208 lines
6.3 KiB
C
208 lines
6.3 KiB
C
/* Copyright (c) 2000, 2015, 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 as published by
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the Free Software Foundation; version 2 of the License.
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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, 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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#include "mysys_priv.h"
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#include "my_sys.h"
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#include "mysys_err.h"
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#include "my_base.h"
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#include <m_string.h>
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#include <errno.h>
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#include "my_thread_local.h"
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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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{
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size_t readbytes;
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int error= 0;
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DBUG_ENTER("my_pread");
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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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{
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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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{
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set_my_errno(errno ? errno : -1);
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if (errno == 0 || (readbytes != (size_t) -1 &&
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(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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{
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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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{
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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),
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my_errno(), 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),
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my_errno(), 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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DBUG_RETURN(MY_FILE_ERROR); /* Return with error */
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}
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if (MyFlags & (MY_NABP | MY_FNABP))
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DBUG_RETURN(0); /* Read went ok; Return 0 */
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DBUG_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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{
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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_ENTER("my_pwrite");
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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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{
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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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writtenbytes= pwrite(Filedes, Buffer, Count, offset);
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#endif
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if(writtenbytes == Count)
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{
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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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{
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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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{
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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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{
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continue; /* Retry */
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}
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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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{
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if (sum_written == initial_count)
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DBUG_RETURN(0); /* Want only errors, not bytes written */
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if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
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{
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char errbuf[MYSYS_STRERROR_SIZE];
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my_error(EE_WRITE, MYF(0), my_filename(Filedes),
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my_errno(), my_strerror(errbuf, sizeof(errbuf), my_errno()));
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}
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DBUG_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)
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DBUG_RETURN(MY_FILE_ERROR);
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DBUG_RETURN(sum_written);
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} /* my_pwrite */
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