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IABSD.fr/src/sbin/dhcp6leased/parse.y

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  • Author : florian
    Date : 2025-04-26 18:05:55
    Hash : dda4025a
    Message : Prevent yacc warning by removing unused rule.

  • sbin/dhcp6leased/parse.y
  • /*	$OpenBSD: parse.y,v 1.11 2025/04/26 18:05:55 florian Exp $	*/
    
    /*
     * Copyright (c) 2018, 2024 Florian Obser <florian@openbsd.org>
     * Copyright (c) 2004, 2005 Esben Norby <norby@openbsd.org>
     * Copyright (c) 2004 Ryan McBride <mcbride@openbsd.org>
     * Copyright (c) 2002, 2003, 2004 Henning Brauer <henning@openbsd.org>
     * Copyright (c) 2001 Markus Friedl.  All rights reserved.
     * Copyright (c) 2001 Daniel Hartmeier.  All rights reserved.
     * Copyright (c) 2001 Theo de Raadt.  All rights reserved.
     *
     * Permission to use, copy, modify, and distribute this software for any
     * purpose with or without fee is hereby granted, provided that the above
     * copyright notice and this permission notice appear in all copies.
     *
     * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
     * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
     * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
     * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
     * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
     * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     */
    
    %{
    #include <sys/types.h>
    #include <sys/queue.h>
    #include <sys/socket.h>
    #include <sys/stat.h>
    
    #include <net/if.h>
    
    #include <netinet/in.h>
    
    #include <arpa/inet.h>
    
    #include <ctype.h>
    #include <err.h>
    #include <errno.h>
    #include <event.h>
    #include <imsg.h>
    #include <limits.h>
    #include <stdarg.h>
    #include <stdio.h>
    #include <string.h>
    #include <syslog.h>
    #include <unistd.h>
    #include <vis.h>
    
    #include "log.h"
    #include "dhcp6leased.h"
    #include "frontend.h"
    
    TAILQ_HEAD(files, file)		 files = TAILQ_HEAD_INITIALIZER(files);
    struct file 	 *file, *topfile;
    int		 check_file_secrecy(int, const char *);
    int		 yyparse(void);
    int		 yylex(void);
    int		 yyerror(const char *, ...)
        __attribute__((__format__ (printf, 1, 2)))
        __attribute__((__nonnull__ (1)));
    int		 lookup(char *);
    int		 igetc(void);
    
    TAILQ_HEAD(symhead, sym)	 symhead = TAILQ_HEAD_INITIALIZER(symhead);
    struct sym {
    	TAILQ_ENTRY(sym)	 entry;
    	int			 used;
    	int			 persist;
    	char			*nam;
    	char			*val;
    };
    
    int	 symset(const char *, const char *, int);
    char	*symget(const char *);
    
    static struct dhcp6leased_conf	*conf;
    static int			 errors;
    
    static struct iface_conf	*iface_conf;
    static struct iface_ia_conf	*iface_ia_conf;
    
    struct iface_conf	*conf_get_iface(char *);
    struct iface_pd_conf	*conf_get_pd_iface(char *, int);
    void			 addressing_plan(struct iface_ia_conf *);
    int			 fls64(uint64_t);
    
    typedef struct {
    	union {
    		int64_t		 number;
    		char		*string;
    	} v;
    	int lineno;
    } YYSTYPE;
    
    %}
    
    %token	ERROR DELEGATION FOR ON PREFIX REQUEST RAPID COMMIT
    
    %token	<v.string>	STRING
    %token	<v.number>	NUMBER
    %type	<v.string>	string
    
    %%
    
    grammar		: /* empty */
    		| grammar '\n'
    		| grammar varset '\n'
    		| grammar conf_main '\n'
    		| grammar ia_pd '\n'
    		| grammar error '\n'		{ file->errors++; }
    		;
    
    string		: string STRING	{
    			if (asprintf(&$$, "%s %s", $1, $2) == -1) {
    				free($1);
    				free($2);
    				yyerror("string: asprintf");
    				YYERROR;
    			}
    			free($1);
    			free($2);
    		}
    		| STRING
    		;
    
