Add full epoll_pwait

regression/apps/epoll/epoll_wait.c

@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: MPL-2.0
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/epoll.h>
+#include <sys/wait.h>
+#include <string.h>
+
+int main(void)
+{
+	int pipefd[2]; // Array to store pipe file descriptors
+	pid_t cpid; // Child process ID
+	char buf[1024]; // Read buffer
+	struct epoll_event ev, events[1];
+	int epfd, nfds;
+
+	// Create a pipe
+	if (pipe(pipefd) == -1) {
+		perror("pipe error");
+		return EXIT_FAILURE;
+	}
+
+	// Create epoll instance
+	if ((epfd = epoll_create1(0)) == -1) {
+		perror("epoll_create1 error");
+		close(pipefd[0]);
+		close(pipefd[1]);
+		return EXIT_FAILURE;
+	}
+
+	// Fork to create child process
+	cpid = fork();
+	if (cpid == -1) {
+		perror("fork error");
+		close(pipefd[0]);
+		close(pipefd[1]);
+		close(epfd);
+		return EXIT_FAILURE;
+	}
+
+	if (cpid == 0) { // Child process
+		close(pipefd[0]); // Child closes read end of the pipe
+		const char *message = "Hello, world!\n";
+		write(pipefd[1], message,
+		      strlen(message)); // Write a string to the pipe
+		close(pipefd[1]); // Close write end of the pipe
+		_exit(EXIT_SUCCESS);
+	} else { // Parent process
+		close(pipefd[1]); // Parent closes write end of the pipe
+
+		// Set up epoll to listen for events
+		ev.events = EPOLLIN; // Listen for input events
+		ev.data.fd = pipefd[0];
+		if (epoll_ctl(epfd, EPOLL_CTL_ADD, pipefd[0], &ev) == -1) {
+			perror("epoll_ctl error");
+			close(pipefd[0]);
+			close(epfd);
+			return EXIT_FAILURE;
+		}
+
+		// Wait for events to occur
+		printf("Waiting for event on pipe...\n");
+		nfds = epoll_wait(epfd, events, 1, -1);
+		if (nfds == -1) {
+			perror("epoll_wait error");
+			close(pipefd[0]);
+			close(epfd);
+			return EXIT_FAILURE;
+		}
+
+		// If we get here, epoll_wait was successful
+		printf("epoll_wait returned successfully.\n");
+		if (events[0].data.fd == pipefd[0]) {
+			// Read data
+			ssize_t count = read(pipefd[0], buf, sizeof(buf) - 1);
+			if (count > 0) {
+				buf[count] =
+					'\0'; // Ensure string is null-terminated
+				printf("Received data: %s",
+				       buf); // Output the entire string
+			} else {
+				perror("read error");
+			}
+		}
+
+		close(pipefd[0]); // Close read end of the pipe
+		close(epfd); // Close the epoll file descriptor
+	}
+
+	// Wait for the child process to complete
+	wait(NULL);
+
+	return EXIT_SUCCESS;
+}