morpheus-base

compile.c (20003B)

---

 /*	$OpenBSD: compile.c,v 1.36 2014/10/08 04:19:08 deraadt Exp $	*/
 
 /*-
  * Copyright (c) 1992 Diomidis Spinellis.
  * Copyright (c) 1992, 1993
  *	The Regents of the University of California.  All rights reserved.
  *
  * This code is derived from software contributed to Berkeley by
  * Diomidis Spinellis of Imperial College, University of London.
  *
  * 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.
  * 3. Neither the name of the University nor the names of its contributors
  *    may be used to endorse or promote products derived from this software
  *    without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
  */
 
 #include <sys/types.h>
 #include <sys/stat.h>
 
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
 #include <regex.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "defs.h"
 #include "extern.h"
 #include "util.h"
 
 #define LHSZ	128
 #define	LHMASK	(LHSZ - 1)
 static struct labhash {
 	struct	labhash *lh_next;
 	u_int	lh_hash;
 	struct	s_command *lh_cmd;
 	int	lh_ref;
 } *labels[LHSZ];
 
 static char	 *compile_addr(char *, struct s_addr *);
 static char	 *compile_ccl(char **, char *);
 static char	 *compile_delimited(char *, char *, int);
 static char	 *compile_flags(char *, struct s_subst *);
 static char	 *compile_re(char *, regex_t **);
 static char	 *compile_subst(char *, struct s_subst *);
 static char	 *compile_text(void);
 static char	 *compile_tr(char *, char **);
 static struct s_command
 		**compile_stream(struct s_command **);
 static char	 *duptoeol(char *, char *, char **);
 static void	  enterlabel(struct s_command *);
 static struct s_command
 		 *findlabel(char *);
 static void	  fixuplabel(struct s_command *, struct s_command *);
 static void	  uselabel(void);
 
 /*
  * Command specification.  This is used to drive the command parser.
  */
 struct s_format {
 	char code;				/* Command code */
 	int naddr;				/* Number of address args */
 	enum e_args args;			/* Argument type */
 };
 
 static struct s_format cmd_fmts[] = {
 	{'{', 2, GROUP},
 	{'}', 0, ENDGROUP},
 	{'a', 1, TEXT},
 	{'b', 2, BRANCH},
 	{'c', 2, TEXT},
 	{'d', 2, EMPTY},
 	{'D', 2, EMPTY},
 	{'g', 2, EMPTY},
 	{'G', 2, EMPTY},
 	{'h', 2, EMPTY},
 	{'H', 2, EMPTY},
 	{'i', 1, TEXT},
 	{'l', 2, EMPTY},
 	{'n', 2, EMPTY},
 	{'N', 2, EMPTY},
 	{'p', 2, EMPTY},
 	{'P', 2, EMPTY},
 	{'q', 1, EMPTY},
 	{'r', 1, RFILE},
 	{'s', 2, SUBST},
 	{'t', 2, BRANCH},
 	{'w', 2, WFILE},
 	{'x', 2, EMPTY},
 	{'y', 2, TR},
 	{'!', 2, NONSEL},
 	{':', 0, LABEL},
 	{'#', 0, COMMENT},
 	{'=', 1, EMPTY},
 	{'\0', 0, COMMENT},
 };
 
 /* The compiled program. */
 struct s_command *prog;
 
 /*
  * Compile the program into prog.
  * Initialise appends.
  */
 void
 compile(void)
 {
 	*compile_stream(&prog) = NULL;
 	fixuplabel(prog, NULL);
 	uselabel();
 	appends = xreallocarray(NULL, appendnum, sizeof(struct s_appends));
 	match = xreallocarray(NULL, maxnsub + 1, sizeof(regmatch_t));
 }
 
 #define EATSPACE() do {							\
 	if (p)								\
 		while (isascii((unsigned char)*p) &&			\
 		    isspace((unsigned char)*p))				\
 			p++;						\
 	} while (0)
 
 static struct s_command **
 compile_stream(struct s_command **link)
 {
 	char *p;
 	static char *lbuf;	/* To avoid excessive malloc calls */
 	static size_t bufsize;
 	struct s_command *cmd, *cmd2, *stack;
 	struct s_format *fp;
 	int naddr;				/* Number of addresses */
 
 	stack = 0;
 	for (;;) {
 		if ((p = cu_fgets(&lbuf, &bufsize)) == NULL) {
 			if (stack != 0)
 				err(COMPILE, "unexpected EOF (pending }'s)");
 			return (link);
 		}
 
 semicolon:	EATSPACE();
 		if (*p == '#' || *p == '\0')
 			continue;
 		if (*p == ';') {
 			p++;
 			goto semicolon;
 		}
 		*link = cmd = xmalloc(sizeof(struct s_command));
 		link = &cmd->next;
 		cmd->nonsel = cmd->inrange = 0;
 		/* First parse the addresses */
 		naddr = 0;
 
