sys/src/cmd/read.c

   1 #include <u.h>
   2 #include <libc.h>
   3
   4 int     multi;
   5 int     nlines;
   6 vlong   nchars;
   7 char    *status = nil;
   8
   9 int
  10 line(int fd, char *file)
  11 {
  12         char c;
  13         int m, n, nalloc;
  14         char *buf;
  15
  16         nalloc = 0;
  17         buf = nil;
  18         for(m=0; ; ){
  19                 n = read(fd, &c, 1);
  20                 if(n < 0){
  21                         fprint(2, "read: error reading %s: %r\n", file);
  22                         exits("read error");
  23                 }
  24                 if(n == 0){
  25                         if(m == 0)
  26                                 status = "eof";
  27                         break;
  28                 }
  29                 if(m == nalloc){
  30                         nalloc += 1024;
  31                         buf = realloc(buf, nalloc);
  32                         if(buf == nil){
  33                                 fprint(2, "read: malloc error: %r\n");
  34                                 exits("malloc");
  35                         }
  36                 }
  37                 buf[m++] = c;
  38                 if(c == '\n')
  39                         break;
  40         }
  41         if(m > 0)
  42                 write(1, buf, m);
  43         free(buf);
  44         return m;
  45 }
  46
  47 void
  48 lines(int fd, char *file)
  49 {
  50         do{
  51                 if(line(fd, file) == 0)
  52                         break;
  53         }while(multi || --nlines>0);
  54 }
  55
  56 void
  57 chars(int fd, char *file)
  58 {
  59         char buf[8*1024];
  60         vlong m;
  61         int n;
  62
  63         for(m = 0; m < nchars; m += n){
  64                 n = sizeof(buf);
  65                 if(n > (nchars - m))
  66                         n = nchars - m;
  67                 if((n = read(fd, buf, n)) < 0){
  68                         fprint(2, "read: error reading %s: %r\n", file);
  69                         exits("read error");
  70                 }
  71                 if(n == 0){
  72                         if(m == 0)
  73                                 status = "eof";
  74                         break;
  75                 }
  76                 write(1, buf, n);
  77         }
  78 }
  79
  80 void
  81 usage(void)
  82 {
  83         fprint(2, "usage: read [-m] [-n nlines] [-c nbytes] [files...]\n");
  84         exits("usage");
  85 }
  86
  87 void
  88 main(int argc, char *argv[])
  89 {
  90         void (*proc)(int, char*);
  91         int i, fd;
  92
  93         proc = lines;
  94         ARGBEGIN{
  95         case 'c':
  96                 nchars = atoll(EARGF(usage()));
  97                 proc = chars;
  98                 break;
  99         case 'n':
 100                 nlines = atoi(EARGF(usage()));
 101                 break;
 102         case 'm':
 103                 multi = 1;
 104                 break;
 105         default:
 106                 usage();
 107         }ARGEND
 108
 109         if(argc == 0)
 110                 (*proc)(0, "<stdin>");
 111         else
 112                 for(i=0; i<argc; i++){
 113                         fd = open(argv[i], OREAD);
 114                         if(fd < 0){
 115                                 fprint(2, "read: can't open %s: %r\n", argv[i]);
 116                                 exits("open");
 117                         }
 118                         (*proc)(fd, argv[i]);
 119                         close(fd);
 120                 }
 121
 122         exits(status);
 123 }