gd_add(3)

NAME
gd_add, gd_madd — add a field to a dirfile

SYNOPSIS
#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);

DESCRIPTION
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.

When adding a metafield, the entry->field member should contain just the metafield's name, not the fully formed <parent-field>/<meta-field> field code. Also, gd_madd() ignores the value of entry->fragment_index, and instead adds the new meta field to the same format specification fragment in which the parent field is defined.

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.

RETURN VALUE
On success, gd_add() and gd_madd() return zero. On error, -1 is returned and the dirfile error is set 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_CODE
    The field name provided in entry->field contained invalid characters. Alternately, the parent field code was not found, or was already a metafield.

GD_E_BAD_DIRFILE
    The supplied dirfile was invalid.

GD_E_BAD_ENTRY
    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.

GD_E_BAD_INDEX
    The entry->fragment_index parameter was out of range.

GD_E_BAD_TYPE
    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.

GD_E_BOUNDS
    The entry->array_len parameter provided with a CARRAY entry was greater than GD_MAX_CARRAY_LENGTH.

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

GD_E_INTERNAL_ERROR
    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.

GD_E_PROTECTED
    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.

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

GD_E_UNKNOWN_ENCODING
    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.

GD_E_UNSUPPORTED
    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 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
GetData artifically limits the number of elements in a CARRAY to the value of the symbol GD_MAX_CARRAY_LENGTH defined in getdata.h. This is done to be certain that the CARRAY won't overrun the line when flushed to disk. On a 32-bit system, this number is 2**24. It is larger on a 64-bit system.

SEE ALSO
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)