/*	$NetBSD: getcap.c,v 1.2 2017/01/28 21:31:50 christos Exp $	*/

/*	NetBSD: getcap.c,v 1.29 1999/03/29 09:27:29 abs Exp	*/

/*-
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Casey Leedom of Lawrence Livermore National Laboratory.
 *
 * 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 <config.h>

#include <krb5/roken.h>

#include <sys/types.h>
#include <ctype.h>
#if defined(HAVE_DB_185_H)
#include <db_185.h>
#elif defined(HAVE_DB_H)
#include <db.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define	BFRAG		1024
#define	ESC		('[' & 037)	/* ASCII ESC */
#define	MAX_RECURSION	32		/* maximum getent recursion */
#define	SFRAG		100		/* cgetstr mallocs in SFRAG chunks */

#define RECOK	(char)0
#define TCERR	(char)1
#define	SHADOW	(char)2

static size_t	 topreclen;	/* toprec length */
static char	*toprec;	/* Additional record specified by cgetset() */
static int	 gottoprec;	/* Flag indicating retrieval of toprecord */

#ifdef USE_DB
static int	cdbget (DB *, char **, const char *);
#endif
static int 	getent (char **, size_t *, char **, int, const char *, int, char *);
static int	nfcmp (char *, char *);


ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL cgetset(const char *ent);
ROKEN_LIB_FUNCTION char * ROKEN_LIB_CALL cgetcap(char *buf, const char *cap, int type);
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL cgetent(char **buf, char **db_array, const char *name);
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL cgetmatch(const char *buf, const char *name);
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL cgetclose(void);
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL cgetstr(char *buf, const char *cap, char **str);
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL cgetustr(char *buf, const char *cap, char **str);
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL cgetnum(char *buf, const char *cap, long *num);
/*
 * Cgetset() allows the addition of a user specified buffer to be added
 * to the database array, in effect "pushing" the buffer on top of the
 * virtual database. 0 is returned on success, -1 on failure.
 */
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
cgetset(const char *ent)
{
    const char *source, *check;
    char *dest;

    if (ent == NULL) {
	if (toprec)
	    free(toprec);
	toprec = NULL;
	topreclen = 0;
	return (0);
    }
    topreclen = strlen(ent);
    if ((toprec = malloc (topreclen + 1)) == NULL) {
	errno = ENOMEM;
	return (-1);
    }
    gottoprec = 0;

    source=ent;
    dest=toprec;
    while (*source) { /* Strip whitespace */
	*dest++ = *source++; /* Do not check first field */
	while (*source == ':') {
	    check=source+1;
	    while (*check && (isspace((unsigned char)*check) ||
			      (*check=='\\' && isspace((unsigned char)check[1]))))
		++check;
	    if( *check == ':' )
		source=check;
	    else
		break;

	}
    }
    *dest=0;

    return (0);
}

/*
 * Cgetcap searches the capability record buf for the capability cap with
 * type `type'.  A pointer to the value of cap is returned on success, NULL
 * if the requested capability couldn't be found.
 *
 * Specifying a type of ':' means that nothing should follow cap (:cap:).
 * In this case a pointer to the terminating ':' or NUL will be returned if
 * cap is found.
 *
 * If (cap, '@') or (cap, terminator, '@') is found before (cap, terminator)
 * return NULL.
 */
ROKEN_LIB_FUNCTION char * ROKEN_LIB_CALL
cgetcap(char *buf, const char *cap, int type)
{
    char *bp;
    const char *cp;

    bp = buf;
    for (;;) {
	/*
	 * Skip past the current capability field - it's either the
	 * name field if this is the first time through the loop, or
	 * the remainder of a field whose name failed to match cap.
	 */
	for (;;)
	    if (*bp == '\0')
		return (NULL);
	    else
		if (*bp++ == ':')
		    break;

	/*
	 * Try to match (cap, type) in buf.
	 */
	for (cp = cap; *cp == *bp && *bp != '\0'; cp++, bp++)
	    continue;
	if (*cp != '\0')
	    continue;
	if (*bp == '@')
	    return (NULL);
	if (type == ':') {
	    if (*bp != '\0' && *bp != ':')
		continue;
	    return(bp);
	}
	if (*bp != type)
	    continue;
	bp++;
	return (*bp == '@' ? NULL : bp);
    }
    /* NOTREACHED */
}

