c - segmentation fault after waking a process -

hey i'm writing simple shell on getting sigstsp pause process , continue on getting more commands. saves suspended process in job list. when try waking suspended process segmentation fault, after (ex)suspended process deals sigcont signal.

this signalhandler

void signalhandle(int sig) { int i,pid,id; sigset_t mask_set; sigset_t old_set; signal(sigtstp,signalhandle); sigfillset(&mask_set); sigprocmask(sig_setmask,&mask_set,&old_set);  //handle sigtstp **if (sig == sigtstp)**{     gpid=getpid();     pid=fork();     if (pid==-1){         perror("(ctrl-z)(signal error)(fork)");     }     else if (pid==0){         susp_bg_pid=gpid;         i=0;         while (getpid(jobslist,i)!=-1){              i=i+1;         }         id=getid(&jobslist,gpid);         if (id==-1){             insertelem(&jobslist, l_fg_cmd, i, gpid, 1);             }         else{             delpid(&jobslist,gpid);             insertelem(&jobslist, l_fg_cmd, id, gpid, 1);         }         gpid=getpid();                                }     else{        susp = 1;        pause();     } }   **if (sig == sigcont){**     printf("process running again\n");     } } 

}

and how try wake process

else if (!strcmp(cmd, "bg"))  {         int pid , new_pid=0;         int id=0;          if (num_arg > 1) {                 illegal_cmd = 1;         }         else{             if (num_arg==1)   {                     id = atoi(args[1]);                     new_pid= getpid(*pjobslist,id);                     if (new_pid!=-1){                         pelem=*pjobslist;                         if (pelem->varvalue!=null){                             while (pelem!=null){                                 if (pelem->pid==new_pid){                                     printf("%s \n", pelem->varvalue);                                 }                                 pelem=pelem->pnext;                             }                         }                         **kill(new_pid,sigcont);**                                                 printf("now finished\n");                     }                     else{                         printf("smash error\n");                     }              }             else{              }          } } 

my console output

smash > sleep 30

^zsmash > bg 0

sleep 30

now finished

smash > process running again

segmentation fault

press [enter] close terminal ...

int insertelem(list_element** plist, char* value, int id, int pid, int susp){ list_element *list; list_element *temp; list = *plist; if (value == null)      return -1;      if (list == null) {       list = (list_element*)malloc(sizeof(list_element));     if (list == null)          exit (-1);       list->varvalue=(char*)malloc(sizeof(char)*(strlen(value)+1));     if (list->varvalue == null)          exit (-1);       strcpy(list->varvalue, value);     list->varname = null; // varname doesn't mean job     list->id = id;     list->pid = pid;     list->suspended = susp;     list->pnext = null;     *plist = list;     return 0;     }  else  {         if (list->id == id)          return insertelem(&list->pnext, value, id+1, pid, susp);     else     {         temp = (list_element*)malloc(sizeof(list_element));          if (temp == null)               exit (-1);          temp->varvalue =(char*) malloc(sizeof(char)*(strlen(list->varvalue)+1));         if (temp->varvalue == null)              exit (-1);          strcpy(temp->varvalue, list->varvalue);         temp->varname = null;         temp->pid = list->pid;         temp->id = list->id;         temp->suspended = list->suspended;         temp->pnext = list->pnext;          free(list->varvalue);         list->varvalue=(char*)malloc(sizeof(char)*(strlen(value)+1));         if (list->varvalue == null)              exit (-1);          strcpy(list->varvalue, value);         list->id = id;         list->pid = pid;         list->suspended = susp;         list->pnext = temp;         return 0;     } }