feat: 实现ppoll系统调用并优化poll相关功能 (#1127)

- 新增ppoll系统调用，支持信号屏蔽和精确超时控制
- 优化poll系统调用，修复超时处理逻辑
- 新增ProcessControlBlock::has_pending_not_masked_signal方法，优化信号检测
- 添加Instant::saturating_sub方法，改进时间计算
- 新增rt_sigpending系统调用，支持获取待处理信号
- 添加ppoll测试程序，验证ppoll功能

Signed-off-by: longjin <longjin@DragonOS.org>

user/apps/test_poll/.gitignore

@@ -1 +1,3 @@
 test_poll
+test_ppoll
+*.o

user/apps/test_poll/Makefile

@@ -8,14 +8,17 @@ BIN_NAME=test_poll
 CC=$(CROSS_COMPILE)gcc
 
 .PHONY: all
-all: main.c
+all: main.c ppoll.c
 	$(CC) -static -o $(BIN_NAME) main.c
+	$(CC) -static -o test_ppoll ppoll.c
 
 .PHONY: install clean
 install: all
 	mv $(BIN_NAME) $(DADK_CURRENT_BUILD_DIR)/$(BIN_NAME)
+	mv test_ppoll $(DADK_CURRENT_BUILD_DIR)/test_ppoll
 
 clean:
 	rm $(BIN_NAME) *.o
+	rm test_ppoll
 
 fmt:

user/apps/test_poll/ppoll.c

@@ -0,0 +1,148 @@
+#include <errno.h>
+#define _GNU_SOURCE
+
+#include <fcntl.h>
+#include <poll.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/poll.h>
+#include <sys/signalfd.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+#define RED "\x1B[31m"
+#define GREEN "\x1B[32m"
+#define RESET "\x1B[0m"
+
+// 测试用例1：基本功能测试（管道I/O）
+void test_basic_functionality() {
+  int pipefd[2];
+  struct pollfd fds[1];
+  struct timespec timeout = {5, 0}; // 5秒超时
+
+  printf("=== Test 1: Basic functionality test ===\n");
+
+  // 创建管道
+  if (pipe(pipefd) == -1) {
+    perror("pipe creation failed");
+    exit(EXIT_FAILURE);
+  }
+
+  // 设置监听读端管道
+  fds[0].fd = pipefd[0];
+  fds[0].events = POLLIN;
+
+  printf("Test scenario 1: Wait with no data (should timeout)\n");
+  int ret = ppoll(fds, 1, &timeout, NULL);
+  if (ret == 0) {
+    printf(GREEN "Test passed: Correct timeout\n" RESET);
+  } else {
+    printf(RED "Test failed: Return value %d\n" RESET, ret);
+  }
+
+  // 向管道写入数据
+  const char *msg = "test data";
+  write(pipefd[1], msg, strlen(msg));
+
+  printf(
+      "\nTest scenario 2: Should return immediately when data is available\n");
+  timeout.tv_sec = 5;
+  ret = ppoll(fds, 1, &timeout, NULL);
+  if (ret > 0 && (fds[0].revents & POLLIN)) {
+    printf(GREEN "Test passed: Data detected\n" RESET);
+  } else {
+    printf(RED "Test failed: Return value %d, revents %d\n" RESET, ret,
+           fds[0].revents);
+  }
+
+  close(pipefd[0]);
+  close(pipefd[1]);
+}
+
+// 测试用例2：信号屏蔽测试
+void test_signal_handling() {
+  printf("\n=== Test 2: Signal handling test ===\n");
+  sigset_t mask, orig_mask;
+  struct timespec timeout = {5, 0};
+  struct pollfd fds[1];
+
+  fds[0].fd = -1;
+  fds[0].events = 0;
+
+  // 设置信号屏蔽
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGUSR1);
+  // 阻塞SIGUSR1，并保存原来的信号掩码
+  if (sigprocmask(SIG_BLOCK, &mask, &orig_mask)) {
+    perror("sigprocmask");
+    exit(EXIT_FAILURE);
+  }
+
+  printf("Test scenario: Signal should not interrupt when masked\n");
+  pid_t pid = fork();
+  if (pid == 0) { // 子进程
+    sleep(2);     // 等待父进程进入ppoll
+    kill(getppid(), SIGUSR1);
+    exit(0);
+  }
+
+  int ret = ppoll(fds, 1, &timeout, &mask);
+
+  if (ret == 0) {
+    printf(GREEN "Test passed: Completed full 5 second wait\n" RESET);
+  } else {
+    printf(RED "Test failed: Premature return %d\n" RESET, errno);
+  }
+
+  waitpid(pid, NULL, 0);
+
+  // 检查并消费挂起的SIGUSR1信号
+  sigset_t pending;
+  sigpending(&pending);
+  if (sigismember(&pending, SIGUSR1)) {
+    int sig;
+    sigwait(&mask, &sig); // 主动消费信号
+
+    printf("Consumed pending SIGUSR1 signal\n");
+  }
+  // 恢复原来的信号掩码
+  sigprocmask(SIG_SETMASK, &orig_mask, NULL);
+}
+
+// 测试用例3：精确超时测试
+void test_timeout_accuracy() {
+  printf("\n=== Test 3: Timeout accuracy test ===\n");
+  struct timespec start, end, timeout = {0, 500000000};
+  struct pollfd fds[1];
+  fds[0].fd = -1;
+  fds[0].events = 0;
+
+  clock_gettime(CLOCK_MONOTONIC, &start);
+  int ret = ppoll(fds, 1, &timeout, NULL);
+  clock_gettime(CLOCK_MONOTONIC, &end);
+
+  long elapsed = (end.tv_sec - start.tv_sec) * 1000000 +
+                 (end.tv_nsec - start.tv_nsec) / 1000;
+
+  printf("Expected timeout: 500ms, Actual elapsed: %.3fms\n", elapsed / 1000.0);
+  if (labs(elapsed - 500000) < 50000) { // 允许±50ms误差
+    printf(GREEN "Test passed: Timeout within acceptable range\n" RESET);
+  } else {
+    printf(RED "Test failed: Timeout deviation too large\n" RESET);
+  }
+}
+
+int main() {
+  // 设置非阻塞标准输入
+  fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK);
+
+  test_basic_functionality();
+  test_signal_handling();
+  test_timeout_accuracy();
+
+  return 0;
+}