- **创建kernel/who.c系统调用API文件，实现sys_iam, sys_whoami** ``` #include #include #include static char myname[24] = {'0'}; static char _name[24]={'0'}; int sys_iam(const char* name) { char c=' '; int i=0,j=0; //printk("sys_iam called, addr: %04x \n\r"); while((c = get_fs_byte(name+i))!='\0') { if(i>=23) { return -EINVAL; } _name[i] = c; ++i; } _name[i] = '\0'; for(;j<24;++j){ myname[j] = _name[j]; } //printk("myname[24]: %s \n\r;",myname); return i; } int sys_whoami(char* name,int size) { int i=0; //printk("sys_whoami called,addr: %04x, size: %d \n\r",name,size); //printk("myname[24]: %s \n\r;",myname); for(;i<24 && myname[i]!='\0';++i) { if(i>size-1) { return -EINVAL; } put_fs_byte(myname[i],name+i); } put_fs_byte('\0',name+i); return i; } ``` - **修改kernel/system_call.s, nr_system_calls = 74 ** ``` nr_system_calls = 74 //增加两个api, 72改成74 ``` - include/linux/sys.h 加上实验的两个api ``` ,,,,,, extern int sys_iam(); extern int sys_whoami(); fn_ptr sys_call_table[] = { ,,,,,sys_setregid, sys_iam, sys_whoami }; ``` - 修改kernel/Makefile加上who.c ``` OBJS = sched.o system_call.o traps.o asm.o fork.o \ panic.o printk.o vsprintf.o sys.o exit.o \ signal.o mktime.o *改为：* OBJS = sched.o system_call.o traps.o asm.o fork.o \ panic.o printk.o vsprintf.o sys.o exit.o \ signal.o mktime.o who.o 另一处： \### Dependencies: exit.s exit.o: exit.c ../include/errno.h ../include/signal.h \ ../include/sys/types.h ../include/sys/wait.h *改成* \### Dependencies: who.s who.o: who.c ../include/errno.h ../include/linux/kernel.h ../include/asm/segment.h exit.s exit.o: exit.c ../include/errno.h ../include/signal.h \ ../include/sys/types.h ../include/sys/wait.h ``` - **至此sys_iam 和 sys_whoami 系统调用已经添加完成，接下来编译生成修改后的内核，并编写系统调用测试程序 iam.c 和whoami.c** **iam.c** ``` #define __LIBRARY__ #include #include _syscall1(int,iam,const char*,name) int main(int argc,char* argv[]) { iam(argv[1]); return 0; } ``` **whoami.c** ``` #define __LIBRARY__ #include #include #include _syscall2(int, whoami,char*,name,int,size); int main(int argc,char* argv[]) { int len = 23; char* gotname=NULL; gotname = (char*)malloc(len+1); if (gotname == NULL) exit(-1); memset(gotname, 0, len+1); int res = whoami(gotname,len); printf("%s", gotname); return res; } ``` **unistd.h修改的地方，注意：在linux0.11系统上编译的时候得将修改后的unistd.h复制到/usr/include/下，使得测试程序能够引用正确的头文件** ``` ...... ...... #define __NR_iam 72 #define __NR_whoami 73 ...... ...... int iam(const char* name); int whoami(char* name, int size); #endif ``` .... - **linux0.11上编译好测试程序** ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1088053-20190623-1561273411455) - **执行testlab2.sh** ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1088053-20190623-1561273464178) - **执行testlab2.c可执行文件test** ![图片描述](https://dn-simplecloud.shiyanlou.com/courses/uid1088053-20190623-1561273521859)

“操作系统原理与实践”实验报告