完善 mmap 示例程序 .

Signed-off-by: rick.chan <chenyang@autoai.com>

Linux/Application/POSIX/MMAP/demo_mmap.c

@@ -8,8 +8,32 @@
  * @copyright	Copyright (c) 2020
  * 
  */
+#include <stdio.h>
+
+#include <fcntl.h>
+#include <unistd.h>
 #include <sys/mman.h>
+#include <sys/user.h>
+
+#include <errno.h>
+#include <string.h>
 
 int main(int argc, char* argv[]) {
+	char* buf;
+	int fd = open("demo_file_name", O_RDWR);
 
-}
+    buf = (char*)mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_LOCKED, fd, 0);
+	if(NULL==buf | MAP_FAILED==buf) {
+		printf("%s\n", strerror(errno));
+	}
+    buf[0] = 'H';
+    buf[1] = 'e';
+    buf[2] = 'l';
+    buf[3] = 'l';
+    buf[4] = 'o';
+    buf[5] = '\0';
+    printf("%s", buf);
+    munmap(buf, PAGE_SIZE);		// 释放内存
+	close(fd);
+    return 0;
+}