/* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ #ifndef ISC_SYMTAB_H #define ISC_SYMTAB_H 1 /***** ***** Module Info *****/ /*! \file isc/symtab.h * \brief Provides a simple memory-based symbol table. * * Keys are C strings, and key comparisons are case-insensitive. A type may * be specified when looking up, defining, or undefining. A type value of * 0 means "match any type"; any other value will only match the given * type. * * It's possible that a client will attempt to define a <key, type, value> * tuple when a tuple with the given key and type already exists in the table. * What to do in this case is specified by the client. Possible policies are: * *\li #isc_symexists_reject Disallow the define, returning #ISC_R_EXISTS *\li #isc_symexists_replace Replace the old value with the new. The * undefine action (if provided) will be called * with the old <key, type, value> tuple. *\li #isc_symexists_add Add the new tuple, leaving the old tuple in * the table. Subsequent lookups will retrieve * the most-recently-defined tuple. * * A lookup of a key using type 0 will return the most-recently defined * symbol with that key. An undefine of a key using type 0 will undefine the * most-recently defined symbol with that key. Trying to define a key with * type 0 is illegal. * * The symbol table library does not make a copy the key field, so the * caller must ensure that any key it passes to isc_symtab_define() will not * change until it calls isc_symtab_undefine() or isc_symtab_destroy(). * * A user-specified action will be called (if provided) when a symbol is * undefined. It can be used to free memory associated with keys and/or * values. * * A symbol table is implemented as a hash table of lists; the size of the * hash table is set by the 'size' parameter to isc_symtbl_create(). When * the number of entries in the symbol table reaches three quarters of this * value, the hash table is reallocated with size doubled, in order to * optimize lookup performance. This has a negative effect on insertion * performance, which can be mitigated by sizing the table appropriately * when creating it. * * \li MP: * The callers of this module must ensure any required synchronization. * * \li Reliability: * No anticipated impact. * * \li Resources: * TBS * * \li Security: * No anticipated impact. * * \li Standards: * None. */ /*** *** Imports. ***/ #include <stdbool.h> #include <isc/lang.h> #include <isc/types.h> /* *** Symbol Tables. ***/ /*% Symbol table value. */ typedef union isc_symvalue { void *as_pointer; const void *as_cpointer; int as_integer; unsigned int as_uinteger; } isc_symvalue_t; typedef void (*isc_symtabaction_t)(char *key, unsigned int type, isc_symvalue_t value, void *userarg); /*% Symbol table exists. */ typedef enum { isc_symexists_reject = 0, /*%< Disallow the define */ isc_symexists_replace = 1, /*%< Replace the old value with the new */ isc_symexists_add = 2 /*%< Add the new tuple */ } isc_symexists_t; ISC_LANG_BEGINDECLS /*% Create a symbol table. */ isc_result_t isc_symtab_create(isc_mem_t *mctx, unsigned int size, isc_symtabaction_t undefine_action, void *undefine_arg, bool case_sensitive, isc_symtab_t **symtabp); /*% Destroy a symbol table. */ void isc_symtab_destroy(isc_symtab_t **symtabp); /*% Lookup a symbol table. */ isc_result_t isc_symtab_lookup(isc_symtab_t *symtab, const char *key, unsigned int type, isc_symvalue_t *value); /*% Define a symbol table. */ isc_result_t isc_symtab_define(isc_symtab_t *symtab, const char *key, unsigned int type, isc_symvalue_t value, isc_symexists_t exists_policy); /*% Undefine a symbol table. */ isc_result_t isc_symtab_undefine(isc_symtab_t *symtab, const char *key, unsigned int type); /*% Return the number of items in a symbol table. */ unsigned int isc_symtab_count(isc_symtab_t *symtab); ISC_LANG_ENDDECLS #endif /* ISC_SYMTAB_H */