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xdgmimecache.c

/* -*- mode: C; c-file-style: "gnu" -*- */
/* xdgmimealias.c: Private file.  mmappable caches for mime data
 *
 * More info can be found at http://www.freedesktop.org/standards/
 *
 * Copyright (C) 2005  Matthias Clasen <mclasen@redhat.com>
 *
 * Licensed under the Academic Free License version 2.0
 * Or under the following terms:
 *
 * This 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 of the License, or (at your option) any later version.
 *
 * This 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 this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

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

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

#include <fcntl.h>
#include <unistd.h>
#include <fnmatch.h>
#include <assert.h>

#include <netinet/in.h> /* for ntohl/ntohs */

#ifdef HAVE_MMAP
#include <sys/mman.h>
#endif

#include <sys/stat.h>
#include <sys/types.h>

#include "xdgmimecache.h"
#include "xdgmimeint.h"

#ifndef MAX
#define MAX(a,b) ((a) > (b) ? (a) : (b))
#endif

#ifndef     FALSE
#define     FALSE (0)
#endif

#ifndef     TRUE
#define     TRUE  (!FALSE)
#endif

#ifndef _O_BINARY
#define _O_BINARY 0
#endif

#ifndef MAP_FAILED
#define MAP_FAILED ((void *) -1)
#endif

#define MAJOR_VERSION 1
#define MINOR_VERSION 0

struct _XdgMimeCache
{
  int ref_count;

  size_t  size;
  char   *buffer;
};

#define GET_UINT16(cache,offset) (ntohs(*(xdg_uint16_t*)((cache) + (offset))))
#define GET_UINT32(cache,offset) (ntohl(*(xdg_uint32_t*)((cache) + (offset))))

XdgMimeCache *
_xdg_mime_cache_ref (XdgMimeCache *cache)
{
  cache->ref_count++;
  return cache;
}

void
_xdg_mime_cache_unref (XdgMimeCache *cache)
{
  cache->ref_count--;

  if (cache->ref_count == 0)
    {
#ifdef HAVE_MMAP
      munmap (cache->buffer, cache->size);
#endif
      free (cache);
    }
}

XdgMimeCache *
_xdg_mime_cache_new_from_file (const char *file_name)
{
  XdgMimeCache *cache = NULL;

#ifdef HAVE_MMAP
  int fd = -1;
  struct stat st;
  char *buffer = NULL;

  /* Open the file and map it into memory */
  fd = open (file_name, O_RDONLY|_O_BINARY, 0);

  if (fd < 0)
    return NULL;
  
  if (fstat (fd, &st) < 0 || st.st_size < 4)
    goto done;

  buffer = (char *) mmap (NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);

  if (buffer == MAP_FAILED)
    goto done;

  /* Verify version */
  if (GET_UINT16 (buffer, 0) != MAJOR_VERSION ||
      GET_UINT16 (buffer, 2) != MINOR_VERSION)
    {
      munmap (buffer, st.st_size);

      goto done;
    }
  
  cache = (XdgMimeCache *) malloc (sizeof (XdgMimeCache));
  cache->ref_count = 1;
  cache->buffer = buffer;
  cache->size = st.st_size;

 done:
  if (fd != -1)
    close (fd);

#endif  /* HAVE_MMAP */

  return cache;
}

static int
cache_magic_matchlet_compare_to_data (XdgMimeCache *cache, 
                              xdg_uint32_t  offset,
                              const void   *data,
                              size_t        len)
{
  xdg_uint32_t range_start = GET_UINT32 (cache->buffer, offset);
  xdg_uint32_t range_length = GET_UINT32 (cache->buffer, offset + 4);
  xdg_uint32_t data_length = GET_UINT32 (cache->buffer, offset + 12);
  xdg_uint32_t data_offset = GET_UINT32 (cache->buffer, offset + 16);
  xdg_uint32_t mask_offset = GET_UINT32 (cache->buffer, offset + 20);
  
  int i, j;

  for (i = range_start; i <= range_start + range_length; i++)
    {
      int valid_matchlet = TRUE;
      
      if (i + data_length > len)
      return FALSE;

