get_mstrings (3) - Linux Manuals

get_mstrings: retrieve a list of string values from a dirfile


get_mstrings --- retrieve a list of string values from a dirfile


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


The get_mstrings() function queries a dirfile(5) database specified by dirfile and returns a read-only list of values of the all STRING type metafields for the supplied parent field.

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, although it is guaranteed to be in the same order as the list of STRING fields returned by get_mfield_list_by_type(3). The array is terminated by a NULL pointer. The number of strings in the array can be obtained from a call to get_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 get_mstrings() is called again with the same arguments, or until the array is deallocated by a call to dirfile_close(3).

A corresponding list of names for these fields may be obtained by calling get_mfield_list_by_type(3).


Upon successful completion, get_mstrings() returns a pointer to an array of strings containing the values of all the STRING metafields for the specified parent field. 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).