diff --git a/Cargo.toml b/Cargo.toml
index f3c801e..f903127 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,7 @@ crate-type = ["staticlib"]
 [dependencies]
 yggdrasil-rt = { git = "https://git.alnyan.me/yggdrasil/yggdrasil-rt.git" }
 libyalloc = { git = "https://git.alnyan.me/yggdrasil/libyalloc.git" }
+bitflags = { version = "2.4.1" }
 
 [build-dependencies]
-cbindgen = "0.26.0"
+cbindgen = { git = "https://git.alnyan.me/yggdrasil/cbindgen.git", branch = "master" }
diff --git a/include/bits/stdio.h b/include/bits/stdio.h
index 6a939aa..0103f3e 100644
--- a/include/bits/stdio.h
+++ b/include/bits/stdio.h
@@ -3,5 +3,12 @@
 
 int printf(const char *format, ...);
 int fprintf(FILE *stream, const char *format, ...);
+int sprintf(FILE *stream, const char *format, ...);
+int snprintf(FILE *stream, size_t len, const char *format, ...);
+int dprintf(int fd, const char *format, ...);
+
+int scanf(const char *format, ...);
+int sscanf(const char *str, const char *format, ...);
+int fscanf(FILE *stream, const char *format, ...);
 
 #endif
diff --git a/src/error.rs b/src/error.rs
index b6d90a0..b227d78 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -4,16 +4,21 @@ use core::{
     ops::{ControlFlow, FromResidual, Try},
 };
 
-use crate::header::errno::Errno;
+use crate::header::{errno::Errno, stdio::EOF};
 
 pub trait CZeroResult {
     fn into_zero_status(self) -> c_int;
+    fn into_eof_status(self) -> c_int;
 }
 
 pub trait CSizeResult {
     fn into_size_status(self) -> usize;
 }
 
+pub trait TryFromExt<T>: Sized {
+    fn e_try_from(value: T) -> EResult<Self>;
+}
+
 pub trait OptionExt<T> {
     fn e_ok_or(self, err: yggdrasil_rt::Error) -> EResult<T>;
 }
@@ -60,6 +65,13 @@ impl CZeroResult for Result<(), Errno> {
             Self::Err(_) => -1,
         }
     }
+
+    fn into_eof_status(self) -> c_int {
+        match self {
+            Self::Ok(_) => 0,
+            Self::Err(_) => EOF,
+        }
+    }
 }
 
 impl CSizeResult for Result<usize, Errno> {
diff --git a/src/file.rs b/src/file.rs
index bda0b46..3ddfdb9 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -1,3 +1,139 @@
-pub trait FileImpl {}
+use yggdrasil_rt::{
+    io::{FileMode, OpenOptions, RawFd, SeekFrom},
+    path::Path,
+    sys as syscall,
+};
 
-pub struct File {}
+use crate::{
+    error::EResult,
+    header::errno::Errno,
+    io::{Read, Seek, Write},
+};
+
+pub enum FileBacking {
+    File(File),
+}
+
+pub struct File {
+    fd: RawFd,
+    reference: bool,
+}
+
+impl File {
+    pub unsafe fn new(fd: RawFd) -> Self {
+        Self {
+            fd,
+            reference: false,
+        }
+    }
+
+    pub fn from_raw(fd: RawFd) -> Self {
+        Self {
+            fd,
+            reference: false,
+        }
+    }
+
+    pub fn open_at<P: AsRef<Path>>(
+        at: Option<RawFd>,
+        pathname: P,
+        opts: OpenOptions,
+        mode: FileMode,
+    ) -> Result<Self, Errno> {
+        let fd =
+            EResult::from(unsafe { syscall::open(at, pathname.as_ref().as_str(), opts, mode) })?;
+        Ok(Self {
+            fd,
+            reference: false,
+        })
+    }
+
+    pub unsafe fn close(&self) -> Result<(), Errno> {
+        yggdrasil_rt::debug_trace!("Close fd {:?}", self.fd);
+        EResult::from(unsafe { syscall::close(self.fd) })?;
+        Ok(())
+    }
+}
+
+impl Write for File {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        let count = EResult::from(unsafe { syscall::write(self.fd, data) })?;
+        Ok(count)
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        // TODO fsync
+        Ok(())
+    }
+}
+
+impl Read for File {
+    fn read(&mut self, data: &mut [u8]) -> Result<usize, Errno> {
+        let count = EResult::from(unsafe { syscall::read(self.fd, data) })?;
+        Ok(count)
+    }
+}
+
+impl Seek for File {
+    fn seek(&mut self, off: SeekFrom) -> Result<u64, Errno> {
+        let pos = EResult::from(unsafe { syscall::seek(self.fd, off) })?;
+        Ok(pos)
+    }
+}
+
+impl Drop for File {
+    fn drop(&mut self) {
+        if !self.reference {
+            unsafe {
+                self.close().ok();
+            }
+        }
+    }
+}
+
+impl FileBacking {
+    pub unsafe fn make_ref(&self) -> Self {
+        match self {
+            Self::File(file) => Self::File(File {
+                fd: file.fd,
+                reference: true,
+            }),
+        }
+    }
+
+    pub fn as_raw_fd(&self) -> EResult<RawFd> {
+        match self {
+            Self::File(file) => EResult::Ok(file.fd),
+        }
+    }
+}
+
+impl Write for FileBacking {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        match self {
+            Self::File(file) => file.write(data),
+        }
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        match self {
+            Self::File(file) => file.flush(),
+        }
+    }
+}
+
+impl Read for FileBacking {
+    fn read(&mut self, data: &mut [u8]) -> Result<usize, Errno> {
+        match self {
+            Self::File(file) => file.read(data),
+        }
+    }
+}
+
+impl Seek for FileBacking {
+    fn seek(&mut self, off: SeekFrom) -> Result<u64, Errno> {
+        match self {
+            Self::File(file) => file.seek(off),
+        }
+    }
+}
diff --git a/src/header/locale/cbindgen.toml b/src/header/locale/cbindgen.toml
index 2b3b191..aae38ca 100644
--- a/src/header/locale/cbindgen.toml
+++ b/src/header/locale/cbindgen.toml
@@ -7,7 +7,8 @@ no_includes = true
 include_guard = "_LOCALE_H"
 trailer = "#include <bits/locale.h>"
 
-usize_is_size_t = true
+usize_type = "size_t"
+isize_type = "ssize_t"
 
 [export]
 include = ["lconv", "locale_t"]
diff --git a/src/header/math/cbindgen.toml b/src/header/math/cbindgen.toml
index 4e5c28a..d5aa13d 100644
--- a/src/header/math/cbindgen.toml
+++ b/src/header/math/cbindgen.toml
@@ -7,6 +7,7 @@ no_includes = true
 include_guard = "_MATH_H"
 trailer = "#include <bits/math.h>"
 
-usize_is_size_t = true
+usize_type = "size_t"
+isize_type = "ssize_t"
 
 [export]
diff --git a/src/header/mod.rs b/src/header/mod.rs
index 583dcf8..6c9bbeb 100644
--- a/src/header/mod.rs
+++ b/src/header/mod.rs
@@ -1,4 +1,4 @@
-#![allow(nonstandard_style)]
+#![allow(nonstandard_style, unused_variables)]
 
 pub mod sys_types;
 pub mod sys_wait;
diff --git a/src/header/stdio/cbindgen.toml b/src/header/stdio/cbindgen.toml
index 4e51ea4..bc66c65 100644
--- a/src/header/stdio/cbindgen.toml
+++ b/src/header/stdio/cbindgen.toml
@@ -1,14 +1,25 @@
 language = "C"
 style = "Type"
 
-sys_includes = ["stdarg.h", "stddef.h", "stdint.h"]
+sys_includes = ["stdarg.h", "stddef.h", "stdint.h", "sys/types.h"]
 no_includes = true
 
 include_guard = "_STDIO_H"
 trailer = "#include <bits/stdio.h>"
 
-usize_is_size_t = true
+usize_type = "size_t"
+isize_type = "ssize_t"
 
 [export]
+include = ["fpos_t"]
 # Varargs are broken for these
-exclude = ["printf", "fprintf"]
+exclude = [
+    "printf",
+    "fprintf",
+    "sprintf",
+    "snprintf",
+    "dprintf",
+    "scanf",
+    "fscanf",
+    "sscanf"
+]
diff --git a/src/header/stdio/file.rs b/src/header/stdio/file.rs
index 78599e6..700ac71 100644
--- a/src/header/stdio/file.rs
+++ b/src/header/stdio/file.rs
@@ -1,15 +1,101 @@
-use core::ffi::{c_char, c_void};
-
-use crate::{
-    error::CSizeResult,
-    traits::{Read, Write},
+use core::{
+    ffi::{c_char, c_int, c_long, c_void, CStr},
+    ptr::null_mut,
 };
 