/*
 * Cgetent extracts the capability record name from the NULL terminated file
 * array db_array and returns a pointer to a malloc'd copy of it in buf.
 * Buf must be retained through all subsequent calls to cgetcap, cgetnum,
 * cgetflag, and cgetstr, but may then be free'd.  0 is returned on success,
 * -1 if the requested record couldn't be found, -2 if a system error was
 * encountered (couldn't open/read a file, etc.), and -3 if a potential
 * reference loop is detected.
 */
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
cgetent(char **buf, char **db_array, const char *name)
{
    size_t dummy;

    return (getent(buf, &dummy, db_array, -1, name, 0, NULL));
}

/*
 * Getent implements the functions of cgetent.  If fd is non-negative,
 * *db_array has already been opened and fd is the open file descriptor.  We
 * do this to save time and avoid using up file descriptors for tc=
 * recursions.
 *
 * Getent returns the same success/failure codes as cgetent.  On success, a
 * pointer to a malloc'ed capability record with all tc= capabilities fully
 * expanded and its length (not including trailing ASCII NUL) are left in
 * *cap and *len.
 *
 * Basic algorithm:
 *	+ Allocate memory incrementally as needed in chunks of size BFRAG
 *	  for capability buffer.
 *	+ Recurse for each tc=name and interpolate result.  Stop when all
 *	  names interpolated, a name can't be found, or depth exceeds
 *	  MAX_RECURSION.
 */
static int
getent(char **cap, size_t *len, char **db_array, int fd,
       const char *name, int depth, char *nfield)
{
    char *r_end, *rp = NULL, **db_p;	/* pacify gcc */
    int myfd = 0, eof, foundit;
    char *record;
    int tc_not_resolved;

    /*
     * Return with ``loop detected'' error if we've recursed more than
     * MAX_RECURSION times.
     */
    if (depth > MAX_RECURSION)
	return (-3);

    /*
     * Check if we have a top record from cgetset().
     */
    if (depth == 0 && toprec != NULL && cgetmatch(toprec, name) == 0) {
	size_t tmplen = topreclen + BFRAG;
	if ((record = malloc (tmplen)) == NULL) {
	    errno = ENOMEM;
	    return (-2);
	}
	(void)strlcpy(record, toprec, tmplen);
	db_p = db_array;
	rp = record + topreclen + 1;
	r_end = rp + BFRAG;
	goto tc_exp;
    }
    /*
     * Allocate first chunk of memory.
     */
    if ((record = malloc(BFRAG)) == NULL) {
	errno = ENOMEM;
	return (-2);
    }
    r_end = record + BFRAG;
    foundit = 0;
    /*
     * Loop through database array until finding the record.
     */

    for (db_p = db_array; *db_p != NULL; db_p++) {
	eof = 0;

	/*
	 * Open database if not already open.
	 */

	if (fd >= 0) {
	    (void)lseek(fd, (off_t)0, SEEK_SET);
	} else {
#ifdef USE_DB
	    char pbuf[_POSIX_PATH_MAX];
	    char *cbuf;
	    size_t clen;
	    int retval;
	    DB *capdbp;

	    (void)snprintf(pbuf, sizeof(pbuf), "%s.db", *db_p);
	    if ((capdbp = dbopen(pbuf, O_RDONLY, 0, DB_HASH, 0))
		!= NULL) {
		free(record);
		retval = cdbget(capdbp, &record, name);
                /* record is no longer for us to free here */
		if (retval < 0) {
		    /* no record available */
		    (void)capdbp->close(capdbp);
		    return (retval);
		}
				/* save the data; close frees it */
		clen = strlen(record);
		cbuf = malloc(clen + 1);
		if (cbuf == NULL)
		    return (-2);
		memmove(cbuf, record, clen + 1);
		if (capdbp->close(capdbp) < 0) {
		    free(cbuf);
		    return (-2);
		}
		*len = clen;
		*cap = cbuf;
		return (retval);
	    } else
#endif
	    {
		fd = open(*db_p, O_RDONLY, 0);
		if (fd < 0) {
		    /* No error on unfound file. */
		    continue;
		}
		myfd = 1;
	    }
	}
	/*
	 * Find the requested capability record ...
	 */
	{
	    char buf[BUFSIZ];
	    char *b_end, *bp, *cp;
	    int c, slash;

