u-tools/apps/tar/gnu/safe-read.c

   1 /* -*- buffer-read-only: t -*- vi: set ro: */
   2 /* DO NOT EDIT! GENERATED AUTOMATICALLY! */
   3 /* An interface to read and write that retries after interrupts.
   4
   5    Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2011 Free Software
   6    Foundation, Inc.
   7
   8    This program is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include <config.h>
  22
  23 /* Specification.  */
  24 #ifdef SAFE_WRITE
  25 # include "safe-write.h"
  26 #else
  27 # include "safe-read.h"
  28 #endif
  29
  30 /* Get ssize_t.  */
  31 #include <sys/types.h>
  32 #include <unistd.h>
  33
  34 #include <errno.h>
  35
  36 #ifdef EINTR
  37 # define IS_EINTR(x) ((x) == EINTR)
  38 #else
  39 # define IS_EINTR(x) 0
  40 #endif
  41
  42 #include <limits.h>
  43
  44 #ifdef SAFE_WRITE
  45 # define safe_rw safe_write
  46 # define rw write
  47 #else
  48 # define safe_rw safe_read
  49 # define rw read
  50 # undef const
  51 # define const /* empty */
  52 #endif
  53
  54 /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
  55    interrupted.  Return the actual number of bytes read(written), zero for EOF,
  56    or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error.  */
  57 size_t
  58 safe_rw (int fd, void const *buf, size_t count)
  59 {
  60   /* Work around a bug in Tru64 5.1.  Attempting to read more than
  61      INT_MAX bytes fails with errno == EINVAL.  See
  62      <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
  63      When decreasing COUNT, keep it block-aligned.  */
  64   enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
  65
  66   for (;;)
  67     {
  68       ssize_t result = rw (fd, buf, count);
  69
  70       if (0 <= result)
  71         return result;
  72       else if (IS_EINTR (errno))
  73         continue;
  74       else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
  75         count = BUGGY_READ_MAXIMUM;
  76       else
  77         return result;
  78     }
  79 }