-use super::FILE;
+use alloc::boxed::Box;
+use yggdrasil_rt::{
+    io::{OpenOptions, RawFd, SeekFrom},
+    path::Path,
+};
+
+use crate::{
+    error::{CSizeResult, CZeroResult},
+    header::{errno::Errno, sys_types::off_t},
+    io::{Read, Seek, Write},
+};
+
+use super::{
+    fpos_t, FileFlags, FileOpenSource, FILE, SEEK_CUR, SEEK_END, SEEK_SET, _IOFBF, _IOLBF, _IONBF,
+};
+
+fn open_inner<O: FileOpenSource>(source: O, mode_str: &[u8]) -> Result<*mut FILE, Errno> {
+    let opts = match mode_str {
+        b"r" | b"rb" => OpenOptions::READ,
+        b"r+" | b"rb+" => OpenOptions::READ | OpenOptions::WRITE,
+        b"w" | b"wb" => OpenOptions::TRUNCATE | OpenOptions::WRITE,
+        b"w+" | b"wb+" => OpenOptions::TRUNCATE | OpenOptions::READ | OpenOptions::WRITE,
+        b"a" | b"ab" => OpenOptions::APPEND | OpenOptions::READ | OpenOptions::WRITE,
+        b"a+" | b"ab+" => OpenOptions::APPEND | OpenOptions::READ | OpenOptions::WRITE,
+        // TODO: errno and fail
+        _ => todo!(),
+    };
+
+    match source.open_with(opts) {
+        Ok(file) => {
+            let file = Box::into_raw(Box::new(file));
+            unsafe {
+                super::register_file(file);
+            }
+            Ok(file)
+        }
+        Err(err) => Err(err),
+    }
+}
 
 #[no_mangle]
 pub unsafe extern "C" fn fopen(pathname: *const c_char, mode: *const c_char) -> *mut FILE {
-    todo!()
+    if pathname.is_null() || mode.is_null() {
+        panic!();
+    }
+    let pathname = CStr::from_ptr(pathname);
+    let pathname = pathname.to_str().unwrap();
+    let mode = CStr::from_ptr(mode);
+
+    match open_inner(Path::from_str(pathname), mode.to_bytes()) {
+        Ok(file) => file,
+        Err(_) => null_mut(),
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn feof(stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    stream.has_flag(FileFlags::EOF) as _
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn ferror(stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    stream.has_flag(FileFlags::ERROR) as _
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn clearerr(stream: *mut FILE) {
+    let stream = stream.as_mut().unwrap();
+    stream.clear_error();
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fclose(stream: *mut FILE) -> c_int {
+    if stream.is_null() {
+        panic!();
+    }
+
+    if !super::deregister_file(stream) {
+        yggdrasil_rt::debug_trace!("fclose() non-registered file: {:p}", stream);
+    }
+
+    stream.close().into_eof_status()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fileno(stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    match stream.as_raw_fd() {
+        Ok(RawFd(fd)) => fd as _,
+        Err(_) => -1,
+    }
 }
 
 #[no_mangle]
@@ -43,3 +129,103 @@ pub unsafe extern "C" fn fread(
 
     stream.read(data).into_size_status() / size
 }
+
+#[no_mangle]
+pub unsafe extern "C" fn fflush(stream: *mut FILE) -> c_int {
+    if let Some(stream) = stream.as_mut() {
+        stream.flush().into_eof_status()
+    } else {
+        super::fflush_all().into_eof_status()
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fseek(stream: *mut FILE, offset: c_long, whence: c_int) -> c_int {
+    fseeko(stream, offset.try_into().unwrap(), whence)
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fseeko(stream: *mut FILE, offset: off_t, whence: c_int) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    let off = match whence {
+        SEEK_SET => SeekFrom::Start(offset.try_into().unwrap()),
+        SEEK_CUR => SeekFrom::Current(offset),
+        SEEK_END => SeekFrom::End(offset),
+        // TODO set errno and fail
+        _ => todo!(),
+    };
+
+    match stream.seek(off) {
+        Ok(_) => 0,
+        Err(_) => -1,
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn ftell(stream: *mut FILE) -> c_long {
+    ftello(stream).try_into().unwrap()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn ftello(stream: *mut FILE) -> off_t {
+    let stream = stream.as_mut().unwrap();
+    match stream.stream_position() {
+        Ok(p) => p.try_into().unwrap(),
+        Err(_) => -1,
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn rewind(stream: *mut FILE) {
+    fseek(stream, 0, SEEK_SET);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fgetpos(stream: *mut FILE, pos: *mut fpos_t) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    let pos = pos.as_mut().unwrap();
+    match stream.stream_position() {
+        Ok(p) => {
+            *pos = p;
+            0
+        }
+        Err(_) => -1,
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fsetpos(stream: *mut FILE, pos: *const fpos_t) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    let pos = pos.as_ref().unwrap();
+    match stream.seek(SeekFrom::Start(*pos as _)) {
+        Ok(_) => 0,
+        Err(_) => -1,
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn setvbuf(
+    stream: *mut FILE,
+    buf: *mut c_char,
+    mode: c_int,
+    size: usize,
+) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    stream.setvbuf(mode, buf, size).into_eof_status()
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn setbuf(stream: *mut FILE, buf: *mut c_char) {
+    setbuffer(stream, buf, 0);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn setbuffer(stream: *mut FILE, buf: *mut c_char, size: usize) {
+    let mode = if buf.is_null() { _IONBF } else { _IOFBF };
+    setvbuf(stream, buf, mode, size);
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn setlinebuf(stream: *mut FILE) {
+    setvbuf(stream, null_mut(), _IOLBF, 0);
+}
diff --git a/src/header/stdio/get_put.rs b/src/header/stdio/get_put.rs
index d6ed374..27278b6 100644
--- a/src/header/stdio/get_put.rs
+++ b/src/header/stdio/get_put.rs
@@ -1,8 +1,11 @@
-use core::ffi::{c_char, c_int, CStr};
+use core::{
+    ffi::{c_char, c_int, CStr},
+    ptr::null_mut,
+};
 
-use crate::{error::CZeroResult, traits::Write};
+use crate::io::{Read, Write};
 
-use super::{stdout, FILE};
+use super::{stdin, stdout, EOF, FILE};
 
 // Chars
 
@@ -11,10 +14,9 @@ unsafe extern "C" fn fputc(c: c_int, stream: *mut FILE) -> c_int {
     let stream = stream.as_mut().unwrap();
     let c = c as u8;
 
-    match stream.putc(c) {
+    match stream.write(&[c]) {
         Ok(_) => c as c_int,
-        // TODO EOF
-        Err(_) => -1,
+        Err(_) => EOF,
     }
 }
 
@@ -32,16 +34,115 @@ unsafe extern "C" fn putchar(c: c_int) -> c_int {
 
 #[no_mangle]
 unsafe extern "C" fn puts(s: *const c_char) -> c_int {
-    fputs(s, stdout)
+    let r = fputs(s, stdout);
+    if r < 0 {
+        return r;
+    }
+    fputc(b'\n' as _, stdout)
 }
 
 #[no_mangle]
 unsafe extern "C" fn fputs(s: *const c_char, stream: *mut FILE) -> c_int {
     let stream = stream.as_mut().unwrap();
     if s.is_null() {
-        return stream.puts(b"(nil)").into_zero_status();
+        panic!();
     }
     let s = CStr::from_ptr(s);
 
-    stream.puts(s.to_bytes()).into_zero_status()
+    match stream.write(s.to_bytes()) {
+        Ok(_) => 0,
+        Err(_) => EOF,
+    }
+}
+
+#[no_mangle]
+unsafe extern "C" fn fgetc(stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    let mut buf = [0];
+    match stream.read(&mut buf) {
+        Ok(1) => buf[0] as c_int,
+        Ok(_) => EOF,
+        Err(_) => EOF,
+    }
+}
+
+#[no_mangle]
+unsafe extern "C" fn getc(stream: *mut FILE) -> c_int {
+    fgetc(stream)
+}
+
+#[no_mangle]
+unsafe extern "C" fn getchar() -> c_int {
+    fgetc(stdin)
+}
+
+#[no_mangle]
+unsafe extern "C" fn fgets(s: *mut c_char, size: c_int, stream: *mut FILE) -> *mut c_char {
+    let stream = stream.as_mut().unwrap();
+
+    if size <= 0 {
+        return null_mut();
+    }
+    // Nothing to read
+    if size == 1 {
+        *s = 0;
+        return s;
+    }
+
+    let size = size as usize;
+    let mut pos = 0;
+    let mut buf = [0];
+
+    while pos < size - 1 {
+        let ch = match stream.read(&mut buf) {
+            Ok(1) => buf[0],
+            Ok(_) => {
+                break;
+            }
+            Err(err) => {
+                return null_mut();
+            }
+        };
+
+        *s.add(pos) = ch as _;
+        pos += 1;
+
+        if ch == b'\n' {
+            break;
+        }
+    }
+
+    if pos == 0 {
+        null_mut()
+    } else {
+        *s.add(pos) = 0;
+        s
+    }
+}
+
+#[no_mangle]
+unsafe extern "C" fn ungetc(c: c_int, stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    if stream.ungetc(c as _) {
+        c
+    } else {
+        EOF
+    }
+}
+
+// Line
+
+#[no_mangle]
+unsafe extern "C" fn getdelim(
+    lineptr: *mut *mut c_char,
+    n: *mut usize,
+    delim: c_int,
+    stream: *mut FILE,
+) -> isize {
+    todo!()
+}
+
+#[no_mangle]
+unsafe extern "C" fn getline(lineptr: *mut *mut c_char, n: *mut usize, stream: *mut FILE) -> isize {
+    todo!()
 }
diff --git a/src/header/stdio/mod.rs b/src/header/stdio/mod.rs
index 3eaace1..70bd238 100644
--- a/src/header/stdio/mod.rs
+++ b/src/header/stdio/mod.rs
@@ -1,30 +1,31 @@
-use core::{fmt, mem::MaybeUninit, ptr};
+use core::{
+    ffi::{c_char, c_int},
+    fmt, ptr,
+};
 
