mangle_hash2.c

samba-3.0.22.tar.gz 编译smb服务器的源码

		M_DEBUG(10,("check_cache: %s -> not mangled\n", name));
		return False;
	}

	/* we need to extract the hash from the 8.3 name */
	hash = base_reverse[(unsigned char)name[7]];
	for (multiplier=36, i=5;i>=mangle_prefix;i--) {
		u32 v = base_reverse[(unsigned char)name[i]];
		hash += multiplier * v;
		multiplier *= 36;
	}

	/* now look in the prefix cache for that hash */
	prefix = cache_lookup(hash);
	if (!prefix) {
		M_DEBUG(10,("check_cache: %s -> %08X -> not found\n", name, hash));
		return False;
	}

	/* we found it - construct the full name */
	if (name[8] == '.') {
		strncpy(extension, name+9, 3);
		extension[3] = 0;
	} else {
		extension[0] = 0;
	}

	if (extension[0]) {
		M_DEBUG(10,("check_cache: %s -> %s.%s\n", name, prefix, extension));
		slprintf(name, maxlen, "%s.%s", prefix, extension);
	} else {
		M_DEBUG(10,("check_cache: %s -> %s\n", name, prefix));
		safe_strcpy(name, prefix, maxlen);
	}

	return True;
}


/*
  look for a DOS reserved name
*/
static BOOL is_reserved_name(const char *name)
{
	if (FLAG_CHECK(name[0], FLAG_POSSIBLE1) &&
	    FLAG_CHECK(name[1], FLAG_POSSIBLE2) &&
	    FLAG_CHECK(name[2], FLAG_POSSIBLE3) &&
	    FLAG_CHECK(name[3], FLAG_POSSIBLE4)) {
		/* a likely match, scan the lot */
		int i;
		for (i=0; reserved_names[i]; i++) {
			int len = strlen(reserved_names[i]);
			/* note that we match on COM1 as well as COM1.foo */
			if (strnequal(name, reserved_names[i], len) &&
			    (name[len] == '.' || name[len] == 0)) {
				return True;
			}
		}
	}

	return False;
}

/*
 See if a filename is a legal long filename.
 A filename ending in a '.' is not legal unless it's "." or "..". JRA.
 A filename ending in ' ' is not legal either. See bug id #2769.
*/

static BOOL is_legal_name(const char *name)
{
	const char *dot_pos = NULL;
	BOOL alldots = True;
	size_t numdots = 0;

	while (*name) {
		if (((unsigned int)name[0]) > 128 && (name[1] != 0)) {
			/* Possible start of mb character. */
			char mbc[2];
			/*
			 * Note that if CH_UNIX is utf8 a string may be 3
			 * bytes, but this is ok as mb utf8 characters don't
			 * contain embedded ascii bytes. We are really checking
			 * for mb UNIX asian characters like Japanese (SJIS) here.
			 * JRA.
			 */
			if (convert_string(CH_UNIX, CH_UCS2, name, 2, mbc, 2, False) == 2) {
				/* Was a good mb string. */
				name += 2;
				continue;
			}
		}

		if (FLAG_CHECK(name[0], FLAG_ILLEGAL)) {
			return False;
		}
		if (name[0] == '.') {
			dot_pos = name;
			numdots++;
		} else {
			alldots = False;
		}
		if ((name[0] == ' ') && (name[1] == '\0')) {
			/* Can't end in ' ' */
			return False;
		}
		name++;
	}

	if (dot_pos) {
		if (alldots && (numdots == 1 || numdots == 2))
			return True; /* . or .. is a valid name */

		/* A valid long name cannot end in '.' */
		if (dot_pos[1] == '\0')
			return False;
	}
	return True;
}

/*
  the main forward mapping function, which converts a long filename to 
  a 8.3 name

  if need83 is not set then we only do the mangling if the name is illegal
  as a long name

  if cache83 is not set then we don't cache the result

  the name parameter must be able to hold 13 bytes
*/
static void name_map(fstring name, BOOL need83, BOOL cache83, int default_case, int snum)
{
	char *dot_p;
	char lead_chars[7];
	char extension[4];
	unsigned int extension_length, i;
	unsigned int prefix_len;
	u32 hash, v;
	char new_name[13];

	/* reserved names are handled specially */
	if (!is_reserved_name(name)) {
		/* if the name is already a valid 8.3 name then we don't need to 
		   do anything */
		if (is_8_3(name, False, False, snum)) {
			return;
		}

		/* if the caller doesn't strictly need 8.3 then just check for illegal 
		   filenames */
		if (!need83 && is_legal_name(name)) {
			return;
		}
	}

	/* find the '.' if any */
	dot_p = strrchr(name, '.');

	if (dot_p) {
		/* if the extension contains any illegal characters or
		   is too long or zero length then we treat it as part
		   of the prefix */
		for (i=0; i<4 && dot_p[i+1]; i++) {
			if (! FLAG_CHECK(dot_p[i+1], FLAG_ASCII)) {
				dot_p = NULL;
				break;
			}
		}
		if (i == 0 || i == 4) dot_p = NULL;
	}

	/* the leading characters in the mangled name is taken from
	   the first characters of the name, if they are ascii otherwise
	   '_' is used
	*/
	for (i=0;i<mangle_prefix && name[i];i++) {
		lead_chars[i] = name[i];
		if (! FLAG_CHECK(lead_chars[i], FLAG_ASCII)) {
			lead_chars[i] = '_';
		}
		lead_chars[i] = toupper_ascii(lead_chars[i]);
	}
	for (;i<mangle_prefix;i++) {
		lead_chars[i] = '_';
	}