 /* Valid characters to start an address */
 #define	addrchar(c)	(strchr("0123456789/\\$", (c)))
 		if (addrchar(*p)) {
 			naddr++;
 			cmd->a1 = xmalloc(sizeof(struct s_addr));
 			p = compile_addr(p, cmd->a1);
 			EATSPACE();				/* EXTENSION */
 			if (*p == ',') {
 				p++;
 				EATSPACE();			/* EXTENSION */
 				naddr++;
 				cmd->a2 = xmalloc(sizeof(struct s_addr));
 				p = compile_addr(p, cmd->a2);
 				EATSPACE();
 			} else {
 				cmd->a2 = 0;
 			}
 		} else {
 			cmd->a1 = cmd->a2 = 0;
 		}
 
 nonsel:		/* Now parse the command */
 		if (!*p)
 			err(COMPILE, "command expected");
 		cmd->code = *p;
 		for (fp = cmd_fmts; fp->code; fp++)
 			if (fp->code == *p)
 				break;
 		if (!fp->code)
 			err(COMPILE, "invalid command code %c", *p);
 		if (naddr > fp->naddr)
 			err(COMPILE,
 			    "command %c expects up to %d address(es), found %d",
 			    *p, fp->naddr, naddr);
 		switch (fp->args) {
 		case NONSEL:			/* ! */
 			p++;
 			EATSPACE();
 			cmd->nonsel = ! cmd->nonsel;
 			goto nonsel;
 		case GROUP:			/* { */
 			p++;
 			EATSPACE();
 			cmd->next = stack;
 			stack = cmd;
 			link = &cmd->u.c;
 			if (*p)
 				goto semicolon;
 			break;
 		case ENDGROUP:
 			/*
 			 * Short-circuit command processing, since end of
 			 * group is really just a noop.
 			 */
 			cmd->nonsel = 1;
 			if (stack == 0)
 				err(COMPILE, "unexpected }");
 			cmd2 = stack;
 			stack = cmd2->next;
 			cmd2->next = cmd;
 			/*FALLTHROUGH*/
 		case EMPTY:		/* d D g G h H l n N p P q x = \0 */
 			p++;
 			EATSPACE();
 			if (*p == ';') {
 				p++;
 				link = &cmd->next;
 				goto semicolon;
 			}
 			if (*p)
 				err(COMPILE,
 "extra characters at the end of %c command", cmd->code);
 			break;
 		case TEXT:			/* a c i */
 			p++;
 			EATSPACE();
 			if (*p != '\\')
 				err(COMPILE, "command %c expects \\ followed by"
 				    " text", cmd->code);
 			p++;
 			EATSPACE();
 			if (*p)
 				err(COMPILE, "extra characters after \\ at the"
 				    " end of %c command", cmd->code);
 			cmd->t = compile_text();
 			break;
 		case COMMENT:			/* \0 # */
 			break;
 		case WFILE:			/* w */
 			p++;
 			EATSPACE();
 			if (*p == '\0')
 				err(COMPILE, "filename expected");
 			cmd->t = duptoeol(p, "w command", NULL);
 			if (aflag)
 				cmd->u.fd = -1;
 			else if ((cmd->u.fd = open(p,
 			    O_WRONLY|O_APPEND|O_CREAT|O_TRUNC,
 			    DEFFILEMODE)) == -1)
 				err(FATAL, "%s: %s", p, strerror(errno));
 			break;
 		case RFILE:			/* r */
 			p++;
 			EATSPACE();
 			cmd->t = duptoeol(p, "read command", NULL);
 			break;
 		case BRANCH:			/* b t */
 			p++;
 			EATSPACE();
 			if (*p == '\0')
 				cmd->t = NULL;
 			else
 				cmd->t = duptoeol(p, "branch", &p);
 			if (*p == ';') {
 				p++;
 				goto semicolon;
 			}
 			break;
 		case LABEL:			/* : */
 			p++;
 			EATSPACE();
 			cmd->t = duptoeol(p, "label", &p);
 			if (strlen(cmd->t) == 0)
 				err(COMPILE, "empty label");
 			enterlabel(cmd);
 			if (*p == ';') {
 				p++;
 				goto semicolon;
 			}
 			break;
 		case SUBST:			/* s */
 			p++;
 			if (*p == '\0' || *p == '\\')
 				err(COMPILE, "substitute pattern can not be"
 				    " delimited by newline or backslash");
 			cmd->u.s = xmalloc(sizeof(struct s_subst));
 			p = compile_re(p, &cmd->u.s->re);
 			if (p == NULL)
 				err(COMPILE, "unterminated substitute pattern");
 			--p;
 			p = compile_subst(p, cmd->u.s);
 			p = compile_flags(p, cmd->u.s);
 			EATSPACE();
 			if (*p == ';') {
 				p++;
 				link = &cmd->next;
 				goto semicolon;
 			}
 			break;
 		case TR:			/* y */
 			p++;
 			p = compile_tr(p, (char **)&cmd->u.y);
 			EATSPACE();
 			if (*p == ';') {
 				p++;
 				link = &cmd->next;
 				goto semicolon;
 			}
 			if (*p)
 				err(COMPILE, "extra text at the end of a"
 				    " transform command");
 			break;
 		}
 	}
 }
 
