Line data    Source code

       1             : /* An interface to read and write that retries after interrupts.
       2             : 
       3             :    Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004, 2005, 2006 Free
       4             :    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 SAFE_WRITE
      23             : # include "safe-write.h"
      24             : #else
      25             : # include "safe-read.h"
      26             : #endif
      27             : 
      28             : /* Get ssize_t.  */
      29             : #include <sys/types.h>
      30             : #include <unistd.h>
      31             : 
      32             : #include <errno.h>
      33             : 
      34             : #ifdef EINTR
      35             : # define IS_EINTR(x) ((x) == EINTR)
      36             : #else
      37             : # define IS_EINTR(x) 0
      38             : #endif
      39             : 
      40             : #include <limits.h>
      41             : 
      42             : #ifdef SAFE_WRITE
      43             : # define safe_rw safe_write
      44             : # define rw write
      45             : #else
      46             : # define safe_rw safe_read
      47             : # define rw read
      48             : # undef const
      49             : # define const /* empty */
      50             : #endif
      51             : 
      52             : /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
      53             :    interrupted.  Return the actual number of bytes read(written), zero for EOF,
      54             :    or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error.  */
      55             : size_t
      56         807 : safe_rw (int fd, void const *buf, size_t count)
      57             : {
      58             :   /* Work around a bug in Tru64 5.1.  Attempting to read more than
      59             :      INT_MAX bytes fails with errno == EINVAL.  See
      60             :      <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
      61             :      When decreasing COUNT, keep it block-aligned.  */
      62             :   enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
      63             : 
      64             :   for (;;)
      65           0 :     {
      66         807 :       ssize_t result = rw (fd, buf, count);
      67             : 
      68         807 :       if (0 <= result)
      69         695 :         return result;
      70         112 :       else if (IS_EINTR (errno))
      71           0 :         continue;
      72         112 :       else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
      73           0 :         count = BUGGY_READ_MAXIMUM;
      74             :       else
      75         112 :         return result;
      76             :     }
      77             : }