Gd_put_constant retrieve a scalar constant from a dirfile database
#include <getdata.h> int gd_put_constant(DIRFILE *dirfile, const char *field_code, gd_type_t data_type, const void *data_in);
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.
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).