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)