      if (mask_offset)
      {
        for (j = 0; j < data_length; j++)
          {
            if ((((unsigned char *)cache->buffer)[data_offset + j] & ((unsigned char *)cache->buffer)[mask_offset + j]) !=
              ((((unsigned char *) data)[j + i]) & ((unsigned char *)cache->buffer)[mask_offset + j]))
            {
              valid_matchlet = FALSE;
              break;
            }
          }
      }
      else
      {
        for (j = 0; j < data_length; j++)
          {
            if (((unsigned char *)cache->buffer)[data_offset + j] != ((unsigned char *) data)[j + i])
            {
              valid_matchlet = FALSE;
              break;
            }
          }
      }
      
      if (valid_matchlet)
      return TRUE;
    }
  
  return FALSE;  
}

static int
cache_magic_matchlet_compare (XdgMimeCache *cache, 
                        xdg_uint32_t  offset,
                        const void   *data,
                        size_t        len)
{
  xdg_uint32_t n_children = GET_UINT32 (cache->buffer, offset + 24);
  xdg_uint32_t child_offset = GET_UINT32 (cache->buffer, offset + 28);

  int i;
  
  if (cache_magic_matchlet_compare_to_data (cache, offset, data, len))
    {
      if (n_children == 0)
      return TRUE;
      
      for (i = 0; i < n_children; i++)
      {
        if (cache_magic_matchlet_compare (cache, child_offset + 32 * i,
                                  data, len))
          return TRUE;
      }
    }
  
  return FALSE;  
}

static const char *
cache_magic_compare_to_data (XdgMimeCache *cache, 
                       xdg_uint32_t  offset,
                       const void   *data, 
                       size_t        len, 
                       int          *prio)
{
  xdg_uint32_t priority = GET_UINT32 (cache->buffer, offset);
  xdg_uint32_t mimetype_offset = GET_UINT32 (cache->buffer, offset + 4);
  xdg_uint32_t n_matchlets = GET_UINT32 (cache->buffer, offset + 8);
  xdg_uint32_t matchlet_offset = GET_UINT32 (cache->buffer, offset + 12);

  int i;

  for (i = 0; i < n_matchlets; i++)
    {
      if (cache_magic_matchlet_compare (cache, matchlet_offset + i * 32, 
                              data, len))
      {
        *prio = priority;
        
        return cache->buffer + mimetype_offset;
      }
    }

  return NULL;
}

static const char *
cache_magic_lookup_data (XdgMimeCache *cache, 
                   const void   *data, 
                   size_t        len, 
                   int          *prio,
                   const char   *mime_types[],
                   int           n_mime_types)
{
  xdg_uint32_t list_offset;
  xdg_uint32_t n_entries;
  xdg_uint32_t offset;

  int j, n;

  *prio = 0;

  list_offset = GET_UINT32 (cache->buffer, 24);
  n_entries = GET_UINT32 (cache->buffer, list_offset);
  offset = GET_UINT32 (cache->buffer, list_offset + 8);
  
  for (j = 0; j < n_entries; j++)
    {
      const char *match;

      match = cache_magic_compare_to_data (cache, offset + 16 * j, 
                                 data, len, prio);
      if (match)
      return match;
      else
      {
        xdg_uint32_t mimetype_offset;
        const char *non_match;
        
        mimetype_offset = GET_UINT32 (cache->buffer, offset + 16 * j + 4);
        non_match = cache->buffer + mimetype_offset;

        for (n = 0; n < n_mime_types; n++)
          {
            if (mime_types[n] && 
              xdg_mime_mime_type_equal (mime_types[n], non_match))
            mime_types[n] = NULL;
          }
      }
    }

  return NULL;
}

static const char *
cache_alias_lookup (const char *alias)
{
  const char *ptr;
  int i, min, max, mid, cmp;

  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];
      xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 4);
      xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
      xdg_uint32_t offset;

      min = 0; 
      max = n_entries - 1;
      while (max >= min) 
      {
        mid = (min + max) / 2;

        offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid);
        ptr = cache->buffer + offset;
        cmp = strcmp (ptr, alias);
        
        if (cmp < 0)
          min = mid + 1;
        else if (cmp > 0)
          max = mid - 1;
        else
          {
            offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid + 4);
            return cache->buffer + offset;
          }
      }
    }

  return NULL;
}

static int
cache_glob_lookup_literal (const char *file_name,
                     const char *mime_types[],
                     int         n_mime_types)
{
  const char *ptr;
  int i, min, max, mid, cmp;

