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/* Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.
This program is also distributed with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation. The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have included with MySQL.
Without limiting anything contained in the foregoing, this file,
which is part of C Driver for MySQL (Connector/C), is also subject to the
Universal FOSS Exception, version 1.0, a copy of which can be found at
http://oss.oracle.com/licenses/universal-foss-exception.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License, version 2.0, for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
/**
@file mysys/my_pread.cc
*/
#include "my_config.h"
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdio.h>
#include <sys/types.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "my_base.h"
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_io.h"
#include "my_sys.h"
#include "my_thread_local.h"
#include "mysys_err.h"
#if defined(_WIN32)
#include "mysys/mysys_priv.h"
#endif
#ifndef _WIN32
// Mock away pwrite() for unit testing.
ssize_t (*mock_pwrite)(int fd, const void *buf, size_t count,
off_t offset) = nullptr;
#endif
/*
Read a chunk of bytes from a file from a given position
SYNOPSIOS
my_pread()
Filedes File decsriptor
Buffer Buffer to read data into
Count Number of bytes to read
offset Position to read from
MyFlags Flags
NOTES
This differs from the normal pread() call in that we don't care
to set the position in the file back to the original position
if the system doesn't support pread().
RETURN
(size_t) -1 Error
# Number of bytes read
*/
size_t my_pread(File Filedes, uchar *Buffer, size_t Count, my_off_t offset,
myf MyFlags) {
size_t readbytes;
int error = 0;
DBUG_ENTER("my_pread");
DBUG_PRINT("my", ("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %d",
Filedes, (ulonglong)offset, Buffer, (ulong)Count, MyFlags));
for (;;) {
errno = 0; /* Linux, Windows don't reset this on EOF/success */
#if defined(_WIN32)
readbytes = my_win_pread(Filedes, Buffer, Count, offset);
#else
readbytes = pread(Filedes, Buffer, Count, offset);
#endif
error = (readbytes != Count);
if (error) {
set_my_errno(errno ? errno : -1);
if (errno == 0 ||
(readbytes != (size_t)-1 && (MyFlags & (MY_NABP | MY_FNABP))))
set_my_errno(HA_ERR_FILE_TOO_SHORT);
DBUG_PRINT("warning", ("Read only %d bytes off %u from %d, errno: %d",
(int)readbytes, (uint)Count, Filedes, my_errno()));
if ((readbytes == 0 || readbytes == (size_t)-1) && errno == EINTR) {
DBUG_PRINT("debug", ("my_pread() was interrupted and returned %d",
(int)readbytes));
continue; /* Interrupted */
}
if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) {
char errbuf[MYSYS_STRERROR_SIZE];
if (readbytes == (size_t)-1)
my_error(EE_READ, MYF(0), my_filename(Filedes), my_errno(),
my_strerror(errbuf, sizeof(errbuf), my_errno()));
else if (MyFlags & (MY_NABP | MY_FNABP))
my_error(EE_EOFERR, MYF(0), my_filename(Filedes), my_errno(),
my_strerror(errbuf, sizeof(errbuf), my_errno()));
}
if (readbytes == (size_t)-1 || (MyFlags & (MY_FNABP | MY_NABP)))
DBUG_RETURN(MY_FILE_ERROR); /* Return with error */
}
if (MyFlags & (MY_NABP | MY_FNABP))
DBUG_RETURN(0); /* Read went ok; Return 0 */
DBUG_RETURN(readbytes); /* purecov: inspected */
}
} /* my_pread */
/**
Write a chunk of bytes to a file at a given position
SYNOPSIOS
my_pwrite()
Filedes File decsriptor
Buffer Buffer to write data from
Count Number of bytes to write
offset Position to write to
MyFlags Flags
NOTES
This differs from the normal pwrite() call in that we don't care
to set the position in the file back to the original position
if the system doesn't support pwrite()
if (MyFlags & (MY_NABP | MY_FNABP))
returns
0 if Count == 0
On succes, 0
On failure, (size_t)-1 == MY_FILE_ERROR
otherwise
returns
0 if Count == 0
On success, the number of bytes written.
On partial success (if less than Count bytes could be written),
the actual number of bytes written.
On failure, (size_t)-1 == MY_FILE_ERROR
*/
size_t my_pwrite(File Filedes, const uchar *Buffer, size_t Count,
my_off_t offset, myf MyFlags) {
size_t writtenbytes;
size_t sum_written = 0;
uint errors = 0;
const size_t initial_count = Count;
DBUG_ENTER("my_pwrite");
DBUG_PRINT("my", ("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %d",
Filedes, offset, Buffer, (ulong)Count, MyFlags));
for (;;) {
errno = 0;
#if defined(_WIN32)
writtenbytes = my_win_pwrite(Filedes, Buffer, Count, offset);
#else
if (mock_pwrite)
writtenbytes = mock_pwrite(Filedes, Buffer, Count, offset);
else
writtenbytes = pwrite(Filedes, Buffer, Count, offset);
#endif
if (writtenbytes == Count) {
sum_written += writtenbytes;
break;
}
set_my_errno(errno);
if (writtenbytes != (size_t)-1) {
sum_written += writtenbytes;
Buffer += writtenbytes;
Count -= writtenbytes;
offset += writtenbytes;
}
DBUG_PRINT("error", ("Write only %u bytes", (uint)writtenbytes));
if (is_killed_hook(NULL))
MyFlags &= ~MY_WAIT_IF_FULL; /* End if aborted by user */
if ((my_errno() == ENOSPC || my_errno() == EDQUOT) &&
(MyFlags & MY_WAIT_IF_FULL)) {
wait_for_free_space(my_filename(Filedes), errors);
errors++;
continue;
}
if (writtenbytes != 0 && writtenbytes != (size_t)-1)
continue;
else if (my_errno() == EINTR) {
continue; /* Retry */
} else if (writtenbytes == 0 && !errors++) /* Retry once */
{
/* We may come here if the file quota is exeeded */
continue;
}
break; /* Return bytes written */
}
if (MyFlags & (MY_NABP | MY_FNABP)) {
if (sum_written == initial_count)
DBUG_RETURN(0); /* Want only errors, not bytes written */
if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) {
char errbuf[MYSYS_STRERROR_SIZE];
my_error(EE_WRITE, MYF(0), my_filename(Filedes), my_errno(),
my_strerror(errbuf, sizeof(errbuf), my_errno()));
}
DBUG_RETURN(MY_FILE_ERROR);
}
DBUG_EXECUTE_IF("check", my_seek(Filedes, -1, SEEK_SET, MYF(0)););
if (sum_written == 0) DBUG_RETURN(MY_FILE_ERROR);
DBUG_RETURN(sum_written);
} /* my_pwrite */
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