/* Cache handling for iconv modules.

   Copyright (C) 2001-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Ulrich Drepper <drepper@cygnus.com>, 2001.

   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

   <http://www.gnu.org/licenses/>.  */

#include <dlfcn.h>

#include <errno.h>

#include <fcntl.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <sys/mman.h>

#include <sys/stat.h>

#include <gconv_int.h>

#include <iconvconfig.h>

#include <not-cancel.h>

#include "../intl/hash-string.h"

static void *gconv_cache;

static size_t cache_size;

static int cache_malloced;

void *

__gconv_get_cache (void)

{

  return gconv_cache;

}

int

__gconv_load_cache (void)

{

  int fd;

  struct stat64 st;

  struct gconvcache_header *header;

  /* We cannot use the cache if the GCONV_PATH environment variable is

     set.  */

  __gconv_path_envvar = getenv ("GCONV_PATH");

  if (__gconv_path_envvar != NULL)

    return -1;

  /* See whether the cache file exists.  */

  fd = __open_nocancel (GCONV_MODULES_CACHE, O_RDONLY, 0);

  if (__builtin_expect (fd, 0) == -1)

    /* Not available.  */

    return -1;

  /* Get information about the file.  */

  if (__builtin_expect (__fxstat64 (_STAT_VER, fd, &st), 0) < 0

      /* We do not have to start looking at the file if it cannot contain

	 at least the cache header.  */

      || (size_t) st.st_size < sizeof (struct gconvcache_header))

    {

    close_and_exit:

      __close_nocancel_nostatus (fd);

      return -1;

    }

  /* Make the file content available.  */

  cache_size = st.st_size;

#ifdef _POSIX_MAPPED_FILES

  gconv_cache = __mmap (NULL, cache_size, PROT_READ, MAP_SHARED, fd, 0);

  if (__glibc_unlikely (gconv_cache == MAP_FAILED))

#endif

    {

      size_t already_read;

      gconv_cache = malloc (cache_size);

      if (gconv_cache == NULL)

	goto close_and_exit;

      already_read = 0;

      do

	{

	  ssize_t n = __read (fd, (char *) gconv_cache + already_read,

			      cache_size - already_read);

	  if (__builtin_expect (n, 0) == -1)

	    {

	      free (gconv_cache);

	      gconv_cache = NULL;

	      goto close_and_exit;

	    }

	  already_read += n;

	}

      while (already_read < cache_size);

      cache_malloced = 1;

    }

  /* We don't need the file descriptor anymore.  */

  __close_nocancel_nostatus (fd);

  /* Check the consistency.  */

  header = (struct gconvcache_header *) gconv_cache;

  if (__builtin_expect (header->magic, GCONVCACHE_MAGIC) != GCONVCACHE_MAGIC

      || __builtin_expect (header->string_offset >= cache_size, 0)

      || __builtin_expect (header->hash_offset >= cache_size, 0)

      || __builtin_expect (header->hash_size == 0, 0)

      || __builtin_expect ((header->hash_offset

			    + header->hash_size * sizeof (struct hash_entry))

			   > cache_size, 0)

      || __builtin_expect (header->module_offset >= cache_size, 0)

      || __builtin_expect (header->otherconv_offset > cache_size, 0))

    {

      if (cache_malloced)

	{

	  free (gconv_cache);

	  cache_malloced = 0;

	}

#ifdef _POSIX_MAPPED_FILES

      else

	__munmap (gconv_cache, cache_size);

#endif

      gconv_cache = NULL;

      return -1;

    }

  /* That worked.  */

  return 0;

}

static int

find_module_idx (const char *str, size_t *idxp)

{

  unsigned int idx;

  unsigned int hval;

  unsigned int hval2;

  const struct gconvcache_header *header;

  const char *strtab;

  const struct hash_entry *hashtab;

  unsigned int limit;

  header = (const struct gconvcache_header *) gconv_cache;

  strtab = (char *) gconv_cache + header->string_offset;

  hashtab = (struct hash_entry *) ((char *) gconv_cache

				   + header->hash_offset);

  hval = __hash_string (str);

  idx = hval % header->hash_size;

  hval2 = 1 + hval % (header->hash_size - 2);

  limit = cache_size - header->string_offset;

  while (hashtab[idx].string_offset != 0)

    if (hashtab[idx].string_offset < limit

	&& strcmp (str, strtab + hashtab[idx].string_offset) == 0)

      {

	*idxp = hashtab[idx].module_idx;

	return 0;

