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Use password/group cache functions and avoid stashing a pointer to
the return value of getgrgid(3) or getgrnam(3) which relies on
undefined behavior.  The rdist server will now use getgroups(2) to
determine group membership of the invoking user.  In addition, there
is now one implementation of tilde expansion instead of two.
OK tb@ tim@

/*	$OpenBSD: expand.c,v 1.17 2018/09/21 19:00:45 millert Exp $	*/

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * 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 <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "client.h"

#define	MAXEARGS	2048
#define LC 		'{'
#define RC 		'}'

static char	shchars[] = "${[*?";

int		which;		/* bit mask of types to expand */
int		eargc;		/* expanded arg count */
char	      **eargv;		/* expanded arg vectors */
char	       *path;
char	       *pathp;
char	       *lastpathp;
char	       *tilde;		/* "~user" if not expanding tilde, else "" */
char	       *tpathp;
char		pathbuf[BUFSIZ];

int		expany;		/* any expansions done? */
char	       *entp;
char	      **sortbase;
char 	       *argvbuf[MAXEARGS];

#define sort()	qsort((char *)sortbase, &eargv[eargc] - sortbase, \
		      sizeof(*sortbase), argcmp), sortbase = &eargv[eargc]

static void Cat(u_char *, u_char *);
static void addpath(int);
static int argcmp(const void *, const void *);

static void
Cat(u_char *s1, u_char *s2)		/* quote in s1 and s2 */
{
	char *cp;
	int len = strlen((char *)s1) + strlen((char *)s2) + 2;

	if ((eargc + 1) >= MAXEARGS) {
		yyerror("Too many names");
		return;
	}

	eargv[++eargc] = NULL;
	eargv[eargc - 1] = cp = xmalloc(len);

	do { 
		if (*s1 == QUOTECHAR) 
			s1++; 
	} while ((*cp++ = *s1++) != '\0');
	cp--;
	do { 
		if (*s2 == QUOTECHAR) 
			s2++; 
	} while ((*cp++ = *s2++) != '\0');
}

static void
addpath(int c)
{
	if (pathp >= lastpathp) {
		yyerror("Pathname too long");
		return;
	} else {
		*pathp++ = c;
		*pathp = CNULL;
	}
}

/*
 * Take a list of names and expand any macros, etc.
 * wh = E_VARS if expanding variables.
 * wh = E_SHELL if expanding shell characters.
 * wh = E_TILDE if expanding `~'.
 * or any of these or'ed together.
 *
 * Major portions of this were snarfed from csh/sh.glob.c.
 */
struct namelist *
expand(struct namelist *list, int wh)		/* quote in list->n_name */
{
	struct namelist *nl, *prev;
	int n;

	if (debug)
		debugmsg(DM_CALL, "expand(%p, %d) start, list = %s", 
			 list, wh, getnlstr(list));

	if (wh == 0)
		fatalerr("expand() contains invalid 'wh' argument.");

	which = wh;
	path = tpathp = pathp = pathbuf;
	*pathp = CNULL;
	lastpathp = &pathbuf[sizeof pathbuf - 2];
	tilde = "";
	eargc = 0;
	eargv = sortbase = argvbuf;
	*eargv = NULL;

	/*
	 * Walk the name list and expand names into eargv[];
	 */
	for (nl = list; nl != NULL; nl = nl->n_next)
		expstr((u_char *)nl->n_name);
	/*
	 * Take expanded list of names from eargv[] and build a new list.
	 */
	list = prev = NULL;
	for (n = 0; n < eargc; n++) {
		nl = makenl(NULL);
		nl->n_name = eargv[n];
		if (prev == NULL)
			list = prev = nl;
		else {
			prev->n_next = nl;
			prev = nl;
		}
	}

	return(list);
}

/*
 * xstrchr() is a version of strchr() that
 * handles u_char buffers.
 */
u_char *
xstrchr(u_char *str, int ch)
{
	u_char *cp;

	for (cp = str; cp && *cp != CNULL; ++cp)
		if (ch == *cp)
			return(cp);

	return(NULL);
}

void
expstr(u_char *s)
{
	u_char *cp, *cp1;
	struct namelist *tp;
	u_char *tail;
	u_char ebuf[BUFSIZ];
	u_char varbuff[BUFSIZ];
	int savec, oeargc;

	if (s == NULL || *s == CNULL)
		return;

	/*
	 * Remove quoted characters
	 */
	if (IS_ON(which, E_VARS)) {
		if (strlen((char *)s) > sizeof(varbuff)) {
			yyerror("Variable is too large.");
			return;
		}
		for (cp = s, cp1 = varbuff; cp && *cp; ++cp) {
			/* 
			 * remove quoted character if the next
			 * character is not $
			 */
			if (*cp == QUOTECHAR && *(cp+1) != '$')
				++cp;
			else
				*cp1++ = *cp;
		}
		*cp1 = CNULL;
		s = varbuff;
	}

