sys/src/libbio/bread.c

   1 #include        <u.h>
   2 #include        <libc.h>
   3 #include        <bio.h>
   4
   5 long
   6 Bread(Biobufhdr *bp, void *ap, long count)
   7 {
   8         long c;
   9         uchar *p;
  10         int i, n, ic;
  11
  12         p = ap;
  13         c = count;
  14         ic = bp->icount;
  15
  16         while(c > 0) {
  17                 n = -ic;
  18                 if(n > c)
  19                         n = c;
  20                 if(n == 0) {
  21                         if(bp->state != Bractive)
  22                                 break;
  23                         i = bp->iof(bp, bp->bbuf, bp->bsize);
  24                         if(i <= 0) {
  25                                 bp->state = Bracteof;
  26                                 if(i < 0) {
  27                                         Berror(bp, "read error: %r");
  28                                         bp->state = Binactive;
  29                                 }
  30                                 break;
  31                         }
  32                         bp->gbuf = bp->bbuf;
  33                         bp->offset += i;
  34                         if(i < bp->bsize) {
  35                                 memmove(bp->ebuf-i, bp->bbuf, i);
  36                                 bp->gbuf = bp->ebuf-i;
  37                         }
  38                         ic = -i;
  39                         continue;
  40                 }
  41                 memmove(p, bp->ebuf+ic, n);
  42                 c -= n;
  43                 ic += n;
  44                 p += n;
  45         }
  46         bp->icount = ic;
  47         if(count == c && bp->state == Binactive)
  48                 return -1;
  49         return count-c;
  50 }