      }

    else

      if ((idx += hval2) >= header->hash_size)

	idx -= header->hash_size;

  /* Nothing found.  */

  return -1;

}

#ifndef STATIC_GCONV

static int

find_module (const char *directory, const char *filename,

	     struct __gconv_step *result)

{

  size_t dirlen = strlen (directory);

  size_t fnamelen = strlen (filename) + 1;

  char fullname[dirlen + fnamelen];

  int status = __GCONV_NOCONV;

  memcpy (__mempcpy (fullname, directory, dirlen), filename, fnamelen);

  result->__shlib_handle = __gconv_find_shlib (fullname);

  if (result->__shlib_handle != NULL)

    {

      status = __GCONV_OK;

      result->__modname = NULL;

      result->__fct = result->__shlib_handle->fct;

      result->__init_fct = result->__shlib_handle->init_fct;

      result->__end_fct = result->__shlib_handle->end_fct;

      /* These settings can be overridden by the init function.  */

      result->__btowc_fct = NULL;

      result->__data = NULL;

      /* Call the init function.  */

      __gconv_init_fct init_fct = result->__init_fct;

#ifdef PTR_DEMANGLE

      PTR_DEMANGLE (init_fct);

#endif

      if (init_fct != NULL)

	{

	  status = DL_CALL_FCT (init_fct, (result));

#ifdef PTR_MANGLE

	  PTR_MANGLE (result->__btowc_fct);

#endif

	}

    }

  return status;

}

#endif

int

__gconv_compare_alias_cache (const char *name1, const char *name2, int *result)

{

  size_t name1_idx;

  size_t name2_idx;

  if (gconv_cache == NULL)

    return -1;

  if (find_module_idx (name1, &name1_idx) != 0

      || find_module_idx (name2, &name2_idx) != 0)

    *result = strcmp (name1, name2);

  else

    *result = (int) (name1_idx - name2_idx);

  return 0;

}

int

__gconv_lookup_cache (const char *toset, const char *fromset,

		      struct __gconv_step **handle, size_t *nsteps, int flags)

{

  const struct gconvcache_header *header;

  const char *strtab;

  size_t fromidx;

  size_t toidx;

  const struct module_entry *modtab;

  const struct module_entry *from_module;

  const struct module_entry *to_module;

  struct __gconv_step *result;

  if (gconv_cache == NULL)

    /* We have no cache available.  */

    return __GCONV_NODB;

  header = (const struct gconvcache_header *) gconv_cache;

  strtab = (char *) gconv_cache + header->string_offset;

  modtab = (const struct module_entry *) ((char *) gconv_cache

					  + header->module_offset);

  if (find_module_idx (fromset, &fromidx) != 0

      || (header->module_offset + (fromidx + 1) * sizeof (struct module_entry)

	  > cache_size))

    return __GCONV_NOCONV;

  from_module = &modtab[fromidx];

  if (find_module_idx (toset, &toidx) != 0

      || (header->module_offset + (toidx + 1) * sizeof (struct module_entry)

	  > cache_size))

    return __GCONV_NOCONV;

  to_module = &modtab[toidx];

  /* Avoid copy-only transformations if the user requests.   */

  if (__builtin_expect (flags & GCONV_AVOID_NOCONV, 0) && fromidx == toidx)

    return __GCONV_NULCONV;

  /* If there are special conversions available examine them first.  */

  if (fromidx != 0 && toidx != 0

      && __builtin_expect (from_module->extra_offset, 0) != 0)

    {

      /* Search through the list to see whether there is a module

	 matching the destination character set.  */

      const struct extra_entry *extra;

      /* Note the -1.  This is due to the offset added in iconvconfig.

	 See there for more explanations.  */

      extra = (const struct extra_entry *) ((char *) gconv_cache

					    + header->otherconv_offset

					    + from_module->extra_offset - 1);

      while (extra->module_cnt != 0

	     && extra->module[extra->module_cnt - 1].outname_offset != toidx)

	extra = (const struct extra_entry *) ((char *) extra

					      + sizeof (struct extra_entry)

					      + (extra->module_cnt

						 * sizeof (struct extra_entry_module)));

      if (extra->module_cnt != 0)

	{

	  /* Use the extra module.  First determine how many steps.  */

	  char *fromname;

	  int idx;

	  *nsteps = extra->module_cnt;

