gd_alter_frameoffset(3) GETDATA gd_alter_frameoffset(3)NAMEgd_alter_frameoffset — modify the starting frame of fields in a dirfile
SYNOPSIS
#include <getdata.h>
int gd_alter_frameoffset(DIRFILE *dirfile, off_t offset, int
fragment_index, int recode);
DESCRIPTION
The gd_alter_frameoffset() function sets the frame offset of the format
specification fragment given by fragment_index to offset in the
dirfile(5) database specified by dirfile. The frame offset of a frag‐
ment indicate the frame number of the first sample of data stored in
binary files associated with RAW fields defined in the specified frag‐
ment. The frame offset of a fragment containing no RAW fields is ig‐
nored. The frame offset may not be negative.
The dirfile argument must point to a valid DIRFILE object previously
created by a call to gd_open(3).
In addition to being simply a valid fragment index, fragment_index may
also be the special value GD_ALL_FRAGMENTS, which indicates that the
frame offset of all fragments in the database should be changed.
If the recode argument is non-zero, this call will shift the binary da‐
ta of affected RAW fields to account for the change in frame offset.
If the new frame offset is larger than the old frame offset, this will
result in permanent deletion of data from the database. If the new
frame offset is smaller than the old frame offset, the binary file will
be padded at the front with zeroes. If recode is zero, affected binary
files are left untouched.
RETURN VALUE
Upon successful completion, gd_alter_frameoffset() returns zero. On
error, it returns -1 and sets the dirfile error to a non-zero error
value. Possible error values are:
GD_E_ACCMODE
The specified dirfile was opened read-only.
GD_E_ALLOC
The library was unable to allocate memory.
GD_E_BAD_DIRFILE
The supplied dirfile was invalid.
GD_E_BAD_INDEX
The supplied index was out of range.
GD_E_PROTECTED
The metadata of the given format specification fragment was
protected from change, or the binary data of the fragment was
protected from change and binary file shifting was requested.
GD_E_RANGE
The supplied offset was less than zero.
GD_E_RAW_IO
An I/O error occurred while attempting to shift a binary file.
GD_E_UNCLEAN_DB
An error occurred while moving the shifted file into place. As
a result, the database may be in an unclean state. See the
NOTES section below for recovery instructions. In this case,
the dirfile will be flagged as invalid, to prevent further
database corruption. It should be immediately closed.
GD_E_UNKNOWN_ENCODING
The encoding scheme of the fragment is unknown.
GD_E_UNSUPPORTED
The encoding scheme of the fragment does not support binary
file shifting.
The dirfile error may be retrieved by calling gd_error(3). A descrip‐
tive error string for the last error encountered can be obtained from a
call to gd_error_string(3).
NOTES
A binary file shift occurs out-of-place. As a result, sufficient space
must be present on the filesystem for the binary files of all RAW
fields in the fragment both before and after translation. If all frag‐
ments are updated by specifying GD_ALL_FRAGMENTS, the shifting occurs
one fragment at a time.
An error code of GD_E_UNCLEAN_DB indicates a system error occurred
while moving the shifted binary data into place or when deleting the
old data. If this happens, the database may be left in an unclean
state. The caller should check the filesystem directly to ascertain
the state of the dirfile data before continuing. For recovery instruc‐
tions, see the file /usr/share/doc/getdata/unclean_database_recov‐
ery.txt.
SEE ALSOgd_open(3), gd_error(3), gd_error_string(3), gd_frameoffset(3),
dirfile(5), dirfile-format(5)Version 0.7.0 20 July 2010 gd_alter_frameoffset(3)
