path: root/iconv/gconv_db.c

/* Provide access to the collection of available transformation modules.
   Copyright (C) 1997-2025 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <assert.h>
#include <limits.h>
#include <search.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <libc-lock.h>
#include <locale/localeinfo.h>

#include <dlfcn.h>
#include <gconv_int.h>
#include <pointer_guard.h>


/* Simple data structure for alias mapping.  We have two names, `from'
   and `to'.  */
void *__gconv_alias_db;

/* Array with available modules.  */
struct gconv_module *__gconv_modules_db;

/* We modify global data.   */
__libc_lock_define_initialized (, __gconv_lock)


/* Provide access to module database.  */
struct gconv_module *
__gconv_get_modules_db (void)
{
  return __gconv_modules_db;
}

void *
__gconv_get_alias_db (void)
{
  return __gconv_alias_db;
}


/* Function for searching alias.  */
int
__gconv_alias_compare (const void *p1, const void *p2)
{
  const struct gconv_alias *s1 = (const struct gconv_alias *) p1;
  const struct gconv_alias *s2 = (const struct gconv_alias *) p2;
  return strcmp (s1->fromname, s2->fromname);
}


/* To search for a derivation we create a list of intermediate steps.
   Each element contains a pointer to the element which precedes it
   in the derivation order.  */
struct derivation_step
{
  const char *result_set;
  size_t result_set_len;
  int cost_lo;
  int cost_hi;
  struct gconv_module *code;
  struct derivation_step *last;
  struct derivation_step *next;
};

#define NEW_STEP(result, hi, lo, module, last_mod) \
  ({ struct derivation_step *newp = alloca (sizeof (struct derivation_step)); \
     newp->result_set = result;						      \
     newp->result_set_len = strlen (result);				      \
     newp->cost_hi = hi;						      \
     newp->cost_lo = lo;						      \
     newp->code = module;						      \
     newp->last = last_mod;						      \
     newp->next = NULL;							      \
     newp; })


/* If a specific transformation is used more than once we should not need
   to start looking for it again.  Instead cache each successful result.  */
struct known_derivation
{
  const char *from;
  const char *to;
  struct __gconv_step *steps;