Add a scheduler which just keeps of processes for now, and a

with_process to interact with them. User space now has it's own address
space and mapper which means we will be able to allocate memory for it.
I added a bunch of functions as stubs into libxunil which are required
for doomgeneric.

user/libxunil/src/lib.rs

@@ -1,20 +1,24 @@
 #![no_std]
-#![no_main]
+#![feature(c_variadic)]
+
+use core::ptr::null;
 
 use crate::syscall::syscall3;
 
+pub mod file;
+pub mod mem;
 pub mod syscall;
 
 const SYS_EXIT: usize = 1;
 const SYS_WRITE: usize = 60;
 
 #[unsafe(no_mangle)]
-extern "C" fn write(fd: i32, buf: *const u8, count: usize) -> isize {
+extern "C" fn write(fd: i64, buf: *const u8, count: usize) -> isize {
     unsafe { syscall3(SYS_WRITE, fd as usize, buf as usize, count) }
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn exit(code: i32) -> ! {
+extern "C" fn exit(code: i64) -> ! {
     unsafe { syscall3(SYS_EXIT, code as usize, 0, 0) };
     loop {}
 }
@@ -36,14 +40,26 @@ extern "C" fn puts(s: *const u8) -> isize {
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn abs(n: i32) -> i32 {
+extern "C" fn putchar(s: i32) -> isize {
+    write(1, (s as u8 + b'0') as *const u8, 1);
+
+    0
+}
+
+#[unsafe(no_mangle)]
+extern "C" fn abs(n: i64) -> i64 {
     n.abs()
 }
 
 #[unsafe(no_mangle)]
-extern "C" fn atoi(mut c: *const u8) -> i32 {
-    let mut value: i32 = 0;
-    let mut sign: i32 = 1;
+unsafe extern "C" fn printf(format: *const u8, args: ...) {
+    unsafe { syscall3(SYS_WRITE, 1, format as usize, strlen(format)) };
+}
+
+#[unsafe(no_mangle)]
+extern "C" fn atoi(mut c: *const u8) -> i64 {
+    let mut value: i64 = 0;
+    let mut sign: i64 = 1;
     unsafe {
         if (*c) == b'+' || (*c) == b'-' {
             if *c == b'-' {
@@ -53,7 +69,7 @@ extern "C" fn atoi(mut c: *const u8) -> i32 {
         }
         while (*c).is_ascii_digit() {
             value *= 10;
-            value += ((*c) - b'0') as i32;
+            value += ((*c) - b'0') as i64;
             c = c.add(1);
         }
     }
@@ -61,6 +77,115 @@ extern "C" fn atoi(mut c: *const u8) -> i32 {
     value * sign
 }
 
+#[unsafe(no_mangle)]
+extern "C" fn atof(mut c: *const u8) -> f64 {
+    0.0
+}
+
+pub fn compare_str(str_1: *const u8, str_2: *const u8, case: bool, n: usize) -> i32 {
+    let mut len = 0;
+
+    while len < n {
+        let mut c_1 = unsafe { *str_1.add(len) };
+        let mut c_2 = unsafe { *str_2.add(len) };
+
+        if case {
+            c_1 = c_1.to_ascii_lowercase();
+            c_2 = c_2.to_ascii_lowercase();
+        }
+
+        if c_1 != c_2 {
+            return (c_1 - c_2) as i32;
+        }
+
+        if c_1 == 0 {
+            return 0;
+        }
+
+        len += 1;
+    }
+
+    0
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strcasecmp(str_1: *const u8, str_2: *const u8) -> i32 {
+    compare_str(str_1, str_2, true, 999999999999999)
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strcmp(str_1: *const u8, str_2: *const u8) -> i32 {
+    compare_str(str_1, str_2, false, 999999999999999)
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strncasecmp(str_1: *const u8, str_2: *const u8, n: i32) -> i32 {
+    compare_str(str_1, str_2, true, n as usize)
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strncmp(str_1: *const u8, str_2: *const u8, n: i32) -> i32 {
+    compare_str(str_1, str_2, false, n as usize)
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strncopy(s: *const u8, n: i32) -> *const u8 {
+    null()
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strdup(s: *const u8) -> *const u8 {
+    null()
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strstr(s: *const u8) -> *const u8 {
+    null()
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strchr(s: *const u8, ch: u8) -> *const u8 {
+    null()
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn strrchr(s: *const u8, ch: u8) -> *const u8 {
+    let mut n = 0;
+    let mut last: *const u8 = null();
+
+    if ch == 0 {
+        while unsafe { *s.add(n) } != 0 {
+            n += 1;
+        }
+        unsafe { s.add(n + 1) }
+    } else {
+        while unsafe { *s.add(n) } != 0 {
+            let cur_ch = unsafe { s.add(n) };
+            if unsafe { *cur_ch == ch } {
+                last = cur_ch;
+            }
+            n += 1;
+        }
+
+        last
+    }
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn toupper(char: u8) -> u8 {
+    char.to_ascii_uppercase()
+}
+
+#[unsafe(no_mangle)]
+unsafe extern "C" fn tolower(char: u8) -> u8 {
+    char.to_ascii_lowercase()
+}
+
+#[unsafe(no_mangle)]
+extern "C" fn system(cmd: *const u8) -> i32 {
+    0
+}
+
 #[panic_handler]
 fn panic(_: &core::panic::PanicInfo) -> ! {
     loop {}