NAME¶
gd_mfield_list_by_type — retrieve a list of fields in a dirfile
SYNOPSIS¶
#include <getdata.h>
const char **gd_mfield_list_by_type(DIRFILE
*dirfile, const char *parent, gd_entype_t
type);
DESCRIPTION¶
The
gd_mfield_list_by_type() function queries a
dirfile(5) database
specified by
dirfile and returns a read-only list of names of the all
metafields of the indicated type for the supplied parent field.
The
dirfile argument must point to a valid DIRFILE object previously
created by a call to
gd_open(3). The
type argument should be one
of the following symbols indicating the desired field type:
- GD_BIT_ENTRY, GD_CARRAY_ENTRY, GD_CONST_ENTRY,
GD_DIVIDE_ENTRY, GD_INDEX_ENTRY, GD_LINCOM_ENTRY,
GD_LINTERP_ENTRY, GD_MULTIPLY_ENTRY, GD_PHASE_ENTRY,
GD_POLYNOM_ENTRY, GD_RECIP_ENTRY, GD_SBIT_ENTRY,
GD_STRING_ENTRY.
The array returned will be de-allocated by a call to
gd_close(3) and
should not be de-allocated by the caller. The list returned should not be
assumed to be in any particular order. The array is terminated by a NULL
pointer. The number of fields in the array can be obtained from a call to
gd_nmfields_by_type(3).
The caller may not modify any strings in the array, or the array itself. Doing
so may cause database corruption. The pointer returned is guaranteed to be
valid until
gd_mfield_list_by_type() is called again with the same
arguments, or until the array is de-allocated by a call to
gd_close(3).
For
CONST,
CARRAY, and
STRING field types, corresponding
lists of values for may be obtained by calling
gd_mconstants(3) or
gd_mstrings(3).
RETURN VALUE¶
Upon successful completion,
gd_mfield_list_by_type() returns a pointer to
an array of strings containing the names of all the metafields of the specific
type for the given parent. On error it returns NULL and sets the dirfile error
to a non-zero error value. Possible error values are:
- GD_E_ALLOC
- The library was unable to allocate memory.
- GD_E_BAD_CODE
- The supplied parent field code was not found, or referred to a metafield
itself.
- GD_E_BAD_DIRFILE
- The supplied dirfile was invalid.
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).
SEE ALSO¶
dirfile(5),
gd_error(3),
gd_error_string(3),
gd_field_list_by_type(3),
gd_mconstants(3),
gd_mfield_list(3),
gd_mstrings(3),
gd_nmfields_by_type(3),
gd_open(3)