NAME

       gd_alter_encoding — modify the binary encoding of data in a Dirfile

SYNOPSIS

       #include <getdata.h>

       int gd_alter_encoding(DIRFILE *dirfile, unsigned int encoding, int fragment_index, int recode);

DESCRIPTION

       The  gd_alter_encoding()  function sets the binary encoding of the format specification fragment given by
       fragment_index to the encoding specified by encoding in the dirfile(5)  database  specified  by  dirfile.
       The  binary  encoding  of a fragment indicate the encoding of data stored in binary files associated with
       RAW fields defined in the specified fragment.  The binary encoding of a fragment containing no RAW fields
       is ignored.

       The encoding argument should be one of the following symbols:

              GD_UNENCODED, GD_BZIP2_ENCODED, GD_FLAC_ENCODED, GD_GZIP_ENCODED, GD_LZMA_ENCODED,
              GD_SLIM_ENCODED, GD_SIE_ENCODED, GD_TEXT_ENCODED.

       See gd_open(3) and dirfile-encoding(5) for the meanings of these symbols and details on the supported en‐
       coding schemes.

       In addition to being simply a valid  fragment  index,  fragment_index  may  also  be  the  special  value
       GD_ALL_FRAGMENTS, which indicates that the encoding of all fragments in the database should be changed.

       If  the  recode argument is non-zero, this call will recode the binary data of affected RAW fields to ac‐
       count for the change in binary encoding.  If the encoding of the fragment is encoding insensitive, or  if
       the data type is only one byte in size, no change is made.  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_encoding() returns zero.  On error, it returns a negative-valued er‐
       ror 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 recode 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 recoding was requested.

       GD_E_UNCLEAN_DB
               An error occurred while moving the recoded 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 immedi‐
               ately 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 recoding.

       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 recoding 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 recoding occurs one fragment at a time.

       An error code of GD_E_UNCLEAN_DB indicates a system error occurred while moving the re-encoded binary da‐
       ta 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_recov‐
       ery.txt.

HISTORY

       The function dirfile_alter_encoding() appeared in GetData-0.5.0.

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

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

SEE ALSO

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

Version 0.10.0                                  25 December 2016                            gd_alter_encoding(3)