	/* the prefix is anything up to the first dot */
	if (dot_p) {
		prefix_len = PTR_DIFF(dot_p, name);
	} else {
		prefix_len = strlen(name);
	}

	/* the extension of the mangled name is taken from the first 3
	   ascii chars after the dot */
	extension_length = 0;
	if (dot_p) {
		for (i=1; extension_length < 3 && dot_p[i]; i++) {
			char c = dot_p[i];
			if (FLAG_CHECK(c, FLAG_ASCII)) {
				extension[extension_length++] = toupper_ascii(c);
			}
		}
	}
	   
	/* find the hash for this prefix */
	v = hash = mangle_hash(name, prefix_len);

	/* now form the mangled name. */
	for (i=0;i<mangle_prefix;i++) {
		new_name[i] = lead_chars[i];
	}
	new_name[7] = base_forward(v % 36);
	new_name[6] = '~';	
	for (i=5; i>=mangle_prefix; i--) {
		v = v / 36;
		new_name[i] = base_forward(v % 36);
	}

	/* add the extension */
	if (extension_length) {
		new_name[8] = '.';
		memcpy(&new_name[9], extension, extension_length);
		new_name[9+extension_length] = 0;
	} else {
		new_name[8] = 0;
	}

	if (cache83) {
		/* put it in the cache */
		cache_insert(name, prefix_len, hash);
	}

	M_DEBUG(10,("name_map: %s -> %08X -> %s (cache=%d)\n", 
		   name, hash, new_name, cache83));

	/* and overwrite the old name */
	fstrcpy(name, new_name);

	/* all done, we've managed to mangle it */
}


/* initialise the flags table 

  we allow only a very restricted set of characters as 'ascii' in this
  mangling backend. This isn't a significant problem as modern clients
  use the 'long' filenames anyway, and those don't have these
  restrictions. 
*/
static void init_tables(void)
{
	int i;

	memset(char_flags, 0, sizeof(char_flags));

	for (i=1;i<128;i++) {
		if (i <= 0x1f) {
			/* Control characters. */
			char_flags[i] |= FLAG_ILLEGAL;
		}

		if ((i >= '0' && i <= '9') || 
		    (i >= 'a' && i <= 'z') || 
		    (i >= 'A' && i <= 'Z')) {
			char_flags[i] |=  (FLAG_ASCII | FLAG_BASECHAR);
		}
		if (strchr("_-$~", i)) {
			char_flags[i] |= FLAG_ASCII;
		}

		if (strchr("*\\/?<>|\":", i)) {
			char_flags[i] |= FLAG_ILLEGAL;
		}

		if (strchr("*?\"<>", i)) {
			char_flags[i] |= FLAG_WILDCARD;
		}
	}

	memset(base_reverse, 0, sizeof(base_reverse));
	for (i=0;i<36;i++) {
		base_reverse[(unsigned char)base_forward(i)] = i;
	}	

	/* fill in the reserved names flags. These are used as a very
	   fast filter for finding possible DOS reserved filenames */
	for (i=0; reserved_names[i]; i++) {
		unsigned char c1, c2, c3, c4;

		c1 = (unsigned char)reserved_names[i][0];
		c2 = (unsigned char)reserved_names[i][1];
		c3 = (unsigned char)reserved_names[i][2];
		c4 = (unsigned char)reserved_names[i][3];

		char_flags[c1] |= FLAG_POSSIBLE1;
		char_flags[c2] |= FLAG_POSSIBLE2;
		char_flags[c3] |= FLAG_POSSIBLE3;
		char_flags[c4] |= FLAG_POSSIBLE4;
		char_flags[tolower_ascii(c1)] |= FLAG_POSSIBLE1;
		char_flags[tolower_ascii(c2)] |= FLAG_POSSIBLE2;
		char_flags[tolower_ascii(c3)] |= FLAG_POSSIBLE3;
		char_flags[tolower_ascii(c4)] |= FLAG_POSSIBLE4;

		char_flags[(unsigned char)'.'] |= FLAG_POSSIBLE4;
	}
}

/*
  the following provides the abstraction layer to make it easier
  to drop in an alternative mangling implementation */
static struct mangle_fns mangle_fns = {
	mangle_reset,
	is_mangled,
	is_8_3,
	check_cache,
	name_map
};

/* return the methods for this mangling implementation */
struct mangle_fns *mangle_hash2_init(void)
{
	/* the mangle prefix can only be in the mange 1 to 6 */
	mangle_prefix = lp_mangle_prefix();
	if (mangle_prefix > 6) {
		mangle_prefix = 6;
	}
	if (mangle_prefix < 1) {
		mangle_prefix = 1;
	}

	init_tables();
	mangle_reset();

	if (!cache_init()) {
		return NULL;
	}

	return &mangle_fns;
}

static void posix_mangle_reset(void)
{;}

static BOOL posix_is_mangled(const char *s, int snum)
{
	return False;
}

static BOOL posix_is_8_3(const char *fname, BOOL check_case, BOOL allow_wildcards, int snum)
{
	return False;
}

static BOOL posix_check_cache( char *s, size_t maxlen, int snum )
{
	return False;
}

static void posix_name_map(char *OutName, BOOL need83, BOOL cache83, int default_case, int snum)
{
	if (need83) {
		memset(OutName, '\0', 13);
	}
}

/* POSIX paths backend - no mangle. */
static struct mangle_fns posix_mangle_fns = {
        posix_mangle_reset,
        posix_is_mangled,
        posix_is_8_3,
        posix_check_cache,
        posix_name_map
};

struct mangle_fns *posix_mangle_init(void)
{
	return &posix_mangle_fns;
}