skalibs

Mirror/fork of https://skarnet.org/software/skalibs/
git clone https://ccx.te2000.cz/git/skalibs
Log | Files | Refs | README | LICENSE

fd_catn.c (606B)

      1 /* ISC license. */
      2 
      3 #include <unistd.h>
      4 #include <errno.h>
      5 
      6 #include <skalibs/allreadwrite.h>
      7 #include <skalibs/djbunix.h>
      8 
      9 #define BSIZE 65536
     10 
     11 off_t fd_catn (int from, int to, off_t n)
     12 {
     13   off_t w = 0 ;
     14   char buf[BSIZE] ;
     15   while (n >= BSIZE)
     16   {
     17     size_t v ;
     18     ssize_t r = fd_read(from, buf, BSIZE) ;
     19     if (r == -1) return w ;
     20     if (!r) return (errno = EPIPE, w) ;
     21     v = allwrite(to, buf, r) ;
     22     if (v < r) return w + v ;
     23     n -= r ; w += r ;
     24   }
     25 
     26   if (n)
     27   {
     28     size_t r = allread(from, buf, n) ;
     29     size_t v = 0 ;
     30     if (r) v = allwrite(to, buf, r) ;
     31     w += v ;
     32   }
     33   return w ;
     34 }