diff options
Diffstat (limited to 'mysql/mysys/my_pread.c')
| -rw-r--r-- | mysql/mysys/my_pread.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/mysql/mysys/my_pread.c b/mysql/mysys/my_pread.c new file mode 100644 index 0000000..1511fd7 --- /dev/null +++ b/mysql/mysys/my_pread.c @@ -0,0 +1,207 @@ +/* Copyright (c) 2000, 2015, 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 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 02110-1301 USA */ + +#include "mysys_priv.h" +#include "my_sys.h" +#include "mysys_err.h" +#include "my_base.h" +#include <m_string.h> +#include <errno.h> +#include "my_thread_local.h" + + +/* + 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 + 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 */ |