Line data    Source code

       1             : /* An interface to read and write that retries (if necessary) until complete.
       2             : 
       3             :    Copyright (C) 1993, 1994, 1997, 1998, 1999, 2000, 2001, 2002, 2003,
       4             :    2004, 2005, 2006 Free Software Foundation, Inc.
       5             : 
       6             :    This program is free software: you can redistribute it and/or modify
       7             :    it under the terms of the GNU General Public License as published by
       8             :    the Free Software Foundation; either version 3 of the License, or
       9             :    (at your option) any later version.
      10             : 
      11             :    This program is distributed in the hope that it will be useful,
      12             :    but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             :    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             :    GNU General Public License for more details.
      15             : 
      16             :    You should have received a copy of the GNU General Public License
      17             :    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
      18             : 
      19             : #include <config.h>
      20             : 
      21             : /* Specification.  */
      22             : #ifdef FULL_READ
      23             : # include "full-read.h"
      24             : #else
      25             : # include "full-write.h"
      26             : #endif
      27             : 
      28             : #include <errno.h>
      29             : 
      30             : #ifdef FULL_READ
      31             : # include "safe-read.h"
      32             : # define safe_rw safe_read
      33             : # define full_rw full_read
      34             : # undef const
      35             : # define const /* empty */
      36             : #else
      37             : # include "safe-write.h"
      38             : # define safe_rw safe_write
      39             : # define full_rw full_write
      40             : #endif
      41             : 
      42             : #ifdef FULL_READ
      43             : /* Set errno to zero upon EOF.  */
      44             : # define ZERO_BYTE_TRANSFER_ERRNO 0
      45             : #else
      46             : /* Some buggy drivers return 0 when one tries to write beyond
      47             :    a device's end.  (Example: Linux 1.2.13 on /dev/fd0.)
      48             :    Set errno to ENOSPC so they get a sensible diagnostic.  */
      49             : # define ZERO_BYTE_TRANSFER_ERRNO ENOSPC
      50             : #endif
      51             : 
      52             : /* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if
      53             :    interrupted or if a partial write(read) occurs.  Return the number
      54             :    of bytes transferred.
      55             :    When writing, set errno if fewer than COUNT bytes are written.
      56             :    When reading, if fewer than COUNT bytes are read, you must examine
      57             :    errno to distinguish failure from EOF (errno == 0).  */
      58             : size_t
      59         153 : full_rw (int fd, const void *buf, size_t count)
      60             : {
      61         153 :   size_t total = 0;
      62         153 :   const char *ptr = (const char *) buf;
      63             : 
      64         457 :   while (count > 0)
      65             :     {
      66         184 :       size_t n_rw = safe_rw (fd, ptr, count);
      67         184 :       if (n_rw == (size_t) -1)
      68           2 :         break;
      69         182 :       if (n_rw == 0)
      70             :         {
      71          31 :           errno = ZERO_BYTE_TRANSFER_ERRNO;
      72          31 :           break;
      73             :         }
      74         151 :       total += n_rw;
      75         151 :       ptr += n_rw;
      76         151 :       count -= n_rw;
      77             :     }
      78             : 
      79         153 :   return total;
      80             : }