 /*
  * Get a delimited string.  P points to the delimeter of the string; d points
  * to a buffer area.  Newline and delimiter escapes are processed; other
  * escapes are ignored.
  *
  * Returns a pointer to the first character after the final delimiter or NULL
  * in the case of a non-terminated string.  The character array d is filled
  * with the processed string.
  */
 static char *
 compile_delimited(char *p, char *d, int is_tr)
 {
 	char c;
 
 	c = *p++;
 	if (c == '\0')
 		return (NULL);
 	else if (c == '\\')
 		err(COMPILE, "\\ can not be used as a string delimiter");
 	else if (c == '\n')
 		err(COMPILE, "newline can not be used as a string delimiter");
 	while (*p) {
 		if (*p == '[' && *p != c) {
 			if ((d = compile_ccl(&p, d)) == NULL)
 				err(COMPILE, "unbalanced brackets ([])");
 			continue;
 		} else if (*p == '\\' && p[1] == '[') {
 			*d++ = *p++;
 		} else if (*p == '\\' && p[1] == c) {
 			p++;
 		} else if (*p == '\\' && p[1] == 'n') {
 			*d++ = '\n';
 			p += 2;
 			continue;
 		} else if (*p == '\\' && p[1] == '\\') {
 			if (is_tr)
 				p++;
 			else
 				*d++ = *p++;
 		} else if (*p == c) {
 			*d = '\0';
 			return (p + 1);
 		}
 		*d++ = *p++;
 	}
 	return (NULL);
 }
 
 
 /* compile_ccl: expand a POSIX character class */
 static char *
 compile_ccl(char **sp, char *t)
 {
 	int c, d;
 	char *s = *sp;
 
 	*t++ = *s++;
 	if (*s == '^')
 		*t++ = *s++;
 	if (*s == ']')
 		*t++ = *s++;
 	for (; *s && (*t = *s) != ']'; s++, t++)
 		if (*s == '[' && ((d = *(s+1)) == '.' || d == ':' || d == '=')) {
 			*++t = *++s, t++, s++;
 			for (c = *s; (*t = *s) != ']' || c != d; s++, t++)
 				if ((c = *s) == '\0')
 					return NULL;
 		} else if (*s == '\\' && s[1] == 'n') {
 			*t = '\n';
 			s++;
 		}
 	if (*s == ']') {
 		*sp = ++s;
 		return (++t);
 	} else {
 		return (NULL);
 	}
 }
 
