localealias.c

/* Handle aliases for locale names.
   Copyright (C) 1995-1999, 2000, 2001 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU Library General Public License as published
   by the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
   USA.  */

/* Tell glibc's <string.h> to provide a prototype for mempcpy().
   This must come before <config.h> because <config.h> may include
   <features.h>, and once <features.h> has been included, it's too late.  */
#ifndef _GNU_SOURCE
# define _GNU_SOURCE    1
#endif

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <ctype.h>
#include <stdio.h>
#if defined _LIBC || defined HAVE___FSETLOCKING
# include <stdio_ext.h>
#endif
#include <sys/types.h>

#ifdef __GNUC__
# define alloca __builtin_alloca
# define HAVE_ALLOCA 1
#else
# if defined HAVE_ALLOCA_H || defined _LIBC
#  include <alloca.h>
# else
#  ifdef _AIX
 #pragma alloca
#  else
#   ifndef alloca
char *alloca ();
#   endif
#  endif
# endif
#endif

#include <stdlib.h>
#include <string.h>

#include "gettextP.h"

/* @@ end of prolog @@ */

#ifdef _LIBC
/* Rename the non ANSI C functions.  This is required by the standard
   because some ANSI C functions will require linking with this object
   file and the name space must not be polluted.  */
# define strcasecmp __strcasecmp

# ifndef mempcpy
#  define mempcpy __mempcpy
# endif
# define HAVE_MEMPCPY   1
# define HAVE___FSETLOCKING     1

/* We need locking here since we can be called from different places.  */
# include <bits/libc-lock.h>

__libc_lock_define_initialized (static, lock);
#endif

#ifndef internal_function
# define internal_function
#endif

/* Some optimizations for glibc.  */
#ifdef _LIBC
# define FEOF(fp)               feof_unlocked (fp)
# define FGETS(buf, n, fp)      fgets_unlocked (buf, n, fp)
#else
# define FEOF(fp)               feof (fp)
# define FGETS(buf, n, fp)      fgets (buf, n, fp)
#endif

/* For those losing systems which don't have `alloca' we have to add
   some additional code emulating it.  */
#ifdef HAVE_ALLOCA
# define freea(p) /* nothing */
#else
# define alloca(n) malloc (n)
# define freea(p) free (p)
#endif

#if defined _LIBC_REENTRANT || defined HAVE_FGETS_UNLOCKED
# undef fgets
# define fgets(buf, len, s) fgets_unlocked (buf, len, s)
#endif
#if defined _LIBC_REENTRANT || defined HAVE_FEOF_UNLOCKED
# undef feof
# define feof(s) feof_unlocked (s)
#endif


struct alias_map
{
  const char *alias;
  const char *value;
};


static char *string_space;
static size_t string_space_act;
static size_t string_space_max;
static struct alias_map *map;
static size_t nmap;
static size_t maxmap;


/* Prototypes for local functions.  */
static size_t read_alias_file PARAMS ((const char *fname, int fname_len))
     internal_function;
static int extend_alias_table PARAMS ((void));
static int alias_compare PARAMS ((const struct alias_map *map1,
                                  const struct alias_map *map2));


const char *
_nl_expand_alias (name)
    const char *name;
{
  static const char *locale_alias_path;
  struct alias_map *retval;
  const char *result = NULL;
  size_t added;

#ifdef _LIBC
  __libc_lock_lock (lock);
#endif

  if (locale_alias_path == NULL)
    locale_alias_path = LOCALE_ALIAS_PATH;

  do
    {
      struct alias_map item;

      item.alias = name;

      if (nmap > 0)
        retval = (struct alias_map *) bsearch (&item, map, nmap,
                                               sizeof (struct alias_map),
                                               (int (*) PARAMS ((const void *,
                                                                 const void *))
                                                ) alias_compare);
      else
        retval = NULL;

      /* We really found an alias.  Return the value.  */
      if (retval != NULL)
        {
          result = retval->value;
          break;
        }

      /* Perhaps we can find another alias file.  */
      added = 0;
      while (added == 0 && locale_alias_path[0] != '\0')
        {
          const char *start;

          while (locale_alias_path[0] == PATH_SEPARATOR)
            ++locale_alias_path;
          start = locale_alias_path;

          while (locale_alias_path[0] != '\0'
                 && locale_alias_path[0] != PATH_SEPARATOR)
            ++locale_alias_path;

          if (start < locale_alias_path)
            added = read_alias_file (start, locale_alias_path - start);
        }
    }
  while (added != 0);

#ifdef _LIBC
  __libc_lock_unlock (lock);
#endif

  return result;
}


static size_t
internal_function
read_alias_file (fname, fname_len)
     const char *fname;
     int fname_len;
{
  FILE *fp;
  char *full_fname;
  size_t added;
  static const char aliasfile[] = "/locale.alias";

  full_fname = (char *) alloca (fname_len + sizeof aliasfile);
#ifdef HAVE_MEMPCPY
  mempcpy (mempcpy (full_fname, fname, fname_len),
           aliasfile, sizeof aliasfile);
#else
  memcpy (full_fname, fname, fname_len);
  memcpy (&full_fname[fname_len], aliasfile, sizeof aliasfile);
#endif

  fp = fopen (full_fname, "r");
  freea (full_fname);
  if (fp == NULL)
    return 0;

