UNIX — универсальная среда программирования

  if (index(file, '/') != NULL) /* strchr in some systems */
  error("won't handle '/'s in %s", file);
  if (stat(file, &sti) == -1)
  error("can't stat %s", file);
  if (stat(target, &sto) == -1) /* target not present */
  sto.st_mtime = 0; /* so make it look old */
  if (sti.st_mtime < sto.st_mtime) /* target is newer */
  fprintf(stderr, "%s: %s not copied\n", progname, file);
  else if ((fin = open(file, 0)) == -1)
  error("can't open file %s", file);
  else if ((fout = creat(target, sti.st_mode)) == -1)
  error("can't create %s", target);
  while ((n = read(fin, buf, sizeof buf)) > 0)
  if (write(fout, buf, n) != n)
  error("error writing %s", target);
  close(fin);
  close(fout);
 }

 #include "error.c"

3.8.52 system1.c

 #include <signal.h>

 system(s) /* run command line s */
  char *s;
 {
  int status, pid, w, tty;
  int (*istat), (*qstat);

  ...
  if ((pid = fork) == 0) {
  ...
  execlp("sh", "sh", "-c", s, (char*)0);
  exit(127);
  }
  ...
  istat = signal(SIGINT, SIG_IGN);
  qstat = signal(SIGQUIT, SIG_IGN);
  while ((w = wait(&status)) != pid && w != -1)
  ;
  if (w == -1)
  status = -1;
  signal(SIGINT, istat);
  signal(SIGQUIT, qstat);
  return status;
 }

3.8.53 system.c

 /*
  * Safer version of system for interactive programs
  */

 #include <signal.h>
 #include <stdio.h>

 system(s) /* run command line s */
  char *s;
 {
  int status, pid, w, tty;
  int (*istat), (*qstat);
  extern char *progname;

  fflush(stdout);
  tty = open("/dev/tty", 2);
  if (tty == -1) {
  fprintf (stderr, "%s: can't open /dev/tty\n", progname);
  return -1;
  }
  if ((pid = fork) == 0) {
  close(0);
  dup(tty);
  close(1);
  dup(tty);
  close(2);
  dup(tty);
  close(tty);
  execlp("sh", "sh", "-c", s, (char*)0);
  exit(127);
  }
  close(tty);
  istat = signal(SIGINT, SIG_IGN);
  qstat = signal(SIGQUIT, SIG_IGN);
  while ((w = wait(&status)) != pid && w != -1)
  ;
  if (w == -1)
  status = -1;
  signal(SIGINT, istat);
  signal(SIGQUIT, qstat);
  return status;
 }

3.8.54 timeout.c

 /* timeout: set time limit on a process */
 #include <stdio.h>
 #include <signal.h>
 int pid; /* child process id */
 char *progname;

 main(argc, argv)
  int argc;
  char *argv[];
 {
  int sec = 10, status, onalarm;

  progname = argv[0];
  if (argc > 1 && argv[1][0] == '-') {
  sec = atoi(&argv[1][1]);
  argc--;
  argv++;
  }
  if (argc < 2)
  error("Usage: %s [-10] command", progname);
  if ((pid=fork) == 0) {
  execvp(argv[1], &argv[1]);
  error("couldn't start %s", argv[1]);
  }
  signal(SIGALRM, onalarm);
  alarm(sec);
  if (wait(&status) == -1 || (status & 0177) != 0)
  error("%s killed", argv[1]);
  exit((status >> 8) & 0377);
 }

 onalarm /* kill child when alarm arrives */
 {
  kill(pid, SIGKILL);
 }

 #include "error.c"

3.8.55 toolong

 length($0) > 72 { print "Line", NR, "too long:", substr($0,1,60) }