//! stdio implementation for Redox, following http://pubs.opengroup.org/onlinepubs/7908799/xsh/stdio.h.html

#![no_std]
// For Vec
#![feature(alloc)]
#![feature(const_fn)]

#[macro_use]
extern crate alloc;
extern crate errno;
extern crate fcntl;
#[macro_use]
extern crate lazy_static;
extern crate platform;
extern crate string;
extern crate va_list as vl;

use core::fmt::Write as WriteFmt;
use core::fmt::{self, Error, Result};
use core::sync::atomic::{AtomicBool, Ordering};
use core::{mem, ptr, str};

use alloc::vec::Vec;
use errno::STR_ERROR;
use platform::types::*;
use platform::{c_str, errno, Read, Write};
use vl::VaList as va_list;

mod printf;
mod scanf;

mod default;
pub use default::*;

mod constants;
pub use constants::*;

mod helpers;

mod internal;

///
/// This struct gets exposed to the C API.
///
pub struct FILE {
    flags: i32,
    read: Option<(usize, usize)>,
    write: Option<(usize, usize, usize)>,
    fd: c_int,
    buf: Vec<u8>,
    buf_char: i8,
    lock: AtomicBool,
    unget: usize,
}

impl FILE {
    pub fn can_read(&mut self) -> bool {
        /*
        if self.flags & constants::F_BADJ > 0 {
            // Static and needs unget region
            self.buf = unsafe { self.buf.add(self.unget) };
            self.flags &= !constants::F_BADJ;
        }
        */

        if let Some(_) = self.read {
            return true;
        }
        if let Some(_) = self.write {
            self.write(&[]);
        }
        self.write = None;
        if self.flags & constants::F_NORD > 0 {
            self.flags |= constants::F_ERR;
            return false;
        }
        self.read = Some((self.buf.len() - 1, self.buf.len() - 1));
        if self.flags & constants::F_EOF > 0 {
            false
        } else {
            true
        }
    }
    pub fn can_write(&mut self) -> bool {
        /*
        if self.flags & constants::F_BADJ > 0 {
            // Static and needs unget region
            self.buf = unsafe { self.buf.add(self.unget) };
            self.flags &= !constants::F_BADJ;
        }
        */

        if self.flags & constants::F_NOWR > 0 {
            self.flags &= constants::F_ERR;
            return false;
        }
        // Buffer repositioning
        if let Some(_) = self.write {
            return true;
        }
        self.read = None;
        self.write = Some((self.unget, self.unget, self.buf.len() - 1));
        return true;
    }
    pub fn write(&mut self, to_write: &[u8]) -> usize {
        if let Some((wbase, wpos, _)) = self.write {
            let len = wpos - wbase;
            let mut advance = 0;
            let mut f_buf = &self.buf[wbase..wpos];
            let mut f_filled = false;
            let mut rem = f_buf.len() + to_write.len();
            loop {
                let mut count = if f_filled {
                    platform::write(self.fd, &f_buf[advance..])
                } else {
                    platform::write(self.fd, &f_buf[advance..]) + platform::write(self.fd, to_write)
                };
                if count == rem as isize {
                    self.write = Some((self.unget, self.unget, self.buf.len() - 1));
                    return to_write.len();
                }
                if count < 0 {
                    self.write = None;
                    self.flags |= constants::F_ERR;
                    return 0;
                }
                rem -= count as usize;
                if count as usize > len {
                    count -= len as isize;
                    f_buf = to_write;
                    f_filled = true;
                    advance = 0;
                }
                advance += count as usize;
            }
        }
        // self.can_write() should always be called before self.write()
        // and should automatically fill self.write if it returns true.
        // Thus, we should never reach this
        //            -- Tommoa (20/6/2018)
        unreachable!()
    }
    pub fn read(&mut self, buf: &mut [u8]) -> usize {
        let adj = if self.buf.len() > 0 { 0 } else { 1 };
        let mut file_buf = &mut self.buf[self.unget..];
        let count = if buf.len() <= 1 + adj {
            platform::read(self.fd, &mut file_buf)
        } else {
            platform::read(self.fd, buf) + platform::read(self.fd, &mut file_buf)
        };
        if count <= 0 {
            self.flags |= if count == 0 {
                constants::F_EOF
            } else {
                constants::F_ERR
            };
            return 0;
        }
        if count as usize <= buf.len() - adj {
            return count as usize;
        }
        // Adjust pointers
        if buf.len() > 0 {
            self.read = Some((self.unget + 1, self.unget + (count as usize)));
            buf[buf.len() - 1] = file_buf[0];
        } else {
            self.read = Some((self.unget, self.unget + (count as usize)));
        }
        buf.len()
    }
    pub fn seek(&self, off: off_t, whence: c_int) -> off_t {
        platform::lseek(self.fd, off, whence)
    }
}
impl fmt::Write for FILE {
    fn write_str(&mut self, s: &str) -> Result {
        if !self.can_write() {
            return Err(Error);
        }
        let s = s.as_bytes();
        if self.write(s) != s.len() {
            Err(Error)
        } else {
            Ok(())
        }
    }
}
impl Write for FILE {
    fn write_u8(&mut self, byte: u8) -> Result {
        if !self.can_write() {
            return Err(Error);
        }
        if self.write(&[byte]) != 1 {
            Err(Error)
        } else {
            Ok(())
        }
    }
}
impl Read for FILE {
    fn read_u8(&mut self, byte: &mut u8) -> bool {
        let mut buf = [*byte];
        let n = self.read(&mut buf);
        *byte = buf[0];
        n > 0
    }
}

