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Diffstat (limited to '')
| -rw-r--r-- | mysys/my_seek.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/mysys/my_seek.c b/mysys/my_seek.c new file mode 100644 index 00000000..db364ccd --- /dev/null +++ b/mysys/my_seek.c @@ -0,0 +1,103 @@ +/* + Copyright (c) 2000, 2010, Oracle and/or its affiliates + + 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" + +/* + Seek to a position in a file. + + ARGUMENTS + File fd The file descriptor + my_off_t pos The expected position (absolute or relative) + int whence A direction parameter and one of + {SEEK_SET, SEEK_CUR, SEEK_END} + myf MyFlags MY_THREADSAFE must be set in case my_seek may be mixed + with my_pread/my_pwrite calls and fd is shared among + threads. + + DESCRIPTION + The my_seek function is a wrapper around the system call lseek and + repositions the offset of the file descriptor fd to the argument + offset according to the directive whence as follows: + SEEK_SET The offset is set to offset bytes. + SEEK_CUR The offset is set to its current location plus offset bytes + SEEK_END The offset is set to the size of the file plus offset bytes + + RETURN VALUE + my_off_t newpos The new position in the file. + MY_FILEPOS_ERROR An error was encountered while performing + the seek. my_errno is set to indicate the + actual error. +*/ + +my_off_t my_seek(File fd, my_off_t pos, int whence, myf MyFlags) +{ + os_off_t newpos= -1; + DBUG_ENTER("my_seek"); + DBUG_PRINT("my",("fd: %d Pos: %llu Whence: %d MyFlags: %lu", + fd, (ulonglong) pos, whence, MyFlags)); + DBUG_ASSERT(pos != MY_FILEPOS_ERROR); /* safety check */ + + /* + Make sure we are using a valid file descriptor! + */ + DBUG_ASSERT(fd != -1); +#ifdef _WIN32 + newpos= my_win_lseek(fd, pos, whence); +#else + newpos= lseek(fd, pos, whence); +#endif + if (newpos == (os_off_t) -1) + { + my_errno= errno; + if (MyFlags & MY_WME) + my_error(EE_CANT_SEEK, MYF(0), my_filename(fd), my_errno); + DBUG_PRINT("error", ("lseek: %llu errno: %d", (ulonglong) newpos, errno)); + DBUG_RETURN(MY_FILEPOS_ERROR); + } + if ((my_off_t) newpos != pos) + { + DBUG_PRINT("exit",("pos: %llu", (ulonglong) newpos)); + } + DBUG_RETURN((my_off_t) newpos); +} /* my_seek */ + + + /* Tell current position of file */ + /* ARGSUSED */ + +my_off_t my_tell(File fd, myf MyFlags) +{ + os_off_t pos; + DBUG_ENTER("my_tell"); + DBUG_PRINT("my",("fd: %d MyFlags: %lu",fd, MyFlags)); + DBUG_ASSERT(fd >= 0); +#if defined (HAVE_TELL) && !defined (_WIN32) && !defined(_AIX) + pos= tell(fd); +#else + pos= my_seek(fd, 0L, MY_SEEK_CUR,0); +#endif + if (pos == (os_off_t) -1) + { + my_errno= errno; + if (MyFlags & MY_WME) + my_error(EE_CANT_SEEK, MYF(0), my_filename(fd), my_errno); + DBUG_PRINT("error", ("tell: %llu errno: %d", (ulonglong) pos, my_errno)); + } + DBUG_PRINT("exit",("pos: %llu", (ulonglong) pos)); + DBUG_RETURN((my_off_t) pos); +} /* my_tell */ |