NAME¶

gd_frameoffset — report the starting frame of fields in a Dirfile

SYNOPSIS¶

#include <getdata.h>

off_t gd_frameoffset(DIRFILE *dirfile, int fragment_index);

DESCRIPTION¶

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).

RETURN VALUE¶

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:

GD_E_BAD_DIRFILE

The supplied dirfile was invalid.

GD_E_BAD_INDEX

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).

HISTORY¶

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.

SEE ALSO¶

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