gd_put_constant(3)

NAME
gd_put_constant — retrieve a scalar constant from a dirfile database

SYNOPSIS
#include <getdata.h>

int gd_put_constant(DIRFILE *dirfile, const char *field_code, gd_type_t data_type, const void *data_in);

DESCRIPTION
The gd_put_constant() function queries a dirfile(5) database specified by dirfile and sets the CONST scalar field_code , which may not contain a representation suffix, to the value specified in data_in, which should be of the type indicated by data_type.

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

The data_type argument should be one of the following symbols, which indicates the desired return type of the data:

    GD_UINT8
        unsigned 8-bit integer

    GD_INT8
        signed (two's complement) 8-bit integer

    GD_UINT16
        unsigned 16-bit integer

    GD_INT16
        signed (two's complement) 16-bit integer

    GD_UINT32
        unsigned 32-bit integer

    GD_INT32
        signed (two's complement) 32-bit integer

    GD_UINT64
        unsigned 64-bit integer

    GD_INT64
        signed (two's complement) 64-bit integer

    GD_FLOAT32 or GD_FLOAT
        IEEE-754 standard 32-bit single precision floating point number

    GD_FLOAT64 or GD_DOUBLE
        IEEE-754 standard 64-bit double precision floating point number

The data type of the supplied value need not be the same as the type of the storage type of the constant in the database. Type conversion will be performed as necessary to return the requested type. The argument data_out must point to valid data type of the specified type.

Because constant values are stored in the dirfile metadata, the new value of field_code won't be written to disk until the dirfile metadata is flushed with gd_metaflush(3), or until the dirfile is closed.

RETURN VALUE
On success, gd_put_constant() returns zero. On error, it returns -1 and sets the dirfile error to a non-zero value. Possible error values are:

GD_E_ACCMODE
    The specified dirfile was opened read-only.

GD_E_BAD_CODE
    The field specified by field_code was not found in the database.

GD_E_BAD_DIRFILE
    An invalid dirfile was supplied.

GD_E_BAD_FIELD_TYPE
    The supplied field_code referred to a field of type other than CONST. The caller should use gd_putdata(3), gd_put_carray(3), or gd_put_string(3) instead.

GD_E_BAD_REPR
    The representation suffix specified in field_code was not recognised.

GD_E_BAD_TYPE
    An invalid data_type was specified.

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 maintainer.

GD_E_PROTECTED
    The fragment containing the constant was protected from change.

The dirfile error may be retrieved by calling gd_error(3). A descriptive error string for the last error encountered may be obtained from a call to gd_error_string(3).

SEE ALSO
dirfile(5), gd_metaflush(3), gd_get_constant(3), gd_error(3), gd_error_string(3), gd_open(3), gd_put_carray(3), gd_put_string(3), gd_putdata(3)