From 862ef8dc224e868e4f3e35e46142ffa448762f30 Mon Sep 17 00:00:00 2001
From: Nilstrieb <48135649+Nilstrieb@users.noreply.github.com>
Date: Tue, 3 Oct 2023 21:48:54 +0200
Subject: [PATCH] more error handling

---
 libuwuc/src/error/mod.rs              | 36 +++++++++++++++++++++++++++
 libuwuc/src/io/fd.rs                  | 13 +++++-----
 libuwuc/src/io/mod.rs                 | 12 ++++-----
 libuwuc/src/sys/x86_64/syscall/mod.rs | 14 +++++------
 4 files changed, 54 insertions(+), 21 deletions(-)

diff --git a/libuwuc/src/error/mod.rs b/libuwuc/src/error/mod.rs
index aaa6190..08cfcc1 100644
--- a/libuwuc/src/error/mod.rs
+++ b/libuwuc/src/error/mod.rs
@@ -29,6 +29,42 @@ impl Debug for Error {
     }
 }
 
+pub trait SyscallResultExt: Sized {
+    fn syscall_resultify<N: FromSyscall>(self) -> Result<N, Error>;
+}
+
+pub trait FromSyscall {
+    fn from_isize(n: isize) -> Self;
+}
+
+macro_rules! usize_int_impl {
+    ($($ty:ty)*) => {
+        $(impl FromSyscall for $ty {
+            fn from_isize(n: isize) -> Self {
+                n as _
+            }
+        })*
+    };
+}
+
+usize_int_impl!(isize usize u64 i64 u32 i32);
+
+impl FromSyscall for Fd {
+    fn from_isize(n: isize) -> Self {
+        Self(n as _)
+    }
+}
+
+impl SyscallResultExt for isize {
+    fn syscall_resultify<N: FromSyscall>(self) -> Result<N, Error> {
+        if (-4096..0).contains(&self) {
+            Err(Error(-self as i32))
+        } else {
+            Ok(N::from_isize(self))
+        }
+    }
+}
+
 pub trait IntoOkOrErrno {
     type Int: ReturnInt;
     fn into_ok_or_errno(self) -> Self::Int;
diff --git a/libuwuc/src/io/fd.rs b/libuwuc/src/io/fd.rs
index 11c25b6..be7d9cd 100644
--- a/libuwuc/src/io/fd.rs
+++ b/libuwuc/src/io/fd.rs
@@ -1,4 +1,7 @@
-use crate::{utils::SharedThinCstr, println, error::Error};
+use crate::{
+    error::{Error, SyscallResultExt},
+    utils::SharedThinCstr,
+};
 
 #[repr(transparent)]
 pub struct Fd(pub i32);
@@ -8,13 +11,9 @@ pub fn open(arg: SharedThinCstr<'_>, flags: i32) -> Result<Fd, Error> {
 }
 
 pub fn sys_open(arg: SharedThinCstr<'_>, flags: i32) -> Result<Fd, Error> {
-    let fd = unsafe { crate::syscall::syscall!(crate::syscall::SYS_OPEN, arg.as_raw(), flags) };
-
-    if fd < 0 {
-        println!("fd: {fd}");
+    unsafe {
+        crate::syscall::syscall!(crate::syscall::SYS_OPEN, arg.as_raw(), flags).syscall_resultify()
     }
-
-    todo!()
 }
 
 pub const O_ACCMODE: i32 = 0o0003;
diff --git a/libuwuc/src/io/mod.rs b/libuwuc/src/io/mod.rs
index a5a90a4..1a45752 100644
--- a/libuwuc/src/io/mod.rs
+++ b/libuwuc/src/io/mod.rs
@@ -6,7 +6,10 @@ pub use traits::IoWrite;
 
 use core::ffi::c_char;
 
-use crate::{error::Error, sys::syscall};
+use crate::{
+    error::{Error, SyscallResultExt},
+    sys::syscall,
+};
 
 pub const STDIN: i32 = 0;
 pub const STDOUT: i32 = 1;
@@ -35,12 +38,7 @@ macro_rules! println {
 pub use println;
 
 pub unsafe fn sys_write(fd: i32, buf: &[u8]) -> Result<usize, Error> {
-    let result = syscall::syscall!(syscall::SYS_WRITE, fd, buf.as_ptr(), buf.len()) as i64;
-    if result < 0 {
-        Err(Error(result as _))
-    } else {
-        Ok(result as _)
-    }
+    syscall::syscall!(syscall::SYS_WRITE, fd, buf.as_ptr(), buf.len()).syscall_resultify()
 }
 
 pub unsafe fn write_all(fd: i32, mut buf: &[u8]) -> Result<(), Error> {
diff --git a/libuwuc/src/sys/x86_64/syscall/mod.rs b/libuwuc/src/sys/x86_64/syscall/mod.rs
index ac7003f..c0480b2 100644
--- a/libuwuc/src/sys/x86_64/syscall/mod.rs
+++ b/libuwuc/src/sys/x86_64/syscall/mod.rs
@@ -7,7 +7,7 @@ pub use values::*;
 #[macro_export]
 macro_rules! syscall {
     ($number:expr) => {{
-        let out: i64;
+        let out: isize;
         ::core::arch::asm!(
             "syscall",
             in("rdi") $number,
@@ -19,7 +19,7 @@ macro_rules! syscall {
         out
     }};
     ($number:expr, $arg1:expr) => {{
-        let out: i64;
+        let out: isize;
         ::core::arch::asm!(
             "syscall",
             in("rax") $number,
@@ -32,7 +32,7 @@ macro_rules! syscall {
         out
     }};
     ($number:expr, $arg1:expr, $arg2:expr) => {{
-        let out: i64;
+        let out: isize;
         ::core::arch::asm!(
             "syscall",
             in("rax") $number,
@@ -46,7 +46,7 @@ macro_rules! syscall {
         out
     }};
     ($number:expr, $arg1:expr, $arg2:expr, $arg3:expr) => {{
-        let out: i64;
+        let out: isize;
         ::core::arch::asm!(
             "syscall",
             in("rax") $number,
@@ -61,7 +61,7 @@ macro_rules! syscall {
         out
     }};
     ($number:expr, $arg1:expr, $arg2:expr, $arg3:expr, $arg4:expr) => {{
-        let out: i64;
+        let out: isize;
         ::core::arch::asm!(
             "syscall",
             in("rax") $number,
@@ -77,7 +77,7 @@ macro_rules! syscall {
         out
     }};
     ($number:expr, $arg1:expr, $arg2:expr, $arg3:expr, $arg4:expr, $arg5:expr) => {{
-        let out: i64;
+        let out: isize;
         ::core::arch::asm!(
             "syscall",
             in("rax") $number,
@@ -94,7 +94,7 @@ macro_rules! syscall {
         out
     }};
     ($number:expr, $arg1:expr, $arg2:expr, $arg3:expr, $arg4:expr, $arg5:expr, $arg6:expr) => {{
-        let out: i64;
+        let out: isize;
         ::core::arch::asm!(
             "syscall",
             in("rax") $number,