	  *handle = result =

	    (struct __gconv_step *) malloc (extra->module_cnt

					    * sizeof (struct __gconv_step));

	  if (result == NULL)

	    return __GCONV_NOMEM;

	  fromname = (char *) strtab + from_module->canonname_offset;

	  idx = 0;

	  do

	    {

	      result[idx].__from_name = fromname;

	      fromname = result[idx].__to_name =

		(char *) strtab + modtab[extra->module[idx].outname_offset].canonname_offset;

	      result[idx].__counter = 1;

	      result[idx].__data = NULL;

#ifndef STATIC_GCONV

	      if (strtab[extra->module[idx].dir_offset] != '\0')

		{

		  /* Load the module, return handle for it.  */

		  int res;

		  res = find_module (strtab + extra->module[idx].dir_offset,

				     strtab + extra->module[idx].name_offset,

				     &result[idx]);

		  if (__builtin_expect (res, __GCONV_OK) != __GCONV_OK)

		    {

		      /* Something went wrong.  */

		      free (result);

		      goto try_internal;

		    }

		}

	      else

#endif

		/* It's a builtin transformation.  */

		__gconv_get_builtin_trans (strtab

					   + extra->module[idx].name_offset,

					   &result[idx]);

	    }

	  while (++idx < extra->module_cnt);

	  return __GCONV_OK;

	}

    }

 try_internal:

  /* See whether we can convert via the INTERNAL charset.  */

  if ((fromidx != 0 && __builtin_expect (from_module->fromname_offset, 1) == 0)

      || (toidx != 0 && __builtin_expect (to_module->toname_offset, 1) == 0)

      || (fromidx == 0 && toidx == 0))

    /* Not possible.  Nothing we can do.  */

    return __GCONV_NOCONV;

  /* We will use up to two modules.  Always allocate room for two.  */

  result = (struct __gconv_step *) malloc (2 * sizeof (struct __gconv_step));

  if (result == NULL)

    return __GCONV_NOMEM;

  *handle = result;

  *nsteps = 0;

  /* Generate data structure for conversion to INTERNAL.  */

  if (fromidx != 0)

    {

      result[0].__from_name = (char *) strtab + from_module->canonname_offset;

      result[0].__to_name = (char *) "INTERNAL";

      result[0].__counter = 1;

      result[0].__data = NULL;

#ifndef STATIC_GCONV

      if (strtab[from_module->todir_offset] != '\0')

	{

	  /* Load the module, return handle for it.  */

	  int res = find_module (strtab + from_module->todir_offset,

				 strtab + from_module->toname_offset,

				 &result[0]);

	  if (__builtin_expect (res, __GCONV_OK) != __GCONV_OK)

	    {

	      /* Something went wrong.  */

	      free (result);

	      return res;

	    }

	}

      else

#endif

	/* It's a builtin transformation.  */

	__gconv_get_builtin_trans (strtab + from_module->toname_offset,

				   &result[0]);

      ++*nsteps;

    }

  /* Generate data structure for conversion from INTERNAL.  */

  if (toidx != 0)

    {

      int idx = *nsteps;

      result[idx].__from_name = (char *) "INTERNAL";

      result[idx].__to_name = (char *) strtab + to_module->canonname_offset;

      result[idx].__counter = 1;

      result[idx].__data = NULL;

#ifndef STATIC_GCONV

      if (strtab[to_module->fromdir_offset] != '\0')

	{

	  /* Load the module, return handle for it.  */

	  int res = find_module (strtab + to_module->fromdir_offset,

				 strtab + to_module->fromname_offset,

				 &result[idx]);

	  if (__builtin_expect (res, __GCONV_OK) != __GCONV_OK)

	    {

	      /* Something went wrong.  */

	      if (idx != 0)

		__gconv_release_step (&result[0]);

	      free (result);

	      return res;

	    }

	}

      else

#endif

	/* It's a builtin transformation.  */

	__gconv_get_builtin_trans (strtab + to_module->fromname_offset,

				   &result[idx]);

      ++*nsteps;

    }

  return __GCONV_OK;

}

/* Free memory allocated for the transformation record.  */

void

__gconv_release_cache (struct __gconv_step *steps, size_t nsteps)

{

  if (gconv_cache != NULL)

    /* The only thing we have to deallocate is the record with the

       steps.  */

    free (steps);

}

/* Free all resources if necessary.  */

libc_freeres_fn (free_mem)

{

  if (cache_malloced)

    free (gconv_cache);

#ifdef _POSIX_MAPPED_FILES

  else if (gconv_cache != NULL)

    __munmap (gconv_cache, cache_size);

#endif

}