skill.c

linux下获取一些环境信息的代码

  if(argv[1][2]=='\0' && (argv[1][1]=='s' || argv[1][1]=='n')){
    sigptr = argv[2];
    argv+=3;
    argc-=3;
  }else{
    sigptr = argv[1]+1;
    argv+=2;
    argc-=2;
  }
  signo = signal_name_to_number(sigptr);
  if(signo<0){
    fprintf(stderr, "ERROR: unknown signal name \"%s\".\n", sigptr);
    kill_usage();
  }
no_more_args:
  if(!argc) kill_usage();  /* nothing to kill? */
  while(argc--){
    long pid;
    char *endp;
    pid = strtol(argv[argc],&endp,10);
    if(!*endp){
      if(!kill((pid_t)pid,signo)) continue;
      exitvalue = 1;
      continue;
    }
    fprintf(stderr, "ERROR: garbage process ID \"%s\".\n", argv[argc]);
    kill_usage();
  }
  exit(exitvalue);
}

/***** skill/snice help */
static void skillsnice_usage(void) NORETURN;
static void skillsnice_usage(void){
  if(program==PROG_SKILL){
    fprintf(stderr,
      "Usage:   skill [signal to send] [options] process selection criteria\n"
      "Example: skill -KILL -v pts/*\n"
      "\n"
      "The default signal is TERM. Use -l or -L to list available signals.\n"
      "Particularly useful signals include HUP, INT, KILL, STOP, CONT, and 0.\n"
      "Alternate signals may be specified in three ways: -SIGKILL -KILL -9\n"
    );
  }else{
    fprintf(stderr,
      "Usage:   snice [new priority] [options] process selection criteria\n"
      "Example: snice netscape crack +7\n"
      "\n"
      "The default priority is +4. (snice +4 ...)\n"
      "Priority numbers range from +20 (slowest) to -20 (fastest).\n"
      "Negative priority numbers are restricted to administrative users.\n"
    );
  }
  fprintf(stderr,
    "\n"
    "General options:\n"
    "-f  fast mode            This is not currently useful.\n"
    "-i  interactive use      You will be asked to approve each action.\n"
    "-v  verbose output       Display information about selected processes.\n"
    "-w  warnings enabled     This is not currently useful.\n"
    "-n  no action            This only displays the process ID.\n"
    "\n"
    "Selection criteria can be: terminal, user, pid, command.\n"
    "The options below may be used to ensure correct interpretation.\n"
    "-t  The next argument is a terminal (tty or pty).\n"
    "-u  The next argument is a username.\n"
    "-p  The next argument is a process ID number.\n"
    "-c  The next argument is a command name.\n"
  );
  exit(1);
}

#if 0
static void _skillsnice_usage(int line){
  fprintf(stderr,"Something at line %d.\n", line);
  skillsnice_usage();
}
#define skillsnice_usage() _skillsnice_usage(__LINE__)
#endif

#define NEXTARG (argc?( argc--, ((argptr=*++argv)) ):NULL)

