gd_alter_encoding(3)

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 byte_sex 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 byte_sex argument should be one of the following:

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

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

RETURN VALUE
Upon successful completion, gd_alter_encoding() 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 recoding was requested.

GD_E_RAW_IO
    An I/O error occurred while attempting to recode a binary file.

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 dirfile error may be retrieved by calling gd_error(3). A descriptive error string for the last error encountered can be obtained from a call to 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 @absolute_docdir@/unclean_database_recovery.txt.

SEE ALSO
gd_cbopen(3), gd_error(3), gd_error_string(3), gd_encoding(3), dirfile(5), dirfile-format(5)