    varset		: STRING '=' string		{
    			char *s = $1;
    			if (log_getverbose() == 1)
    				printf("%s = \"%s\"\n", $1, $3);
    			while (*s++) {
    				if (isspace((unsigned char)*s)) {
    					yyerror("macro name cannot contain "
    					    "whitespace");
    					free($1);
    					free($3);
    					YYERROR;
    				}
    			}
    			if (symset($1, $3, 0) == -1)
    				fatal("cannot store variable");
    			free($1);
    			free($3);
    		}
    		;
    
    optnl		: '\n' optnl		/* zero or more newlines */
    		| /*empty*/
    		;
    
    conf_main	: REQUEST RAPID COMMIT {
    			conf->rapid_commit = 1;
    		}
    		;
    
    ia_pd		: REQUEST PREFIX DELEGATION ON STRING FOR {
    			iface_conf = conf_get_iface($5);
    			iface_ia_conf = calloc(1, sizeof(*iface_ia_conf));
    			if (iface_ia_conf == NULL)
    				err(1, "%s: calloc", __func__);
    			iface_ia_conf->id = iface_conf->ia_count++;
    			if (iface_conf->ia_count > MAX_IA) {
    				yyerror("Too many prefix delegation requests");
    				YYERROR;
    			}
    			SIMPLEQ_INIT(&iface_ia_conf->iface_pd_list);
    			SIMPLEQ_INSERT_TAIL(&iface_conf->iface_ia_list,
    			    iface_ia_conf, entry);
    		} iface_block {
    			iface_conf = NULL;
    			iface_ia_conf = NULL;
    		}
    		;
    
    iface_block	: '{' optnl ifaceopts_l '}'
    		| ifaceoptsl
    		;
    
    ifaceopts_l	: ifaceopts_l ifaceoptsl optnl
    		| ifaceoptsl optnl
    		;
    
    ifaceoptsl	: STRING {
    			struct iface_pd_conf	*iface_pd_conf;
    			int			 prefixlen;
    			char			*p;
    			const char		*errstr;
    
    			p = strchr($1, '/');
    			if (p != NULL) {
    				*p++ = '\0';
    				prefixlen = strtonum(p, 0, 128, &errstr);
    				if (errstr != NULL) {
    					yyerror("error parsing interface "
    					    "\"%s/%s\"", $1, p);
    					free($1);
    					YYERROR;
    				}
    			} else
    				prefixlen = 64;
    			if ((iface_pd_conf = conf_get_pd_iface($1, prefixlen))
    			    == NULL) {
    				yyerror("duplicate interface %s", $1);
    				free($1);
    				YYERROR;
    			}
    		}
    		;
    %%
    
    struct keywords {
    	const char	*k_name;
    	int		 k_val;
    };
    
    int
    yyerror(const char *fmt, ...)
    {
    	va_list		 ap;
    	char		*msg;
    
    	file->errors++;
    	va_start(ap, fmt);
    	if (vasprintf(&msg, fmt, ap) == -1)
    		fatalx("yyerror vasprintf");
    	va_end(ap);
    	logit(LOG_CRIT, "%s:%d: %s", file->name, yylval.lineno, msg);
    	free(msg);
    	return (0);
    }
    
    int
    kw_cmp(const void *k, const void *e)
    {
    	return (strcmp(k, ((const struct keywords *)e)->k_name));
    }
    
    int
    lookup(char *s)
    {
    	/* This has to be sorted always. */
    	static const struct keywords keywords[] = {
    		{"commit",	COMMIT},
    		{"delegation",	DELEGATION},
    		{"for",		FOR},
    		{"on",		ON},
    		{"prefix",	PREFIX},
    		{"rapid",	RAPID},
    		{"request",	REQUEST},
    	};
    	const struct keywords	*p;
    
    	p = bsearch(s, keywords, sizeof(keywords)/sizeof(keywords[0]),
    	    sizeof(keywords[0]), kw_cmp);
    
    	if (p)
    		return (p->k_val);
    	else
    		return (STRING);
    }
    
    #define START_EXPAND	1
    #define DONE_EXPAND	2
    
    static int	expanding;
    
    int
    igetc(void)
    {
    	int	c;
    
    	while (1) {
    		if (file->ungetpos > 0)
    			c = file->ungetbuf[--file->ungetpos];
    		else
    			c = getc(file->stream);
    
    		if (c == START_EXPAND)
    			expanding = 1;
    		else if (c == DONE_EXPAND)
    			expanding = 0;
    		else
    			break;
    	}
    	return (c);
    }
    