/***** common skill/snice argument parsing code */
#define NO_PRI_VAL ((int)0xdeafbeef)
static void skillsnice_parse(int argc, const char *restrict const *restrict argv){
  int signo = -1;
  int prino = NO_PRI_VAL;
  int force = 0;
  int num_found = 0;
  const char *restrict argptr;
  if(argc<2) skillsnice_usage();
  if(argc==2 && argv[1][0]=='-'){
    if(!strcmp(argv[1],"-L")){
      pretty_print_signals();
      exit(0);
    }
    if(!strcmp(argv[1],"-l")){
      unix_print_signals();
      exit(0);
    }
    if(!strcmp(argv[1],"-V")|| !strcmp(argv[1],"--version")){
      display_kill_version();
      exit(0);
    }
    skillsnice_usage();
  }
  NEXTARG;
  /* Time for serious parsing. What does "skill -int 123 456" mean? */
  while(argc){
    if(force && !num_found){  /* if forced, _must_ find something */
      fprintf(stderr,"ERROR: -%c used with bad data.\n", force);
      skillsnice_usage();
    }
    force = 0;
    if(program==PROG_SKILL && signo<0 && *argptr=='-'){
      signo = signal_name_to_number(argptr+1);
      if(signo>=0){      /* found a signal */
        if(!NEXTARG) break;
        continue;
      }
    }
    if(program==PROG_SNICE && prino==NO_PRI_VAL
    && (*argptr=='+' || *argptr=='-') && argptr[1]){
      long val;
      char *endp;
      val = strtol(argptr,&endp,10);
      if(!*endp && val<=999 && val>=-999){
        prino=val;
        if(!NEXTARG) break;
        continue;
      }
    }
    /* If '-' found, collect any flags. (but lone "-" is a tty) */
    if(*argptr=='-' && argptr[1]){
      argptr++;
      do{
        switch(( force = *argptr++ )){
        default:  skillsnice_usage();
        case 't':
        case 'u':
        case 'p':
        case 'c':
          if(!*argptr){ /* nothing left here, *argptr is '\0' */
            if(!NEXTARG){
              fprintf(stderr,"ERROR: -%c with nothing after it.\n", force);
              skillsnice_usage();
            }
          }
          goto selection_collection;
        case 'f': f_flag++; break;
        case 'i': i_flag++; break;
        case 'v': v_flag++; break;
        case 'w': w_flag++; break;
        case 'n': n_flag++; break;
        case 0:
          NEXTARG;
          /*
           * If no more arguments, all the "if(argc)..." tests will fail
           * and the big loop will exit.
           */
        } /* END OF SWITCH */
      }while(force);
    } /* END OF IF */
selection_collection:
    num_found = 0; /* we should find at least one thing */
    switch(force){ /* fall through each data type */
    default: skillsnice_usage();
    case 0: /* not forced */
    case 't':
      if(argc){
        struct stat sbuf;
        char path[32];
        if(!argptr) skillsnice_usage(); /* Huh? Maybe "skill -t ''". */
        snprintf(path,32,"/dev/%s",argptr);
        if(stat(path, &sbuf)>=0 && S_ISCHR(sbuf.st_mode)){
          num_found++;
          ENLIST(tty,sbuf.st_rdev);
          if(!NEXTARG) break;
        }else if(!(argptr[1])){  /* if only 1 character */
          switch(*argptr){
          default:
            if(stat(argptr,&sbuf)<0) break; /* the shell eats '?' */
          case '-':
          case '?':
            num_found++;
            ENLIST(tty,0);
            if(!NEXTARG) break;
          }
        }
      }
      if(force) continue;
    case 'u':
      if(argc){
        struct passwd *passwd_data;
        passwd_data = getpwnam(argptr);
        if(passwd_data){
          num_found++;
          ENLIST(uid,passwd_data->pw_uid);
          if(!NEXTARG) break;
        }
      }
      if(force) continue;
    case 'p':
      if(argc && *argptr>='0' && *argptr<='9'){
        char *endp;
        int num;
        num = strtol(argptr, &endp, 0);
        if(*endp == '\0'){
          num_found++;
          ENLIST(pid,num);
          if(!NEXTARG) break;
        }
      }
      if(force) continue;
      if(num_found) continue; /* could still be an option */
    case 'c':
      if(argc){
        num_found++;
        ENLIST(cmd,argptr);
        if(!NEXTARG) break;
      }
    } /* END OF SWITCH */
  } /* END OF WHILE */
  /* No more arguments to process. Must sanity check. */
  if(!tty_count && !uid_count && !cmd_count && !pid_count){
    fprintf(stderr,"ERROR: no process selection criteria.\n");
    skillsnice_usage();
  }
  if((f_flag|i_flag|v_flag|w_flag|n_flag) & ~1){
    fprintf(stderr,"ERROR: general flags may not be repeated.\n");
    skillsnice_usage();
  }
  if(i_flag && (v_flag|f_flag|n_flag)){
    fprintf(stderr,"ERROR: -i makes no sense with -v, -f, and -n.\n");
    skillsnice_usage();
  }
  if(v_flag && (i_flag|f_flag)){
    fprintf(stderr,"ERROR: -v makes no sense with -i and -f.\n");
    skillsnice_usage();
  }
  /* OK, set up defaults */
  if(prino==NO_PRI_VAL) prino=4;
  if(signo<0) signo=SIGTERM;
  if(n_flag){
    program=PROG_SKILL;
    signo=0; /* harmless */
  }
  if(program==PROG_SKILL) sig_or_pri = signo;
  else sig_or_pri = prino;
}

/***** main body */
int main(int argc, const char *argv[]){
  const char *tmpstr;
  my_pid = getpid();
  saved_argc = argc;
  if(!argc){
    fprintf(stderr,"ERROR: could not determine own name.\n");
    exit(1);
  }
  tmpstr=strrchr(*argv,'/');
  if(tmpstr) tmpstr++;
  if(!tmpstr) tmpstr=*argv;
  program = PROG_GARBAGE;
  if(*tmpstr=='s'){
    setpriority(PRIO_PROCESS,my_pid,-20);
    if(!strcmp(tmpstr,"snice")) program = PROG_SNICE;
    if(!strcmp(tmpstr,"skill")) program = PROG_SKILL;
  }else{
    if(!strcmp(tmpstr,"kill")) program = PROG_KILL;
  }
  switch(program){
  case PROG_SNICE:
  case PROG_SKILL:
    skillsnice_parse(argc, argv);
/*    show_lists(); */
    iterate(); /* this is it, go get them */
    break;
  case PROG_KILL:
    kill_main(argc, argv);
    break;
  default:
    fprintf(stderr,"ERROR: no \"%s\" support.\n",tmpstr);
  }
  return 0;
}