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
/usr/share/doc/getdata/unclean_database_recovery.txt.
SEE ALSO¶
gd_cbopen(3),
gd_error(3),
gd_error_string(3),
gd_encoding(3),
dirfile(5),
dirfile-format(5)