    int
    lgetc(int quotec)
    {
    	int		c, next;
    
    	if (quotec) {
    		if ((c = igetc()) == EOF) {
    			yyerror("reached end of file while parsing "
    			    "quoted string");
    			if (file == topfile || popfile() == EOF)
    				return (EOF);
    			return (quotec);
    		}
    		return (c);
    	}
    
    	while ((c = igetc()) == '\\') {
    		next = igetc();
    		if (next != '\n') {
    			c = next;
    			break;
    		}
    		yylval.lineno = file->lineno;
    		file->lineno++;
    	}
    
    	if (c == EOF) {
    		/*
    		 * Fake EOL when hit EOF for the first time. This gets line
    		 * count right if last line in included file is syntactically
    		 * invalid and has no newline.
    		 */
    		if (file->eof_reached == 0) {
    			file->eof_reached = 1;
    			return ('\n');
    		}
    		while (c == EOF) {
    			if (file == topfile || popfile() == EOF)
    				return (EOF);
    			c = igetc();
    		}
    	}
    	return (c);
    }
    
    void
    lungetc(int c)
    {
    	if (c == EOF)
    		return;
    
    	if (file->ungetpos >= file->ungetsize) {
    		void *p = reallocarray(file->ungetbuf, file->ungetsize, 2);
    		if (p == NULL)
    			err(1, "lungetc");
    		file->ungetbuf = p;
    		file->ungetsize *= 2;
    	}
    	file->ungetbuf[file->ungetpos++] = c;
    }
    
    int
    findeol(void)
    {
    	int	c;
    
    	/* Skip to either EOF or the first real EOL. */
    	while (1) {
    		c = lgetc(0);
    		if (c == '\n') {
    			file->lineno++;
    			break;
    		}
    		if (c == EOF)
    			break;
    	}
    	return (ERROR);
    }
    
    int
    yylex(void)
    {
    	char	 buf[8096];
    	char	*p, *val;
    	int	 quotec, next, c;
    	int	 token;
    
    top:
    	p = buf;
    	while ((c = lgetc(0)) == ' ' || c == '\t')
    		; /* nothing */
    
    	yylval.lineno = file->lineno;
    	if (c == '#')
    		while ((c = lgetc(0)) != '\n' && c != EOF)
    			; /* nothing */
    	if (c == '$' && !expanding) {
    		while (1) {
    			if ((c = lgetc(0)) == EOF)
    				return (0);
    
    			if (p + 1 >= buf + sizeof(buf) - 1) {
    				yyerror("string too long");
    				return (findeol());
    			}
    			if (isalnum(c) || c == '_') {
    				*p++ = c;
    				continue;
    			}
    			*p = '\0';
    			lungetc(c);
    			break;
    		}
    		val = symget(buf);
    		if (val == NULL) {
    			yyerror("macro '%s' not defined", buf);
    			return (findeol());
    		}
    		p = val + strlen(val) - 1;
    		lungetc(DONE_EXPAND);
    		while (p >= val) {
    			lungetc((unsigned char)*p);
    			p--;
    		}
    		lungetc(START_EXPAND);
    		goto top;
    	}
    
    	switch (c) {
    	case '\'':
    	case '"':
    		quotec = c;
    		while (1) {
    			if ((c = lgetc(quotec)) == EOF)
    				return (0);
    			if (c == '\n') {
    				file->lineno++;
    				continue;
    			} else if (c == '\\') {
    				if ((next = lgetc(quotec)) == EOF)
    					return (0);
    				if (next == quotec || next == ' ' ||
    				    next == '\t')
    					c = next;
    				else if (next == '\n') {
    					file->lineno++;
    					continue;
    				} else
    					lungetc(next);
    			} else if (c == quotec) {
    				*p = '\0';
    				break;
    			} else if (c == '\0') {
    				yyerror("syntax error");
    				return (findeol());
    			}
    			if (p + 1 >= buf + sizeof(buf) - 1) {
    				yyerror("string too long");
    				return (findeol());
    			}
    			*p++ = c;
    		}
    		yylval.v.string = strdup(buf);
    		if (yylval.v.string == NULL)
    			err(1, "yylex: strdup");
    		return (STRING);
    	}
    
