/* -*- mode: C; c-file-style: "gnu" -*- */

/* xdgmimemagic.: Private file.  Datastructure for storing magic files.

 *

 * More info can be found at http://www.freedesktop.org/standards/

 *

 * Copyright (C) 2003  Red Hat, Inc.

 * Copyright (C) 2003  Jonathan Blandford <jrb@alum.mit.edu>

 *

 * 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 2.1 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, see <http://www.gnu.org/licenses/>.

 */

#include "config.h"

#include <assert.h>

#include "xdgmimemagic.h"

#include "xdgmimeint.h"

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <ctype.h>

#include <errno.h>

#include <limits.h>

#ifndef	FALSE

#define	FALSE	(0)

#endif

#ifndef	TRUE

#define	TRUE	(!FALSE)

#endif

#if !defined getc_unlocked && !defined HAVE_GETC_UNLOCKED

# define getc_unlocked(fp) getc (fp)

#endif

typedef struct XdgMimeMagicMatch XdgMimeMagicMatch;

typedef struct XdgMimeMagicMatchlet XdgMimeMagicMatchlet;

typedef enum

{

  XDG_MIME_MAGIC_SECTION,

  XDG_MIME_MAGIC_MAGIC,

  XDG_MIME_MAGIC_ERROR,

  XDG_MIME_MAGIC_EOF

} XdgMimeMagicState;

struct XdgMimeMagicMatch

{

  const char *mime_type;

  int priority;

  XdgMimeMagicMatchlet *matchlet;

  XdgMimeMagicMatch *next;

};

struct XdgMimeMagicMatchlet

{

  int indent;

  int offset;

  unsigned int value_length;

  unsigned char *value;

  unsigned char *mask;

  unsigned int range_length;

  unsigned int word_size;

  XdgMimeMagicMatchlet *next;

};

struct XdgMimeMagic

{

  XdgMimeMagicMatch *match_list;

  int max_extent;

};

static XdgMimeMagicMatch *

_xdg_mime_magic_match_new (void)

{

  return calloc (1, sizeof (XdgMimeMagicMatch));

}

static XdgMimeMagicMatchlet *

_xdg_mime_magic_matchlet_new (void)

{

  XdgMimeMagicMatchlet *matchlet;

  matchlet = malloc (sizeof (XdgMimeMagicMatchlet));

  matchlet->indent = 0;

  matchlet->offset = 0;

  matchlet->value_length = 0;

  matchlet->value = NULL;

  matchlet->mask = NULL;

  matchlet->range_length = 1;

  matchlet->word_size = 1;

  matchlet->next = NULL;

  return matchlet;

}

static void

_xdg_mime_magic_matchlet_free (XdgMimeMagicMatchlet *mime_magic_matchlet)

{

  if (mime_magic_matchlet)

    {

      if (mime_magic_matchlet->next)

	_xdg_mime_magic_matchlet_free (mime_magic_matchlet->next);

      if (mime_magic_matchlet->value)

	free (mime_magic_matchlet->value);

      if (mime_magic_matchlet->mask)

	free (mime_magic_matchlet->mask);

      free (mime_magic_matchlet);

    }

}

/* Frees mime_magic_match and the remainder of its list

 */

static void

_xdg_mime_magic_match_free (XdgMimeMagicMatch *mime_magic_match)

{

  XdgMimeMagicMatch *ptr, *next;

  ptr = mime_magic_match;

  while (ptr)

    {

      next = ptr->next;

      if (ptr->mime_type)

	free ((void *) ptr->mime_type);

      if (ptr->matchlet)

	_xdg_mime_magic_matchlet_free (ptr->matchlet);

      free (ptr);

      ptr = next;

    }

}

/* Reads in a hunk of data until a newline character or a '\000' is hit.  The

 * returned string is null terminated, and doesn't include the newline.

 */

static unsigned char *

_xdg_mime_magic_read_to_newline (FILE *magic_file,

				 int  *end_of_file)

{

  unsigned char *retval;

  int c;

  int len, pos;

  len = 128;

  pos = 0;

  retval = malloc (len);

  *end_of_file = FALSE;

  while (TRUE)

    {

      c = getc_unlocked (magic_file);

      if (c == EOF)

	{

	  *end_of_file = TRUE;

	  break;

	}

      if (c == '\n' || c == '\000')

	break;

      retval[pos++] = (unsigned char) c;

      if (pos % 128 == 127)

	{

	  len = len + 128;

	  retval = realloc (retval, len);

	}

    }

  retval[pos] = '\000';

  return retval;

}

/* Returns the number read from the file, or -1 if no number could be read.