 /*
  * Get a regular expression.  P points to the delimiter of the regular
  * expression; repp points to the address of a regexp pointer.  Newline
  * and delimiter escapes are processed; other escapes are ignored.
  * Returns a pointer to the first character after the final delimiter
  * or NULL in the case of a non terminated regular expression.  The regexp
  * pointer is set to the compiled regular expression.
  * Cflags are passed to regcomp.
  */
 static char *
 compile_re(char *p, regex_t **repp)
 {
 	int eval;
 	char *re;
 
 	re = xmalloc(strlen(p) + 1); /* strlen(re) <= strlen(p) */
 	p = compile_delimited(p, re, 0);
 	if (p && strlen(re) == 0) {
 		*repp = NULL;
 		free(re);
 		return (p);
 	}
 	*repp = xmalloc(sizeof(regex_t));
 	if (p && (eval = regcomp(*repp, re, Eflag ? REG_EXTENDED : 0)) != 0)
 		err(COMPILE, "RE error: %s", strregerror(eval, *repp));
 	if (maxnsub < (*repp)->re_nsub)
 		maxnsub = (*repp)->re_nsub;
 	free(re);
 	return (p);
 }
 
 /*
  * Compile the substitution string of a regular expression and set res to
  * point to a saved copy of it.  Nsub is the number of parenthesized regular
  * expressions.
  */
 static char *
 compile_subst(char *p, struct s_subst *s)
 {
 	static char *lbuf;
 	static size_t bufsize;
 	int asize, ref, size;
 	char c, *text, *op, *sp;
 	int sawesc = 0;
 
 	c = *p++;			/* Terminator character */
 	if (c == '\0')
 		return (NULL);
 
 	s->maxbref = 0;
 	s->linenum = linenum;
 	text = NULL;
 	asize = size = 0;
 	do {
 		size_t len = ROUNDLEN(strlen(p) + 1);
 		if (asize - size < len) {
 			do {
 				asize += len;
 			} while (asize - size < len);
 			text = xrealloc(text, asize);
 		}
 		op = sp = text + size;
 		for (; *p; p++) {
 			if (*p == '\\' || sawesc) {
 				/*
 				 * If this is a continuation from the last
 				 * buffer, we won't have a character to
 				 * skip over.
 				 */
 				if (sawesc)
 					sawesc = 0;
 				else
 					p++;
 
 				if (*p == '\0') {
 					/*
 					 * This escaped character is continued
 					 * in the next part of the line.  Note
 					 * this fact, then cause the loop to
 					 * exit w/ normal EOL case and reenter
 					 * above with the new buffer.
 					 */
 					sawesc = 1;
 					p--;
 					continue;
 				} else if (strchr("123456789", *p) != NULL) {
 					*sp++ = '\\';
 					ref = *p - '0';
 					if (s->re != NULL &&
 					    ref > s->re->re_nsub)
 						err(COMPILE,
 "\\%c not defined in the RE", *p);
 					if (s->maxbref < ref)
 						s->maxbref = ref;
 				} else if (*p == '&' || *p == '\\')
 					*sp++ = '\\';
 			} else if (*p == c) {
 				p++;
 				*sp++ = '\0';
 				size += sp - op;
 				s->new = xrealloc(text, size);
 				return (p);
 			} else if (*p == '\n') {
 				err(COMPILE,
 "unescaped newline inside substitute pattern");
 				/* NOTREACHED */
 			}
 			*sp++ = *p;
 		}
 		size += sp - op;
 	} while ((p = cu_fgets(&lbuf, &bufsize)));
 	err(COMPILE, "unterminated substitute in regular expression");
 	/* NOTREACHED */
 	return NULL;
 }
 
 /*
  * Compile the flags of the s command
  */
 static char *
 compile_flags(char *p, struct s_subst *s)
 {
 	int gn;			/* True if we have seen g or n */
 	long l;
 	char wfile[PATH_MAX], *q;
 