    #define allowed_to_end_number(x) \
    	(isspace(x) || x == ')' || x ==',' || x == '/' || x == '}' || x == '=')
    
    	if (c == '-' || isdigit(c)) {
    		do {
    			*p++ = c;
    			if ((size_t)(p-buf) >= sizeof(buf)) {
    				yyerror("string too long");
    				return (findeol());
    			}
    		} while ((c = lgetc(0)) != EOF && isdigit(c));
    		lungetc(c);
    		if (p == buf + 1 && buf[0] == '-')
    			goto nodigits;
    		if (c == EOF || allowed_to_end_number(c)) {
    			const char *errstr = NULL;
    
    			*p = '\0';
    			yylval.v.number = strtonum(buf, LLONG_MIN,
    			    LLONG_MAX, &errstr);
    			if (errstr) {
    				yyerror("\"%s\" invalid number: %s",
    				    buf, errstr);
    				return (findeol());
    			}
    			return (NUMBER);
    		} else {
    nodigits:
    			while (p > buf + 1)
    				lungetc((unsigned char)*--p);
    			c = (unsigned char)*--p;
    			if (c == '-')
    				return (c);
    		}
    	}
    
    #define allowed_in_string(x) \
    	(isalnum(x) || (ispunct(x) && x != '(' && x != ')' && \
    	x != '{' && x != '}' && \
    	x != '!' && x != '=' && x != '#' && \
    	x != ','))
    
    	if (isalnum(c) || c == ':' || c == '_') {
    		do {
    			*p++ = c;
    			if ((size_t)(p-buf) >= sizeof(buf)) {
    				yyerror("string too long");
    				return (findeol());
    			}
    		} while ((c = lgetc(0)) != EOF && (allowed_in_string(c)));
    		lungetc(c);
    		*p = '\0';
    		if ((token = lookup(buf)) == STRING)
    			if ((yylval.v.string = strdup(buf)) == NULL)
    				err(1, "yylex: strdup");
    		return (token);
    	}
    	if (c == '\n') {
    		yylval.lineno = file->lineno;
    		file->lineno++;
    	}
    	if (c == EOF)
    		return (0);
    	return (c);
    }
    
    int
    check_file_secrecy(int fd, const char *fname)
    {
    	struct stat	st;
    
    	if (fstat(fd, &st)) {
    		log_warn("cannot stat %s", fname);
    		return (-1);
    	}
    	if (st.st_uid != 0 && st.st_uid != getuid()) {
    		log_warnx("%s: owner not root or current user", fname);
    		return (-1);
    	}
    	if (st.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)) {
    		log_warnx("%s: group writable or world read/writable", fname);
    		return (-1);
    	}
    	return (0);
    }
    
    struct file *
    pushfile(const char *name, int secret)
    {
    	struct file	*nfile;
    
    	if ((nfile = calloc(1, sizeof(struct file))) == NULL) {
    		log_warn("calloc");
    		return (NULL);
    	}
    	if ((nfile->name = strdup(name)) == NULL) {
    		log_warn("strdup");
    		free(nfile);
    		return (NULL);
    	}
    	if ((nfile->stream = fopen(nfile->name, "r")) == NULL) {
    		log_warn("%s", nfile->name);
    		free(nfile->name);
    		free(nfile);
    		return (NULL);
    	} else if (secret &&
    	    check_file_secrecy(fileno(nfile->stream), nfile->name)) {
    		fclose(nfile->stream);
    		free(nfile->name);
    		free(nfile);
    		return (NULL);
    	}
    	nfile->lineno = TAILQ_EMPTY(&files) ? 1 : 0;
    	nfile->ungetsize = 16;
    	nfile->ungetbuf = malloc(nfile->ungetsize);
    	if (nfile->ungetbuf == NULL) {
    		log_warn("malloc");
    		fclose(nfile->stream);
    		free(nfile->name);
    		free(nfile);
    		return (NULL);
    	}
    	TAILQ_INSERT_TAIL(&files, nfile, entry);
    	return (nfile);
    }
    
    int
    popfile(void)
    {
    	struct file	*prev;
    
    	if ((prev = TAILQ_PREV(file, files, entry)) != NULL)
    		prev->errors += file->errors;
    
