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229 lines
7.4 KiB
229 lines
7.4 KiB
/* Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
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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, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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Without limiting anything contained in the foregoing, this file,
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which is part of C Driver for MySQL (Connector/C), is also subject to the
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Universal FOSS Exception, version 1.0, a copy of which can be found at
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http://oss.oracle.com/licenses/universal-foss-exception.
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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, version 2.0, 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, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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/**
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@file mysys/my_pread.cc
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*/
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#include "my_config.h"
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#include <errno.h>
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#include <fcntl.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <sys/types.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include "my_base.h"
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#include "my_dbug.h"
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#include "my_inttypes.h"
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#include "my_io.h"
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#include "my_sys.h"
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#include "my_thread_local.h"
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#include "mysys_err.h"
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#if defined(_WIN32)
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#include "mysys/mysys_priv.h"
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#endif
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#ifndef _WIN32
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// Mock away pwrite() for unit testing.
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ssize_t (*mock_pwrite)(int fd, const void *buf, size_t count,
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off_t offset) = nullptr;
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#endif
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/*
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Read a chunk of bytes from a file from a given position
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SYNOPSIOS
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my_pread()
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Filedes File decsriptor
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Buffer Buffer to read data into
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Count Number of bytes to read
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offset Position to read from
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MyFlags Flags
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NOTES
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This differs from the normal pread() call in that we don't care
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to set the position in the file back to the original position
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if the system doesn't support pread().
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RETURN
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(size_t) -1 Error
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# Number of bytes read
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*/
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size_t my_pread(File Filedes, uchar *Buffer, size_t Count, my_off_t offset,
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myf MyFlags) {
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size_t readbytes;
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int error = 0;
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DBUG_TRACE;
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DBUG_PRINT("my", ("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %d",
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Filedes, (ulonglong)offset, Buffer, (ulong)Count, MyFlags));
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for (;;) {
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errno = 0; /* Linux, Windows don't reset this on EOF/success */
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#if defined(_WIN32)
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readbytes = my_win_pread(Filedes, Buffer, Count, offset);
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#else
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readbytes = pread(Filedes, Buffer, Count, offset);
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#endif
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error = (readbytes != Count);
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if (error) {
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set_my_errno(errno ? errno : -1);
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if (errno == 0 ||
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(readbytes != (size_t)-1 && (MyFlags & (MY_NABP | MY_FNABP))))
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set_my_errno(HA_ERR_FILE_TOO_SHORT);
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DBUG_PRINT("warning", ("Read only %d bytes off %u from %d, errno: %d",
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(int)readbytes, (uint)Count, Filedes, my_errno()));
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if ((readbytes == 0 || readbytes == (size_t)-1) && errno == EINTR) {
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DBUG_PRINT("debug", ("my_pread() was interrupted and returned %d",
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(int)readbytes));
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continue; /* Interrupted */
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}
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if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) {
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char errbuf[MYSYS_STRERROR_SIZE];
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if (readbytes == (size_t)-1)
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my_error(EE_READ, MYF(0), my_filename(Filedes), my_errno(),
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my_strerror(errbuf, sizeof(errbuf), my_errno()));
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else if (MyFlags & (MY_NABP | MY_FNABP))
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my_error(EE_EOFERR, MYF(0), my_filename(Filedes), my_errno(),
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my_strerror(errbuf, sizeof(errbuf), my_errno()));
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}
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if (readbytes == (size_t)-1 || (MyFlags & (MY_FNABP | MY_NABP)))
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return MY_FILE_ERROR; /* Return with error */
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}
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if (MyFlags & (MY_NABP | MY_FNABP)) return 0; /* Read went ok; Return 0 */
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return readbytes; /* purecov: inspected */
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}
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} /* my_pread */
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/**
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Write a chunk of bytes to a file at a given position
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SYNOPSIOS
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my_pwrite()
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Filedes File decsriptor
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Buffer Buffer to write data from
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Count Number of bytes to write
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offset Position to write to
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MyFlags Flags
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NOTES
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This differs from the normal pwrite() call in that we don't care
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to set the position in the file back to the original position
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if the system doesn't support pwrite()
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if (MyFlags & (MY_NABP | MY_FNABP))
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returns
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0 if Count == 0
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On succes, 0
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On failure, (size_t)-1 == MY_FILE_ERROR
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otherwise
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returns
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0 if Count == 0
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On success, the number of bytes written.
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On partial success (if less than Count bytes could be written),
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the actual number of bytes written.
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On failure, (size_t)-1 == MY_FILE_ERROR
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*/
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size_t my_pwrite(File Filedes, const uchar *Buffer, size_t Count,
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my_off_t offset, myf MyFlags) {
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size_t writtenbytes;
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size_t sum_written = 0;
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uint errors = 0;
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const size_t initial_count = Count;
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DBUG_TRACE;
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DBUG_PRINT("my", ("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %d",
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Filedes, offset, Buffer, (ulong)Count, MyFlags));
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for (;;) {
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errno = 0;
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#if defined(_WIN32)
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writtenbytes = my_win_pwrite(Filedes, Buffer, Count, offset);
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#else
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if (mock_pwrite)
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writtenbytes = mock_pwrite(Filedes, Buffer, Count, offset);
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else
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writtenbytes = pwrite(Filedes, Buffer, Count, offset);
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#endif
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if (writtenbytes == Count) {
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sum_written += writtenbytes;
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break;
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}
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set_my_errno(errno);
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if (writtenbytes != (size_t)-1) {
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sum_written += writtenbytes;
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Buffer += writtenbytes;
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Count -= writtenbytes;
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offset += writtenbytes;
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}
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DBUG_PRINT("error", ("Write only %u bytes", (uint)writtenbytes));
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if (is_killed_hook(NULL))
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MyFlags &= ~MY_WAIT_IF_FULL; /* End if aborted by user */
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if ((my_errno() == ENOSPC || my_errno() == EDQUOT) &&
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(MyFlags & MY_WAIT_IF_FULL)) {
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wait_for_free_space(my_filename(Filedes), errors);
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errors++;
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continue;
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}
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if (writtenbytes != 0 && writtenbytes != (size_t)-1)
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continue;
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else if (my_errno() == EINTR) {
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continue; /* Retry */
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} else if (writtenbytes == 0 && !errors++) /* Retry once */
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{
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/* We may come here if the file quota is exeeded */
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continue;
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}
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break; /* Return bytes written */
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}
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if (MyFlags & (MY_NABP | MY_FNABP)) {
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if (sum_written == initial_count)
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return 0; /* Want only errors, not bytes written */
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if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) {
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char errbuf[MYSYS_STRERROR_SIZE];
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my_error(EE_WRITE, MYF(0), my_filename(Filedes), my_errno(),
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my_strerror(errbuf, sizeof(errbuf), my_errno()));
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}
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return MY_FILE_ERROR;
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}
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DBUG_EXECUTE_IF("check", my_seek(Filedes, -1, SEEK_SET, MYF(0)););
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if (sum_written == 0) return MY_FILE_ERROR;
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return sum_written;
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} /* my_pwrite */
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