get_mfield_list (3) - Linux Manuals

get_mfield_list: retrieve a list of fields in a dirfile


get_mfield_list --- retrieve a list of fields in a dirfile


#include <getdata.h>
const char **get_mfield_list(DIRFILE *dirfile, const char *parent);


The get_mfield_list() function queries a dirfile(5) database specified by dirfile and returns a read-only list of names of the all metafields for the specified parent field in the database.

The dirfile argument must point to a valid DIRFILE object previously created by a call to dirfile_open(3).

The array returned will be de-allocated by a call to dirfile_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 strings in the array can be obtained from a call to get_nmfields(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 get_mfield_list() is called again with the same arguments, or until the array is deallocated by a call to dirfile_close(3).


Upon successful completion, get_mfield_list() returns a pointer to an array of strings containing the names of all the metafields of the given parent. On error it returns NULL and sets the dirfile error to a non-zero error value. Possible error values are:
The library was unable to allocate memory.
The supplied parent field code was not found, or referred to a metafield itself.
The supplied dirfile was invalid. The dirfile error may be retrieved by calling get_error(3). A descriptive error string for the last error encountered can be obtained from a call to get_error_string(3).