sys/src/cmd/read.c

   1 #include <u.h>
   2 #include <libc.h>
   3
   4 int     multi;
   5 int     nlines;
   6 char    *status = nil;
   7
   8 int
   9 line(int fd, char *file)
  10 {
  11         char c;
  12         int m, n, nalloc;
  13         char *buf;
  14
  15         nalloc = 0;
  16         buf = nil;
  17         for(m=0; ; ){
  18                 n = read(fd, &c, 1);
  19                 if(n < 0){
  20                         fprint(2, "read: error reading %s: %r\n", file);
  21                         exits("read error");
  22                 }
  23                 if(n == 0){
  24                         if(m == 0)
  25                                 status = "eof";
  26                         break;
  27                 }
  28                 if(m == nalloc){
  29                         nalloc += 1024;
  30                         buf = realloc(buf, nalloc);
  31                         if(buf == nil){
  32                                 fprint(2, "read: malloc error: %r\n");
  33                                 exits("malloc");
  34                         }
  35                 }
  36                 buf[m++] = c;
  37                 if(c == '\n')
  38                         break;
  39         }
  40         if(m > 0)
  41                 write(1, buf, m);
  42         free(buf);
  43         return m;
  44 }
  45
  46 void
  47 lines(int fd, char *file)
  48 {
  49         do{
  50                 if(line(fd, file) == 0)
  51                         break;
  52         }while(multi || --nlines>0);
  53 }
  54
  55 void
  56 main(int argc, char *argv[])
  57 {
  58         int i, fd;
  59         char *s;
  60
  61         ARGBEGIN{
  62         case 'm':
  63                 multi = 1;
  64                 break;
  65         case 'n':
  66                 s = ARGF();
  67                 if(s){
  68                         nlines = atoi(s);
  69                         break;
  70                 }
  71                 /* fall through */
  72         default:
  73                 fprint(2, "usage: read [-m] [-n nlines] [files...]\n");
  74                 exits("usage");
  75         }ARGEND
  76
  77         if(argc == 0)
  78                 lines(0, "<stdin>");
  79         else
  80                 for(i=0; i<argc; i++){
  81                         fd = open(argv[i], OREAD);
  82                         if(fd < 0){
  83                                 fprint(2, "read: can't open %s: %r\n", argv[i]);
  84                                 exits("open");
  85                         }
  86                         lines(fd, argv[i]);
  87                         close(fd);
  88                 }
  89
  90         exits(status);
  91 }