	    /*
	     * Loop invariants:
	     *	There is always room for one more character in record.
	     *	R_end always points just past end of record.
	     *	Rp always points just past last character in record.
	     *	B_end always points just past last character in buf.
	     *	Bp always points at next character in buf.
	     *	Cp remembers where the last colon was.
	     */
	    b_end = buf;
	    bp = buf;
	    cp = 0;
	    slash = 0;
	    for (;;) {

		/*
		 * Read in a line implementing (\, newline)
		 * line continuation.
		 */
		rp = record;
		for (;;) {
		    if (bp >= b_end) {
			int n;

			n = read(fd, buf, sizeof(buf));
			if (n <= 0) {
			    if (myfd)
				(void)close(fd);
			    if (n < 0) {
				free(record);
				return (-2);
			    } else {
				fd = -1;
				eof = 1;
				break;
			    }
			}
			b_end = buf+n;
			bp = buf;
		    }

		    c = *bp++;
		    if (c == '\n') {
			if (slash) {
			    slash = 0;
			    rp--;
			    continue;
			} else
			    break;
		    }
		    if (slash) {
			slash = 0;
			cp = 0;
		    }
		    if (c == ':') {
			/*
			 * If the field was `empty' (i.e.
			 * contained only white space), back up
			 * to the colon (eliminating the
			 * field).
			 */
			if (cp)
			    rp = cp;
			else
			    cp = rp;
		    } else if (c == '\\') {
			slash = 1;
		    } else if (c != ' ' && c != '\t') {
			/*
			 * Forget where the colon was, as this
			 * is not an empty field.
			 */
			cp = 0;
		    }
		    *rp++ = c;

				/*
				 * Enforce loop invariant: if no room
				 * left in record buffer, try to get
				 * some more.
				 */
		    if (rp >= r_end) {
			u_int pos;
                        char *tmp;
			size_t newsize;

			pos = rp - record;
			newsize = r_end - record + BFRAG;
			tmp = realloc(record, newsize);
			if (tmp == NULL) {
			    errno = ENOMEM;
			    if (myfd)
				(void)close(fd);
                            free(record);
			    return (-2);
			}
                        record = tmp;
			r_end = record + newsize;
			rp = record + pos;
		    }
		}
		/* Eliminate any white space after the last colon. */
		if (cp)
		    rp = cp + 1;
		/* Loop invariant lets us do this. */
		*rp++ = '\0';

		/*
		 * If encountered eof check next file.
		 */
		if (eof)
		    break;

		/*
		 * Toss blank lines and comments.
		 */
		if (*record == '\0' || *record == '#')
		    continue;

		/*
		 * See if this is the record we want ...
		 */
		if (cgetmatch(record, name) == 0) {
		    if (nfield == NULL || !nfcmp(nfield, record)) {
			foundit = 1;
			break;	/* found it! */
		    }
		}
	    }
	}
	if (foundit)
	    break;
    }

    if (!foundit) {
        free(record);
	return (-1);
    }

    /*
     * Got the capability record, but now we have to expand all tc=name
     * references in it ...
     */
 tc_exp:	{
	char *newicap, *s;
	size_t ilen, newilen;
	int diff, iret, tclen;
	char *icap, *scan, *tc, *tcstart, *tcend;

	/*
	 * Loop invariants:
	 *	There is room for one more character in record.
	 *	R_end points just past end of record.
	 *	Rp points just past last character in record.
	 *	Scan points at remainder of record that needs to be
	 *	scanned for tc=name constructs.
	 */
	scan = record;
	tc_not_resolved = 0;
	for (;;) {
	    if ((tc = cgetcap(scan, "tc", '=')) == NULL)
		break;

	    /*
	     * Find end of tc=name and stomp on the trailing `:'
	     * (if present) so we can use it to call ourselves.
	     */
	    s = tc;
	    for (;;)
		if (*s == '\0')
		    break;
		else
		    if (*s++ == ':') {
			*(s - 1) = '\0';
			break;
		    }
	    tcstart = tc - 3;
	    tclen = s - tcstart;
	    tcend = s;

	    iret = getent(&icap, &ilen, db_p, fd, tc, depth+1,
			  NULL);
	    newicap = icap;		/* Put into a register. */
	    newilen = ilen;
	    if (iret != 0) {
				/* an error */
		if (iret < -1) {
		    if (myfd)
			(void)close(fd);
		    free(record);
		    return (iret);
		}
		if (iret == 1)
		    tc_not_resolved = 1;
				/* couldn't resolve tc */
		if (iret == -1) {
		    *(s - 1) = ':';
		    scan = s - 1;
		    tc_not_resolved = 1;
		    continue;

