DB_lseek

[Russell]

Hi. I'm new to dcmtk361.
In dcmqrdbi.cc function DB_IdxAdd, there is a call to
[481] DB_lseek (phandle -> pidx, (long) SIZEOF_STUDYDESC, SEEK_SET) ;
but the return value pos is not used. And all 3 parameters are by values.
So, what is the purpose of this function?

[J. Riesmeier]

Did you read the comment that is associated with DB_lseek()?

Code: Select all

/******************************
 *      Seek to a file position and do error checking
 *
 * Motivation:
 * We have had situations during demonstrations where size of the DB index file
 * has exploded.  It seems that a record is being written to a position
 * way past the end of file.
 * This seek function does some sanity error checking to try to identify
 * the problem.
 */

The main purpose of this function is error checking and logging (if there is something the user should be aware of).

[Russell]

Dear J. Riesmeier:
Thank you for the quick reply.
I'm trying to access the database through index.dat.
If DB_lseek is only for error checking, is there a
better function I should be using to read an
arbitrary element of the database?

[J. Riesmeier]

Sorry for being somewhat imprecise in my previous posting. Of course, the call of lseek() is the main purpose of DB_lseek()... but the rest of the function is error checking and logging. Don't ask me why the return value of DB_lseek() is never checked. This code is about 23 years old and has been implemented for demonstration purposes only (e.g. shown at RSNA '93).