 	s->n = 1;				/* Default */
 	s->p = 0;
 	s->wfile = NULL;
 	s->wfd = -1;
 	for (gn = 0;;) {
 		EATSPACE();			/* EXTENSION */
 		switch (*p) {
 		case 'g':
 			if (gn)
 				err(COMPILE, "more than one number or 'g' in"
 				    " substitute flags");
 			gn = 1;
 			s->n = 0;
 			break;
 		case '\0':
 		case '\n':
 		case ';':
 			return (p);
 		case 'p':
 			s->p = 1;
 			break;
 		case '1': case '2': case '3':
 		case '4': case '5': case '6':
 		case '7': case '8': case '9':
 			if (gn)
 				err(COMPILE, "more than one number or 'g' in"
 				    " substitute flags");
 			gn = 1;
 			l = strtol(p, &p, 10);
 			if (l <= 0 || l >= INT_MAX)
 				err(COMPILE,
 				    "number in substitute flags out of range");
 			s->n = (int)l;
 			continue;
 		case 'w':
 			p++;
 #ifdef HISTORIC_PRACTICE
 			if (*p != ' ') {
 				err(WARNING, "space missing before w wfile");
 				return (p);
 			}
 #endif
 			EATSPACE();
 			q = wfile;
 			while (*p) {
 				if (*p == '\n')
 					break;
 				*q++ = *p++;
 			}
 			*q = '\0';
 			if (q == wfile)
 				err(COMPILE, "no wfile specified");
 			s->wfile = strdup(wfile);
 			if (!aflag && (s->wfd = open(wfile,
 			    O_WRONLY|O_APPEND|O_CREAT|O_TRUNC,
 			    DEFFILEMODE)) == -1)
 				err(FATAL, "%s: %s", wfile, strerror(errno));
 			return (p);
 		default:
 			err(COMPILE,
 			    "bad flag in substitute command: '%c'", *p);
 			break;
 		}
 		p++;
 	}
 }
 
 /*
  * Compile a translation set of strings into a lookup table.
  */
 static char *
 compile_tr(char *p, char **transtab)
 {
 	int i;
 	char *lt, *op, *np;
 	char *old = NULL, *new = NULL;
 
 	if (*p == '\0' || *p == '\\')
 		err(COMPILE,
 "transform pattern can not be delimited by newline or backslash");
 	old = xmalloc(strlen(p) + 1);
 	p = compile_delimited(p, old, 1);
 	if (p == NULL) {
 		err(COMPILE, "unterminated transform source string");
 		goto bad;
 	}
 	new = xmalloc(strlen(p) + 1);
 	p = compile_delimited(--p, new, 1);
 	if (p == NULL) {
 		err(COMPILE, "unterminated transform target string");
 		goto bad;
 	}
 	EATSPACE();
 	if (strlen(new) != strlen(old)) {
 		err(COMPILE, "transform strings are not the same length");
 		goto bad;
 	}
 	/* We assume characters are 8 bits */
 	lt = xmalloc(UCHAR_MAX + 1);
 	for (i = 0; i <= UCHAR_MAX; i++)
 		lt[i] = (char)i;
 	for (op = old, np = new; *op; op++, np++)
 		lt[(u_char)*op] = *np;
 	*transtab = lt;
 	free(old);
 	free(new);
 	return (p);
 bad:
 	free(old);
 	free(new);
 	return (NULL);
 }
 
 /*
  * Compile the text following an a, c, or i command.
  */
 static char *
 compile_text(void)
 {
 	int asize, esc_nl, size;
 	char *lbuf, *text, *p, *op, *s;
 	size_t bufsize;
 
 	lbuf = text = NULL;
 	asize = size = 0;
 	while ((p = cu_fgets(&lbuf, &bufsize))) {
 		size_t len = ROUNDLEN(strlen(p) + 1);
 		if (asize - size < len) {
 			do {
 				asize += len;
 			} while (asize - size < len);
 			text = xrealloc(text, asize);
 		}
 		op = s = text + size;
 		for (esc_nl = 0; *p != '\0'; p++) {
 			if (*p == '\\' && p[1] != '\0' && *++p == '\n')
 				esc_nl = 1;
 			*s++ = *p;
 		}
 		size += s - op;
 		if (!esc_nl) {
 			*s = '\0';
 			break;
 		}
 	}
 	free(lbuf);
 	text = xrealloc(text, size + 1);
 	text[size] = '\0';
 	return (text);
 }
 
 /*
  * Get an address and return a pointer to the first character after
  * it.  Fill the structure pointed to according to the address.
  */
 static char *
 compile_addr(char *p, struct s_addr *a)
 {
 	char *end;
 
 	switch (*p) {
 	case '\\':				/* Context address */
 		++p;
 		/* FALLTHROUGH */
 	case '/':				/* Context address */
 		p = compile_re(p, &a->u.r);
 		if (p == NULL)
 			err(COMPILE, "unterminated regular expression");
 		a->type = AT_RE;
 		return (p);
 
 	case '$':				/* Last line */
 		a->type = AT_LAST;
 		return (p + 1);
 						/* Line number */
 	case '0': case '1': case '2': case '3': case '4':
 	case '5': case '6': case '7': case '8': case '9':
 		a->type = AT_LINE;
 		a->u.l = strtoul(p, &end, 10);
 		return (end);
 	default:
 		err(COMPILE, "expected context address");
 		return (NULL);
 	}
 }
 