impl Drop for FILE {
    fn drop(&mut self) {
        // Flush
        if let Some(_) = self.write {
            self.write(&[]);
        }
    }
}

/// Clears EOF and ERR indicators on a stream
#[no_mangle]
pub extern "C" fn clearerr(stream: &mut FILE) {
    stream.flags &= !(F_EOF | F_ERR);
}

// #[no_mangle]
pub extern "C" fn ctermid(_s: *mut c_char) -> *mut c_char {
    unimplemented!();
}

// #[no_mangle]
pub extern "C" fn cuserid(_s: *mut c_char) -> *mut c_char {
    unimplemented!();
}

/// Close a file
/// This function does not guarentee that the file buffer will be flushed or that the file
/// descriptor will be closed, so if it is important that the file be written to, use `fflush()`
/// prior to using this function.
#[no_mangle]
pub extern "C" fn fclose(stream: &mut FILE) -> c_int {
    flockfile(stream);
    let r = helpers::fflush_unlocked(stream) | platform::close(stream.fd);
    if stream.flags & constants::F_PERM == 0 {
        // Not one of stdin, stdout or stderr
        unsafe {
            platform::free(stream as *mut FILE as *mut c_void);
        }
    } else {
        funlockfile(stream);
    }
    r
}

/// Open a file from a file descriptor
#[no_mangle]
pub extern "C" fn fdopen(fildes: c_int, mode: *const c_char) -> *mut FILE {
    use core::ptr;
    if let Some(f) = unsafe { helpers::_fdopen(fildes, mode) } {
        f
    } else {
        ptr::null_mut()
    }
}

/// Check for EOF
#[no_mangle]
pub extern "C" fn feof(stream: &mut FILE) -> c_int {
    flockfile(stream);
    let ret = stream.flags & F_EOF;
    funlockfile(stream);
    ret
}

/// Check for ERR
#[no_mangle]
pub extern "C" fn ferror(stream: &mut FILE) -> c_int {
    flockfile(stream);
    let ret = stream.flags & F_ERR;
    funlockfile(stream);
    ret
}

/// Flush output to stream, or sync read position
/// Ensure the file is unlocked before calling this function, as it will attempt to lock the file
/// itself.
#[no_mangle]
pub unsafe extern "C" fn fflush(stream: &mut FILE) -> c_int {
    flockfile(stream);

    let ret = helpers::fflush_unlocked(stream);

    funlockfile(stream);
    ret
}

/// Get a single char from a stream
#[no_mangle]
pub extern "C" fn fgetc(stream: &mut FILE) -> c_int {
    flockfile(stream);
    let c = getc_unlocked(stream);
    funlockfile(stream);
    c
}

/// Get the position of the stream and store it in pos
#[no_mangle]
pub extern "C" fn fgetpos(stream: &mut FILE, pos: Option<&mut fpos_t>) -> c_int {
    let off = internal::ftello(stream);
    if off < 0 {
        return -1;
    }
    if let Some(pos) = pos {
        *pos = off;
        0
    } else {
        -1
    }
}

/// Get a string from the stream
#[no_mangle]
pub extern "C" fn fgets(s: *mut c_char, n: c_int, stream: &mut FILE) -> *mut c_char {
    use core::slice;
    flockfile(stream);
    let st = unsafe { slice::from_raw_parts_mut(s, n as usize) };

    let mut len = n;

