NAME

       gd_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 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 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 data 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.  The I/O pointer of all affected RAW fields is reset to
       the beginning-of-frame.

       If recode is zero, affected binary files are left untouched.

RETURN VALUE

       Upon successful completion, gd_alter_frameoffset() returns zero.  On error, it  returns  a
       negative-valued error code.  Possible error codes 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_IO An I/O error occurred while attempting to shift a binary file.

       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_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 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).

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 fragments  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  instructions,
       see the file /usr/share/doc/getdata/unclean_database_recovery.txt.

HISTORY

       The function dirfile_alter_frameoffset() appeared in GetData-0.5.0.

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

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

SEE ALSO

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