  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];
      xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 12);
      xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
      xdg_uint32_t offset;

      min = 0; 
      max = n_entries - 1;
      while (max >= min) 
      {
        mid = (min + max) / 2;

        offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid);
        ptr = cache->buffer + offset;
        cmp = strcmp (ptr, file_name);
        
        if (cmp < 0)
          min = mid + 1;
        else if (cmp > 0)
          max = mid - 1;
        else
          {
            offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * mid + 4);
            mime_types[0] = (const char *)(cache->buffer + offset);
            
            return 1;
          }
      }
    }

  return 0;
}

static int
cache_glob_lookup_fnmatch (const char *file_name,
                     const char *mime_types[],
                     int         n_mime_types)
{
  const char *mime_type;
  const char *ptr;

  int i, j, n;

  n = 0;
  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];

      xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 20);
      xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);

      for (j = 0; j < n_entries && n < n_mime_types; j++)
      {
        xdg_uint32_t offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * j);
        xdg_uint32_t mimetype_offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * j + 4);
        ptr = cache->buffer + offset;
        mime_type = cache->buffer + mimetype_offset;

        /* FIXME: Not UTF-8 safe */
        if (fnmatch (ptr, file_name, 0) == 0)
          mime_types[n++] = mime_type;
      }

      if (n > 0)
      return n;
    }
  
  return 0;
}

static int
cache_glob_node_lookup_suffix (XdgMimeCache *cache,
                         xdg_uint32_t  n_entries,
                         xdg_uint32_t  offset,
                         const char   *suffix, 
                         int           ignore_case,
                         const char   *mime_types[],
                         int           n_mime_types)
{
  xdg_unichar_t character;
  xdg_unichar_t match_char;
  xdg_uint32_t mimetype_offset;
  xdg_uint32_t n_children;
  xdg_uint32_t child_offset; 

  int min, max, mid, n, i;

  character = _xdg_utf8_to_ucs4 (suffix);
  if (ignore_case)
    character = _xdg_ucs4_to_lower (character);

  min = 0;
  max = n_entries - 1;
  while (max >= min)
    {
      mid = (min + max) /  2;

      match_char = GET_UINT32 (cache->buffer, offset + 16 * mid);

      if (match_char < character)
      min = mid + 1;
      else if (match_char > character)
      max = mid - 1;
      else 
      {
        suffix = _xdg_utf8_next_char (suffix);
        if (*suffix == '\0')
          {
            mimetype_offset = GET_UINT32 (cache->buffer, offset + 16 * mid + 4);
            n = 0;
            mime_types[n++] = cache->buffer + mimetype_offset;
            
            n_children = GET_UINT32 (cache->buffer, offset + 16 * mid + 8);
            child_offset = GET_UINT32 (cache->buffer, offset + 16 * mid + 12);
            i = 0;
            while (n < n_mime_types && i < n_children)
            {
              match_char = GET_UINT32 (cache->buffer, child_offset + 16 * i);
              mimetype_offset = GET_UINT32 (cache->buffer, offset + 16 * i + 4);
              if (match_char != 0)
                break;

              mime_types[n++] = cache->buffer + mimetype_offset;
              i++;
            }

            return n;
          }
        else
          {
            n_children = GET_UINT32 (cache->buffer, offset + 16 * mid + 8);
            child_offset = GET_UINT32 (cache->buffer, offset + 16 * mid + 12);
      
            return cache_glob_node_lookup_suffix (cache, 
                                        n_children, child_offset,
                                        suffix, ignore_case,
                                        mime_types,
                                        n_mime_types);
          }
      }
    }

  return 0;
}

static int
cache_glob_lookup_suffix (const char *suffix, 
                    int         ignore_case,
                    const char *mime_types[],
                    int         n_mime_types)
{
  int i, n;

