap: VaList) -> c_int {
-    extern "C" {
-        fn strlen(s: *const c_char) -> size_t;
-    }
+pub unsafe fn printf<W: Write>(mut w: W, format: *const c_char, mut ap: VaList) -> c_int {
+    let format = unsafe { slice::from_raw_parts(format as *const u8, usize::max_value()) };
 
-    let format = slice::from_raw_parts(format as *const u8, strlen(format));
-
-    let mut i = 0;
     let mut found_percent = false;
-    while i < format.len() {
-        let b = format[i];
+    for &b in format.iter() {
+        // check for NUL
+        if b == 0 {
+            break;
+        }
 
         if found_percent {
             match b as char {
@@ -24,7 +23,7 @@ pub unsafe fn printf<W: fmt::Write>(mut w: W, format: *const c_char, mut ap: VaL
                 'c' => {
                     let a = ap.get::<u32>();
 
-                    w.write_char(a as u8 as char);
+                    w.write_u8(a as u8);
 
                     found_percent = false;
                 }
@@ -57,9 +56,8 @@ pub unsafe fn printf<W: fmt::Write>(mut w: W, format: *const c_char, mut ap: VaL
                 's' => {
                     let a = ap.get::<usize>();
 
-                    w.write_str(str::from_utf8_unchecked(slice::from_raw_parts(
-                        a as *const u8,
-                        strlen(a as *const c_char),
+                    w.write_str(str::from_utf8_unchecked(platform::c_str(
+                        a as *const c_char,
                     )));
 
                     found_percent = false;
@@ -102,10 +100,8 @@ pub unsafe fn printf<W: fmt::Write>(mut w: W, format: *const c_char, mut ap: VaL
         } else if b == b'%' {
             found_percent = true;
         } else {
-            w.write_char(b as char);
+            w.write_u8(b);
         }
-
-        i += 1;
     }
 
     0

src/string/src/lib.rs

@@ -58,12 +58,7 @@ pub unsafe extern "C" fn memcmp(s1: *const c_void, s2: *const c_void, n: usize)
 
 #[no_mangle]
 pub unsafe extern "C" fn memcpy(s1: *mut c_void, s2: *const c_void, n: usize) -> *mut c_void {
-    let mut i = 0;
-    while i < n {
-        *(s1 as *mut u8).offset(i as isize) = *(s2 as *const u8).offset(i as isize);
-        i += 1;
-    }
-    s1
+    platform::memcpy(s1, s2, n)
 }
 
 #[no_mangle]
@@ -385,10 +380,3 @@ pub extern "C" fn strtok_r(
 pub extern "C" fn strxfrm(s1: *mut c_char, s2: *const c_char, n: usize) -> size_t {
     unimplemented!();
 }
-
-/*
-#[no_mangle]
-pub extern "C" fn func(args) -> c_int {
-    unimplemented!();
-}
-*/

tests/printf.c

@@ -2,9 +2,10 @@
 
 int main(int argc, char ** argv) {
     printf(
-        "percent: %%\nstring: %s\nchar: %c\nint: %d\nuint: %u\nhex: %x\nHEX: %X\nstring: %s\n",
+        "percent: %%\nstring: %s\nchar: %c\nchar: %c\nint: %d\nuint: %u\nhex: %x\nHEX: %X\nstring: %s\n",
         "String",
         'c',
+        254,
         -16,
         32,
         0xbeef,