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 encoding 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  account 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 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 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 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 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  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_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)