 */

static int

_xdg_mime_magic_read_a_number (FILE *magic_file,

			       int  *end_of_file)

{

  /* LONG_MAX is about 20 characters on my system */

#define MAX_NUMBER_SIZE 30

  char number_string[MAX_NUMBER_SIZE + 1];

  int pos = 0;

  int c;

  long retval = -1;

  while (TRUE)

    {

      c = getc_unlocked (magic_file);

      if (c == EOF)

	{

	  *end_of_file = TRUE;

	  break;

	}

      if (! isdigit (c))

	{

	  ungetc (c, magic_file);

	  break;

	}

      number_string[pos] = (char) c;

      pos++;

      if (pos == MAX_NUMBER_SIZE)

	break;

    }

  if (pos > 0)

    {

      number_string[pos] = '\000';

      errno = 0;

      retval = strtol (number_string, NULL, 10);

      if ((retval < INT_MIN) || (retval > INT_MAX) || (errno != 0))

	return -1;

    }

  return retval;

}

/* Headers are of the format:

 * [<priority>:<mime-type>]

 */

static XdgMimeMagicState

_xdg_mime_magic_parse_header (FILE *magic_file, XdgMimeMagicMatch *match)

{

  int c;

  char *buffer;

  char *end_ptr;

  int end_of_file = 0;

  assert (magic_file != NULL);

  assert (match != NULL);

  c = getc_unlocked (magic_file);

  if (c == EOF)

    return XDG_MIME_MAGIC_EOF;

  if (c != '[')

    return XDG_MIME_MAGIC_ERROR;

  match->priority = _xdg_mime_magic_read_a_number (magic_file, &end_of_file);

  if (end_of_file)

    return XDG_MIME_MAGIC_EOF;

  if (match->priority == -1)

    return XDG_MIME_MAGIC_ERROR;

  c = getc_unlocked (magic_file);

  if (c == EOF)

    return XDG_MIME_MAGIC_EOF;

  if (c != ':')

    return XDG_MIME_MAGIC_ERROR;

  buffer = (char *)_xdg_mime_magic_read_to_newline (magic_file, &end_of_file);

  if (end_of_file)

    {

      free (buffer);

      return XDG_MIME_MAGIC_EOF;

    }

  end_ptr = buffer;

  while (*end_ptr != ']' && *end_ptr != '\000' && *end_ptr != '\n')

    end_ptr++;

  if (*end_ptr != ']')

    {

      free (buffer);

      return XDG_MIME_MAGIC_ERROR;

    }

  *end_ptr = '\000';

  match->mime_type = strdup (buffer);

  free (buffer);

  return XDG_MIME_MAGIC_MAGIC;

}

static XdgMimeMagicState

_xdg_mime_magic_parse_error (FILE *magic_file)

{

  int c;

  while (1)

    {

      c = getc_unlocked (magic_file);

      if (c == EOF)

	return XDG_MIME_MAGIC_EOF;

      if (c == '\n')

	return XDG_MIME_MAGIC_SECTION;

    }

}

/* Headers are of the format:

 * [ indent ] ">" start-offset "=" value

 * [ "&" mask ] [ "~" word-size ] [ "+" range-length ] "\n"

 */

static XdgMimeMagicState

_xdg_mime_magic_parse_magic_line (FILE              *magic_file,

				  XdgMimeMagicMatch *match)

{

  XdgMimeMagicMatchlet *matchlet;

  int c;

  int end_of_file;

  int indent = 0;

  int bytes_read;

  assert (magic_file != NULL);

  /* Sniff the buffer to make sure it's a valid line */

  c = getc_unlocked (magic_file);

  if (c == EOF)

    return XDG_MIME_MAGIC_EOF;

  else if (c == '[')

    {

      ungetc (c, magic_file);

      return XDG_MIME_MAGIC_SECTION;

    }

  else if (c == '\n')

    return XDG_MIME_MAGIC_MAGIC;

  /* At this point, it must be a digit or a '>' */

  end_of_file = FALSE;

  if (isdigit (c))

    {

      ungetc (c, magic_file);

      indent = _xdg_mime_magic_read_a_number (magic_file, &end_of_file);

      if (end_of_file)

	return XDG_MIME_MAGIC_EOF;

      if (indent == -1)

	return XDG_MIME_MAGIC_ERROR;

      c = getc_unlocked (magic_file);

      if (c == EOF)

	return XDG_MIME_MAGIC_EOF;

