Solve stdin/out/err UB in a better way

src/stdio/src/default.rs

@@ -1,37 +1,23 @@
 use super::{constants, BUFSIZ, FILE, UNGET};
 use core::cell::UnsafeCell;
+use core::ptr;
 use core::sync::atomic::AtomicBool;
 
-struct GlobalFile(UnsafeCell<FILE>);
+pub struct GlobalFile(UnsafeCell<FILE>);
 impl GlobalFile {
     const fn new(file: FILE) -> Self {
         GlobalFile(UnsafeCell::new(file))
     }
-    fn get(&self) -> *mut FILE {
+    pub fn get(&self) -> *mut FILE {
         self.0.get()
     }
 }
 // statics need to be Sync
 unsafe impl Sync for GlobalFile {}
 
-#[no_mangle]
-pub extern "C" fn __stdin() -> *mut FILE {
-    default_stdin.get()
-}
-
-#[no_mangle]
-pub extern "C" fn __stdout() -> *mut FILE {
-    default_stdout.get()
-}
-
-#[no_mangle]
-pub extern "C" fn __stderr() -> *mut FILE {
-    default_stderr.get()
-}
-
 lazy_static! {
     #[allow(non_upper_case_globals)]
-    static ref default_stdin: GlobalFile = GlobalFile::new(FILE {
+    pub static ref default_stdin: GlobalFile = GlobalFile::new(FILE {
         flags: constants::F_PERM | constants::F_NOWR,
         read: None,
         write: None,
@@ -43,7 +29,7 @@ lazy_static! {
     });
 
     #[allow(non_upper_case_globals)]
-    static ref default_stdout: GlobalFile = GlobalFile::new(FILE {
+    pub static ref default_stdout: GlobalFile = GlobalFile::new(FILE {
         flags: constants::F_PERM | constants::F_NORD,
         read: None,
         write: None,
@@ -55,7 +41,7 @@ lazy_static! {
     });
 
     #[allow(non_upper_case_globals)]
-    static ref default_stderr: GlobalFile = GlobalFile::new(FILE {
+    pub static ref default_stderr: GlobalFile = GlobalFile::new(FILE {
         flags: constants::F_PERM | constants::F_NORD,
         read: None,
         write: None,
@@ -66,3 +52,10 @@ lazy_static! {
         lock: AtomicBool::new(false),
     });
 }
+
+#[no_mangle]
+pub static mut stdin: *mut FILE = ptr::null_mut();
+#[no_mangle]
+pub static mut stdout: *mut FILE = ptr::null_mut();
+#[no_mangle]
+pub static mut stderr: *mut FILE = ptr::null_mut();

src/stdio/src/lib.rs

@@ -643,7 +643,7 @@ pub extern "C" fn getc(stream: &mut FILE) -> c_int {
 /// Get a single char from `stdin`
 #[no_mangle]
 pub extern "C" fn getchar() -> c_int {
-    fgetc(unsafe { &mut *__stdin() })
+    fgetc(unsafe { &mut *stdin })
 }
 
 /// Get a char from a stream without locking the stream
@@ -676,14 +676,14 @@ pub extern "C" fn getc_unlocked(stream: &mut FILE) -> c_int {
 /// Get a char from `stdin` without locking `stdin`
 #[no_mangle]
 pub extern "C" fn getchar_unlocked() -> c_int {
-    getc_unlocked(unsafe { &mut *__stdin() })
+    getc_unlocked(unsafe { &mut *stdin })
 }
 
 /// Get a string from `stdin`
 #[no_mangle]
 pub extern "C" fn gets(s: *mut c_char) -> *mut c_char {
     use core::i32;
-    fgets(s, i32::MAX, unsafe { &mut *__stdin() })
+    fgets(s, i32::MAX, unsafe { &mut *stdin })
 }
 
 /// Get an integer from `stream`
@@ -740,7 +740,7 @@ pub extern "C" fn putc(c: c_int, stream: &mut FILE) -> c_int {
 /// Put a character `c` into `stdout`
 #[no_mangle]
 pub extern "C" fn putchar(c: c_int) -> c_int {
-    fputc(c, unsafe { &mut *__stdout() })
+    fputc(c, unsafe { &mut *stdout })
 }
 
 /// Put a character `c` into `stream` without locking `stream`
@@ -768,13 +768,13 @@ pub extern "C" fn putc_unlocked(c: c_int, stream: &mut FILE) -> c_int {
 /// Put a character `c` into `stdout` without locking `stdout`
 #[no_mangle]
 pub extern "C" fn putchar_unlocked(c: c_int) -> c_int {
-    putc_unlocked(c, unsafe { &mut *__stdout() })
+    putc_unlocked(c, unsafe { &mut *stdout })
 }
 
 /// Put a string `s` into `stdout`
 #[no_mangle]
 pub extern "C" fn puts(s: *const c_char) -> c_int {
-    let ret = (fputs(s, unsafe { &mut *__stdout() }) > 0) || (putchar_unlocked(b'\n' as c_int) > 0);
+    let ret = (fputs(s, unsafe { &mut *stdout }) > 0) || (putchar_unlocked(b'\n' as c_int) > 0);
     if ret {
         0
     } else {
@@ -918,7 +918,7 @@ pub unsafe extern "C" fn vfprintf(file: &mut FILE, format: *const c_char, ap: va
 
 #[no_mangle]
 pub unsafe extern "C" fn vprintf(format: *const c_char, ap: va_list) -> c_int {
-    vfprintf(&mut *__stdout(), format, ap)
+    vfprintf(&mut *stdout, format, ap)
 }
 
 #[no_mangle]
@@ -947,7 +947,7 @@ pub unsafe extern "C" fn vfscanf(file: &mut FILE, format: *const c_char, ap: va_
 
 #[no_mangle]
 pub unsafe extern "C" fn vscanf(format: *const c_char, ap: va_list) -> c_int {
-    vfscanf(&mut *__stdin(), format, ap)
+    vfscanf(&mut *stdin, format, ap)
 }
 
 #[no_mangle]