add os[1-8]-ref for os refereces, add guide, add README

os7-ref/src/syscall/process.rs

@@ -0,0 +1,160 @@
+//! Process management syscalls
+
+use crate::mm::{translated_refmut, translated_ref, translated_str};
+use crate::task::{
+    add_task, current_task, current_user_token, exit_current_and_run_next,
+    suspend_current_and_run_next, TaskStatus,
+};
+use crate::fs::{open_file, OpenFlags};
+use crate::timer::get_time_us;
+use alloc::sync::Arc;
+use alloc::vec::Vec;
+use crate::config::MAX_SYSCALL_NUM;
+use alloc::string::String;
+
+#[repr(C)]
+#[derive(Debug)]
+pub struct TimeVal {
+    pub sec: usize,
+    pub usec: usize,
+}
+
+#[derive(Clone, Copy)]
+pub struct TaskInfo {
+    pub status: TaskStatus,
+    pub syscall_times: [u32; MAX_SYSCALL_NUM],
+    pub time: usize,
+}
+
+pub fn sys_exit(exit_code: i32) -> ! {
+    debug!("[kernel] Application exited with code {}", exit_code);
+    exit_current_and_run_next(exit_code);
+    panic!("Unreachable in sys_exit!");
+}
+
+/// current task gives up resources for other tasks
+pub fn sys_yield() -> isize {
+    suspend_current_and_run_next();
+    0
+}
+
+pub fn sys_getpid() -> isize {
+    current_task().unwrap().pid.0 as isize
+}
+
+/// Syscall Fork which returns 0 for child process and child_pid for parent process
+pub fn sys_fork() -> isize {
+    let current_task = current_task().unwrap();
+    let new_task = current_task.fork();
+    let new_pid = new_task.pid.0;
+    // modify trap context of new_task, because it returns immediately after switching
+    let trap_cx = new_task.inner_exclusive_access().get_trap_cx();
+    // we do not have to move to next instruction since we have done it before
+    // for child process, fork returns 0
+    trap_cx.x[10] = 0;
+    // add new task to scheduler
+    add_task(new_task);
+    new_pid as isize
+}
+
+/// Syscall Exec which accepts the elf path
+pub fn sys_exec(path: *const u8, mut args: *const usize) -> isize {
+    let token = current_user_token();
+    let path = translated_str(token, path);
+    let mut args_vec: Vec<String> = Vec::new();
+    loop {
+        let arg_str_ptr = *translated_ref(token, args);
+        if arg_str_ptr == 0 {
+            break;
+        }
+        args_vec.push(translated_str(token, arg_str_ptr as *const u8));
+        unsafe {
+            args = args.add(1);
+        }
+    }
+    if let Some(app_inode) = open_file(path.as_str(), OpenFlags::RDONLY) {
+        let all_data = app_inode.read_all();
+        let task = current_task().unwrap();
+        let argc = args_vec.len();
+        task.exec(all_data.as_slice(), args_vec);
+        argc as isize
+    } else {
+        -1
+    }
+}
+
+
+/// If there is not a child process whose pid is same as given, return -1.
+/// Else if there is a child process but it is still running, return -2.
+pub fn sys_waitpid(pid: isize, exit_code_ptr: *mut i32) -> isize {
+    let task = current_task().unwrap();
+    // find a child process
+
+    // ---- access current TCB exclusively
+    let mut inner = task.inner_exclusive_access();
+    if !inner
+        .children
+        .iter()
+        .any(|p| pid == -1 || pid as usize == p.getpid())
+    {
+        return -1;
+        // ---- release current PCB
+    }
+    let pair = inner.children.iter().enumerate().find(|(_, p)| {
+        // ++++ temporarily access child PCB lock exclusively
+        p.inner_exclusive_access().is_zombie() && (pid == -1 || pid as usize == p.getpid())
+        // ++++ release child PCB
+    });
+    if let Some((idx, _)) = pair {
+        let child = inner.children.remove(idx);
+        // confirm that child will be deallocated after removing from children list
+        assert_eq!(Arc::strong_count(&child), 1);
+        let found_pid = child.getpid();
+        // ++++ temporarily access child TCB exclusively
+        let exit_code = child.inner_exclusive_access().exit_code;
+        // ++++ release child PCB
+        *translated_refmut(inner.memory_set.token(), exit_code_ptr) = exit_code;
+        found_pid as isize
+    } else {
+        -2
+    }
+    // ---- release current PCB lock automatically
+}
+
+// YOUR JOB: 引入虚地址后重写 sys_get_time
+pub fn sys_get_time(_ts: *mut TimeVal, _tz: usize) -> isize {
+    let _us = get_time_us();
+    // unsafe {
+    //     *ts = TimeVal {
+    //         sec: us / 1_000_000,
+    //         usec: us % 1_000_000,
+    //     };
+    // }
+    0
+}
+
+// YOUR JOB: 引入虚地址后重写 sys_task_info
+pub fn sys_task_info(ti: *mut TaskInfo) -> isize {
+    -1
+}
+
+// YOUR JOB: 实现sys_set_priority，为任务添加优先级
+pub fn sys_set_priority(_prio: isize) -> isize {
+    -1
+}
+
+// YOUR JOB: 扩展内核以实现 sys_mmap 和 sys_munmap
+pub fn sys_mmap(_start: usize, _len: usize, _port: usize) -> isize {
+    -1
+}
+
+pub fn sys_munmap(_start: usize, _len: usize) -> isize {
+    -1
+}
+
+//
+// YOUR JOB: 实现 sys_spawn 系统调用
+// ALERT: 注意在实现 SPAWN 时不需要复制父进程地址空间，SPAWN != FORK + EXEC 
+pub fn sys_spawn(_path: *const u8) -> isize {
+    -1
+}