	/*
	 * Consider string 's' a variable that should be expanded if
	 * there is a '$' in 's' that is not quoted.
	 */
	if (IS_ON(which, E_VARS) && 
	    ((cp = xstrchr(s, '$')) && !(cp > s && *(cp-1) == QUOTECHAR))) {
		*cp++ = CNULL;
		if (*cp == CNULL) {
			yyerror("no variable name after '$'");
			return;
		}
		if (*cp == LC) {
			cp++;
			for (cp1 = cp; ; cp1 = tail + 1) {
				if ((tail = xstrchr(cp1, RC)) == NULL) {
					yyerror("unmatched '{'");
					return;
				}
				if (tail[-1] != QUOTECHAR) break;
			}
			*tail++ = savec = CNULL;
			if (*cp == CNULL) {
				yyerror("no variable name after '$'");
				return;
			}
		} else {
			tail = cp + 1;
			savec = *tail;
			*tail = CNULL;
		}
		tp = lookup((char *)cp, LOOKUP, NULL);
		if (savec != CNULL)
			*tail = savec;
		if (tp != NULL) {
			for (; tp != NULL; tp = tp->n_next) {
				(void) snprintf((char *)ebuf, sizeof(ebuf),
					        "%s%s%s", s, tp->n_name, tail);
				expstr(ebuf);
			}
			return;
		}
		(void) snprintf((char *)ebuf, sizeof(ebuf), "%s%s", s, tail);
		expstr(ebuf);
		return;
	}
	if ((which & ~E_VARS) == 0 || !strcmp((char *)s, "{") || 
	    !strcmp((char *)s, "{}")) {
		Cat(s, (u_char *)"");
		sort();
		return;
	}
	if (*s == '~') {
		if ((cp = strchr(s, '/')) == NULL) {
			tilde = "~";
			s++;
		} else {
			tilde = memcpy(ebuf, s, (cp - s));
			ebuf[cp - s] = '\0';
			s = cp;
		}
		cp = exptilde(path, tilde, sizeof(pathbuf));
		tpathp = pathp = (char *)cp;
	} else {
		tpathp = pathp = path;
		tilde = "";
	}
	*pathp = CNULL;
	if (!(which & E_SHELL)) {
		if (which & E_TILDE)
			Cat((u_char *)path, s);
		else
			Cat((u_char *)tilde, s);
		sort();
		return;
	}
	oeargc = eargc;
	expany = 0;
	expsh(s);
	if (eargc == oeargc)
		Cat(s, (u_char *)"");		/* "nonomatch" is set */
	sort();
}

static int
argcmp(const void *v1, const void *v2)
{
	const char *const *a1 = v1, *const *a2 = v2;

	return (strcmp(*a1, *a2));
}

/*
 * If there are any Shell meta characters in the name,
 * expand into a list, after searching directory
 */
void
expsh(u_char *s)			/* quote in s */
{
	u_char *cp, *oldcp;
	char *spathp;
	struct stat stb;

	spathp = pathp;
	cp = s;
	while (!any(*cp, shchars)) {
		if (*cp == CNULL) {
			if (!expany || stat(path, &stb) >= 0) {
				if (which & E_TILDE)
					Cat((u_char *)path, (u_char *)"");
				else
					Cat((u_char *)tilde, (u_char *)tpathp);
			}
			goto endit;
		}
		if (*cp == QUOTECHAR) cp++;
		addpath(*cp++);
	}
	oldcp = cp;
	while (cp > s && *cp != '/')
		cp--, pathp--;
	if (*cp == '/')
		cp++, pathp++;
	*pathp = CNULL;
	if (*oldcp == '{') {
		(void) execbrc(cp, NULL);
		return;
	}
	matchdir((char *)cp);
endit:
	pathp = spathp;
	*pathp = CNULL;
}

void
matchdir(char *pattern)			/* quote in pattern */
{
	struct stat stb;
	struct dirent *dp;
	DIR *dirp;

	dirp = opendir(path);
	if (dirp == NULL) {
		if (expany)
			return;
		goto patherr2;
	}
	if (fstat(dirfd(dirp), &stb) < 0)
		goto patherr1;
	if (!S_ISDIR(stb.st_mode)) {
		errno = ENOTDIR;
		goto patherr1;
	}
	while ((dp = readdir(dirp)) != NULL)
		if (match(dp->d_name, pattern)) {
			if (which & E_TILDE)
				Cat((u_char *)path, (u_char *)dp->d_name);
			else {
				(void) strlcpy(pathp, dp->d_name,
				    lastpathp - pathp + 2);
				Cat((u_char *)tilde, (u_char *)tpathp);
				*pathp = CNULL;
			}
		}
	closedir(dirp);
	return;