-use alloc::{boxed::Box, vec, vec::Vec};
-use yggdrasil_rt::{io::RawFd, sys as syscall};
+use alloc::{boxed::Box, collections::BTreeSet, vec::Vec};
+use bitflags::bitflags;
+use yggdrasil_rt::{
+    io::{FileMode, OpenOptions, RawFd, SeekFrom},
+    path::Path,
+};
 
 use crate::{
-    error::EResult,
+    error::{EResult, TryFromExt},
+    file::{File, FileBacking},
+    io::{
+        buffered::{BufWriter, FileWriter, LineWriter, ReadBuffer, UnbufferedWriter},
+        BufRead, Read, Seek, Write,
+    },
     sync::{Mutex, RawMutex},
-    traits::{Read, Write},
 };
 
 use super::errno::Errno;
 
 // TODO:
-//
-// fpos_t
-// off_t -> sys/types.h
-// ssize_t -> sys/types.h
-//
-// BUFSIZ
 // L_ctermid
 // L_tmpnam
 //
-// _IOFBF
-// _IOLBF
-// _IONBF
-//
 // SEEK_CUR
 // SEEK_END
 // SEEK_SET
@@ -38,196 +39,427 @@ use super::errno::Errno;
 // P_tmpdir
 
 /*
-void     clearerr(FILE *);
 char    *ctermid(char *);
-int      dprintf(int, const char *restrict, ...)
-int      fclose(FILE *);
 FILE    *fdopen(int, const char *);
-int      feof(FILE *);
-int      ferror(FILE *);
-int      fflush(FILE *);
-int      fgetc(FILE *);
-int      fgetpos(FILE *restrict, fpos_t *restrict);
-char    *fgets(char *restrict, int, FILE *restrict);
-int      fileno(FILE *);
 void     flockfile(FILE *);
 FILE    *fmemopen(void *restrict, size_t, const char *restrict);
-FILE    *fopen(const char *restrict, const char *restrict);
-int      fprintf(FILE *restrict, const char *restrict, ...);
-int      fputc(int, FILE *);
-size_t   fread(void *restrict, size_t, size_t, FILE *restrict);
 FILE    *freopen(const char *restrict, const char *restrict,
              FILE *restrict);
-int      fscanf(FILE *restrict, const char *restrict, ...);
-int      fseek(FILE *, long, int);
-int      fseeko(FILE *, off_t, int);
-int      fsetpos(FILE *, const fpos_t *);
-long     ftell(FILE *);
-off_t    ftello(FILE *);
 int      ftrylockfile(FILE *);
 void     funlockfile(FILE *);
-int      getc(FILE *);
-int      getchar(void);
-int      getc_unlocked(FILE *);
-int      getchar_unlocked(void);
-ssize_t  getdelim(char **restrict, size_t *restrict, int,
-             FILE *restrict);
-ssize_t  getline(char **restrict, size_t *restrict, FILE *restrict);
-char    *gets(char *);
 FILE    *open_memstream(char **, size_t *);
 int      pclose(FILE *);
 void     perror(const char *);
 FILE    *popen(const char *, const char *);
-int      putc(int, FILE *);
-int      putchar(int);
-int      putc_unlocked(int, FILE *);
-int      putchar_unlocked(int);
 int      remove(const char *);
 int      rename(const char *, const char *);
 int      renameat(int, const char *, int, const char *);
-void     rewind(FILE *);
-int      scanf(const char *restrict, ...);
-void     setbuf(FILE *restrict, char *restrict);
-int      setvbuf(FILE *restrict, char *restrict, int, size_t);
-int      snprintf(char *restrict, size_t, const char *restrict, ...);
-int      sprintf(char *restrict, const char *restrict, ...);
-int      sscanf(const char *restrict, const char *restrict, ...);
 char    *tempnam(const char *, const char *);
 FILE    *tmpfile(void);
 char    *tmpnam(char *);
-int      ungetc(int, FILE *);
-int      vdprintf(int, const char *restrict, va_list);
-int      vfscanf(FILE *restrict, const char *restrict, va_list);
-int      vscanf(const char *restrict, va_list);
-int      vsnprintf(char *restrict, size_t, const char *restrict,
-             va_list);
-int      vsprintf(char *restrict, const char *restrict, va_list);
-int      vsscanf(const char *restrict, const char *restrict, va_list);
+
+
+
+
+
 */
 
+macro_rules! locked_op {
+    ($self:expr, $op:expr) => {{
+        $self.lock.lock();
+        let result = unsafe { $op };
+        unsafe { $self.lock.release() }
+        result
+    }};
+}
+
 mod file;
 mod get_put;
 mod printf;
+mod scanf;
+mod unlocked;
 
-struct FileInner(RawFd);
+pub trait FileOpenSource {
+    fn open_with(self, opts: OpenOptions) -> Result<FILE, Errno>;
+}
+
+pub enum BufferingMode {
+    Full,
+    Line,
+    None,
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum Direction {
+    Read,
+    Write,
+}
+
+bitflags! {
+    pub struct FileFlags: u32 {
+        const ERROR = 1 << 0;
+        const EOF = 1 << 1;
+        const READ = 1 << 2;
+        const WRITE = 1 << 3;
+        const BUILTIN = 1 << 4;
+    }
+}
 
 pub struct FILE {
     lock: RawMutex,
 
-    file: FileInner,
+    inner: FileBacking,
+    output: Box<dyn FileWriter>,
+    read_buffer: Option<ReadBuffer<'static>>,
 
-    error: bool,
-    eof: bool,
+    flags: FileFlags,
 
-    buffer: Vec<u8>,
-    unget_buffer: Vec<u8>,
-    read_pos: usize,
-    read_size: usize,
-}
+    ungetc: Vec<u8>,
 
-impl FileInner {
-    unsafe fn read(&mut self, data: &mut [u8]) -> Result<usize, Errno> {
-        let count = EResult::from(syscall::read(self.0, data))?;
-        Ok(count)
-    }
+    // NOTE:
+    // man setvbuf(3):
+    //  The setvbuf() function may be used only after opening a stream and
+    //  before any other  operations have been performed on it.
+    last_operation: Option<Direction>,
 }
 
 impl FILE {
-    unsafe fn new_builtin(fd: RawFd) -> Self {
+    pub unsafe fn from_c_file(file: File, flags: FileFlags) -> Self {
+        assert!(!flags.contains(FileFlags::BUILTIN));
+        let inner = FileBacking::File(file);
+        // TODO run is_terminal on file and check for desired buffering mode
         Self {
             lock: RawMutex::new(),
 
-            file: FileInner(fd),
+            output: Box::new(BufWriter::with_capacity(inner.make_ref(), BUFSIZ)),
+            inner,
+            read_buffer: Some(ReadBuffer::owned(BUFSIZ)),
 
-            eof: false,
-            error: false,
+            flags,
 
-            buffer: vec![0; 1024],
-            unget_buffer: vec![],
-            read_pos: 0,
-            read_size: 0,
+            ungetc: Vec::new(),
+
+            last_operation: None,
         }
     }
 
-    pub fn puts(&mut self, data: &[u8]) -> Result<(), Errno> {
-        self.write(data)?;
-        self.write(b"\n")?;
-        Ok(())
-    }
+    pub unsafe fn new_builtin(fd: RawFd, flags: FileFlags) -> Self {
+        let inner = FileBacking::File(File::new(fd));
+        Self {
+            lock: RawMutex::new(),
 