    	TAILQ_REMOVE(&files, file, entry);
    	fclose(file->stream);
    	free(file->name);
    	free(file->ungetbuf);
    	free(file);
    	file = prev;
    	return (file ? 0 : EOF);
    }
    
    struct dhcp6leased_conf *
    parse_config(const char *filename)
    {
    	struct sym		*sym, *next;
    	struct iface_conf	*iface;
    	struct iface_ia_conf	*ia_conf;
    
    	conf = config_new_empty();
    
    	file = pushfile(filename, 0);
    	if (file == NULL) {
    		free(conf);
    		return (NULL);
    	}
    	topfile = file;
    
    	yyparse();
    	errors = file->errors;
    	popfile();
    
    	/* Free macros and check which have not been used. */
    	TAILQ_FOREACH_SAFE(sym, &symhead, entry, next) {
    		if ((log_getverbose() == 2) && !sym->used)
    			fprintf(stderr, "warning: macro '%s' not used\n",
    			    sym->nam);
    		if (!sym->persist) {
    			free(sym->nam);
    			free(sym->val);
    			TAILQ_REMOVE(&symhead, sym, entry);
    			free(sym);
    		}
    	}
    
    	if (errors) {
    		config_clear(conf);
    		return (NULL);
    	}
    
    	SIMPLEQ_FOREACH(iface, &conf->iface_list, entry) {
    		SIMPLEQ_FOREACH(ia_conf, &iface->iface_ia_list, entry) {
    			addressing_plan(ia_conf);
    		}
    	}
    	return (conf);
    }
    
    int
    symset(const char *nam, const char *val, int persist)
    {
    	struct sym	*sym;
    
    	TAILQ_FOREACH(sym, &symhead, entry) {
    		if (strcmp(nam, sym->nam) == 0)
    			break;
    	}
    
    	if (sym != NULL) {
    		if (sym->persist == 1)
    			return (0);
    		else {
    			free(sym->nam);
    			free(sym->val);
    			TAILQ_REMOVE(&symhead, sym, entry);
    			free(sym);
    		}
    	}
    	if ((sym = calloc(1, sizeof(*sym))) == NULL)
    		return (-1);
    
    	sym->nam = strdup(nam);
    	if (sym->nam == NULL) {
    		free(sym);
    		return (-1);
    	}
    	sym->val = strdup(val);
    	if (sym->val == NULL) {
    		free(sym->nam);
    		free(sym);
    		return (-1);
    	}
    	sym->used = 0;
    	sym->persist = persist;
    	TAILQ_INSERT_TAIL(&symhead, sym, entry);
    	return (0);
    }
    
    char *
    symget(const char *nam)
    {
    	struct sym	*sym;
    
    	TAILQ_FOREACH(sym, &symhead, entry) {
    		if (strcmp(nam, sym->nam) == 0) {
    			sym->used = 1;
    			return (sym->val);
    		}
    	}
    	return (NULL);
    }
    
    struct iface_conf *
    conf_get_iface(char *name)
    {
    	struct iface_conf	*iface;
    	size_t			 n;
    
    	SIMPLEQ_FOREACH(iface, &conf->iface_list, entry) {
    		if (strcmp(name, iface->name) == 0)
    			return (iface);
    	}
    
    	iface = calloc(1, sizeof(*iface));
    	if (iface == NULL)
    		errx(1, "%s: calloc", __func__);
    	n = strlcpy(iface->name, name, sizeof(iface->name));
    	if (n >= sizeof(iface->name))
    		errx(1, "%s: name too long", __func__);
    	SIMPLEQ_INIT(&iface->iface_ia_list);
    
    	SIMPLEQ_INSERT_TAIL(&conf->iface_list, iface, entry);
    
    	return (iface);
    }
    
    struct iface_pd_conf *
    conf_get_pd_iface(char *name, int prefixlen)
    {
    	struct iface_ia_conf	*iface_ia;
    	struct iface_pd_conf	*iface_pd;
    	size_t			 n;
    
    	if (strcmp(name, "reserve") != 0) {
    		SIMPLEQ_FOREACH(iface_ia, &iface_conf->iface_ia_list,
    		    entry) {
    			SIMPLEQ_FOREACH(iface_pd, &iface_ia->iface_pd_list,
    			    entry) {
    				if (strcmp(name, iface_pd->name) == 0)
    					return NULL;
    			}
    		}
    	}
    
    	iface_pd = calloc(1, sizeof(*iface_pd));
    	if (iface_pd == NULL)
    		err(1, "%s: calloc", __func__);
    	n = strlcpy(iface_pd->name, name, sizeof(iface_pd->name));
    	if (n >= sizeof(iface_pd->name))
    		errx(1, "%s: name too long", __func__);
    	iface_pd->prefix_len = prefixlen;
    