    }

  if (c != '>')

    return XDG_MIME_MAGIC_ERROR;

  matchlet = _xdg_mime_magic_matchlet_new ();

  matchlet->indent = indent;

  matchlet->offset = _xdg_mime_magic_read_a_number (magic_file, &end_of_file);

  if (end_of_file)

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      return XDG_MIME_MAGIC_EOF;

    }

  if (matchlet->offset == -1)

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      return XDG_MIME_MAGIC_ERROR;

    }

  c = getc_unlocked (magic_file);

  if (c == EOF)

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      return XDG_MIME_MAGIC_EOF;

    }

  else if (c != '=')

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      return XDG_MIME_MAGIC_ERROR;

    }

  /* Next two bytes determine how long the value is */

  matchlet->value_length = 0;

  c = getc_unlocked (magic_file);

  if (c == EOF)

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      return XDG_MIME_MAGIC_EOF;

    }

  matchlet->value_length = c & 0xFF;

  matchlet->value_length = matchlet->value_length << 8;

  c = getc_unlocked (magic_file);

  if (c == EOF)

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      return XDG_MIME_MAGIC_EOF;

    }

  matchlet->value_length = matchlet->value_length + (c & 0xFF);

  matchlet->value = malloc (matchlet->value_length);

  /* OOM */

  if (matchlet->value == NULL)

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      return XDG_MIME_MAGIC_ERROR;

    }

  bytes_read = fread (matchlet->value, 1, matchlet->value_length, magic_file);

  if (bytes_read != matchlet->value_length)

    {

      _xdg_mime_magic_matchlet_free (matchlet);

      if (feof (magic_file))

	return XDG_MIME_MAGIC_EOF;

      else

	return XDG_MIME_MAGIC_ERROR;

    }

  c = getc_unlocked (magic_file);

  if (c == '&')

    {

      matchlet->mask = malloc (matchlet->value_length);

      /* OOM */

      if (matchlet->mask == NULL)

	{

	  _xdg_mime_magic_matchlet_free (matchlet);

	  return XDG_MIME_MAGIC_ERROR;

	}

      bytes_read = fread (matchlet->mask, 1, matchlet->value_length, magic_file);

      if (bytes_read != matchlet->value_length)

	{

	  _xdg_mime_magic_matchlet_free (matchlet);

	  if (feof (magic_file))

	    return XDG_MIME_MAGIC_EOF;

	  else

	    return XDG_MIME_MAGIC_ERROR;

	}

      c = getc_unlocked (magic_file);

    }

  if (c == '~')

    {

      matchlet->word_size = _xdg_mime_magic_read_a_number (magic_file, &end_of_file);

      if (end_of_file)

	{

	  _xdg_mime_magic_matchlet_free (matchlet);

	  return XDG_MIME_MAGIC_EOF;

	}

      if (matchlet->word_size != 0 &&

	  matchlet->word_size != 1 &&

	  matchlet->word_size != 2 &&

	  matchlet->word_size != 4)

	{

	  _xdg_mime_magic_matchlet_free (matchlet);

	  return XDG_MIME_MAGIC_ERROR;

	}

      c = getc_unlocked (magic_file);

    }

  if (c == '+')

    {

      matchlet->range_length = _xdg_mime_magic_read_a_number (magic_file, &end_of_file);

      if (end_of_file)

	{

	  _xdg_mime_magic_matchlet_free (matchlet);

	  return XDG_MIME_MAGIC_EOF;

	}

      if (matchlet->range_length == -1)

	{

	  _xdg_mime_magic_matchlet_free (matchlet);

	  return XDG_MIME_MAGIC_ERROR;

	}

      c = getc_unlocked (magic_file);

    }

  if (c == '\n')

    {

      /* We clean up the matchlet, byte swapping if needed */

      if (matchlet->word_size > 1)

	{

#if LITTLE_ENDIAN

	  int i;

#endif

	  if (matchlet->value_length % matchlet->word_size != 0)

	    {

	      _xdg_mime_magic_matchlet_free (matchlet);

	      return XDG_MIME_MAGIC_ERROR;

	    }

	  /* FIXME: need to get this defined in a <config.h> style file */

#if LITTLE_ENDIAN

	  for (i = 0; i < matchlet->value_length; i = i + matchlet->word_size)

	    {

	      if (matchlet->word_size == 2)

		*((xdg_uint16_t *) matchlet->value + i) = SWAP_BE16_TO_LE16 (*((xdg_uint16_t *) (matchlet->value + i)));

	      else if (matchlet->word_size == 4)