patherr1:
	closedir(dirp);
patherr2:
	(void) strlcat(path, ": ", lastpathp - path + 2);
	(void) strlcat(path, SYSERR, lastpathp - path + 2);
	yyerror(path);
}

int
execbrc(u_char *p, u_char *s)		/* quote in p */
{
	u_char restbuf[BUFSIZ + 2];
	u_char *pe, *pm, *pl;
	int brclev = 0;
	u_char *lm, savec;
	char *spathp;

	for (lm = restbuf; *p != '{'; *lm++ = *p++)
		if (*p == QUOTECHAR) *lm++ = *p++;

	for (pe = ++p; *pe; pe++)
		switch (*pe) {

		case '{':
			brclev++;
			continue;

		case '}':
			if (brclev == 0)
				goto pend;
			brclev--;
			continue;

		case '[':
			for (pe++; *pe && *pe != ']'; pe++)
				if (*p == QUOTECHAR) pe++;
			if (!*pe)
				yyerror("Missing ']'");
			continue;

		case QUOTECHAR:		/* skip this character */
			pe++;
			continue;
		}
pend:
	if (brclev || !*pe) {
		yyerror("Missing '}'");
		return (0);
	}
	for (pl = pm = p; pm <= pe; pm++)
		/* the strip code was a noop */
		switch (*pm) {

		case '{':
			brclev++;
			continue;

		case '}':
			if (brclev) {
				brclev--;
				continue;
			}
			goto doit;

		case ',':
			if (brclev)
				continue;
doit:
			savec = *pm;
			*pm = 0;
			*lm = 0;
			(void) strlcat((char *)restbuf, (char *)pl,
			    sizeof(restbuf));
			(void) strlcat((char *)restbuf, (char *)pe + 1,
			    sizeof(restbuf));
			*pm = savec;
			if (s == 0) {
				spathp = pathp;
				expsh(restbuf);
				pathp = spathp;
				*pathp = 0;
			} else if (amatch((char *)s, restbuf))
				return (1);
			sort();
			pl = pm + 1;
			continue;

		case '[':
			for (pm++; *pm && *pm != ']'; pm++)
				if (*pm == QUOTECHAR) pm++;
			if (!*pm)
				yyerror("Missing ']'");
			continue;

		case QUOTECHAR:			/* skip one character */
			pm++;
			continue;
		}
	return (0);
}

int
match(char *s, char *p)				/* quote in p */
{
	int c;
	char *sentp;
	char sexpany = expany;

	if (*s == '.' && *p != '.')
		return (0);
	sentp = entp;
	entp = s;
	c = amatch(s, p);
	entp = sentp;
	expany = sexpany;
	return (c);
}

int
amatch(char *s, u_char *p)			/* quote in p */
{
	int scc;
	int ok, lc;
	char *spathp;
	struct stat stb;
	int c, cc;

	expany = 1;
	for (;;) {
		scc = *s++;
		switch (c = *p++) {

		case '{':
			return (execbrc((u_char *)p - 1, (u_char *)s - 1));

		case '[':
			ok = 0;
			lc = 077777;
			while ((cc = *p++) != '\0') {
				if (cc == ']') {
					if (ok)
						break;
					return (0);
				}
				if (cc == QUOTECHAR) cc = *p++;
				if (cc == '-') {
					if (lc <= scc && scc <= (int)*p++)
						ok++;
				} else
					if (scc == (lc = cc))
						ok++;
			}
			if (cc == 0) {
				yyerror("Missing ']'");
				return (0);
			}
			continue;

		case '*':
			if (!*p)
				return (1);
			if (*p == '/') {
				p++;
				goto slash;
			}
			for (s--; *s; s++)
				if (amatch(s, p))
					return (1);
			return (0);

		case CNULL:
			return (scc == CNULL);

		default:
			if (c != scc)
				return (0);
			continue;

		case '?':
			if (scc == CNULL)
				return (0);
			continue;

		case '/':
			if (scc)
				return (0);
slash:
			s = entp;
			spathp = pathp;
			while (*s)
				addpath(*s++);
			addpath('/');
			if (stat(path, &stb) == 0 && S_ISDIR(stb.st_mode)) {
				if (*p == CNULL) {
					if (which & E_TILDE) {
						Cat((u_char *)path, 
						    (u_char *)"");
					} else {
						Cat((u_char *)tilde, 
						    (u_char *)tpathp);
					}
				} else
					expsh(p);
			}
			pathp = spathp;
			*pathp = CNULL;
			return (0);
		}
	}
}