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77 lines
2.1 KiB
77 lines
2.1 KiB
/* An interface to read and write that retries after interrupts. |
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Copyright (C) 1993-1994, 1998, 2002-2006, 2009-2017 Free Software |
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Foundation, Inc. |
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This program is free software: you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 3 of the License, or |
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(at your option) any later version. |
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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You should have received a copy of the GNU General Public License |
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along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
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#include <config.h> |
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/* Specification. */ |
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#ifdef SAFE_WRITE |
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# include "safe-write.h" |
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#else |
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# include "safe-read.h" |
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#endif |
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/* Get ssize_t. */ |
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#include <sys/types.h> |
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#include <unistd.h> |
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#include <errno.h> |
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#ifdef EINTR |
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# define IS_EINTR(x) ((x) == EINTR) |
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#else |
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# define IS_EINTR(x) 0 |
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#endif |
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#include <limits.h> |
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#ifdef SAFE_WRITE |
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# define safe_rw safe_write |
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# define rw write |
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#else |
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# define safe_rw safe_read |
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# define rw read |
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# undef const |
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# define const /* empty */ |
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#endif |
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/* Read(write) up to COUNT bytes at BUF from(to) descriptor FD, retrying if |
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interrupted. Return the actual number of bytes read(written), zero for EOF, |
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or SAFE_READ_ERROR(SAFE_WRITE_ERROR) upon error. */ |
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size_t |
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safe_rw (int fd, void const *buf, size_t count) |
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{ |
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/* Work around a bug in Tru64 5.1. Attempting to read more than |
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INT_MAX bytes fails with errno == EINVAL. See |
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<http://lists.gnu.org/archive/html/bug-gnu-utils/2002-04/msg00010.html>. |
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When decreasing COUNT, keep it block-aligned. */ |
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enum { BUGGY_READ_MAXIMUM = INT_MAX & ~8191 }; |
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for (;;) |
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{ |
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ssize_t result = rw (fd, buf, count); |
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if (0 <= result) |
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return result; |
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else if (IS_EINTR (errno)) |
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continue; |
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else if (errno == EINVAL && BUGGY_READ_MAXIMUM < count) |
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count = BUGGY_READ_MAXIMUM; |
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else |
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return result; |
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} |
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}
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