    // We can only fit one or less chars in
    if n <= 1 {
        funlockfile(stream);
        if n <= 0 {
            return ptr::null_mut();
        }
        unsafe {
            (*s) = b'\0' as i8;
        }
        return s;
    }
    // Scope this so we can reuse stream mutably
    {
        // We can't read from this stream
        if !stream.can_read() {
            return ptr::null_mut();
        }
    }

    // TODO: Look at this later to determine correctness and efficiency
    'outer: while stream.read(&mut []) == 0 && stream.flags & F_ERR == 0 {
        if let Some((rpos, rend)) = stream.read {
            let mut idiff = 0usize;
            for _ in (0..(len - 1) as usize).take_while(|x| rpos + x < rend) {
                let pos = (n - len) as usize;
                st[pos] = stream.buf[rpos + idiff] as i8;
                idiff += 1;
                len -= 1;
                if st[pos] == b'\n' as i8 || st[pos] == stream.buf_char {
                    break 'outer;
                }
            }
            stream.read = Some((rpos + idiff, rend));
            if len <= 1 {
                break;
            }
        }
        // We can read, there's been no errors. We should have stream.read setbuf
        //            -- Tommoa (3/7/2018)
        unreachable!()
    }

    st[(n - len) as usize] = 0;
    funlockfile(stream);
    s
}

/// Get the underlying file descriptor
#[no_mangle]
pub extern "C" fn fileno(stream: &mut FILE) -> c_int {
    flockfile(stream);
    funlockfile(stream);
    stream.fd
}

/// Lock the file
/// Do not call any functions other than those with the `_unlocked` postfix while the file is
/// locked
#[no_mangle]
pub extern "C" fn flockfile(file: &mut FILE) {
    while ftrylockfile(file) != 0 {}
}

/// Open the file in mode `mode`
#[no_mangle]
pub extern "C" fn fopen(filename: *const c_char, mode: *const c_char) -> *mut FILE {
    use core::ptr;
    let initial_mode = unsafe { *mode };
    if initial_mode != b'r' as i8 && initial_mode != b'w' as i8 && initial_mode != b'a' as i8 {
        unsafe { platform::errno = errno::EINVAL };
        return ptr::null_mut();
    }

    let flags = unsafe { helpers::parse_mode_flags(mode) };

    let fd = fcntl::sys_open(filename, flags, 0o666);
    if fd < 0 {
        return ptr::null_mut();
    }

    if flags & fcntl::O_CLOEXEC > 0 {
        fcntl::sys_fcntl(fd, fcntl::F_SETFD, fcntl::FD_CLOEXEC);
    }

    if let Some(f) = unsafe { helpers::_fdopen(fd, mode) } {
        f
    } else {
        platform::close(fd);
        ptr::null_mut()
    }
}

/// Insert a character into the stream
#[no_mangle]
pub extern "C" fn fputc(c: c_int, stream: &mut FILE) -> c_int {
    flockfile(stream);
    let c = putc_unlocked(c, stream);
    funlockfile(stream);
    c
}

/// Insert a string into a stream
#[no_mangle]
pub extern "C" fn fputs(s: *const c_char, stream: &mut FILE) -> c_int {
    extern "C" {
        fn strlen(s: *const c_char) -> size_t;
    }
    let len = unsafe { strlen(s) };
    (fwrite(s as *const c_void, 1, len, stream) == len) as c_int - 1
}

/// Read `nitems` of size `size` into `ptr` from `stream`
#[no_mangle]
pub extern "C" fn fread(ptr: *mut c_void, size: usize, nitems: usize, stream: &mut FILE) -> usize {
    use core::ptr::copy_nonoverlapping;
    use core::slice;
    let mut dest = ptr as *mut u8;
    let len = size * nitems;
    let mut l = len as isize;

    flockfile(stream);

    if !stream.can_read() {
        return 0;
    }

    if let Some((rpos, rend)) = stream.read {
        if rend > rpos {
            // We have some buffered data that can be read
            let diff = rend - rpos;
            let k = if diff < l as usize { diff } else { l as usize };
            unsafe {
                // Copy data
                copy_nonoverlapping(&stream.buf[rpos..] as *const _ as *const u8, dest, k);
                // Reposition pointers
                dest = dest.add(k);
            }
            stream.read = Some((rpos + k, rend));
            l -= k as isize;
        }