 /*
  * duptoeol --
  *	Return a copy of all the characters up to \n or \0.
  */
 static char *
 duptoeol(char *s, char *ctype, char **semi)
 {
 	size_t len;
 	int ws;
 	char *start;
 
 	ws = 0;
 	if (semi) {
 		for (start = s; *s != '\0' && *s != '\n' && *s != ';'; ++s)
 			ws = isspace((unsigned char)*s);
 	} else {
 		for (start = s; *s != '\0' && *s != '\n'; ++s)
 			ws = isspace((unsigned char)*s);
 		*s = '\0';
 	}
 	if (ws)
 		err(WARNING, "whitespace after %s", ctype);
 	len = s - start + 1;
 	if (semi)
 		*semi = s;
 	s = xmalloc(len);
 	strlcpy(s, start, len);
 	return (s);
 }
 
 /*
  * Convert goto label names to addresses, and count a and r commands, in
  * the given subset of the script.  Free the memory used by labels in b
  * and t commands (but not by :).
  *
  * TODO: Remove } nodes
  */
 static void
 fixuplabel(struct s_command *cp, struct s_command *end)
 {
 
 	for (; cp != end; cp = cp->next)
 		switch (cp->code) {
 		case 'a':
 		case 'r':
 			appendnum++;
 			break;
 		case 'b':
 		case 't':
 			/* Resolve branch target. */
 			if (cp->t == NULL) {
 				cp->u.c = NULL;
 				break;
 			}
 			if ((cp->u.c = findlabel(cp->t)) == NULL)
 				err(COMPILE2, "undefined label '%s'", cp->t);
 			free(cp->t);
 			break;
 		case '{':
 			/* Do interior commands. */
 			fixuplabel(cp->u.c, cp->next);
 			break;
 		}
 }
 
 /*
  * Associate the given command label for later lookup.
  */
 static void
 enterlabel(struct s_command *cp)
 {
 	struct labhash **lhp, *lh;
 	u_char *p;
 	u_int h, c;
 
 	for (h = 0, p = (u_char *)cp->t; (c = *p) != 0; p++)
 		h = (h << 5) + h + c;
 	lhp = &labels[h & LHMASK];
 	for (lh = *lhp; lh != NULL; lh = lh->lh_next)
 		if (lh->lh_hash == h && strcmp(cp->t, lh->lh_cmd->t) == 0)
 			err(COMPILE2, "duplicate label '%s'", cp->t);
 	lh = xmalloc(sizeof *lh);
 	lh->lh_next = *lhp;
 	lh->lh_hash = h;
 	lh->lh_cmd = cp;
 	lh->lh_ref = 0;
 	*lhp = lh;
 }
 
 /*
  * Find the label contained in the command l in the command linked
  * list cp.  L is excluded from the search.  Return NULL if not found.
  */
 static struct s_command *
 findlabel(char *name)
 {
 	struct labhash *lh;
 	u_char *p;
 	u_int h, c;
 
 	for (h = 0, p = (u_char *)name; (c = *p) != 0; p++)
 		h = (h << 5) + h + c;
 	for (lh = labels[h & LHMASK]; lh != NULL; lh = lh->lh_next) {
 		if (lh->lh_hash == h && strcmp(name, lh->lh_cmd->t) == 0) {
 			lh->lh_ref = 1;
 			return (lh->lh_cmd);
 		}
 	}
 	return (NULL);
 }
 
 /*
  * Warn about any unused labels.  As a side effect, release the label hash
  * table space.
  */
 static void
 uselabel(void)
 {
 	struct labhash *lh, *next;
 	int i;
 
 	for (i = 0; i < LHSZ; i++) {
 		for (lh = labels[i]; lh != NULL; lh = next) {
 			next = lh->lh_next;
 			if (!lh->lh_ref)
 				err(WARNING, "unused label '%s'",
 				    lh->lh_cmd->t);
 			free(lh);
 		}
 	}
 }