gd_validate man page
gd_validate — check a Dirfile field code for validity
int gd_validate(DIRFILE *dirfile, const char *field_code);
The gd_validate() function queries a dirfile(5) database specified by dirfile and checks whether field_code, which may contain a representation suffix, specifies a valid field.
The dirfile argument must point to a valid DIRFILE object previously created by a call to gd_open(3).
This function checks whether the field and its input fields (if any) are found, and also that all non-literal parameters specify valid scalar fields.
If all checks pass, gd_validate() returns zero. On error, it returns a negative-valued error code. Possible error codes are:
The field specified by field_code or one of the fields it uses as input was not found in the database.
The supplied dirfile was invalid.
A non-literal scalar used in the definition of the field or one of its inputs was not found, or was not a CONST or CARRAY field.
A scalar field was found where a vector field was expected.
The error code is also stored in the DIRFILE object and may be retrieved after this function returns by calling gd_error(3). A descriptive error string for the error may be obtained by calling gd_error_string(3).
It is not necessary to call this function before passing a field code to another GetData function: all functions which accept field codes perform these checks themselves.
The dirfile_validate(3) function appared in GetData-0.6.0.
In GetData-0.7.0, this function was renamed to gd_validate(3).
In GetData-0.10.0, the error return from this function changed from -1 to a negative-valued error code.
gd_error(3), gd_error_string(3), gd_getdata(3), gd_open(3), dirfile(5)