        while l > 0 {
            let k = if !stream.can_read() {
                0
            } else {
                stream.read(unsafe { slice::from_raw_parts_mut(dest, l as usize) })
            };

            if k == 0 {
                funlockfile(stream);
                return (len - l as usize) / 2;
            }

            l -= k as isize;
            unsafe {
                // Reposition
                dest = dest.add(k);
            }
        }

        funlockfile(stream);
        nitems
    } else {
        unreachable!()
    }
}

#[no_mangle]
pub extern "C" fn freopen(
    filename: *const c_char,
    mode: *const c_char,
    stream: &mut FILE,
) -> *mut FILE {
    let mut flags = unsafe { helpers::parse_mode_flags(mode) };
    flockfile(stream);

    helpers::fflush_unlocked(stream);
    if filename.is_null() {
        // Reopen stream in new mode
        if flags & fcntl::O_CLOEXEC > 0 {
            fcntl::sys_fcntl(stream.fd, fcntl::F_SETFD, fcntl::FD_CLOEXEC);
        }
        flags &= !(fcntl::O_CREAT | fcntl::O_EXCL | fcntl::O_CLOEXEC);
        if fcntl::sys_fcntl(stream.fd, fcntl::F_SETFL, flags) < 0 {
            funlockfile(stream);
            fclose(stream);
            return ptr::null_mut();
        }
    } else {
        let new = fopen(filename, mode);
        if new.is_null() {
            funlockfile(stream);
            fclose(stream);
            return ptr::null_mut();
        }
        let new = unsafe { &mut *new }; // Should be safe, new is not null
        if new.fd == stream.fd {
            new.fd = -1;
        } else if platform::dup2(new.fd, stream.fd) < 0
            || fcntl::sys_fcntl(stream.fd, fcntl::F_SETFL, flags & fcntl::O_CLOEXEC) < 0
        {
            fclose(new);
            funlockfile(stream);
            fclose(stream);
            return ptr::null_mut();
        }
        stream.flags = (stream.flags & constants::F_PERM) | new.flags;
        fclose(new);
    }
    funlockfile(stream);
    stream
}

/// Seek to an offset `offset` from `whence`
#[no_mangle]
pub extern "C" fn fseek(stream: &mut FILE, offset: c_long, whence: c_int) -> c_int {
    if fseeko(stream, offset as off_t, whence) != -1 {
        return 0;
    }
    -1
}

/// Seek to an offset `offset` from `whence`
#[no_mangle]
pub extern "C" fn fseeko(stream: &mut FILE, offset: off_t, whence: c_int) -> c_int {
    let mut off = offset;
    flockfile(stream);
    // Adjust for what is currently in the buffer
    let rdiff = if let Some((rpos, rend)) = stream.read {
        rend - rpos
    } else {
        0
    };
    if whence == SEEK_CUR {
        off -= (rdiff) as i64;
    }
    if let Some(_) = stream.write {
        stream.write(&[]);
    }
    stream.write = None;
    if stream.seek(off, whence) < 0 {
        return -1;
    }
    stream.read = None;
    stream.flags &= !F_EOF;
    funlockfile(stream);
    0
}

/// Seek to a position `pos` in the file from the beginning of the file
#[no_mangle]
pub unsafe extern "C" fn fsetpos(stream: &mut FILE, pos: Option<&fpos_t>) -> c_int {
    fseek(
        stream,
        *pos.expect("You must specify a valid position"),
        SEEK_SET,
    )
}

/// Get the current position of the cursor in the file
#[no_mangle]
pub extern "C" fn ftell(stream: &mut FILE) -> c_long {
    ftello(stream) as c_long
}

/// Get the current position of the cursor in the file
#[no_mangle]
pub extern "C" fn ftello(stream: &mut FILE) -> off_t {
    flockfile(stream);
    let pos = internal::ftello(stream);
    funlockfile(stream);
    pos
}

/// Try to lock the file. Returns 0 for success, 1 for failure
#[no_mangle]
pub extern "C" fn ftrylockfile(file: &mut FILE) -> c_int {
    file.lock.compare_and_swap(false, true, Ordering::Acquire) as c_int
}

/// Unlock the file
#[no_mangle]
pub extern "C" fn funlockfile(file: &mut FILE) {
    file.lock.store(false, Ordering::Release);
}