-    unsafe fn fill_buf(&mut self) -> Result<&[u8], Errno> {
-        if self.read_pos == self.read_size {
-            self.read_size = match self.file.read(&mut self.buffer) {
-                Ok(0) => {
-                    self.eof = true;
-                    0
-                }
-                Ok(n) => n,
-                Err(err) => {
-                    self.error = true;
-                    return Err(err);
-                }
-            };
-            self.read_pos = 0;
+            output: Box::new(LineWriter::with_capacity(inner.make_ref(), BUFSIZ)),
+            inner,
+            read_buffer: Some(ReadBuffer::owned(BUFSIZ)),
+
+            flags: FileFlags::BUILTIN | flags,
+
+            ungetc: Vec::new(),
+
+            last_operation: None,
         }
-
-        Ok(&self.buffer[self.read_pos..self.read_size])
     }
 
-    unsafe fn consume(&mut self, len: usize) {
-        self.read_pos = (self.read_pos + len).min(self.read_size);
+    pub unsafe fn close(self: *mut Self) -> Result<(), Errno> {
+        // TODO lock needed?
+        let r = self.as_mut().unwrap();
+        r.flush()?;
+        if r.flags.contains(FileFlags::BUILTIN) {
+            // NOTE The OS will close the file for us
+            Ok(())
+        } else {
+            // Drop the file
+            drop(Box::from_raw(self));
+            Ok(())
+        }
+    }
+
+    pub unsafe fn as_raw_fd_unlocked(&mut self) -> Result<RawFd, Errno> {
+        let fd = self.inner.as_raw_fd()?;
+        Ok(fd)
+    }
+
+    pub fn as_raw_fd(&mut self) -> Result<RawFd, Errno> {
+        locked_op!(self, self.as_raw_fd_unlocked())
+    }
+
+    pub unsafe fn clear_error_unlocked(&mut self) {
+        self.flags &= !FileFlags::ERROR;
+    }
+
+    pub fn clear_error(&mut self) {
+        locked_op!(self, self.clear_error_unlocked());
+    }
+
+    pub fn has_flag(&mut self, flag: FileFlags) -> bool {
+        locked_op!(self, self.has_flag_unlocked(flag))
+    }
+
+    pub unsafe fn has_flag_unlocked(&self, flag: FileFlags) -> bool {
+        self.flags.contains(flag)
+    }
+
+    pub fn setvbuf(
+        &mut self,
+        mode: c_int,
+        buffer: *mut c_char,
+        capacity: usize,
+    ) -> Result<(), Errno> {
+        locked_op!(self, self.setvbuf_unlocked(mode, buffer, capacity))
+    }
+
+    pub unsafe fn write_unlocked(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        self.set_direction(Direction::Write)?;
+
+        match self.output.write(data) {
+            Ok(amount) => Ok(amount),
+            Err(err) => {
+                self.flags |= FileFlags::ERROR;
+                Err(err)
+            }
+        }
+    }
+
+    pub unsafe fn flush_unlocked(&mut self) -> Result<(), Errno> {
+        match self.output.flush() {
+            Ok(()) => {
+                self.last_operation = None;
+                Ok(())
+            }
+            Err(err) => {
+                self.flags |= FileFlags::ERROR;
+                Err(err)
+            }
+        }
     }
 
     pub unsafe fn read_unlocked(&mut self, data: &mut [u8]) -> Result<usize, Errno> {
-        let unget_len = core::cmp::min(self.unget_buffer.len(), data.len());
-        for i in 0..unget_len {
-            data[i] = self.unget_buffer.pop().unwrap();
-        }
-        if unget_len != 0 {
-            return Ok(unget_len);
-        }
-        let len = {
-            let buf = unsafe { self.fill_buf()? };
-            let len = buf.len().min(data.len());
+        self.set_direction(Direction::Read)?;
 
+        if !self.ungetc.is_empty() {
+            // Read from ungetc
+            let amount = core::cmp::min(self.ungetc.len(), data.len());
+            data[..amount].copy_from_slice(&self.ungetc[..amount]);
+            self.ungetc.drain(..amount);
+            return Ok(amount);
+        }
+
+        if self.read_buffer.is_some() {
+            let buf = self.fill_buf()?;
+            let len = core::cmp::min(data.len(), buf.len());
             data[..len].copy_from_slice(&buf[..len]);
-            len
-        };
-        unsafe {
             self.consume(len);
+            Ok(len)
+        } else {
+            match self.inner.read(data) {
+                Ok(0) => {
+                    self.flags |= FileFlags::EOF;
+                    Ok(0)
+                }
+                Ok(n) => Ok(n),
+                Err(err) => {
+                    self.flags |= FileFlags::ERROR;
+                    Err(err)
+                }
+            }
         }
-        Ok(len)
     }
-}
 
-impl Read for FILE {
-    fn read(&mut self, data: &mut [u8]) -> Result<usize, Errno> {
-        self.lock.lock();
-        let result = unsafe { self.read_unlocked(data) };
-        unsafe {
-            self.lock.release();
+    unsafe fn ungetc_unlocked(&mut self, ch: u8) -> bool {
+        // ungetc() for write doesn't make any sense
+        if self.set_direction(Direction::Read).is_err() {
+            return false;
         }
-        result
+        if self.ungetc.len() == UNGETC_MAX {
+            return false;
+        }
+        self.ungetc.push(ch);
+        true
     }
-}
 
-impl Write for FILE {
-    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
-        // TODO
-        self.lock.lock();
-        let count = EResult::from(unsafe { syscall::write(self.file.0, data) })?;
-        unsafe {
-            self.lock.release();
+    pub fn ungetc(&mut self, ch: u8) -> bool {
+        locked_op!(self, self.ungetc_unlocked(ch))
+    }
+
+    fn reset(&mut self) {
+        if let Some(read_buffer) = self.read_buffer.as_mut() {
+            read_buffer.reset();
+        }
+        self.output.reset();
+        self.ungetc.clear();
+        self.last_operation = None;
+        self.flags &= !(FileFlags::ERROR | FileFlags::EOF);
+    }
+
+    unsafe fn setvbuf_unlocked(
+        &mut self,
+        mode: c_int,
+        buffer: *mut c_char,
+        capacity: usize,
+    ) -> Result<(), Errno> {
+        let mode = BufferingMode::e_try_from(mode)?;
+
+        if self.last_operation.is_some() {
+            // TODO EINVAL?
+            todo!();
+        }
+
+        let mut read_capacity = capacity;
+        let mut write_capacity = capacity;
+
+        // Set read buffer
+        match mode {
+            BufferingMode::None => self.read_buffer = None,
+            BufferingMode::Full | BufferingMode::Line => {
+                if buffer.is_null() || read_capacity == 0 {
+                    if read_capacity == 0 {
+                        read_capacity = BUFSIZ;
+                    }
+
+                    self.read_buffer = Some(ReadBuffer::owned(read_capacity));
+                } else {
+                    let slice =
+                        unsafe { core::slice::from_raw_parts_mut(buffer as *mut _, capacity) };
+                    self.read_buffer = Some(ReadBuffer::borrowed(slice));
+                }
+            }
+        }
+
+        // Set write buffer
+        let file_ref = unsafe { self.inner.make_ref() };
+        match mode {
+            BufferingMode::None => self.output = Box::new(UnbufferedWriter::new(file_ref)),
+            BufferingMode::Line => {
+                if write_capacity == 0 {
+                    write_capacity = BUFSIZ;
+                }
+                self.output = Box::new(LineWriter::with_capacity(file_ref, write_capacity))
+            }
+            BufferingMode::Full => {
+                if write_capacity == 0 {
+                    write_capacity = BUFSIZ;
+                }
+                self.output = Box::new(LineWriter::with_capacity(file_ref, write_capacity))
+            }
+        }
+
+        Ok(())
+    }
+
+    unsafe fn seek_unlocked(&mut self, off: SeekFrom) -> Result<u64, Errno> {
+        self.flush_unlocked()?;
+        self.ungetc.clear();
+
+        match self.inner.seek(off) {
+            Ok(pos) => {
+                self.flags &= !FileFlags::EOF;
+                Ok(pos)
+            }
+            Err(err) => {
+                self.flags |= FileFlags::ERROR;
+                Err(err)
+            }
+        }
+    }
+
+    unsafe fn set_direction(&mut self, direction: Direction) -> Result<(), Errno> {
+        match self.last_operation.replace(direction) {
+            Some(dir) if dir != direction => {
+                self.flags |= FileFlags::ERROR;
+                todo!()
+            }
+            _ => Ok(()),
         }
-        Ok(count)
     }
 }
 
