✨ 128 闹钟

docs/07 任务管理/128 闹钟.md

@@ -0,0 +1,12 @@
+# 闹钟
+
+利用信号 `SIGALRM` [^alarm] 实现闹钟。使得程序可以在特定的时间之后执行某函数。
+
+```c++
+// 设置闹钟
+int alarm(int sec);
+```
+
+## 参考
+
+[^alarm]: <https://man7.org/linux/man-pages/man2/alarm.2.html>

src/builtin/alarm.c

@@ -0,0 +1,22 @@
+#include <onix/syscall.h>
+#include <onix/stdio.h>
+#include <onix/signal.h>
+
+static int signal_handler(int sig)
+{
+    printf("pid %d when %d signal %d happened \a\n", getpid(), time(), sig);
+    signal(SIGALRM, (int)signal_handler);
+    alarm(2);
+}
+
+int main(int argc, char const *argv[])
+{
+    signal(SIGALRM, (int)signal_handler);
+    alarm(2);
+    while (true)
+    {
+        printf("pid %d when %d sleeping 1 second\n", getpid(), time());
+        sleep(1000);
+    }
+    return 0;
+}

src/include/onix/syscall.h

@@ -30,6 +30,7 @@ typedef enum syscall_t
     SYS_NR_GETPID = 20,
     SYS_NR_MOUNT = 21,
     SYS_NR_UMOUNT = 22,
+    SYS_NR_ALARM = 27,
     SYS_NR_FSTAT = 28,
     SYS_NR_STTY = 31,
     SYS_NR_GTTY = 32,
@@ -177,4 +178,7 @@ int gtty();
 // 发送信号
 int kill(pid_t pid, int signal);
 
+// 设置闹钟
+int alarm(int sec);
+
 #endif

src/include/onix/task.h

@@ -57,6 +57,7 @@ typedef struct task_t
     struct file_t *files[TASK_FILE_NR]; // 进程文件表
     u32 signal;                         // 进程信号位图
     u32 blocked;                        // 进程信号屏蔽位图
+    struct timer_t *alarm;              // 闹钟定时器
     sigaction_t actions[MAXSIG];        // 信号处理函数
     u32 magic;                          // 内核魔数，用于检测栈溢出
 } task_t;

src/kernel/alarm.c

@@ -0,0 +1,20 @@
+#include <onix/task.h>
+#include <onix/timer.h>
+
+extern int sys_kill();
+
+static void task_alarm(timer_t *timer)
+{
+    timer->task->alarm = NULL;
+    sys_kill(timer->task->pid, SIGALRM);
+}
+
+int sys_alarm(int sec)
+{
+    task_t *task = running_task();
+    if (task->alarm)
+    {
+        timer_put(task->alarm);
+    }
+    task->alarm = timer_add(sec * 1000, task_alarm, 0);
+}

src/kernel/gate.c

@@ -107,6 +107,8 @@ extern int sys_sgetmask();
 extern int sys_ssetmask();
 extern int sys_sigaction();
 
+extern int sys_alarm();
+
 extern int sys_mkfs();
 
 void syscall_init()
@@ -184,4 +186,5 @@ void syscall_init()
     syscall_table[SYS_NR_SGETMASK] = sys_sgetmask;
     syscall_table[SYS_NR_SSETMASK] = sys_ssetmask;
     syscall_table[SYS_NR_SIGACTION] = sys_sigaction;
+    syscall_table[SYS_NR_ALARM] = sys_alarm;
 }

src/kernel/task.c

@@ -172,7 +172,10 @@ void task_unblock(task_t *task, int reason)
 {
     assert(!get_interrupt_state());
 
-    list_remove(&task->node);
+    if (task->node.next)
+    {
+        list_remove(&task->node);
+    }
 
     assert(task->node.next == NULL);
     assert(task->node.prev == NULL);

src/kernel/timer.c

@@ -29,7 +29,7 @@ void timer_put(timer_t *timer)
 
 void default_timeout(timer_t *timer)
 {
-    assert(timer->task->node.next);
+    // assert(timer->task->node.next);
     task_unblock(timer->task, -ETIME);
 }
 

src/lib/syscall.c

@@ -104,6 +104,11 @@ int kill(pid_t pid, int signal)
     return _syscall2(SYS_NR_KILL, pid, signal);
 }
 
+int alarm(int sec)
+{
+    return _syscall1(SYS_NR_ALARM, sec);
+}
+
 void yield()
 {
     _syscall0(SYS_NR_YIELD);

src/makefile

@@ -54,6 +54,7 @@ BUILTIN_APPS := \
 	$(BUILD)/builtin/dup.out \
 	$(BUILD)/builtin/err.out \
 	$(BUILD)/builtin/count.out \
+	$(BUILD)/builtin/alarm.out \
 
 $(BUILD)/builtin/%.out: $(BUILD)/builtin/%.o \
 	$(BUILD)/lib/libc.o \
@@ -98,6 +99,7 @@ $(BUILD)/kernel.bin: \
 	$(BUILD)/kernel/system.o \
 	$(BUILD)/kernel/execve.o \
 	$(BUILD)/kernel/signal.o \
+	$(BUILD)/kernel/alarm.o \
 	$(BUILD)/fs/super.o \
 	$(BUILD)/fs/bmap.o \
 	$(BUILD)/fs/inode.o \