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Annotation of embedaddon/libiconv/srclib/safe-read.c, revision 1.1.1.1

1.1       misho       1: /* An interface to read and write that retries after interrupts.
                      2: 
                      3:    Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2011 Free Software
                      4:    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: 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:     {
                     66:       ssize_t result = rw (fd, buf, count);
                     67: 
                     68:       if (0 <= result)
                     69:         return result;
                     70:       else if (IS_EINTR (errno))
                     71:         continue;
                     72:       else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
                     73:         count = BUGGY_READ_MAXIMUM;
                     74:       else
                     75:         return result;
                     76:     }
                     77: }