  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];

      xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 16);
      xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
      xdg_uint32_t offset = GET_UINT32 (cache->buffer, list_offset + 4);

      n = cache_glob_node_lookup_suffix (cache, 
                               n_entries, offset, 
                               suffix, ignore_case,
                               mime_types,
                               n_mime_types);
      if (n > 0)
      return n;
    }

  return 0;
}

static void
find_stopchars (char *stopchars)
{
  int i, j, k, l;
 
  k = 0;
  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];

      xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 16);
      xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
      xdg_uint32_t offset = GET_UINT32 (cache->buffer, list_offset + 4);

      for (j = 0; j < n_entries; j++)
      {
        xdg_uint32_t match_char = GET_UINT32 (cache->buffer, offset);
        
        if (match_char < 128)
          {
            for (l = 0; l < k; l++)
            if (stopchars[l] == match_char)
              break;
            if (l == k)
            {
              stopchars[k] = (char) match_char;
              k++;
            }
          }

        offset += 16;
      }
    }

  stopchars[k] = '\0';
}

static int
cache_glob_lookup_file_name (const char *file_name, 
                       const char *mime_types[],
                       int         n_mime_types)
{
  const char *ptr;
  char stopchars[128];
  int n;
  
  assert (file_name != NULL);

  /* First, check the literals */
  n = cache_glob_lookup_literal (file_name, mime_types, n_mime_types);
  if (n > 0)
    return n;

  find_stopchars (stopchars);

  /* Next, check suffixes */
  ptr = strpbrk (file_name, stopchars);
  while (ptr)
    {
      n = cache_glob_lookup_suffix (ptr, FALSE, mime_types, n_mime_types);
      if (n > 0)
      return n;
      
      n = cache_glob_lookup_suffix (ptr, TRUE, mime_types, n_mime_types);
      if (n > 0)
      return n;

      ptr = strpbrk (ptr + 1, stopchars);
    }
  
  /* Last, try fnmatch */
  return cache_glob_lookup_fnmatch (file_name, mime_types, n_mime_types);
}

int
_xdg_mime_cache_get_max_buffer_extents (void)
{
  xdg_uint32_t offset;
  xdg_uint32_t max_extent;
  int i;

  max_extent = 0;
  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];

      offset = GET_UINT32 (cache->buffer, 24);
      max_extent = MAX (max_extent, GET_UINT32 (cache->buffer, offset + 4));
    }

  return max_extent;
}

static const char *
cache_get_mime_type_for_data (const void *data,
                        size_t      len,
                        const char *mime_types[],
                        int         n_mime_types)
{
  const char *mime_type;
  int i, n, priority;

  priority = 0;
  mime_type = NULL;
  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];

      int prio;
      const char *match;

      match = cache_magic_lookup_data (cache, data, len, &prio, 
                               mime_types, n_mime_types);
      if (prio > priority)
      {
        priority = prio;
        mime_type = match;
      }
    }

  if (priority > 0)
    return mime_type;

  for (n = 0; n < n_mime_types; n++)
    {
      if (mime_types[n])
      return mime_types[n];
    }

  return XDG_MIME_TYPE_UNKNOWN;
}

const char *
_xdg_mime_cache_get_mime_type_for_data (const void *data,
                              size_t      len)
{
  return cache_get_mime_type_for_data (data, len, NULL, 0);
}

const char *
_xdg_mime_cache_get_mime_type_for_file (const char  *file_name,
                              struct stat *statbuf)
{
  const char *mime_type;
  const char *mime_types[2];
  FILE *file;
  unsigned char *data;
  int max_extent;
  int bytes_read;
  struct stat buf;
  const char *base_name;
  int n;

  if (file_name == NULL)
    return NULL;

  if (! _xdg_utf8_validate (file_name))
    return NULL;

  base_name = _xdg_get_base_name (file_name);
  n = cache_glob_lookup_file_name (base_name, mime_types, 2);

  if (n == 1)
    return mime_types[0];

  if (!statbuf)
    {
      if (stat (file_name, &buf) != 0)
      return XDG_MIME_TYPE_UNKNOWN;

      statbuf = &buf;
    }

  if (!S_ISREG (statbuf->st_mode))
    return XDG_MIME_TYPE_UNKNOWN;

