| 1 | /* An interface to read and write that retries after interrupts.
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| 2 |
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| 3 | Copyright (C) 1993, 1994, 1998, 2002, 2003, 2004, 2005, 2006 Free
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| 4 | Software Foundation, Inc.
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| 5 |
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| 6 | This program is free software; you can redistribute it and/or modify
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| 7 | it under the terms of the GNU General Public License as published by
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| 8 | the Free Software Foundation; either version 2, or (at your option)
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| 9 | any later version.
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| 10 |
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| 11 | This program is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU General Public License
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| 17 | along with this program; if not, write to the Free Software Foundation,
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| 18 | Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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| 19 |
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| 20 | #include <config.h>
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| 21 |
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| 22 | /* Specification. */
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| 23 | #ifdef SAFE_WRITE
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| 24 | # include "safe-write.h"
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| 25 | #else
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| 26 | # include "safe-read.h"
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| 27 | #endif
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| 28 |
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| 29 | /* Get ssize_t. */
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| 30 | #include <sys/types.h>
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| 31 | #include <unistd.h>
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| 32 |
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| 33 | #include <errno.h>
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| 34 |
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| 35 | #ifdef EINTR
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| 36 | # define IS_EINTR(x) ((x) == EINTR)
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| 37 | #else
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| 38 | # define IS_EINTR(x) 0
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| 39 | #endif
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| 40 |
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| 41 | #include <limits.h>
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| 42 |
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| 43 | #ifdef SAFE_WRITE
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| 44 | # define safe_rw safe_write
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| 45 | # define rw write
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| 46 | #else
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| 47 | # define safe_rw safe_read
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| 48 | # define rw read
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| 49 | # undef const
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| 50 | # define const /* empty */
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| 51 | #endif
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| 52 |
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| 53 | /* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if
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| 54 | interrupted. Return the actual number of bytes read(written), zero for EOF,
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| 55 | or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */
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| 56 | size_t
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| 57 | safe_rw (int fd, void const *buf, size_t count)
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| 58 | {
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| 59 | /* Work around a bug in Tru64 5.1. Attempting to read more than
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| 60 | INT_MAX bytes fails with errno == EINVAL. See
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| 61 | <http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>.
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| 62 | When decreasing COUNT, keep it block-aligned. */
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| 63 | enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 };
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| 64 |
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| 65 | for (;;)
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| 66 | {
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| 67 | ssize_t result = rw (fd, buf, count);
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| 68 |
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| 69 | if (0 <= result)
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| 70 | return result;
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| 71 | else if (IS_EINTR (errno))
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| 72 | continue;
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| 73 | else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count)
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| 74 | count = BUGGY_READ_MAXIMUM;
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| 75 | else
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| 76 | return result;
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| 77 | }
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| 78 | }
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