plucky (3) gd_mcarrays.3.gz

NAME

       gd_carrays, gd_mcarrays — retrieve a list of CARRAY values from a Dirfile

SYNOPSIS

       #include <getdata.h>

       const gd_carray_t *gd_carrays(DIRFILE *dirfile, gd_type_t return_type);

       const gd_carray_t *gd_mcarrays(DIRFILE *dirfile, const char *parent, gd_type_t return_type);

DESCRIPTION

       The  gd_carrays()  function  queries a dirfile(5) database specified by dirfile and generates a read-only
       list of values of the all top-level CARRAY fields defined in the database, after type conversion  to  the
       data  type  specified  by  return_type.   For  a  list  of  valid symbols to use for return_type, see the
       gd_get_carray(3) manual page.

       The gd_mcarrays() function behaves similarly, but creates a list of values of CARRAY subfields under  the
       parent field parent.

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

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

RETURN VALUE

       Upon successful completion, gd_carrays() and gd_mcarrays(3) return a pointer to an array  of  gd_carray_t
       objects  containing  the  values  of  all  the  CARRAYs defined in the dirfile database.  The gd_carray_t
       structure is defined as:

              typedef struct {
                size_t       n;              /* array_len */
                void        *d;              /* CARRAY data */
              } gd_carray_t;

       where n specifies the length of the CARRAY data, and d is an array of  the  data  values  themselves.  If
       return_type  was  GD_NULL,  d will be NULL.  Otherwise, the caller should cast the void pointer to a type
       appropriate for the return_type specified.  The list is terminated by an end-of-list marker consisting of
       a gd_carray_t item with n set to zero.

       If no CARRAYs are defined in the database, a list containing only the end-of-list marker is returned.

       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,  except  that  it  is
       guaranteed  to  be in the same order as the list of CARRAY fields returned by gd_field_list_by_type(3) or
       gd_mfield_list_by_type(3).  The  number  of  values  in  the  array  can  be  obtained  from  a  call  to
       gd_nfields_by_type(3) or gd_nmfields_by_type(3).

       The  caller  may  not  modify any values in the array, nor the array itself.  Doing so may cause database
       corruption.  The pointer returned is guaranteed to be valid only until the function is called  again,  or
       until  the dirfile's metadata is modified (by adding, modifying or deleting an entry), or until the array
       is de-allocated by a call to gd_close(3) or gd_discard(3).

       On error, gd_carrays() returns NULL and stores a negative-valued error code in the DIRFILE  object  which
       may be retrieved by a subsequent call to gd_error(3).  Possible error codes are:

       GD_E_ALLOC
               The library was unable to allocate memory.

       GD_E_BAD_DIRFILE
               The supplied dirfile was invalid.

       GD_E_BAD_TYPE
               The return_type specified was invalid.

       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.

       A descriptive error string for the error may be obtained by calling gd_error_string(3).

HISTORY

       The gd_carrays() and gd_mcarrays() functions appeared in GetData-0.7.0.

SEE ALSO

       dirfile(5),     gd_error(3),     gd_error_string(3),     gd_field_list_by_type(3),      gd_get_carray(3),
       gd_mfield_list_by_type(3), gd_nfields_by_type(3) gd_nmfields_by_type(3) gd_open(3)