diff options
Diffstat (limited to 'mysys/my_seek.c')
| -rw-r--r-- | mysys/my_seek.c | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/mysys/my_seek.c b/mysys/my_seek.c index e5b1905e551..269d1a65b31 100644 --- a/mysys/my_seek.c +++ b/mysys/my_seek.c @@ -16,8 +16,30 @@ #include "mysys_priv.h" - /* Seek to position in file */ - /*ARGSUSED*/ +/* + 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 Not used. + + 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 __attribute__((unused))) @@ -29,8 +51,13 @@ my_off_t my_seek(File fd, my_off_t pos, int whence, whence, MyFlags)); DBUG_ASSERT(pos != MY_FILEPOS_ERROR); /* safety check */ - if (-1 != fd) - newpos=lseek(fd, pos, whence); + /* + Make sure we are using a valid file descriptor! + */ + DBUG_ASSERT(fd != -1); + + newpos= lseek(fd, pos, whence); + if (newpos == (os_off_t) -1) { my_errno=errno; |