sys/src/cmd/aux/rdwr.c

   1 #include <u.h>
   2 #include <libc.h>
   3
   4 int wrrd;
   5
   6 void
   7 usage(void)
   8 {
   9         fprint(2, "usage: rdwr [-w] file\n");
  10         exits("usage");
  11 }
  12
  13 void
  14 main(int argc, char **argv)
  15 {
  16         int fd;
  17         char buf[8192];
  18         int n;
  19
  20         ARGBEGIN{
  21         case 'w':
  22                 wrrd = 1;
  23                 break;
  24         default:
  25                 usage();
  26         }ARGEND;
  27
  28         if(argc != 1)
  29                 usage();
  30
  31         if((fd = open(argv[0], ORDWR)) < 0)
  32                 sysfatal("open: %r");
  33
  34         if(wrrd){
  35                 n = read(fd, buf, sizeof buf);
  36                 if(n < 0)
  37                         fprint(2, "read error: %r\n");
  38                 else{
  39                         write(1, buf, n);
  40                         print("\n");
  41                 }
  42         }
  43
  44         while(print("> "), (n = read(0, buf, 1000)) > 0) {
  45                 seek(fd, 0, 0);
  46                 if(write(fd, buf, n-1) != n-1)  /* n-1: no newline */
  47                         fprint(2, "write error: %r\n");
  48                 seek(fd, 0, 0);
  49                 n = read(fd, buf, sizeof buf);
  50                 if(n < 0)
  51                         fprint(2, "read error: %r\n");
  52                 else{
  53                         write(1, buf, n);
  54                         print("\n");
  55                 }
  56         }
  57 }