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gd_add, gd_madd — add a field to a Dirfile


#include <getdata.h>

int gd_add(DIRFILE *dirfile, const gd_entry_t *entry);

int gd_madd(DIRFILE *dirfile, const gd_entry_t *entry, const char *parent);


The gd_add() function adds the field described by entry to the dirfile specified by dirfile. The gd_madd() function behaves similarly, but adds the field as a metafield under the field indicated by the field code parent.

The form of entry is described in detail on the gd_entry(3) man page. All relevant members of entry for the field type specified must be properly initialised. If entry specifies a CONST or CARRAY field, the field’s data will be set to zero. If entry specifies a STRING field, the field data will be set to the empty string.

The only flags in the entry->flags member which are honoured are GD_EN_HIDDEN, which should be set or cleared to set the hiddenness of the entry (see gd_hidden(3)), and GD_EN_COMPSCAL, which indicates whether scalar parameters are initialised from the complex valued or purely real member, which both are present (LINCOM, POLYNOM, RECIP).

A metafield may be added either by calling gd_madd() with entry->field containing only the metafield’s name, or else by calling gd_add() with the fully formed "<parent-field>/<meta-field>" field code in entry-> field. Regardless of which interface is used, when adding a metafield the value of entry->fragment_index is ignored and GetData will add the new metafield to the same format specification fragment in which the parent field is defined. If the specified parent field name is an alias, the canonical name of the field will be substituted.

Fields added with this interface may contain either literal parameters or parameters based on scalar fields. If an element of the entry-> scalar array defined for the specified field type is non-NULL, this element will be used as the scalar field code, and the corresponding numerical member will be ignored, and need not be initialised. Conversely, if numerical parameters are intended, the corresponding entry->scalar elements should be set to NULL. If using an element of a CARRAY field, entry->scalar_ind should also be set.


On success, gd_add() and gd_madd() return zero. On error, a negative-valued error code is returned. Possible error codes are:

The specified dirfile was opened read-only.


The library was unable to allocate memory.


The field name provided in entry->field contained invalid characters; or it or an input field did not contain the affected fragment’s prefix or suffix. Alternately, the parent field code was not found, or was already a metafield.


The supplied dirfile was invalid.


There was an error in the specification of the field described by entry, or the caller attempted to add a field of type RAW as a metafield.


The entry->fragment_index parameter was out of range.


The entry->data_type parameter provided with a RAW entry, or the entry->const_type parameter provided with a CONST or CARRAY entry, was invalid.


The field name provided in entry->field duplicated that of an already existing field.


An internal error occurred in the library while trying to perform the task. This indicates a bug in the library. Please report the incident to the GetData developers.


An I/O error occurred while creating an empty binary file to be associated with a newly added RAW field.


The metadata of the fragment was protected from change. Or, the creation of a RAW field was attempted and the data of the fragment was protected.


The encoding scheme of the indicated format specification fragment is not known to the library. As a result, the library was unable to create an empty binary file to be associated with a newly added RAW field.


The encoding scheme of the indicated format specification fragment does not support creating an empty binary file to be associated with a newly added RAW field.

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).


The functions dirfile_add() and dirfile_madd() appeared in GetData-0.4.0.

In GetData-0.7.0, the functions were renamed to gd_add() and gd_madd().

In GetData-0.8.0, gd_add() first allowed adding metafields by providing the full (slashed) field name. This was the first version supporting fragment affixes, and in this version, gd_add() would apply the destination fragment’s affixes to the supplied entry->field name. In GetData-0.8.1, this changed: gd_add() now assumes entry->field contains the full field name, including any necessary affixes.

In GetData-0.10.0, the error return from these functions changed from -1 to a negative-valued error code.

See gd_entry(3) for the history of the gd_entry_t structure.


gd_add_bit(3), gd_add_carray(3), gd_add_const(3), gd_add_divide(3), gd_add_lincom(3), gd_add_linterp(3), gd_add_multiply(3), gd_add_phase(3), gd_add_polynom(3), gd_add_raw(3), gd_add_recip(3), gd_add_sbit(3), gd_add_spec(3), gd_add_string(3), gd_entry(3), gd_error(3), gd_error_string(3), gd_madd_bit(3), gd_madd_carray(3), gd_madd_const(3), gd_madd_divide(3), gd_madd_lincom(3), gd_madd_linterp(3), gd_madd_multiply(3), gd_madd_phase(3), gd_madd_polynom(3), gd_madd_recip(3), gd_madd_sbit(3), gd_madd_spec(3), gd_madd_string(3), gd_metaflush(3), gd_open(3), dirfile-format(5)