 impl fmt::Write for FILE {
     fn write_str(&mut self, s: &str) -> fmt::Result {
-        match self.write(s.as_bytes()) {
-            Ok(_) => Ok(()),
-            Err(_) => Err(fmt::Error),
+        self.write_all(s.as_bytes()).map_err(|_| fmt::Error)
+    }
+}
+
+impl Write for FILE {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        locked_op!(self, self.write_unlocked(data))
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        locked_op!(self, self.flush_unlocked())
+    }
+}
+
+impl Read for FILE {
+    fn read(&mut self, data: &mut [u8]) -> Result<usize, Errno> {
+        locked_op!(self, self.read_unlocked(data))
+    }
+}
+
+// NOTE assumes file is locked
+impl BufRead for FILE {
+    fn fill_buf(&mut self) -> Result<&[u8], Errno> {
+        let buffer = self.read_buffer.as_mut().unwrap();
+        match buffer.fill_from(&mut self.inner) {
+            Ok(slice) => {
+                if slice.len() == 0 {
+                    self.flags |= FileFlags::EOF;
+                }
+                Ok(slice)
+            }
+            Err(err) => {
+                self.flags |= FileFlags::ERROR;
+                Err(err)
+            }
+        }
+    }
+
+    fn consume(&mut self, amount: usize) {
+        let buffer = self.read_buffer.as_mut().unwrap();
+        buffer.consume(amount)
+    }
+}
+
+impl Seek for FILE {
+    fn seek(&mut self, off: SeekFrom) -> Result<u64, Errno> {
+        locked_op!(self, self.seek_unlocked(off))
+    }
+}
+
+impl FileOpenSource for &Path {
+    fn open_with(self, opts: OpenOptions) -> Result<FILE, Errno> {
+        let f = File::open_at(None, self, opts, FileMode::default_file())?;
+        let mut flags = FileFlags::empty();
+        if opts.contains(OpenOptions::READ) {
+            flags |= FileFlags::READ;
+        }
+        if opts.contains(OpenOptions::WRITE) {
+            flags |= FileFlags::WRITE;
+        }
+        Ok(unsafe { FILE::from_c_file(f, flags) })
+    }
+}
+
+impl FileOpenSource for RawFd {
+    fn open_with(self, opts: OpenOptions) -> Result<FILE, Errno> {
+        let f = File::from_raw(self);
+        let mut flags = FileFlags::empty();
+        if opts.contains(OpenOptions::READ) {
+            flags |= FileFlags::READ;
+        }
+        if opts.contains(OpenOptions::WRITE) {
+            flags |= FileFlags::WRITE;
+        }
+        Ok(unsafe { FILE::from_c_file(f, flags) })
+    }
+}
+
+impl TryFromExt<c_int> for BufferingMode {
+    fn e_try_from(value: c_int) -> EResult<Self> {
+        match value {
+            _IOFBF => EResult::Ok(Self::Full),
+            _IOLBF => EResult::Ok(Self::Line),
+            _IONBF => EResult::Ok(Self::None),
+            _ => EResult::Err(yggdrasil_rt::Error::InvalidArgument),
         }
     }
 }
@@ -239,12 +471,68 @@ pub static mut stdout: *mut FILE = ptr::null_mut();
 #[no_mangle]
 pub static mut stderr: *mut FILE = ptr::null_mut();
 
+pub const _IOFBF: c_int = 0;
+pub const _IOLBF: c_int = 1;
+pub const _IONBF: c_int = 2;
+
+pub const SEEK_SET: c_int = 0;
+pub const SEEK_CUR: c_int = 1;
+pub const SEEK_END: c_int = 2;
+
+pub const EOF: c_int = -1;
+
+pub type fpos_t = u64;
+
+pub const BUFSIZ: usize = 8192;
+
+const UNGETC_MAX: usize = 128;
+
+pub static OPEN_FILES: Mutex<BTreeSet<*mut FILE>> = Mutex::new(BTreeSet::new());
+
+pub unsafe fn register_file(file: *mut FILE) {
+    OPEN_FILES.lock().insert(file);
+}
+
+pub unsafe fn deregister_file(file: *mut FILE) -> bool {
+    OPEN_FILES.lock().remove(&file)
+}
+
 pub unsafe fn setup_default_files() {
-    let stdin_ = Box::into_raw(Box::new(FILE::new_builtin(RawFd::STDIN)));
-    let stdout_ = Box::into_raw(Box::new(FILE::new_builtin(RawFd::STDOUT)));
-    let stderr_ = Box::into_raw(Box::new(FILE::new_builtin(RawFd::STDERR)));
+    let stdin_ = Box::into_raw(Box::new(FILE::new_builtin(RawFd::STDIN, FileFlags::READ)));
+    let stdout_ = Box::into_raw(Box::new(FILE::new_builtin(RawFd::STDOUT, FileFlags::WRITE)));
+    let stderr_ = Box::into_raw(Box::new(FILE::new_builtin(RawFd::STDERR, FileFlags::WRITE)));
 
     stdin = stdin_;
     stdout = stdout_;
     stderr = stderr_;
+
+    let mut open_files = OPEN_FILES.lock();
+    open_files.insert(stdin);
+    open_files.insert(stdout);
+    open_files.insert(stderr);
+}
+
+pub fn fflush_all() -> Result<(), Errno> {
+    let open_files = OPEN_FILES.lock();
+    for &file in open_files.iter() {
+        unsafe {
+            file.as_mut().unwrap().flush()?;
+        }
+    }
+    Ok(())
+}
+
+pub unsafe fn fflush_all_unlocked() -> Result<(), Errno> {
+    let open_files = OPEN_FILES.lock();
+    for &file in open_files.iter() {
+        file.as_mut().unwrap().flush_unlocked()?;
+    }
+    Ok(())
+}
+
+pub unsafe fn cleanup() {
+    let mut open_files = OPEN_FILES.lock();
+    while let Some(file) = open_files.pop_first() {
+        file.close().ok();
+    }
 }
diff --git a/src/header/stdio/printf/float.rs b/src/header/stdio/printf/float.rs
index daeb0df..fafdd88 100644
--- a/src/header/stdio/printf/float.rs
+++ b/src/header/stdio/printf/float.rs
@@ -1,10 +1,10 @@
-use core::{ffi::c_double, num::FpCategory};
+use core::{ffi::c_double, fmt, num::FpCategory};
 
 use alloc::{format, string::String};
 
 use crate::{
     header::errno::{Errno, EINVAL},
-    traits::Write,
+    io::Write,
 };
 
 use super::format::FmtOpts;
@@ -30,7 +30,7 @@ fn float_exp(mut val: c_double) -> (c_double, isize) {
     (val, exp)
 }
 
-fn fmt_float_exp<W: Write>(
+fn fmt_float_exp<W: Write + fmt::Write>(
     val: c_double,
     exp: isize,
     exp_fmt: u8,
@@ -38,9 +38,6 @@ fn fmt_float_exp<W: Write>(
     precision: usize,
     opts: &FmtOpts,
 ) -> Result<usize, Errno> {
-    // TODO padding
-    use core::fmt::Write as FW;
-
     let mut exp2 = exp;
     let mut exp_len = 1;
     while exp2 >= 10 {
@@ -65,7 +62,7 @@ fn fmt_float_string(val: c_double, precision: usize) -> String {
     string
 }
 
-fn fmt_float_finite<W: Write>(
+fn fmt_float_finite<W: Write + fmt::Write>(
     val: c_double,
     output: &mut W,
     precision: usize,
@@ -78,7 +75,7 @@ fn fmt_float_finite<W: Write>(
     Ok(lpad + flen + rpad)
 }
 
-fn fmt_float_nonfinite<W: Write>(
+fn fmt_float_nonfinite<W: Write + fmt::Write>(
     val: c_double,
     output: &mut W,
     upper: bool,
@@ -108,7 +105,7 @@ fn fmt_float_nonfinite<W: Write>(
     Ok(len + lpad + flen + rpad)
 }
 
-pub fn fmt_float<W: Write>(
+pub fn fmt_float<W: Write + fmt::Write>(
     val: c_double,
     output: &mut W,
     upper: bool,
@@ -121,7 +118,7 @@ pub fn fmt_float<W: Write>(
     }
 }
 
-pub fn fmt_float_scientific<W: Write>(
+pub fn fmt_float_scientific<W: Write + fmt::Write>(
     val: c_double,
     output: &mut W,
     upper: bool,
@@ -141,7 +138,7 @@ pub fn fmt_float_scientific<W: Write>(
     }
 }
 
-pub fn fmt_float_any<W: Write>(
+pub fn fmt_float_any<W: Write + fmt::Write>(
     val: c_double,
     output: &mut W,
     upper: bool,
diff --git a/src/header/stdio/printf/format.rs b/src/header/stdio/printf/format.rs
index 7192901..5901eb2 100644
--- a/src/header/stdio/printf/format.rs
+++ b/src/header/stdio/printf/format.rs
@@ -1,11 +1,14 @@
-use core::ffi::{
-    c_char, c_double, c_int, c_long, c_longlong, c_short, c_uchar, c_uint, c_ulong, c_ulonglong,
-    c_ushort, CStr, VaList,
+use core::{
+    ffi::{
+        c_char, c_double, c_int, c_long, c_longlong, c_short, c_uchar, c_uint, c_ulong,
+        c_ulonglong, c_ushort, CStr, VaList,
+    },
+    fmt,
 };
 
 use alloc::string::String;
 
-use crate::{header::errno::Errno, traits::Write, types::wchar_t};
+use crate::{header::errno::Errno, io::Write, types::wchar_t};
 
 use super::float::{fmt_float, fmt_float_any, fmt_float_scientific};
 