		*((xdg_uint32_t *) matchlet->value + i) = SWAP_BE32_TO_LE32 (*((xdg_uint32_t *) (matchlet->value + i)));

	      if (matchlet->mask)

		{

		  if (matchlet->word_size == 2)

		    *((xdg_uint16_t *) matchlet->mask + i) = SWAP_BE16_TO_LE16 (*((xdg_uint16_t *) (matchlet->mask + i)));

		  else if (matchlet->word_size == 4)

		    *((xdg_uint32_t *) matchlet->mask + i) = SWAP_BE32_TO_LE32 (*((xdg_uint32_t *) (matchlet->mask + i)));

		}

	    }

#endif

	}

      matchlet->next = match->matchlet;

      match->matchlet = matchlet;

      return XDG_MIME_MAGIC_MAGIC;

    }

  _xdg_mime_magic_matchlet_free (matchlet);

  if (c == EOF)

    return XDG_MIME_MAGIC_EOF;

  return XDG_MIME_MAGIC_ERROR;

}

static int

_xdg_mime_magic_matchlet_compare_to_data (XdgMimeMagicMatchlet *matchlet,

					  const void           *data,

					  size_t                len)

{

  int i, j;

  for (i = matchlet->offset; i < matchlet->offset + matchlet->range_length; i++)

    {

      int valid_matchlet = TRUE;

      if (i + matchlet->value_length > len)

	return FALSE;

      if (matchlet->mask)

	{

	  for (j = 0; j < matchlet->value_length; j++)

	    {

	      if ((matchlet->value[j] & matchlet->mask[j]) !=

		  ((((unsigned char *) data)[j + i]) & matchlet->mask[j]))

		{

		  valid_matchlet = FALSE;

		  break;

		}

	    }

	}

      else

	{

	  for (j = 0; j <  matchlet->value_length; j++)

	    {

	      if (matchlet->value[j] != ((unsigned char *) data)[j + i])

		{

		  valid_matchlet = FALSE;

		  break;

		}

	    }

	}

      if (valid_matchlet)

	return TRUE;

    }

  return FALSE;

}

static int

_xdg_mime_magic_matchlet_compare_level (XdgMimeMagicMatchlet *matchlet,

					const void           *data,

					size_t                len,

					int                   indent)

{

  while ((matchlet != NULL) && (matchlet->indent == indent))

    {

      if (_xdg_mime_magic_matchlet_compare_to_data (matchlet, data, len))

	{

	  if ((matchlet->next == NULL) ||

	      (matchlet->next->indent <= indent))

	    return TRUE;

	  if (_xdg_mime_magic_matchlet_compare_level (matchlet->next,

						      data,

						      len,

						      indent + 1))

	    return TRUE;

	}

      do

	{

	  matchlet = matchlet->next;

	}

      while (matchlet && matchlet->indent > indent);

    }

  return FALSE;

}

static int

_xdg_mime_magic_match_compare_to_data (XdgMimeMagicMatch *match,

				       const void        *data,

				       size_t             len)

{

  return _xdg_mime_magic_matchlet_compare_level (match->matchlet, data, len, 0);

}

static void

_xdg_mime_magic_insert_match (XdgMimeMagic      *mime_magic,

			      XdgMimeMagicMatch *match)

{

  XdgMimeMagicMatch *list;

  if (mime_magic->match_list == NULL)

    {

      mime_magic->match_list = match;

      return;

    }

  if (match->priority > mime_magic->match_list->priority)

    {

      match->next = mime_magic->match_list;

      mime_magic->match_list = match;

      return;

    }

  list = mime_magic->match_list;

  while (list->next != NULL)

    {

      if (list->next->priority < match->priority)

	{

	  match->next = list->next;

	  list->next = match;

	  return;

	}

      list = list->next;

    }

  list->next = match;

  match->next = NULL;

}

XdgMimeMagic *

_xdg_mime_magic_new (void)

{

  return calloc (1, sizeof (XdgMimeMagic));

}

void

_xdg_mime_magic_free (XdgMimeMagic *mime_magic)

{

  if (mime_magic) {

    _xdg_mime_magic_match_free (mime_magic->match_list);

    free (mime_magic);

  }

}

int

_xdg_mime_magic_get_buffer_extents (XdgMimeMagic *mime_magic)

{

  return mime_magic->max_extent;

}

const char *

_xdg_mime_magic_lookup_data (XdgMimeMagic *mime_magic,

			     const void   *data,

			     size_t        len,

			     int           *result_prio,

                             const char   *mime_types[],

                             int           n_mime_types)

