80 lines
2.2 KiB
C
80 lines
2.2 KiB
C
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/* An interface to read and write that retries (if necessary) until complete.
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Copyright (C) 1993-1994, 1997-2006, 2009-2020 Free Software 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 <https://www.gnu.org/licenses/>. */
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#include <config.h>
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/* Specification. */
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#ifdef FULL_READ
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# include "full-read.h"
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#else
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# include "full-write.h"
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#endif
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#include <errno.h>
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#ifdef FULL_READ
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# include "safe-read.h"
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# define safe_rw safe_read
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# define full_rw full_read
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# undef const
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# define const /* empty */
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#else
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# include "safe-write.h"
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# define safe_rw safe_write
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# define full_rw full_write
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#endif
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#ifdef FULL_READ
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/* Set errno to zero upon EOF. */
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# define ZERO_BYTE_TRANSFER_ERRNO 0
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#else
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/* Some buggy drivers return 0 when one tries to write beyond
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a device's end. (Example: Linux 1.2.13 on /dev/fd0.)
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Set errno to ENOSPC so they get a sensible diagnostic. */
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# define ZERO_BYTE_TRANSFER_ERRNO ENOSPC
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#endif
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/* Write(read) COUNT bytes at BUF to(from) descriptor FD, retrying if
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interrupted or if a partial write(read) occurs. Return the number
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of bytes transferred.
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When writing, set errno if fewer than COUNT bytes are written.
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When reading, if fewer than COUNT bytes are read, you must examine
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errno to distinguish failure from EOF (errno == 0). */
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size_t
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full_rw (int fd, const void *buf, size_t count)
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{
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size_t total = 0;
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const char *ptr = (const char *) buf;
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while (count > 0)
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{
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size_t n_rw = safe_rw (fd, ptr, count);
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if (n_rw == (size_t) -1)
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break;
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if (n_rw == 0)
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{
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errno = ZERO_BYTE_TRANSFER_ERRNO;
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break;
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}
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total += n_rw;
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ptr += n_rw;
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count -= n_rw;
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}
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return total;
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}
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