Security Guards
Before a primitive procedure accesses the filesystem or creates a network connection, it should first consult the current security guard to determine whether such access is allowed for the current thread.
File access is normally preceded by a call to scheme_expand_filename, which accepts flags to indicate the kind of filesystem access needed, so that the security guard is consulted automatically.
An explicit filesystem-access check can be made by calling scheme_security_check_file. Similarly, an explicit network-access check is performed by calling scheme_security_check_network.
15.1 Library Functions
¤ void scheme_security_check_file(const char *who, char *filename,
int guards)
Consults the current security manager to determine whether access is
allowed to filename. The guards argument should be a
bitwise combination of the following:
The filename argument can be NULL (in which case
#f is sent to the security manager's procedure), and
guards should be SCHEME_GUARD_FILE_EXISTS in that
case.
If access is denied, an exception is raised.
¤ void scheme_security_check_network(const char *who, char *host,
int portno)
Consults the current security manager to determine whether access is
allowed for creating a client connection to host on port number
portno. If host is NULL, the security manager is
consulted for creating a server at port number portno.
If access is denied, an exception is raised.