gd_move(3)

NAME

gd_move—move a Dirfile entry between format specification fragments

SYNOPSIS

#include <getdata.h>

int gd_move(DIRFILE *dirfile, const char *field_code, int new_fragment, unsigned int flags);

DESCRIPTION

The gd_move() function transfers the field or alias specified by field_code, which should not have a representation suffix, defined in the dirfile specified by dirfile from it's current format specification fragment to the fragment indexed by new_fragment. If the field is already defined in the fragment index by new_fragment, this function does nothing and returns no error.

If the new fragment has different affixes, the field will be renamed as part of the move. See gd_rename(3) for details on field renaming. The field is closed before moving, resulting in it's I/O pointer being reset to the beginning-of-field.

The flags parameter should be zero or more of the following flags, bitwise or'd together:

GD_REN_DANGLE

By default, if the move results in a change of name for the field due to differing fragment affixes, ALIAS entries pointing to this field will be updated with the field's new name. Specifying this flag prohibits this behaviour, turning these aliases into dangling aliases. If moving the field doesn't rename it, this flag is ignored.

GD_REN_DATA

If field_code specifies a RAW field, the binary file associated with the field will be translated to account for the possibly different encoding, endianness, and frame offset of the new format specification fragment. It will also be moved to a new directory, if necessary.

If this flag is not specified, no changes will be made to the binary file. If field_code specifies a field of type other than RAW, this flag is ignored.

If the binary file is translated, and the frame offset of the destination fragment is larger than that of the source fragment, this will result in permanent deletion of data from the database. If the new frame offset is smaller than the old frame offset, the binary file will be padded at the front with zeroes.

GD_REN_FORCE

Skip updating entries which would be invalid (see gd_rename(3) for details). By default, an invalid field causes the move to fail. If moving the field doesn't rename it, this flag is ignored.

GD_REN_UPDB

If moving the field renames it, update entries which use this field as an input to account for the new name (see gd_rename(3)). If moving the field doesn't rename it, this flag is ignored.

RETURN VALUE

On success, gd_move() returns zero. On error, a negative-valued error code is returned. 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_CODE: The field specified by field_code was not found, or else the move resulted in the field being renamed and the resultant metadata update tried to change a field code into something prohibited by a fragment's affixes.
GD_E_BAD_DIRFILE: The supplied dirfile was invalid.
GD_E_BAD_FIELD_TYPE: An attempt was made to move the immutable INDEX field.
GD_E_BAD_INDEX: The new_fragment argument did not index a valid format specification fragment.
GD_E_IO: An I/O error occurred while attempting to translate a binary file.
GD_E_PROTECTED: The metadata of the source or destination format specification fragments was protected from change, or the binary data of the source or destination fragments was protected from change and binary file translation was requested.
GD_E_UNKNOWN_ENCODING: The encoding scheme of the source or destination fragment is unknown.
GD_E_UNSUPPORTED: The encoding scheme of the source or destination fragment does not support binary file translation.

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 translation occurs out-of-place. As a result, sufficient space must be present on the filesystem for both the binary file before translation and the binary file after translation.

HISTORY

The dirfile_move() function appeared in GetData-0.5.0. It had no flags parameter. In place of flags was int move_data. Passing a non-zero value for this parameter had the same effect as the GD_REN_DATA flag does now.

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

In all GetData-0.8.x releases, passing an alias name to this function would move the target of the alias. To move an alias itself, a separate function, gd_move_alias() was available.

In GetData-0.9.0, gd_move_alias() was removed. Also in this release, the move_data parameter was repaced with the flags parameter.

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