  /* FIXME: Need to make sure that max_extent isn't totally broken.  This could
   * be large and need getting from a stream instead of just reading it all
   * in. */
  max_extent = _xdg_mime_cache_get_max_buffer_extents ();
  data = malloc (max_extent);
  if (data == NULL)
    return XDG_MIME_TYPE_UNKNOWN;
        
  file = fopen (file_name, "r");
  if (file == NULL)
    {
      free (data);
      return XDG_MIME_TYPE_UNKNOWN;
    }

  bytes_read = fread (data, 1, max_extent, file);
  if (ferror (file))
    {
      free (data);
      fclose (file);
      return XDG_MIME_TYPE_UNKNOWN;
    }

  mime_type = cache_get_mime_type_for_data (data, bytes_read,
                                  mime_types, n);

  free (data);
  fclose (file);

  return mime_type;
}

const char *
_xdg_mime_cache_get_mime_type_from_file_name (const char *file_name)
{
  const char *mime_type;

  if (cache_glob_lookup_file_name (file_name, &mime_type, 1))
    return mime_type;
  else
    return XDG_MIME_TYPE_UNKNOWN;
}

#if 1
static int
is_super_type (const char *mime)
{
  int length;
  const char *type;

  length = strlen (mime);
  type = &(mime[length - 2]);

  if (strcmp (type, "/*") == 0)
    return 1;

  return 0;
}
#endif

int
_xdg_mime_cache_mime_type_subclass (const char *mime,
                            const char *base)
{
  const char *umime, *ubase;

  int i, j, min, max, med, cmp;
  
  umime = _xdg_mime_cache_unalias_mime_type (mime);
  ubase = _xdg_mime_cache_unalias_mime_type (base);

  if (strcmp (umime, ubase) == 0)
    return 1;

  /* We really want to handle text/ * in GtkFileFilter, so we just
   * turn on the supertype matching
   */
#if 1
  /* Handle supertypes */
  if (is_super_type (ubase) &&
      xdg_mime_media_type_equal (umime, ubase))
    return 1;
#endif

  /*  Handle special cases text/plain and application/octet-stream */
  if (strcmp (ubase, "text/plain") == 0 && 
      strncmp (umime, "text/", 5) == 0)
    return 1;

  if (strcmp (ubase, "application/octet-stream") == 0)
    return 1;
 
  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];
      
      xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 8);
      xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);
      xdg_uint32_t offset, n_parents, parent_offset;

      min = 0; 
      max = n_entries - 1;
      while (max >= min)
      {
        med = (min + max)/2;
        
        offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * med);
        cmp = strcmp (cache->buffer + offset, umime);
        if (cmp < 0)
          min = med + 1;
        else if (cmp > 0)
          max = med - 1;
        else
          {
            offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * med + 4);
            n_parents = GET_UINT32 (cache->buffer, offset);
            
            for (j = 0; j < n_parents; j++)
            {
              parent_offset = GET_UINT32 (cache->buffer, offset + 4 + 4 * j);
              if (_xdg_mime_cache_mime_type_subclass (cache->buffer + parent_offset, ubase))
                return 1;
            }

            break;
          }
      }
    }

  return 0;
}

const char *
_xdg_mime_cache_unalias_mime_type (const char *mime)
{
  const char *lookup;
  
  lookup = cache_alias_lookup (mime);
  
  if (lookup)
    return lookup;
  
  return mime;  
}

char **
_xdg_mime_cache_list_mime_parents (const char *mime)
{
  int i, j, p;
  char *all_parents[128]; /* we'll stop at 128 */ 
  char **result;

  p = 0;
  for (i = 0; _caches[i]; i++)
    {
      XdgMimeCache *cache = _caches[i];
  
      xdg_uint32_t list_offset = GET_UINT32 (cache->buffer, 8);
      xdg_uint32_t n_entries = GET_UINT32 (cache->buffer, list_offset);

      for (j = 0; j < n_entries; j++)
      {
        xdg_uint32_t mimetype_offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * i);
        xdg_uint32_t parents_offset = GET_UINT32 (cache->buffer, list_offset + 4 + 8 * i + 4);
        
        if (strcmp (cache->buffer + mimetype_offset, mime) == 0)
          {
            xdg_uint32_t n_parents = GET_UINT32 (cache->buffer, parents_offset);
            
            for (j = 0; j < n_parents; j++)
            all_parents[p++] = cache->buffer + parents_offset + 4 + 4 * j;

            break;
          }
      }
    }
  all_parents[p++] = 0;
  
  result = (char **) malloc (p * sizeof (char *));
  memcpy (result, all_parents, p * sizeof (char *));

  return result;
}


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