Lab 4: Process Creation and Management

Transcription

1 1.Objective 2.Syabus Lab 4: Process Creation and Management Learn the creation and management of Linux process Understand the concepts and principe of process Impement the creation and management of process using C or C++ 3.Prerequisite C or C++ anguage Computer which run Linux system (e.g. Ubuntu) Understand the concept of process 4.Concepts and Principes of Process Pease refer to the chapter 3 of the text book. The main contents have been ectured in the third week, 09/26/2016. The side of this chapter can be found in the course website: 5.Experimenta Contents 5.1 Basic Program Description: A simpe program to create a chid process using fork. Parent wait for chid to coect the exit status of chid. The function of fork() wi create a new process. The function of getpid() wi get the current process id. The function of getppid() wi get the current parent process id. The function of wait() wi wait for the chid process to finish. The function of exit() wi finish a process and exit. The fie name is basic_fork.c #incude<stdio.h> #incude<unistd.h> #incude<fcnt.h> #incude<stdib.h> int main() int ret_va, pid, pidc; int ret_va2; /*create a chid*/ pid = fork(); if(pid < 0) perror("fork faied\n"); if(pid > 0) /*parent code*/

2 printf("parent code pid=%d\n",getpid()); /*wait for chid to terminate and catch the exit code*/ pidc = wait(&ret_va); printf("pidc = %d\n",pidc); if(pidc == -1) perror("error in wait\n"); if(wifexited(ret_va)) /*chid terminated sucessfuy*/ printf("chid exited with status %d\n",wexitstatus(ret_va)); ese if (WIFSIGNALED(ret_va)) printf("kied by signa %d\n", WTERMSIG(ret_va)); ese if (WIFSTOPPED(ret_va)) printf("stopped by signa %d\n", WSTOPSIG(ret_va)); ese if (WIFCONTINUED(ret_va)) printf("continued\n"); ese /*chid code*/ printf("chid pid=%d, parent pid=%d\n",getpid(), getppid()); return EXIT_SUCCESS; How to Run: gcc -o basic_fork basic_fork.c./basic_fork 5.2 Chid-of-Chid Description: Program to make beow given hierarchy using fork. The fie name is chid_of_chid.c parent chid chid chid #incude<stdio.h> #incude<stdib.h> #incude<unistd.h> #define NUM_CHILD 3 int main()

3 int ret_pid; int ret_va; int i; for (i = 0;i < NUM_CHILD;i++) ret_pid = fork(); if (ret_pid == -1) perror("error in fork:"); if (ret_pid > 0) /*parent code*/ printf("parent code, pid = %d,parent pid = %d\n",getpid(),getppid()); break; ese /*chid code*/ printf("chid code, pid = %d,parent pid = %d\n",getpid(),getppid()); /*ast one wi not have any chid,so exit from here*/ if (i == NUM_CHILD-1) ret_pid = wait(&ret_va); if(ret_pid == -1) perror("error in wait:"); printf("terminated pid = %d,status = %d\n",ret_pid,ret_va); return EXIT_SUCCESS; How to Run: gcc -o chid_of_chid chid_of_chid.c./chid_of_chid 5.3 Mutipe Chid Description: Program to make 3 chid process from a parent process using fork. The fie name is mutipe_chid.c. Parent - chid - chid `- chid #incude<stdio.h>

4 #incude<stdib.h> #incude<unistd.h> #define NUM_CHILD 3 int main() int ret_pid; int ret_va; int i; for (i = 0;i < NUM_CHILD;i++) ret_pid = fork(); if (ret_pid == -1) perror("error in fork:"); if (ret_pid > 0) /*parent code*/ printf("parent code, pid = %d,parent pid = %d\n",getpid(),getppid()); ese /*chid code*/ printf("chid code, pid = %d,parent pid = %d\n",getpid(),getppid()); for(i = 0;i < NUM_CHILD ; i++) ret_pid = wait(&ret_va); if(ret_pid == -1) perror("error in wait:"); printf("terminated pid = %d,status = %d\n",ret_pid,ret_va); return EXIT_SUCCESS; How to Run: gcc -o mutipe_chid mutipe_chid.c./mutipe_chid 5.4 Open and Write Fie Description: A simpe program to create a chid process using fork(). Parent opens a fie and chid writes some data to fie. And then parent waits for the chid and reads

5 data from the same fie. The fie name is open_write.c #incude<stdio.h> #incude<unistd.h> #incude<fcnt.h> #incude<stdib.h> int main() int ret_va,pid,pidc; int fd; char buff[] = "heo to the word of inux"; char read_buff[32]; fd = open("test",o_creato_rdwr,s_irusrs_iwusr); if(fd < 0) perror("error in oepning fie"); /*create a chid*/ pid = fork(); if(pid < 0) perror("fork faied\n"); if(pid > 0) /*wait for chid to terminate and catch the exit code*/ pidc = wait(&ret_va); if(wifexited(ret_va)) printf("chid exited with status %d\n",wexitstatus(ret_va)); /*parent has written in fie so the see to the beginnin of fie*/ seek(fd,0,seek_set); ret_va = read(fd,read_buff,sizeof(read_buff)); printf("ret_va =%d %s",ret_va,read_buff); /*cose the fie and exit*/ cose(fd); ese /*write some data to fie*/ if(write(fd,buff,sizeof(buff) < 0) perror("error in writing fie\n");