#ifdef HAVE___FSETLOCKING
  /* No threads present.  */
  __fsetlocking (fp, FSETLOCKING_BYCALLER);
#endif

  added = 0;
  while (!FEOF (fp))
    {
      /* It is a reasonable approach to use a fix buffer here because
         a) we are only interested in the first two fields
         b) these fields must be usable as file names and so must not
            be that long
       */
      char buf[BUFSIZ];
      char *alias;
      char *value;
      char *cp;

      if (FGETS (buf, sizeof buf, fp) == NULL)
        /* EOF reached.  */
        break;

      /* Possibly not the whole line fits into the buffer.  Ignore
         the rest of the line.  */
      if (strchr (buf, '\n') == NULL)
        {
          char altbuf[BUFSIZ];
          do
            if (FGETS (altbuf, sizeof altbuf, fp) == NULL)
              /* Make sure the inner loop will be left.  The outer loop
                 will exit at the `feof' test.  */
              break;
          while (strchr (altbuf, '\n') == NULL);
        }

      cp = buf;
      /* Ignore leading white space.  */
      while (isspace ((unsigned char) cp[0]))
        ++cp;

      /* A leading '#' signals a comment line.  */
      if (cp[0] != '\0' && cp[0] != '#')
        {
          alias = cp++;
          while (cp[0] != '\0' && !isspace ((unsigned char) cp[0]))
            ++cp;
          /* Terminate alias name.  */
          if (cp[0] != '\0')
            *cp++ = '\0';

          /* Now look for the beginning of the value.  */
          while (isspace ((unsigned char) cp[0]))
            ++cp;

          if (cp[0] != '\0')
            {
              size_t alias_len;
              size_t value_len;

              value = cp++;
              while (cp[0] != '\0' && !isspace ((unsigned char) cp[0]))
                ++cp;
              /* Terminate value.  */
              if (cp[0] == '\n')
                {
                  /* This has to be done to make the following test
                     for the end of line possible.  We are looking for
                     the terminating '\n' which do not overwrite here.  */
                  *cp++ = '\0';
                  *cp = '\n';
                }
              else if (cp[0] != '\0')
                *cp++ = '\0';

              if (nmap >= maxmap)
                if (__builtin_expect (extend_alias_table (), 0))
                  return added;

              alias_len = strlen (alias) + 1;
              value_len = strlen (value) + 1;

              if (string_space_act + alias_len + value_len > string_space_max)
                {
                  /* Increase size of memory pool.  */
                  size_t new_size = (string_space_max
                                     + (alias_len + value_len > 1024
                                        ? alias_len + value_len : 1024));
                  char *new_pool = (char *) realloc (string_space, new_size);
                  if (new_pool == NULL)
                    return added;

                  if (__builtin_expect (string_space != new_pool, 0))
                    {
                      size_t i;

                      for (i = 0; i < nmap; i++)
                        {
                          map[i].alias += new_pool - string_space;
                          map[i].value += new_pool - string_space;
                        }
                    }

                  string_space = new_pool;
                  string_space_max = new_size;
                }

              map[nmap].alias = memcpy (&string_space[string_space_act],
                                        alias, alias_len);
              string_space_act += alias_len;

              map[nmap].value = memcpy (&string_space[string_space_act],
                                        value, value_len);
              string_space_act += value_len;

              ++nmap;
              ++added;
            }
        }
    }

  /* Should we test for ferror()?  I think we have to silently ignore
     errors.  --drepper  */
  fclose (fp);

  if (added > 0)
    qsort (map, nmap, sizeof (struct alias_map),
           (int (*) PARAMS ((const void *, const void *))) alias_compare);

  return added;
}


static int
extend_alias_table ()
{
  size_t new_size;
  struct alias_map *new_map;

  new_size = maxmap == 0 ? 100 : 2 * maxmap;
  new_map = (struct alias_map *) realloc (map, (new_size
                                                * sizeof (struct alias_map)));
  if (new_map == NULL)
    /* Simply don't extend: we don't have any more core.  */
    return -1;

  map = new_map;
  maxmap = new_size;
  return 0;
}


#ifdef _LIBC
static void __attribute__ ((unused))
free_mem (void)
{
  if (string_space != NULL)
    free (string_space);
  if (map != NULL)
    free (map);
}
text_set_element (__libc_subfreeres, free_mem);
#endif


static int
alias_compare (map1, map2)
     const struct alias_map *map1;
     const struct alias_map *map2;
{
#if defined _LIBC || defined HAVE_STRCASECMP
  return strcasecmp (map1->alias, map2->alias);
#else
  const unsigned char *p1 = (const unsigned char *) map1->alias;
  const unsigned char *p2 = (const unsigned char *) map2->alias;
  unsigned char c1, c2;

  if (p1 == p2)
    return 0;

  do
    {
      /* I know this seems to be odd but the tolower() function in
         some systems libc cannot handle nonalpha characters.  */
      c1 = isupper (*p1) ? tolower (*p1) : *p1;
      c2 = isupper (*p2) ? tolower (*p2) : *p2;
      if (c1 == '\0')
        break;
      ++p1;
      ++p2;
    }
  while (c1 == c2);

  return c1 - c2;
#endif
}

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