/// Write `nitems` of size `size` from `ptr` to `stream`
#[no_mangle]
pub extern "C" fn fwrite(
    ptr: *const c_void,
    size: usize,
    nitems: usize,
    stream: &mut FILE,
) -> usize {
    let l = size * nitems;
    let nitems = if size == 0 { 0 } else { nitems };
    flockfile(stream);
    let k = helpers::fwritex(ptr as *const u8, l, stream);
    funlockfile(stream);
    if k == l {
        nitems
    } else {
        k / size
    }
}

/// Get a single char from a stream
#[no_mangle]
pub extern "C" fn getc(stream: &mut FILE) -> c_int {
    flockfile(stream);
    let c = getc_unlocked(stream);
    funlockfile(stream);
    c
}

/// Get a single char from `stdin`
#[no_mangle]
pub extern "C" fn getchar() -> c_int {
    fgetc(unsafe { &mut *stdin })
}

/// Get a char from a stream without locking the stream
#[no_mangle]
pub extern "C" fn getc_unlocked(stream: &mut FILE) -> c_int {
    if !stream.can_read() {
        return -1;
    }
    if let Some((rpos, rend)) = stream.read {
        if rpos < rend {
            let ret = stream.buf[rpos] as c_int;
            stream.read = Some((rpos + 1, rend));
            ret
        } else {
            let mut c = [0u8; 1];
            if stream.read(&mut c) == 1 {
                c[0] as c_int
            } else {
                -1
            }
        }
    } else {
        // We made a prior call to can_read() and are checking it, therefore we
        // should never be in a case where stream.read is None
        //            -- Tommoa (20/6/2018)
        unreachable!()
    }
}

/// Get a char from `stdin` without locking `stdin`
#[no_mangle]
pub extern "C" fn getchar_unlocked() -> c_int {
    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 })
}

/// Get an integer from `stream`
#[no_mangle]
pub extern "C" fn getw(stream: &mut FILE) -> c_int {
    use core::mem;
    let mut ret: c_int = 0;
    if fread(
        &mut ret as *mut c_int as *mut c_void,
        mem::size_of_val(&ret),
        1,
        stream,
    ) > 0
    {
        ret
    } else {
        -1
    }
}

// #[no_mangle]
pub extern "C" fn pclose(_stream: &mut FILE) -> c_int {
    unimplemented!();
}

#[no_mangle]
pub unsafe extern "C" fn perror(s: *const c_char) {
    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 {
        w.write_fmt(format_args!("{}: {}\n", s_str, STR_ERROR[errno as usize]))
            .unwrap();
    } else {
        w.write_fmt(format_args!("{}: Unknown error {}\n", s_str, errno))
            .unwrap();
    }
}

// #[no_mangle]
pub extern "C" fn popen(_command: *const c_char, _mode: *const c_char) -> *mut FILE {
    unimplemented!();
}

/// Put a character `c` into `stream`
#[no_mangle]
pub extern "C" fn putc(c: c_int, stream: &mut FILE) -> c_int {
    flockfile(stream);
    let ret = putc_unlocked(c, stream);
    funlockfile(stream);
    ret
}

/// Put a character `c` into `stdout`
#[no_mangle]
pub extern "C" fn putchar(c: c_int) -> c_int {
    fputc(c, unsafe { &mut *stdout })
}

/// Put a character `c` into `stream` without locking `stream`
#[no_mangle]
pub extern "C" fn putc_unlocked(c: c_int, stream: &mut FILE) -> c_int {
    if stream.can_write() {
        if let Some((wbase, wpos, wend)) = stream.write {
            if c as i8 != stream.buf_char {
                stream.buf[wpos] = c as u8;
                stream.write = Some((wbase, wpos + 1, wend));
                c
            } else if stream.write(&[c as u8]) == 1 {
                c
            } else {
                -1
            }
        } else {
            -1
        }
    } else {
        -1
    }
}

/// 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 })
}

/// 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);
    if ret {
        0
    } else {
        -1
    }
}

/// Put an integer `w` into `stream`
#[no_mangle]
pub extern "C" fn putw(w: c_int, stream: &mut FILE) -> c_int {
    use core::mem;
    fwrite(&w as *const i32 as _, mem::size_of_val(&w), 1, stream) as i32 - 1
}

/// Delete file or directory `path`
#[no_mangle]
pub extern "C" fn remove(path: *const c_char) -> c_int {
    let r = platform::unlink(path);
    if r == -errno::EISDIR {
        platform::rmdir(path)
    } else {
        r
    }
}

#[no_mangle]
pub extern "C" fn rename(oldpath: *const c_char, newpath: *const c_char) -> c_int {
    platform::rename(oldpath, newpath)
}

