diff options
Diffstat (limited to 'mysys/my_pread.c')
| -rw-r--r-- | mysys/my_pread.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/mysys/my_pread.c b/mysys/my_pread.c new file mode 100644 index 00000000..56cc91ae --- /dev/null +++ b/mysys/my_pread.c @@ -0,0 +1,200 @@ +/* Copyright (c) 2000, 2011, Oracle and/or its affiliates. + Copyright (c) 2011, Monty Program 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */ + +#include "mysys_priv.h" +#include "mysys_err.h" +#include "my_base.h" +#include <m_string.h> +#include <errno.h> +#ifndef _WIN32 +#include <unistd.h> +#endif + +/* + Read a chunk of bytes from a file from a given position + + SYNOPSIOS + my_pread() + Filedes File descriptor + 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, save_count= 0; + + DBUG_ENTER("my_pread"); + + DBUG_PRINT("my",("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %lu", + Filedes, (ulonglong)offset, Buffer, (ulong)Count, MyFlags)); + + if (!(MyFlags & (MY_WME | MY_FAE | MY_FNABP))) + MyFlags|= my_global_flags; + + for (;;) + { + errno= 0; /* Linux, Windows don't reset this on EOF/success */ +#ifdef _WIN32 + readbytes= my_win_pread(Filedes, Buffer, Count, offset); +#else + readbytes= pread(Filedes, Buffer, Count, offset); +#endif + + if (readbytes != Count) + { + /* We should never read with wrong file descriptor! */ + DBUG_ASSERT(readbytes != (size_t)-1 || errno != EBADF); + my_errno= errno; + if (errno == 0 || (readbytes != (size_t) -1 && + (MyFlags & (MY_NABP | MY_FNABP)))) + 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 */ + } + + /* Do a read retry if we didn't get enough data on first read */ + if (readbytes != (size_t) -1 && readbytes != 0 && + (MyFlags & MY_FULL_IO)) + { + Buffer+= readbytes; + Count-= readbytes; + save_count+= readbytes; + offset+= readbytes; + continue; + } + + if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) + { + if (readbytes == (size_t) -1) + my_error(EE_READ, + MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))), + my_filename(Filedes),my_errno); + else if (MyFlags & (MY_NABP | MY_FNABP)) + my_error(EE_EOFERR, + MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))), + 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)) + readbytes= 0; /* Read went ok; Return 0 */ + else + readbytes+= save_count; + DBUG_RETURN(readbytes); + } +} /* my_pread */ + + +/* + Write a chunk of bytes to a file at a given position + + SYNOPSIOS + my_pwrite() + Filedes File descriptor + 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 writtenbytes, written; + uint errors; + DBUG_ENTER("my_pwrite"); + DBUG_PRINT("my",("fd: %d Seek: %llu Buffer: %p Count: %lu MyFlags: %lu", + Filedes, (ulonglong)offset, Buffer, (ulong)Count, MyFlags)); + errors= 0; + written= 0; + if (!(MyFlags & (MY_WME | MY_FAE | MY_FNABP))) + MyFlags|= my_global_flags; + + for (;;) + { +#ifdef _WIN32 + writtenbytes= my_win_pwrite(Filedes, Buffer, Count,offset); +#else + writtenbytes= pwrite(Filedes, Buffer, Count, offset); +#endif + if (writtenbytes == Count) + break; + my_errno= errno; + if (writtenbytes != (size_t) -1) + { /* Safegueard */ + written+=writtenbytes; + Buffer+=writtenbytes; + Count-=writtenbytes; + offset+=writtenbytes; + } + DBUG_PRINT("error",("Write only %u bytes", (uint) writtenbytes)); +#ifndef NO_BACKGROUND + if (my_thread_var->abort) + 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 && writtenbytes != (size_t) -1) || my_errno == EINTR) + continue; /* Retry */ +#endif + + /* Don't give a warning if it's ok that we only write part of the data */ + if (MyFlags & (MY_NABP | MY_FNABP)) + { + if (MyFlags & (MY_WME | MY_FAE | MY_FNABP)) + my_error(EE_WRITE, MYF(ME_BELL | (MyFlags & (ME_NOTE | ME_ERROR_LOG))), + my_filename(Filedes),my_errno); + DBUG_RETURN(MY_FILE_ERROR); /* Error on write */ + } + 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(writtenbytes+written); /* purecov: inspected */ +} /* my_pwrite */ |