my_pread.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:5k
- /* Copyright (C) 2000 MySQL AB
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
- 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 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
- #include "mysys_priv.h"
- #include "mysys_err.h"
- #include <errno.h>
- #ifdef HAVE_PREAD
- #include <unistd.h>
- #endif
- /* Read a chunk of bytes from a file */
- uint my_pread(File Filedes, byte *Buffer, uint Count, my_off_t offset,
- myf MyFlags)
- {
- uint readbytes;
- int error;
- DBUG_ENTER("my_pread");
- DBUG_PRINT("my",("Fd: %d Seek: %lu Buffer: 0x%lx Count: %u MyFlags: %d",
- Filedes, (ulong) offset, Buffer, Count, MyFlags));
- for (;;)
- {
- #ifndef __WIN__
- errno=0; /* Linux doesn't reset this */
- #endif
- #ifndef HAVE_PREAD
- pthread_mutex_lock(&my_file_info[Filedes].mutex);
- readbytes= (uint) -1;
- error= (lseek(Filedes, offset, MY_SEEK_SET) == -1L ||
- (readbytes = (uint) read(Filedes, Buffer, Count)) != Count);
- pthread_mutex_unlock(&my_file_info[Filedes].mutex);
- #else
- error=((readbytes = (uint) pread(Filedes, Buffer, Count, offset)) != Count);
- #endif
- if (error)
- {
- my_errno=errno;
- DBUG_PRINT("warning",("Read only %ld bytes off %ld from %d, errno: %d",
- readbytes,Count,Filedes,my_errno));
- #ifdef THREAD
- if (readbytes == 0 && errno == EINTR)
- continue; /* Interrupted */
- #endif
- if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
- {
- if ((int) readbytes == -1)
- my_error(EE_READ, MYF(ME_BELL+ME_WAITTANG),
- my_filename(Filedes),my_errno);
- else if (MyFlags & (MY_NABP | MY_FNABP))
- my_error(EE_EOFERR, MYF(ME_BELL+ME_WAITTANG),
- my_filename(Filedes),my_errno);
- }
- if ((int) readbytes == -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 */
- uint my_pwrite(int Filedes, const byte *Buffer, uint Count, my_off_t offset,
- myf MyFlags)
- {
- uint writenbytes,errors;
- ulong written;
- DBUG_ENTER("my_pwrite");
- DBUG_PRINT("my",("Fd: %d Seek: %lu Buffer: 0x%lx Count: %d MyFlags: %d",
- Filedes, (ulong) offset,Buffer, Count, MyFlags));
- errors=0; written=0L;
- for (;;)
- {
- #ifndef HAVE_PREAD
- int error;
- writenbytes= (uint) -1;
- pthread_mutex_lock(&my_file_info[Filedes].mutex);
- error=(lseek(Filedes, offset, MY_SEEK_SET) != -1L &&
- (writenbytes = (uint) write(Filedes, Buffer, Count)) == Count);
- pthread_mutex_unlock(&my_file_info[Filedes].mutex);
- if (error)
- break;
- #else
- if ((writenbytes = (uint) pwrite(Filedes, Buffer, Count,offset)) == Count)
- break;
- #endif
- if ((int) writenbytes != -1)
- { /* Safegueard */
- written+=writenbytes;
- Buffer+=writenbytes;
- Count-=writenbytes;
- offset+=writenbytes;
- }
- my_errno=errno;
- DBUG_PRINT("error",("Write only %d bytes",writenbytes));
- #ifndef NO_BACKGROUND
- #ifdef THREAD
- if (my_thread_var->abort)
- MyFlags&= ~ MY_WAIT_IF_FULL; /* End if aborted by user */
- #endif
- if ((my_errno == ENOSPC || my_errno == EDQUOT) &&
- (MyFlags & MY_WAIT_IF_FULL))
- {
- if (!(errors++ % MY_WAIT_GIVE_USER_A_MESSAGE))
- my_error(EE_DISK_FULL,MYF(ME_BELL | ME_NOREFRESH),
- my_filename(Filedes),my_errno,MY_WAIT_FOR_USER_TO_FIX_PANIC);
- VOID(sleep(MY_WAIT_FOR_USER_TO_FIX_PANIC));
- continue;
- }
- if ((writenbytes == 0 && my_errno == EINTR) ||
- (writenbytes > 0 && (uint) writenbytes != (uint) -1))
- continue; /* Retry */
- #endif
- if (MyFlags & (MY_NABP | MY_FNABP))
- {
- if (MyFlags & (MY_WME | MY_FAE | MY_FNABP))
- {
- my_error(EE_WRITE, MYF(ME_BELL | ME_WAITTANG),
- my_filename(Filedes),my_errno);
- }
- DBUG_RETURN(MY_FILE_ERROR); /* Error on read */
- }
- else
- break; /* Return bytes written */
- }
- if (MyFlags & (MY_NABP | MY_FNABP))
- DBUG_RETURN(0); /* Want only errors */
- DBUG_RETURN(writenbytes+written); /* purecov: inspected */
- } /* my_pwrite */