/// Rewind `stream` back to the beginning of it
#[no_mangle]
pub extern "C" fn rewind(stream: &mut FILE) {
    fseeko(stream, 0, SEEK_SET);
    flockfile(stream);
    stream.flags &= !F_ERR;
    funlockfile(stream);
}

/// Reset `stream` to use buffer `buf`. Buffer must be `BUFSIZ` in length
#[no_mangle]
pub extern "C" fn setbuf(stream: &mut FILE, buf: *mut c_char) {
    setvbuf(
        stream,
        buf,
        if buf.is_null() { _IONBF } else { _IOFBF },
        BUFSIZ as usize,
    );
}

/// Reset `stream` to use buffer `buf` of size `size`
/// If this isn't the meaning of unsafe, idk what is
#[no_mangle]
pub extern "C" fn setvbuf(stream: &mut FILE, buf: *mut c_char, mode: c_int, size: usize) -> c_int {
    // Set a buffer of size `size` if no buffer is given
    let buf = if buf.is_null() {
        if mode != _IONBF {
            vec![0u8; 1]
        } else {
            Vec::new()
        }
    } else {
        // We trust the user on this one
        //        -- Tommoa (20/6/2018)
        unsafe { Vec::from_raw_parts(buf as *mut u8, size, size) }
    };
    stream.buf_char = -1;
    if mode == _IOLBF {
        stream.buf_char = b'\n' as i8;
    }
    stream.flags |= F_SVB;
    stream.buf = buf;
    0
}

// #[no_mangle]
pub extern "C" fn tempnam(_dir: *const c_char, _pfx: *const c_char) -> *mut c_char {
    unimplemented!();
}

#[no_mangle]
pub extern "C" fn tmpfile() -> *mut FILE {
    extern "C" {
        fn mkstemp(name: *mut c_char) -> c_int;
    }

    let mut file_name = *b"/tmp/tmpfileXXXXXX";
    let file_name = file_name.as_mut_ptr() as *mut c_char;
    let fd = unsafe { mkstemp(file_name) };

    if fd < 0 {
        return ptr::null_mut();
    }

    let fp = fdopen(fd, b"w+".as_ptr() as *const i8);
    platform::unlink(file_name);

    if fp == ptr::null_mut() {
        platform::close(fd);
    }

    fp
}

// #[no_mangle]
pub extern "C" fn tmpnam(_s: *mut c_char) -> *mut c_char {
    unimplemented!();
}

/// Push character `c` back onto `stream` so it'll be read next
#[no_mangle]
pub extern "C" fn ungetc(c: c_int, stream: &mut FILE) -> c_int {
    if c < 0 {
        c
    } else {
        flockfile(stream);
        if stream.read.is_none() {
            stream.can_read();
        }
        if let Some((rpos, rend)) = stream.read {
            if rpos == 0 {
                funlockfile(stream);
                return -1;
            }
            stream.read = Some((rpos - 1, rend));
            stream.buf[rpos - 1] = c as u8;
            stream.flags &= !F_EOF;
            funlockfile(stream);
            c
        } else {
            funlockfile(stream);
            -1
        }
    }
}

#[no_mangle]
pub unsafe extern "C" fn vfprintf(file: &mut FILE, format: *const c_char, ap: va_list) -> c_int {
    printf::printf(file, format, ap)
}

#[no_mangle]
pub unsafe extern "C" fn vprintf(format: *const c_char, ap: va_list) -> c_int {
    vfprintf(&mut *stdout, format, ap)
}

#[no_mangle]
pub unsafe extern "C" fn vsnprintf(
    s: *mut c_char,
    n: usize,
    format: *const c_char,
    ap: va_list,
) -> c_int {
    printf::printf(
        &mut platform::StringWriter(s as *mut u8, n as usize),
        format,
        ap,
    )
}

#[no_mangle]
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 unsafe extern "C" fn vfscanf(file: &mut FILE, format: *const c_char, ap: va_list) -> c_int {
    scanf::scanf(file, format, ap)
}

#[no_mangle]
pub unsafe extern "C" fn vscanf(format: *const c_char, ap: va_list) -> c_int {
    vfscanf(&mut *stdin, format, ap)
}

#[no_mangle]
pub unsafe extern "C" fn vsscanf(s: *const c_char, format: *const c_char, ap: va_list) -> c_int {
    scanf::scanf(
        &mut platform::UnsafeStringReader(s as *const u8),
        format,
        ap,
    )
}