6 printf("data written\n"); return EXIT_SUCCESS; How to Run: gcc -o open_write open_write.c./open_write 5.5 Show Process Information Description: A basic Linux Kerne modue to show the information of a process working. The fie name is Makefie obj-m += process_info.o a: make -C /ib/modues/$(she uname -r)/buid M=$(PWD) modues cean: rm Modue.symvers modues.order process_info.ko process_info.mod.c process_info.mod.o process_info.o The fie name is process_info.c #incude <inux/init.h> #incude <inux/modue.h> #incude <inux/modueparam.h> #incude <inux/sched.h> #incude <inux/rcupdate.h> #incude <inux/fdtabe.h> #incude <inux/fs.h> #incude <inux/fs_struct.h> #incude <inux/dcache.h> #incude <inux/sab.h> #incude <inux/kerne.h> #incude <inux/errno.h> #incude <inux/stat.h> #incude <inux/mm.h> #incude <inux/highmem.h> #incude <asm/pgtabe.h> #define BUFSIZE 100 MODULE_LICENSE("GPL"); MODULE_AUTHOR("Process Information"); static int pid = 0; modue_param( pid, int, S_IRUSR S_IWUSR S_IRGRP S_IWGRP); MODULE_PARM_DESC( pid, "PID of the process"); static int init processinfo_init(void) printk( KERN_INFO "Starting modue...\n"); struct task_struct *task = current; struct task_struct *desiredtask = NULL;

7 for_each_process( task) if ( task->pid == pid) desiredtask = task; if ( desiredtask!= NULL) printk( KERN_INFO "--A process is found with the PID = %d--\n", pid); printk( KERN_INFO "--The curenty opened fies information--\n"); struct fdtabe *fiestabe; struct path fpath; char *fiepath; char *buffer = (char *) kmaoc( GFP_KERNEL, BUFSIZE * sizeof( char) ); fiestabe = fies_fdtabe( desiredtask->fies); int i = 0; whie ( fiestabe->fd[i]) fpath = fiestabe->fd[i]->f_path; fiepath = d_path( &fpath, buffer, BUFSIZE * sizeof( char) ); printk( KERN_INFO "\t%s\n", fiepath); i++; printk( KERN_INFO "--Memory Management Information--\n" ); struct mm_struct* mm = desiredtask->mm; printk( KERN_INFO "[CODE START]\t[CODE END]\t[CODE SIZE]\n"); printk( KERN_INFO "%x\t\t%x\t%u\n", mm->start_code, mm->end_code, mm->end_code - mm->start_code ); printk( KERN_INFO "[DATA START]\t[DATA END]\t[DATA SIZE]\n"); printk( KERN_INFO "%x\t\t%x\t%u\n\n", mm->start_data, mm->end_data, mm->end_data - mm->start_data ); printk( KERN_INFO "\nnotice: The stack data wi be written in virtua memory part.\n" ); printk( KERN_INFO "[ARG START]\t[ARG END]\t[ARG SIZE]\n"); printk( KERN_INFO "%x\t\t%x\t%u\n\n", mm->arg_start, mm->arg_end, mm->arg_end - mm->arg_start ); printk( KERN_INFO "[ENV START]\t[ENV END]\t[ENV SIZE]\n"); printk( KERN_INFO "%x\t\t%x\t%u\n\n", mm->env_start, mm->env_end, mm->env_end - mm->env_start ); printk( KERN_INFO "Tota VM area = %u\n", mm->tota_vm); printk( KERN_INFO "Number of frames used by the process = %u\n\n", get_mm_rss( mm) );

8 struct vm_area_struct *mmap = mm->mmap; printk( KERN_INFO "--Virtua Memory Information--\n" ); printk( KERN_INFO "[VM START]\t[VM_END]\t[VM_SIZE]"); whie( mmap!= NULL ) if( mmap -> vm_next == NULL ) printk( KERN_INFO "\nthe stack information of the process:\n"); printk( KERN_INFO "[STACK START]\t[STACK END]\t[STACK SIZE]\n" ); printk( KERN_INFO "%x\t\t%x\t%u\n", mmap -> vm_start, mmap -> vm_end, mmap -> vm_end - mmap -> vm_start ); mmap = mmap -> vm_next; printk( KERN_INFO "--The fiesystem information--\n"); struct fs_struct *fiesstruct = desiredtask->fs; printk( KERN_INFO "\troot: %s\n", fiesstruct->root.dentry->d_name.name); printk( KERN_INFO "\tworking Directory: %s\n", fiesstruct->pwd.dentry->d_name.name); ese printk( KERN_INFO "There is not a process with PID = %d, exiting...\n", pid); return 0; static void exit processinfo_exit( void) printk( KERN_INFO "The modue successfuy removed.\n"); modue_init( processinfo_init); modue_exit( processinfo_exit) How to Run: make sudo insmod process_info.ko pid=1 //insta Linux kerne modue //pid can be changed to other id dmesg //show the detaied message output by process_info.ko 6.Concusion In this chapter, five experiments have been compete. They have shown how to create and manage a process.