xdgmimemagic.c

台湾人开发的Linux下的文件管理器

/* -*- 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 <[e-mail]>
 *
 * 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 <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

extern int errno;

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)
    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;
    }