Rename regression to test

test/apps/mmap/mmap_and_fork.c

@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: MPL-2.0
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+
+// Make the value not at the page boundary to uncover more bugs
+#define OFFSET 2
+
+void do_test(int shared_flag, int init_value, int new_value, int expected_value)
+{
+	volatile int *shared_memory;
+
+	// Create an anonymous memory region for sharing
+	shared_memory = mmap(NULL, sizeof(int), PROT_READ | PROT_WRITE,
+			     shared_flag | MAP_ANONYMOUS, -1, 0);
+	if (shared_memory == MAP_FAILED) {
+		perror("mmap failed");
+		exit(1);
+	}
+
+	if (init_value != 0) {
+		shared_memory[OFFSET] = init_value;
+	}
+
+	// Create a child process
+	pid_t pid = fork();
+
+	if (pid < 0) {
+		perror("fork");
+		exit(1);
+	} else if (pid == 0) {
+		// Child process
+
+		// Modify the value in the shared memory in the child process
+		shared_memory[OFFSET] = new_value;
+
+		printf("Child process: Value in shared memory: %d\n",
+		       shared_memory[OFFSET]);
+
+		exit(0);
+	} else {
+		// Parent process
+
+		// Wait for the child process to finish
+		int child_status = -1;
+		if (wait(&child_status) < 0) {
+			perror("wait");
+			exit(1);
+		}
+
+		if (child_status != 0) {
+			printf("child process terminates abnormally\n");
+			exit(1);
+		}
+
+		printf("Parent process: Value in shared memory: %d\n",
+		       shared_memory[OFFSET]);
+
+		if (shared_memory[OFFSET] != expected_value) {
+			perror("shared memory contains invalid value");
+			exit(1);
+		}
+
+		// Unmap the memory
+		if (munmap((void *)shared_memory, sizeof(int)) == -1) {
+			perror("munmap failed");
+			exit(1);
+		}
+	}
+}
+
+int main(void)
+{
+	printf("Fork non-accessed shared region\n");
+	do_test(MAP_SHARED, 0, 123, 123);
+
+	printf("Fork accessed shared region\n");
+	do_test(MAP_SHARED, 1, 123, 123);
+
+	printf("Fork non-accessed private region\n");
+	do_test(MAP_PRIVATE, 0, 123, 0);
+
+	printf("Fork accessed private region\n");
+	do_test(MAP_PRIVATE, 1, 123, 1);
+
+	return 0;
+}