{

  XdgMimeMagicMatch *match;

  const char *mime_type;

  int n;

  int prio;

  prio = 0;

  mime_type = NULL;

  for (match = mime_magic->match_list; match; match = match->next)

    {

      if (_xdg_mime_magic_match_compare_to_data (match, data, len))

	{

	  prio = match->priority;

	  mime_type = match->mime_type;

	  break;

	}

      else 

	{

	  for (n = 0; n < n_mime_types; n++)

	    {

	      if (mime_types[n] && 

		  _xdg_mime_mime_type_equal (mime_types[n], match->mime_type))

		mime_types[n] = NULL;

	    }

	}

    }

  if (mime_type == NULL)

    {

      for (n = 0; n < n_mime_types; n++)

	{

	  if (mime_types[n])

	    mime_type = mime_types[n];

	}

    }

  if (result_prio)

    *result_prio = prio;

  return mime_type;

}

static void

_xdg_mime_update_mime_magic_extents (XdgMimeMagic *mime_magic)

{

  XdgMimeMagicMatch *match;

  int max_extent = 0;

  for (match = mime_magic->match_list; match; match = match->next)

    {

      XdgMimeMagicMatchlet *matchlet;

      for (matchlet = match->matchlet; matchlet; matchlet = matchlet->next)

	{

	  int extent;

	  extent = matchlet->value_length + matchlet->offset + matchlet->range_length;

	  if (max_extent < extent)

	    max_extent = extent;

	}

    }

  mime_magic->max_extent = max_extent;

}

static XdgMimeMagicMatchlet *

_xdg_mime_magic_matchlet_mirror (XdgMimeMagicMatchlet *matchlets)

{

  XdgMimeMagicMatchlet *new_list;

  XdgMimeMagicMatchlet *tmp;

  if ((matchlets == NULL) || (matchlets->next == NULL))

    return matchlets;

  new_list = NULL;

  tmp = matchlets;

  while (tmp != NULL)

    {

      XdgMimeMagicMatchlet *matchlet;

      matchlet = tmp;

      tmp = tmp->next;

      matchlet->next = new_list;

      new_list = matchlet;

    }

  return new_list;

}

static void

_xdg_mime_magic_read_magic_file (XdgMimeMagic *mime_magic,

				 FILE         *magic_file)

{

  XdgMimeMagicState state;

  XdgMimeMagicMatch *match = NULL; /* Quiet compiler */

  state = XDG_MIME_MAGIC_SECTION;

  while (state != XDG_MIME_MAGIC_EOF)

    {

      switch (state)

	{

	case XDG_MIME_MAGIC_SECTION:

	  match = _xdg_mime_magic_match_new ();

	  state = _xdg_mime_magic_parse_header (magic_file, match);

	  if (state == XDG_MIME_MAGIC_EOF || state == XDG_MIME_MAGIC_ERROR)

	    _xdg_mime_magic_match_free (match);

	  break;

	case XDG_MIME_MAGIC_MAGIC:

	  state = _xdg_mime_magic_parse_magic_line (magic_file, match);

	  if (state == XDG_MIME_MAGIC_SECTION ||

	      (state == XDG_MIME_MAGIC_EOF && match->mime_type))

	    {

	      match->matchlet = _xdg_mime_magic_matchlet_mirror (match->matchlet);

	      _xdg_mime_magic_insert_match (mime_magic, match);

	    }

	  else if (state == XDG_MIME_MAGIC_EOF || state == XDG_MIME_MAGIC_ERROR)

	    _xdg_mime_magic_match_free (match);

	  break;

	case XDG_MIME_MAGIC_ERROR:

	  state = _xdg_mime_magic_parse_error (magic_file);

	  break;

	case XDG_MIME_MAGIC_EOF:

	default:

	  /* Make the compiler happy */

	  assert (0);

	}

    }

  _xdg_mime_update_mime_magic_extents (mime_magic);

}

void

_xdg_mime_magic_read_from_file (XdgMimeMagic *mime_magic,

				const char   *file_name)

{

  FILE *magic_file;

  char header[12];

  magic_file = fopen (file_name, "r");

  if (magic_file == NULL)

    return;

  if (fread (header, 1, 12, magic_file) == 12)

    {

      if (memcmp ("MIME-Magic\0\n", header, 12) == 0)

        _xdg_mime_magic_read_magic_file (mime_magic, magic_file);

    }

  fclose (magic_file);

}