sys/src/libstdio/fread.c

   1 /*
   2  * pANS stdio -- fread
   3  */
   4 #include "iolib.h"
   5
   6 #define BIGN (BUFSIZ/2)
   7
   8 long fread(void *p, long recl, long nrec, FILE *f){
   9         char *s;
  10         int n, d, c;
  11
  12         s=(char *)p;
  13         n=recl*nrec;
  14         while(n>0){
  15                 d=f->wp-f->rp;
  16                 if(d>0){
  17                         if(d>n)
  18                                 d=n;
  19                         memmove(s, f->rp, d);
  20                         f->rp+=d;
  21                 }else{
  22                         if(n >= BIGN && f->state==RD && !(f->flags&STRING) && f->buf!=f->unbuf){
  23                                 d=read(f->fd, s, n);
  24                                 if(d<=0){
  25                                         f->state=(d==0)?END:ERR;
  26                                         goto ret;
  27                                 }
  28                         }else{
  29                                 c=_IO_getc(f);
  30                                 if(c==EOF)
  31                                         goto ret;
  32                                 *s=c;
  33                                 d=1;
  34                         }
  35                 }
  36                 s+=d;
  37                 n-=d;
  38         }
  39     ret:
  40         return (s-(char *)p)/(recl?recl:1);
  41 }