@@ -140,7 +143,7 @@ impl FmtSize {
 }
 
 impl FmtOpts {
-    fn pad<W: Write>(&self, output: &mut W, len: usize) -> Result<usize, Errno> {
+    fn pad<W: Write + fmt::Write>(&self, output: &mut W, len: usize) -> Result<usize, Errno> {
         let pad = self.width - core::cmp::min(self.width, len);
         for _ in 0..pad {
             output.write(&[self.pad_char])?;
@@ -148,7 +151,11 @@ impl FmtOpts {
         Ok(pad)
     }
 
-    pub fn left_pad<W: Write>(&self, output: &mut W, len: usize) -> Result<usize, Errno> {
+    pub fn left_pad<W: Write + fmt::Write>(
+        &self,
+        output: &mut W,
+        len: usize,
+    ) -> Result<usize, Errno> {
         if !self.left_adjust {
             self.pad(output, len)
         } else {
@@ -156,7 +163,11 @@ impl FmtOpts {
         }
     }
 
-    pub fn right_pad<W: Write>(&self, output: &mut W, len: usize) -> Result<usize, Errno> {
+    pub fn right_pad<W: Write + fmt::Write>(
+        &self,
+        output: &mut W,
+        len: usize,
+    ) -> Result<usize, Errno> {
         if self.left_adjust {
             self.pad(output, len)
         } else {
@@ -164,7 +175,7 @@ impl FmtOpts {
         }
     }
 
-    pub fn fmt<W: Write>(
+    pub fn fmt<W: Write + fmt::Write>(
         &self,
         spec: FmtSpec,
         output: &mut W,
diff --git a/src/header/stdio/printf/mod.rs b/src/header/stdio/printf/mod.rs
index 36f89ad..8ec712f 100644
--- a/src/header/stdio/printf/mod.rs
+++ b/src/header/stdio/printf/mod.rs
@@ -1,6 +1,11 @@
-use core::ffi::{c_char, c_int, CStr, VaList};
+use core::{
+    ffi::{c_char, c_int, CStr, VaList},
+    fmt,
+};
 
-use crate::{header::errno::Errno, traits::Write};
+use yggdrasil_rt::{io::RawFd, sys as syscall};
+
+use crate::{error::EResult, header::errno::Errno, io::Write};
 
 use self::format::{FmtOpts, FmtRadix, FmtSign, FmtSize, FmtSpec};
 
@@ -9,14 +14,86 @@ use super::{stdout, FILE};
 mod float;
 mod format;
 
-fn printf_inner<W: Write>(output: &mut W, format: &[u8], mut ap: VaList) -> Result<usize, Errno> {
+struct StringWriter {
+    buffer: *mut c_char,
+    position: usize,
+    capacity: usize,
+}
+
+struct FdWriter {
+    fd: RawFd,
+}
+
+impl StringWriter {
+    pub fn new(buffer: *mut c_char, capacity: usize) -> Self {
+        Self {
+            buffer,
+            capacity,
+            position: 0,
+        }
+    }
+}
+
+impl Write for StringWriter {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        let count = core::cmp::min(self.capacity - self.position, data.len());
+        if count > 0 {
+            let dst = unsafe {
+                core::slice::from_raw_parts_mut(self.buffer.add(self.position) as *mut u8, count)
+            };
+            dst.copy_from_slice(&data[..count]);
+            self.position += count;
+        }
+        Ok(count)
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        todo!()
+    }
+}
+
+impl fmt::Write for StringWriter {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write(s.as_bytes()).map_err(|_| fmt::Error)?;
+        Ok(())
+    }
+}
+
+impl FdWriter {
+    pub fn new(fd: RawFd) -> Self {
+        Self { fd }
+    }
+}
+
+impl Write for FdWriter {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        let count = EResult::from(unsafe { syscall::write(self.fd, data) })?;
+        Ok(count)
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        todo!()
+    }
+}
+
+impl fmt::Write for FdWriter {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write(s.as_bytes()).map_err(|_| fmt::Error)?;
+        Ok(())
+    }
+}
+
+fn printf_inner<W: Write + fmt::Write>(
+    output: &mut W,
+    format: &[u8],
+    mut ap: VaList,
+) -> Result<usize, Errno> {
     let mut fmt = format.into_iter();
     let mut count = 0;
 
     while let Some(&c) = fmt.next() {
         if c != b'%' {
-            output.putc(c)?;
-            count += 1;
+            count += output.write(&[c])?;
             continue;
         }
 
@@ -131,3 +208,74 @@ unsafe extern "C" fn vfprintf(stream: *mut FILE, format: *const c_char, ap: VaLi
         Err(_) => -1,
     }
 }
+
+#[no_mangle]
+unsafe extern "C" fn sprintf(str: *mut c_char, format: *const c_char, mut args: ...) -> c_int {
+    vsnprintf(str, usize::MAX, format, args.as_va_list())
+}
+
+#[no_mangle]
+unsafe extern "C" fn snprintf(
+    str: *mut c_char,
+    len: usize,
+    format: *const c_char,
+    mut args: ...
+) -> c_int {
+    vsnprintf(str, len, format, args.as_va_list())
+}
+
+#[no_mangle]
+unsafe extern "C" fn vsprintf(str: *mut c_char, format: *const c_char, ap: VaList) -> c_int {
+    vsnprintf(str, usize::MAX, format, ap)
+}
+
+#[no_mangle]
+unsafe extern "C" fn vsnprintf(
+    str: *mut c_char,
+    len: usize,
+    format: *const c_char,
+    ap: VaList,
+) -> c_int {
+    if format.is_null() {
+        panic!();
+    }
+    if len == 0 {
+        return 0;
+    }
+    if str.is_null() {
+        // TODO output the length
+        todo!()
+    }
+    let mut writer = StringWriter::new(str, len);
+    let format = CStr::from_ptr(format);
+
+    match printf_inner(&mut writer, format.to_bytes(), ap) {
+        // TODO handle this
+        Ok(count) => count as c_int,
+        Err(_) => -1,
+    }
+}
+
+#[no_mangle]
+unsafe extern "C" fn dprintf(fd: c_int, format: *const c_char, mut args: ...) -> c_int {
+    vdprintf(fd, format, args.as_va_list())
+}
+
+#[no_mangle]
+unsafe extern "C" fn vdprintf(fd: c_int, format: *const c_char, ap: VaList) -> c_int {
+    if format.is_null() {
+        panic!();
+    }
+    if fd < 0 {
+        // TODO set errno and return
+        todo!();
+    }
+    let mut writer = FdWriter::new(RawFd(fd as u32));
+    let format = CStr::from_ptr(format);
+
+    match printf_inner(&mut writer, format.to_bytes(), ap) {
+        // TODO handle this
+        Ok(count) => count as c_int,
+        Err(_) => -1,
+    }
+}
diff --git a/src/header/stdio/scanf.rs b/src/header/stdio/scanf.rs
new file mode 100644
index 0000000..906ae63
--- /dev/null
+++ b/src/header/stdio/scanf.rs
@@ -0,0 +1,42 @@
+/*
+int      fscanf(FILE *restrict, const char *restrict, ...);
+int      scanf(const char *restrict, ...);
+int      sscanf(const char *restrict, const char *restrict, ...);
+int      vfscanf(FILE *restrict, const char *restrict, va_list);
+int      vscanf(const char *restrict, va_list);
+int      vsscanf(const char *restrict, const char *restrict, va_list);
+ */
+
+use core::ffi::{c_char, c_int, VaList};
+
+use super::{stdin, FILE};
+
+#[no_mangle]
+unsafe extern "C" fn fscanf(stream: *mut FILE, format: *const c_char, mut args: ...) -> c_int {
+    vfscanf(stream, format, args.as_va_list())
+}
+
+#[no_mangle]
+unsafe extern "C" fn scanf(format: *const c_char, mut args: ...) -> c_int {
+    vfscanf(stdin, format, args.as_va_list())
+}
+
+#[no_mangle]
+unsafe extern "C" fn sscanf(str: *const c_char, format: *const c_char, mut args: ...) -> c_int {
+    vsscanf(str, format, args.as_va_list())
+}
+
+#[no_mangle]
+unsafe extern "C" fn vfscanf(stream: *mut FILE, format: *const c_char, ap: VaList) -> c_int {
+    todo!()
+}
+
+#[no_mangle]
+unsafe extern "C" fn vscanf(format: *const c_char, ap: VaList) -> c_int {
+    vfscanf(stdin, format, ap)
+}
+
+#[no_mangle]
+unsafe extern "C" fn vsscanf(str: *const c_char, format: *const c_char, ap: VaList) -> c_int {
+    todo!()
+}
diff --git a/src/header/stdio/unlocked.rs b/src/header/stdio/unlocked.rs
new file mode 100644
index 0000000..d57b8b6
--- /dev/null
+++ b/src/header/stdio/unlocked.rs
@@ -0,0 +1,90 @@
+use core::ffi::{c_int, c_void};
+
+use yggdrasil_rt::io::RawFd;
+
+use crate::error::{CSizeResult, CZeroResult};
+
+use super::{FileFlags, FILE};
+
+#[no_mangle]
+pub unsafe extern "C" fn feof_unlocked(stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    stream.has_flag_unlocked(FileFlags::EOF) as _
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn ferror_unlocked(stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    stream.has_flag_unlocked(FileFlags::ERROR) as _
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn clearerr_unlocked(stream: *mut FILE) {
+    let stream = stream.as_mut().unwrap();
+    stream.clear_error_unlocked();
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fileno_unlocked(stream: *mut FILE) -> c_int {
+    let stream = stream.as_mut().unwrap();
+    match stream.as_raw_fd_unlocked() {
+        Ok(RawFd(fd)) => fd as _,
+        Err(_) => -1,
+    }
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fwrite_unlocked(
+    ptr: *mut c_void,
+    size: usize,
+    nmemb: usize,
+    stream: *mut FILE,
+) -> usize {
+    if ptr.is_null() {
+        panic!();
+    }
+    let stream = stream.as_mut().unwrap();
+    let data = core::slice::from_raw_parts(ptr as *const u8, size * nmemb);
+
+    stream.write_unlocked(data).into_size_status() / size
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fread_unlocked(
+    ptr: *mut c_void,
+    size: usize,
+    nmemb: usize,
+    stream: *mut FILE,
+) -> usize {
+    if ptr.is_null() {
+        panic!();
+    }
+    let stream = stream.as_mut().unwrap();
+    let data = core::slice::from_raw_parts_mut(ptr as *mut u8, size * nmemb);
+
+    stream.read_unlocked(data).into_size_status() / size
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn fflush_unlocked(stream: *mut FILE) -> c_int {
+    if let Some(stream) = stream.as_mut() {
+        stream.flush_unlocked().into_eof_status()
+    } else {
+        super::fflush_all_unlocked().into_eof_status()
+    }
+}
+
+/*
+int getc_unlocked(FILE *stream);
+int getchar_unlocked(void);
+int putc_unlocked(int c, FILE *stream);
+int putchar_unlocked(int c);
+
+int fgetc_unlocked(FILE *stream);
+int fputc_unlocked(int c, FILE *stream);
+*/
+
+#[no_mangle]
+pub unsafe extern "C" fn getc_unlocked(stream: *mut FILE) -> c_int {
+    todo!()
+}
diff --git a/src/header/stdlib/cbindgen.toml b/src/header/stdlib/cbindgen.toml
index 4758ec7..1667693 100644
--- a/src/header/stdlib/cbindgen.toml
+++ b/src/header/stdlib/cbindgen.toml
@@ -6,7 +6,8 @@ no_includes = true
 
