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gd_frameoffset(3) GETDATA gd_frameoffset(3)


gd_frameoffset — report the starting frame of fields in a Dirfile


#include <getdata.h>

off_t gd_frameoffset(DIRFILE *dirfile, int fragment_index);


The gd_frameoffset() function queries a dirfile(5) database specified by dirfile and returns the frame offset (see dirfile-format(5)) for the fragment indexed by fragment_index. The frame offset of a fragment indicate the frame number of the first sample of data stored in binary files associated with RAW fields defined in the specified fragment. The frame offset of a fragment containing no RAW fields is ignored.

The dirfile argument must point to a valid DIRFILE object previously created by a call to gd_open(3).


Upon successful completion, gd_frameoffset() returns a non-negative integer containing the frame offset of the specified fragment. On error, it returns a negative-valued error code. Possible error codes are:

The supplied dirfile was invalid.
The supplied index was out of range.

The error code is also stored in the DIRFILE object and may be retrieved after this function returns by calling gd_error(3). A descriptive error string for the error may be obtained by calling gd_error_string(3).


The get_frameoffset() function appeared in GetData-0.5.0.

In GetData-0.7.0, this function was renamed to gd_frameoffset().

In GetData-0.10.0, the error return from this function changed from -1 to a negative-valued error code.


gd_alter_frameoffset(3), gd_error(3), gd_error_string(3), gd_open(3), dirfile(5), dirfile-format(5)

25 December 2016 Version 0.10.0