    	SIMPLEQ_INSERT_TAIL(&iface_ia_conf->iface_pd_list, iface_pd, entry);
    
    	return (iface_pd);
    }
    
    static inline uint64_t
    get_shift(int plen)
    {
    	if (plen > 64)
    		plen -= 64;
    
    	return 1ULL << (64 - plen);
    }
    
    void
    addressing_plan(struct iface_ia_conf *ia_conf)
    {
    	struct iface_pd_conf	*pd_conf;
    	uint64_t		*p, lo_counter, hi_counter, lo_shift, hi_shift;
    	int			 prev_plen = -1;
    
    	lo_counter = hi_counter = 0;
    
    	SIMPLEQ_FOREACH(pd_conf, &ia_conf->iface_pd_list, entry) {
    		/* not the first prefix */
    		if (ia_conf->prefix_len != 0) {
    			lo_shift = hi_shift = 0;
    			if (prev_plen > pd_conf->prefix_len) {
    				if (pd_conf->prefix_len > 64)
    					lo_shift =
    					    get_shift(pd_conf->prefix_len);
    				else
    					hi_shift =
    					    get_shift(pd_conf->prefix_len);
    			} else  {
    				if (prev_plen > 64)
    					lo_shift = get_shift(prev_plen);
    				else
    					hi_shift = get_shift(prev_plen);
    			}
    
    			if (lo_shift != 0) {
    				if (lo_counter > UINT64_MAX - lo_shift) {
    					/* overflow */
    					hi_counter++;
    					lo_counter = 0;
    				} else {
    					lo_counter += lo_shift;
    					/* remove all lower bits */
    					lo_counter &= ~(lo_shift - 1);
    				}
    			} else {
    				hi_counter += hi_shift;
    				/* remove all lower bits */
    				hi_counter &= ~(hi_shift - 1);
    				lo_counter = 0;
    			}
    
    		} else
    			ia_conf->prefix_len = pd_conf->prefix_len;
    
    		p = (uint64_t *)&pd_conf->prefix_mask.s6_addr;
    		*p |= htobe64(hi_counter);
    
    		p = (uint64_t *)&pd_conf->prefix_mask.s6_addr[8];
    		*p |= htobe64(lo_counter);
    
    		prev_plen = pd_conf->prefix_len;
    	}
    
    	if (hi_counter != 0)
    		ia_conf->prefix_len = 64 - fls64(hi_counter);
    	else if (lo_counter != 0)
    		ia_conf->prefix_len = 128 - fls64(lo_counter);
    }
    
    /* from NetBSD's sys/sys/bitops.h */
    /*-
     * Copyright (c) 2007, 2010 The NetBSD Foundation, Inc.
     * All rights reserved.
     *
     * This code is derived from software contributed to The NetBSD Foundation
     * by Christos Zoulas and Joerg Sonnenberger.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     * POSSIBILITY OF SUCH DAMAGE.
     */
    int
    fls64(uint64_t _n)
    {
    	int _v;
    
    	if (!_n)
    		return 0;
    
    	_v = 64;
    	if ((_n & 0xFFFFFFFF00000000ULL) == 0) {
    		_n <<= 32;
    		_v -= 32;
    	}
    	if ((_n & 0xFFFF000000000000ULL) == 0) {
    		_n <<= 16;
    		_v -= 16;
    	}
    	if ((_n & 0xFF00000000000000ULL) == 0) {
    		_n <<= 8;
    		_v -= 8;
    	}
    	if ((_n & 0xF000000000000000ULL) == 0) {
    		_n <<= 4;
    		_v -= 4;
    	}
    	if ((_n & 0xC000000000000000ULL) == 0) {
    		_n <<= 2;
    		_v -= 2;
    	}
    	if ((_n & 0x8000000000000000ULL) == 0) {
    		//_n <<= 1;
    		_v -= 1;
    	}
    	return _v;
    }