 include_guard = "_STDLIB_H"
 
-usize_is_size_t = true
+usize_type = "size_t"
+isize_type = "ssize_t"
 
 [export]
 exclude = []
diff --git a/src/header/string/cbindgen.toml b/src/header/string/cbindgen.toml
index f78711c..5220d5e 100644
--- a/src/header/string/cbindgen.toml
+++ b/src/header/string/cbindgen.toml
@@ -6,6 +6,7 @@ no_includes = true
 
 include_guard = "_STRING_H"
 
-usize_is_size_t = true
+usize_type = "size_t"
+isize_type = "ssize_t"
 
 [export]
diff --git a/src/header/sys_types/cbindgen.toml b/src/header/sys_types/cbindgen.toml
index 4d45124..a298792 100644
--- a/src/header/sys_types/cbindgen.toml
+++ b/src/header/sys_types/cbindgen.toml
@@ -1,10 +1,30 @@
 language = "C"
 style = "Type"
 
-sys_includes = ["stddef.h"]
+sys_includes = ["stdint.h", "stddef.h"]
 no_includes = true
 
 include_guard = "_SYS_TYPES_H"
 
 [export]
-include = ["pid_t"]
+include = [
+    "blkcnt_t",
+    "blksize_t",
+    "clock_t",
+    "clockid_t",
+    "dev_t",
+    "fsblkcnt_t",
+    "fsfilcnt_t",
+    "gid_t",
+    "id_t",
+    "ino_t",
+    "mode_t",
+    "nlink_t",
+    "off_t",
+    "pid_t",
+    "ssize_t",
+    "suseconds_t",
+    "time_t",
+    "timer_t",
+    "uid_t"
+]
diff --git a/src/header/sys_types/mod.rs b/src/header/sys_types/mod.rs
index bd17fce..bf1b57c 100644
--- a/src/header/sys_types/mod.rs
+++ b/src/header/sys_types/mod.rs
@@ -1,3 +1,31 @@
-use core::ffi::c_int;
+use core::ffi::c_ulong;
 
 pub type pid_t = i32;
+pub type uid_t = i32;
+pub type gid_t = i32;
+pub type id_t = i32;
+
+pub type dev_t = u32;
+
+pub type clockid_t = i32;
+pub type timer_t = i32;
+
+pub type mode_t = u32;
+
+#[cfg(target_pointer_width = "64")]
+pub type ssize_t = i64;
+
+pub type blkcnt_t = i64;
+pub type blksize_t = c_ulong;
+pub type nlink_t = u64;
+
+pub type fsblkcnt_t = u64;
+pub type fsfilcnt_t = u64;
+pub type ino_t = u64;
+
+pub type clock_t = u64;
+pub type time_t = u64;
+
+pub type off_t = i64;
+
+pub type suseconds_t = c_ulong;
diff --git a/src/header/sys_wait/cbindgen.toml b/src/header/sys_wait/cbindgen.toml
index aa6e2e6..381cc16 100644
--- a/src/header/sys_wait/cbindgen.toml
+++ b/src/header/sys_wait/cbindgen.toml
@@ -6,7 +6,8 @@ no_includes = true
 
 include_guard = "_SYS_WAIT_H"
 
-usize_is_size_t = true
+usize_type = "size_t"
+isize_type = "ssize_t"
 
 [export]
 exclude = []
diff --git a/src/header/unistd/cbindgen.toml b/src/header/unistd/cbindgen.toml
index 97dcd36..58054db 100644
--- a/src/header/unistd/cbindgen.toml
+++ b/src/header/unistd/cbindgen.toml
@@ -7,7 +7,8 @@ no_includes = true
 include_guard = "_UNISTD_H"
 trailer = "#include <bits/unistd.h>"
 
-usize_is_size_t = true
+usize_type = "size_t"
+isize_type = "ssize_t"
 
