NAME

       gd_alter_endianness — modify the byte sex of fields in a Dirfile

SYNOPSIS

       #include <getdata.h>

       int gd_alter_endianness(DIRFILE *dirfile, unsigned long byte_sex, int fragment_index, int recode);

DESCRIPTION

       The  gd_alter_endianness()  function  sets  the  byte  sex  of the format specification fragment given by
       fragment_index to byte_sex in the dirfile(5) database specified by dirfile.  The byte sex of  a  fragment
       indicate  the  endianness of data stored in binary files associated with RAW fields defined in the speci‐
       fied fragment.  The byte sex of a fragment containing no RAW fields is ignored.

       The byte_sex argument should be one of the following:

       0 (zero)
               Indicating that the byte sex should be the native endianness of the host, whichever that may be.

       GD_BIG_ENDIAN
               Indicating that the byte sex should be big endian.

       GD_LITTLE_ENDIAN
               Indicating that the byte sex should be little endian.

       (GD_BIG_ENDIAN | GD_LITTLE_ENDIAN)
               Indicating that the byte sex should be the  opposite  of  the  native  endianness  of  the  host,
               whichever that may be.

       Furthermore, any of these may be bitwise or'd with GD_ARM_ENDIAN or GD_NOT_ARM_ENDIAN indicating that the
       floating point data are stored in the ARM middle-endian format.

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

       If the recode argument is non-zero, this call will byte swap the binary data of affected  RAW  fields  to
       account for the change in byte sex.  If the encoding of the fragment is endianness 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 re‐
       set to the beginning-of-frame.

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

RETURN VALUE

       Upon  successful  completion, gd_alter_endianness() 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_ARGUMENT
               The supplied byte_sex was invalid.

       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 byte swap a binary file.

       GD_E_PROTECTED
               The metadata of the indicated format specification fragment was protected from change, or the bi‐
               nary data of the fragment was protected from change and binary file byte swapping was requested.

       GD_E_UNCLEAN_DB
               An error occurred while moving the byte-swapped 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 im‐
               mediately 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 byte swapping.

       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 byte swap 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 byte swapping  occurs  one  fragment  at  a
       time.

       An  error  code of GD_E_UNCLEAN_DB indicates a system error occurred while moving the byte-swapped 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_recov‐
       ery.txt.

HISTORY

       The function dirfile_alter_endianness() appeared in GetData-0.5.0.

       In  GetData-0.7.0,  this  function  was  renamed  to  gd_alter_endianness().   The  GD_E_ARM_ENDIAN   and
       GD_NOT_ARM_ENDIAN flags also appeared in this version.

       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_endianness(3), dirfile(5), dirfile-format(5)

Version 0.10.0                                  25 December 2016                          gd_alter_endianness(3)