trusty (3) gd_mcarrays.3.gz

Provided by: libgetdata-dev_0.7.3-6ubuntu1_amd64 bug

NAME
       gd_constants — retrieve a list of CARRAY values from a dirfile


SYNOPSIS
       #include <getdata.h>

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


DESCRIPTION
       The  gd_mcarrays()  function  queries  a dirfile(5) database specified by dirfile and returns a read-only
       list of values of the all CARRAY metafields for the supplied parent field, 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) man page.

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

       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_mfield_list_by_type(3).
       The number of values in the array can be obtained from a call to 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 gd_mcarrays() 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).

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


RETURN VALUE
       Upon successful completion, gd_mcarrays() returns 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 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.  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.  On
       error, gd_mcarrays() 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.

       GD_E_BAD_TYPE
               The return_type specified 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_carrays(3), gd_error(3), gd_error_string(3), gd_get_carray(3),  gd_mfield_list_by_type(3),
       gd_nmfields_by_type(3), gd_open(3)