diff options
Diffstat (limited to 'dep/mysqllite/mysys/my_pread.c')
| -rw-r--r-- | dep/mysqllite/mysys/my_pread.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/dep/mysqllite/mysys/my_pread.c b/dep/mysqllite/mysys/my_pread.c new file mode 100644 index 00000000000..3f62f150c91 --- /dev/null +++ b/dep/mysqllite/mysys/my_pread.c @@ -0,0 +1,187 @@ +/* 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; version 2 of the License. + + 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 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: %lu Buffer: 0x%lx Count: %u MyFlags: %d", + Filedes, (ulong) offset, (long) Buffer, (uint) 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) == (my_off_t) -1 || + (readbytes= read(Filedes, Buffer, (uint) Count)) != Count); + pthread_mutex_unlock(&my_file_info[Filedes].mutex); +#else + if ((error= ((readbytes= pread(Filedes, Buffer, Count, offset)) != Count))) + my_errno= errno ? errno : -1; +#endif + if (error || readbytes != Count) + { + DBUG_PRINT("warning",("Read only %d bytes off %u from %d, errno: %d", + (int) readbytes, (uint) Count,Filedes,my_errno)); +#ifdef THREAD + if ((readbytes == 0 || readbytes == (size_t) -1) && errno == EINTR) + { + DBUG_PRINT("debug", ("my_pread() was interrupted and returned %d", + (int) readbytes)); + continue; /* Interrupted */ + } +#endif + if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) + { + if (readbytes == (size_t) -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 (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() + + RETURN + (size_t) -1 Error + # Number of bytes read +*/ + +size_t my_pwrite(int Filedes, const uchar *Buffer, size_t Count, + my_off_t offset, myf MyFlags) +{ + size_t writenbytes, written; + uint errors; + DBUG_ENTER("my_pwrite"); + DBUG_PRINT("my",("Fd: %d Seek: %lu Buffer: 0x%lx Count: %u MyFlags: %d", + Filedes, (ulong) offset, (long) Buffer, (uint) Count, + MyFlags)); + errors= 0; + written= 0; + + for (;;) + { +#ifndef HAVE_PREAD + int error; + writenbytes= (size_t) -1; + pthread_mutex_lock(&my_file_info[Filedes].mutex); + error= (lseek(Filedes, offset, MY_SEEK_SET) != (my_off_t) -1 && + (writenbytes = write(Filedes, Buffer, (uint) Count)) == Count); + pthread_mutex_unlock(&my_file_info[Filedes].mutex); + if (error) + break; +#else + if ((writenbytes= pwrite(Filedes, Buffer, Count,offset)) == Count) + break; + my_errno= errno; +#endif + if (writenbytes != (size_t) -1) + { /* Safegueard */ + written+=writenbytes; + Buffer+=writenbytes; + Count-=writenbytes; + offset+=writenbytes; + } + DBUG_PRINT("error",("Write only %u bytes", (uint) 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)) + { + wait_for_free_space(my_filename(Filedes), errors); + errors++; + continue; + } + if ((writenbytes && writenbytes != (size_t) -1) || my_errno == EINTR) + 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 */ + } + DBUG_EXECUTE_IF("check", my_seek(Filedes, -1, SEEK_SET, MYF(0));); + if (MyFlags & (MY_NABP | MY_FNABP)) + DBUG_RETURN(0); /* Want only errors */ + DBUG_RETURN(writenbytes+written); /* purecov: inspected */ +} /* my_pwrite */ |