 [export]
 exclude = []
diff --git a/src/io/buffered.rs b/src/io/buffered.rs
new file mode 100644
index 0000000..6c329ed
--- /dev/null
+++ b/src/io/buffered.rs
@@ -0,0 +1,231 @@
+use core::{
+    mem::MaybeUninit,
+    ops::{Deref, DerefMut},
+    slice::memchr,
+};
+
+use alloc::{boxed::Box, vec::Vec};
+
+use crate::header::errno::Errno;
+
+use super::{Read, Write};
+
+// Read
+
+enum ReadBufferBacking<'a> {
+    Owned(Box<[MaybeUninit<u8>]>),
+    Borrowed(&'a mut [MaybeUninit<u8>]),
+}
+
+pub struct ReadBuffer<'a> {
+    data: ReadBufferBacking<'a>,
+    position: usize,
+    len: usize,
+}
+
+// Write
+
+pub trait FileWriter: Write {
+    fn reset(&mut self);
+}
+
+pub struct UnbufferedWriter<W: Write> {
+    inner: W,
+}
+
+pub struct BufWriter<W: Write> {
+    inner: W,
+    buffer: Vec<u8>,
+}
+
+pub struct LineWriter<W: Write> {
+    inner: BufWriter<W>,
+    need_flush: bool,
+}
+
+impl<'a> ReadBuffer<'a> {
+    pub fn owned(capacity: usize) -> Self {
+        Self {
+            data: ReadBufferBacking::Owned(Box::new_uninit_slice(capacity)),
+            position: 0,
+            len: 0,
+        }
+    }
+
+    pub fn borrowed(data: &'a mut [MaybeUninit<u8>]) -> Self {
+        Self {
+            data: ReadBufferBacking::Borrowed(data),
+            position: 0,
+            len: 0,
+        }
+    }
+
+    pub fn reset(&mut self) {
+        self.position = 0;
+        self.len = 0;
+    }
+
+    pub fn fill_from<R: Read + ?Sized>(&mut self, source: &mut R) -> Result<&[u8], Errno> {
+        let buffer = unsafe { self.data.as_slice_mut() };
+        if self.position == self.len {
+            let amount = match source.read(buffer) {
+                Ok(0) => return Ok(&buffer[..0]),
+                Ok(n) => n,
+                Err(err) => return Err(err),
+            };
+
+            self.position = 0;
+            self.len = amount;
+        }
+
+        Ok(&mut buffer[self.position..self.len])
+    }
+
+    pub fn consume(&mut self, amount: usize) {
+        self.position = (self.position + amount).min(self.len);
+    }
+}
+
+impl<'a> ReadBufferBacking<'a> {
+    unsafe fn as_slice_mut(&mut self) -> &mut [u8] {
+        MaybeUninit::slice_assume_init_mut(self.deref_mut())
+    }
+}
+
+impl<'a> Deref for ReadBufferBacking<'a> {
+    type Target = [MaybeUninit<u8>];
+
+    fn deref(&self) -> &Self::Target {
+        match self {
+            Self::Owned(owned) => owned.deref(),
+            Self::Borrowed(borrowed) => borrowed.deref(),
+        }
+    }
+}
+
+impl<'a> DerefMut for ReadBufferBacking<'a> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        match self {
+            Self::Owned(owned) => owned.deref_mut(),
+            Self::Borrowed(borrowed) => borrowed.deref_mut(),
+        }
+    }
+}
+
+impl<W: Write> UnbufferedWriter<W> {
+    pub fn new(inner: W) -> Self {
+        Self { inner }
+    }
+}
+
+impl<W: Write> BufWriter<W> {
+    pub fn with_capacity(inner: W, capacity: usize) -> Self {
+        Self {
+            inner,
+            buffer: Vec::with_capacity(capacity),
+        }
+    }
+}
+
+impl<W: Write> LineWriter<W> {
+    pub fn with_capacity(inner: W, capacity: usize) -> Self {
+        Self {
+            inner: BufWriter::with_capacity(inner, capacity),
+            need_flush: false,
+        }
+    }
+}
+
+impl<W: Write> Write for UnbufferedWriter<W> {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        self.inner.write(data)
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        Ok(())
+    }
+}
+
+impl<W: Write> Write for BufWriter<W> {
+    fn write(&mut self, mut data: &[u8]) -> Result<usize, Errno> {
+        if data.len() + self.buffer.len() > self.buffer.capacity() {
+            self.flush()?;
+        }
+
+        let len = data.len();
+
+        if len >= self.buffer.capacity() {
+            // Write directly from `data` until it can be fit into the buffer
+            let (amount, result) = self
+                .inner
+                .write_chunked(&data[..len - self.buffer.capacity()]);
+
+            // Fail if write fails
+            result?;
+
+            data = &data[amount..];
+        }
+
+        // Store the data in the buffer
+        assert!(data.len() < self.buffer.capacity());
+        self.buffer.extend_from_slice(data);
+        Ok(len)
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        let (amount, result) = self.inner.write_chunked(&self.buffer);
+        if amount != 0 {
+            self.buffer.drain(..amount);
+        }
+        result
+    }
+}
+
+impl<W: Write> Write for LineWriter<W> {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno> {
+        if self.need_flush {
+            self.flush()?;
+        }
+
+        let Some(nl_pos) = memchr::memrchr(b'\n', data) else {
+            return self.inner.write(data);
+        };
+
+        // Write up to the last newline and flush
+        let amount = self.inner.write(&data[..nl_pos + 1])?;
+        self.need_flush = true;
+        if self.flush().is_err() || amount != nl_pos + 1 {
+            return Ok(amount);
+        }
+
+        // Write the rest to the buffer
+        match self.inner.write(&data[nl_pos + 1..]) {
+            Ok(amount_to_buffer) => Ok(amount_to_buffer + amount),
+            Err(_) => Ok(amount),
+        }
+    }
+
+    fn flush(&mut self) -> Result<(), Errno> {
+        self.inner.flush()?;
+        self.need_flush = false;
+        Ok(())
+    }
+}
+
+impl<W: Write> FileWriter for UnbufferedWriter<W> {
+    fn reset(&mut self) {
+        // Do nothing
+    }
+}
+
+impl<W: Write> FileWriter for BufWriter<W> {
+    fn reset(&mut self) {
+        self.buffer.clear();
+    }
+}
+
+impl<W: Write> FileWriter for LineWriter<W> {
+    fn reset(&mut self) {
+        self.inner.reset();
+    }
+}
diff --git a/src/io/mod.rs b/src/io/mod.rs
new file mode 100644
index 0000000..d489978
--- /dev/null
+++ b/src/io/mod.rs
@@ -0,0 +1,51 @@
+use yggdrasil_rt::io::SeekFrom;
+
+use crate::header::errno::{Errno, EINTR};
+
+pub mod buffered;
+
+pub trait Write {
+    fn write(&mut self, data: &[u8]) -> Result<usize, Errno>;
+    fn flush(&mut self) -> Result<(), Errno>;
+
+    fn write_chunked(&mut self, data: &[u8]) -> (usize, Result<(), Errno>) {
+        let mut pos = 0;
+        let len = data.len();
+
+        while pos < len {
+            match self.write(data) {
+                Ok(0) => todo!(),
+                Ok(n) => pos += n,
+                Err(err) if err == EINTR => todo!(),
+                Err(err) => return (pos, Err(err)),
+            }
+        }
+
+        (pos, Ok(()))
+    }
+
+    fn write_all(&mut self, data: &[u8]) -> Result<(), Errno> {
+        match self.write(data) {
+            Ok(n) if n == data.len() => Ok(()),
+            Ok(_) => todo!(), // TODO handle partial writes in write_all
+            Err(err) => Err(err),
+        }
+    }
+}
+
+pub trait Read {
+    fn read(&mut self, data: &mut [u8]) -> Result<usize, Errno>;
+}
+
+pub trait BufRead {
+    fn fill_buf(&mut self) -> Result<&[u8], Errno>;
+    fn consume(&mut self, amount: usize);
+}
+
+pub trait Seek {
+    fn seek(&mut self, off: SeekFrom) -> Result<u64, Errno>;
+
+    fn stream_position(&mut self) -> Result<u64, Errno> {
+        self.seek(SeekFrom::Current(0))
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 2e00e84..5e8f4a6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,12 @@
-#![feature(type_alias_impl_trait, c_variadic, try_trait_v2)]
+#![feature(
+    type_alias_impl_trait,
+    c_variadic,
+    try_trait_v2,
+    slice_internals,
+    arbitrary_self_types,
+    new_uninit,
+    maybe_uninit_slice
+)]
 #![no_std]
 
 use core::ffi::{c_char, c_int};
@@ -7,6 +15,8 @@ use alloc::{ffi::CString, vec::Vec};
 use header::unistd::environ;
 use yggdrasil_rt::process::{ExitCode, ProgramArgumentInner};
 
+use crate::header::stdio;
+
 extern crate alloc;
 extern crate yggdrasil_rt;
 
@@ -14,10 +24,11 @@ pub mod header;
 
 pub mod allocator;
 pub mod error;
+pub mod file;
+pub mod io;
 pub mod path;
 pub mod process;
 pub mod sync;
-pub mod traits;
 pub mod types;
 pub mod util;
 
@@ -42,6 +53,10 @@ unsafe fn setup_env(arg: usize) {
     environ = C_ENVS.as_mut_ptr();
 }
 
+unsafe fn cleanup() {
+    stdio::cleanup();
+}
+
 #[no_mangle]
 unsafe extern "C" fn _start(arg: usize) -> ! {
     extern "C" {
@@ -49,12 +64,14 @@ unsafe extern "C" fn _start(arg: usize) -> ! {
     }
 
     setup_env(arg);
-    header::stdio::setup_default_files();
+    stdio::setup_default_files();
 
     // TODO setup signals, allocator, etc.
 
     let code = main(C_ARGS.len() as _, C_ARGS.as_ptr());
 
+    cleanup();
+
     process::exit(code)
 }
 
diff --git a/src/sync.rs b/src/sync.rs
index 4072fec..dd78b57 100644
--- a/src/sync.rs
+++ b/src/sync.rs
@@ -87,6 +87,8 @@ impl<T> Mutex<T> {
     }
 }
 
+unsafe impl<T> Sync for Mutex<T> {}
+
 impl<T> Deref for MutexGuard<'_, T> {
     type Target = T;
 
diff --git a/src/traits.rs b/src/traits.rs
deleted file mode 100644
index 62d9013..0000000
--- a/src/traits.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-use core::fmt;
-
-use crate::header::errno::Errno;
-
-pub trait Write: fmt::Write {
-    fn write(&mut self, data: &[u8]) -> Result<usize, Errno>;
-
-    fn putc(&mut self, ch: u8) -> Result<(), Errno> {
-        self.write(&[ch])?;
-        Ok(())
-    }
-}
-
-pub trait Read {
-    fn read(&mut self, data: &mut [u8]) -> Result<usize, Errno>;
-}
diff --git a/src/types.rs b/src/types.rs
index e4cf0b2..747a85c 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -1,5 +1,3 @@
 #![allow(non_camel_case_types)]
 
-use core::ffi::c_int;
-
 pub type wchar_t = i32;