cbtcommon/sio.c

   1 /*
   2  * Copyright 2001, 2002, 2003 David Mansfield and Cobite, Inc.
   3  * See COPYING file for license information
   4  */
   5
   6 #include <stdio.h>
   7
   8 #ifdef WIN32
   9 #include <io.h>
  10 #else
  11 #include <unistd.h>
  12 #endif
  13
  14 #include <errno.h>
  15
  16 #include "sio.h"
  17 #include "rcsid.h"
  18
  19 RCSID("$Id: sio.c,v 1.5 2001/10/25 18:36:11 adam Exp $");
  20
  21 ssize_t readn(int fd, void *buf, size_t len)
  22 {
  23
  24   int nleft,nread;
  25
  26   nleft = len;
  27
  28   while (nleft > 0)
  29   {
  30     nread = read(fd,buf,nleft);
  31
  32     /* there is an issue which EINTR which could leave us a bit haywire
  33      * if we get a signal after having read some bytes. special handling
  34      * N.B: we *do* return EINTR if no data has been read yet (thanks Karl)
  35      */
  36     if (nread < 0)
  37     {
  38       if (errno == EINTR && nleft != (int)len)
  39         continue;
  40       else
  41             return (nread);
  42     }
  43     else if (nread == 0)
  44       break;
  45
  46     nleft -= nread;
  47
  48     if (nleft)
  49       buf = ((char *)buf) + nread;
  50   }
  51   return (len - nleft);
  52 }
  53
  54 ssize_t writen(int fd, const void *buf, size_t len)
  55 {
  56
  57   int nleft, nwritten;
  58
  59   nleft = len;
  60
  61   while (nleft > 0)
  62   {
  63     nwritten = write(fd,buf,nleft);
  64
  65     /* there is an issue with EINTR if we have already written
  66        a few bytes! return if we have not written any yet */
  67     if (nwritten < 0 && errno == EINTR)
  68     {
  69       if (nleft == (int)len)
  70         return nwritten;
  71
  72       continue;
  73     }
  74
  75
  76     if (nwritten <= 0)
  77       return nwritten;
  78
  79     nleft -= nwritten;
  80
  81     if (nleft)
  82       buf = ((char *)buf) + nwritten;
  83   }
  84
  85   return (len - nleft);
  86 }
  87