（1）添加系统调用号 ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1843962-20211217-1639743564044) （2）后面将要使用的宏模板 ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1843962-20211217-1639743615441) （3）修改系统调用总数 ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1843962-20211217-1639743369323) (4)添加全局声明，并在系统调用表中增加两个函数 ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1843962-20211217-1639743914908) （5）编写系统调用函数 ``` #include #include #include #include static char str[24]; static unsigned long len; int sys_iam(const char* name) { int i; char tmp[24]; for(i = 0; i < 24; i++) { tmp[i] = get_fs_byte(name + i); if(tmp[i] == 0) break; } if(i == 24) { return -(EINVAL); } // clear str for(i = 0; i < 24; i++) { str[i] = 0; } // copy for(i = 0; tmp[i] != 0; i++) { str[i] = tmp[i]; } len = i; return len; } int sys_whoami(char* name, unsigned int size) { int i; if(size < len) { return -(EINVAL); } for(i = 0; i < size && str[i] != 0; i++) { put_fs_byte(str[i], name + i); } put_fs_byte(0, name + i); return len; } ``` (6)修改Makefile ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1843962-20211217-1639744840846) ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1843962-20211217-1639744852244) (7)编写测试程序 ``` // File : iam.c #define __LIBRARY__ #include #include _syscall1(int, iam, char*, name) int main(int argc, char* argv[]) { if(argc <= 1){ printf("input error\n"); return -1; } iam(argv[1]); return 0; } ``` ``` // File : whoami.c #define __LIBRARY__ #include #include _syscall2(int, whoami, char*, name, unsigned int, size) char name[25] = {}; int main(int argc, char* argv[]) { whoami(name, 25); printf("%s\n", name); return 0; } ```

“操作系统原理与实践”实验报告