get_string (3) - Linux Manuals

get_string: retrieve a string from a dirfile database


get_string --- retrieve a string from a dirfile database


#include <getdata.h>
size_t get_string(DIRFILE *dirfile, const char *field_code, size_t len, char *data_out);


The get_string() function queries a dirfile(5) database specified by dirfile for the string scalar field_code, which should not contain a representation suffix. The first len characters of the string scalar are stored in the user-supplied buffer data_out.

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

If len equals zero, or if data_out equals NULL, no data will be copied to data_out, but the length of the string scalar will still be returned by get_string(). Otherwise, the argument data_out must point to a valid memory location of sufficient size to hold at least len characters. If the length of the string scalar is greater than len, data_out will not be NULL-terminated.


On success, get_string() returns the actual length of the specified string scalar, including the trailing NULL character. A return value greater than len indicates that the output string is not null terminated.

On error, it returns 0 and sets the dirfile error to a non-zero value. Possible error values are:

The field specified by field_code was not found in the database.
An invalid dirfile was supplied.
The supplied field_code referred to a field of type other than STRING. The caller should use getdata(3), or get_constant(3) instead.
An invalid return_type was specified.
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. The dirfile error may be retrieved by calling get_error(3). A descriptive error string for the last error encountered may be obtained from a call to get_error_string(3).