		}
	    }
	    /* not interested in name field of tc'ed record */
	    s = newicap;
	    for (;;)
		if (*s == '\0')
		    break;
		else
		    if (*s++ == ':')
			break;
	    newilen -= s - newicap;
	    newicap = s;

	    /* make sure interpolated record is `:'-terminated */
	    s += newilen;
	    if (*(s-1) != ':') {
		*s = ':';	/* overwrite NUL with : */
		newilen++;
	    }

	    /*
	     * Make sure there's enough room to insert the
	     * new record.
	     */
	    diff = newilen - tclen;
	    if (diff >= r_end - rp) {
		u_int pos, tcpos, tcposend;
		size_t newsize;
                char *tmp;

		pos = rp - record;
		newsize = r_end - record + diff + BFRAG;
		tcpos = tcstart - record;
		tcposend = tcend - record;
		tmp = realloc(record, newsize);
		if (tmp == NULL) {
		    errno = ENOMEM;
		    if (myfd)
			(void)close(fd);
		    free(icap);
                    free(record);
		    return (-2);
		}
                record = tmp;
		r_end = record + newsize;
		rp = record + pos;
		tcstart = record + tcpos;
		tcend = record + tcposend;
	    }

	    /*
	     * Insert tc'ed record into our record.
	     */
	    s = tcstart + newilen;
	    memmove(s, tcend,  (size_t)(rp - tcend));
	    memmove(tcstart, newicap, newilen);
	    rp += diff;
	    free(icap);

	    /*
	     * Start scan on `:' so next cgetcap works properly
	     * (cgetcap always skips first field).
	     */
	    scan = s-1;
	}

    }
    /*
     * Close file (if we opened it), give back any extra memory, and
     * return capability, length and success.
     */
    if (myfd)
	(void)close(fd);
    *len = rp - record - 1;	/* don't count NUL */
    if (r_end > rp) {
        char *tmp = realloc(record, (size_t)(rp - record));
	if (tmp == NULL) {
	    errno = ENOMEM;
            free(record);
	    return (-2);
	}
        record = tmp;
    }

    *cap = record;
    if (tc_not_resolved)
	return (1);
    return (0);
}

#ifdef USE_DB
static int
cdbget(DB *capdbp, char **bp, const char *name)
{
	DBT key;
	DBT data;

	/* LINTED key is not modified */
	key.data = (char *)name;
	key.size = strlen(name);

	for (;;) {
		/* Get the reference. */
		switch(capdbp->get(capdbp, &key, &data, 0)) {
		case -1:
			return (-2);
		case 1:
			return (-1);
		}

		/* If not an index to another record, leave. */
		if (((char *)data.data)[0] != SHADOW)
			break;

		key.data = (char *)data.data + 1;
		key.size = data.size - 1;
	}

	*bp = (char *)data.data + 1;
	return (((char *)(data.data))[0] == TCERR ? 1 : 0);
}
#endif /* USE_DB */

/*
 * Cgetmatch will return 0 if name is one of the names of the capability
 * record buf, -1 if not.
 */
int
cgetmatch(const char *buf, const char *name)
{
    const char *np, *bp;

    /*
     * Start search at beginning of record.
     */
    bp = buf;
    for (;;) {
	/*
	 * Try to match a record name.
	 */
	np = name;
	for (;;)
	    if (*np == '\0') {
		if (*bp == '|' || *bp == ':' || *bp == '\0')
		    return (0);
		else
		    break;
	    } else
		if (*bp++ != *np++)
		    break;

	/*
	 * Match failed, skip to next name in record.
	 */
	bp--;	/* a '|' or ':' may have stopped the match */
	for (;;)
	    if (*bp == '\0' || *bp == ':')
		return (-1);	/* match failed totally */
	    else
		if (*bp++ == '|')
		    break;	/* found next name */
    }
}

static FILE *pfp;
static int slash;
static char **dbp;

ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
cgetclose(void)
{
    if (pfp != NULL) {
	(void)fclose(pfp);
	pfp = NULL;
    }
    dbp = NULL;
    gottoprec = 0;
    slash = 0;
    return(0);
}

/*
 * Cgetstr retrieves the value of the string capability cap from the
 * capability record pointed to by buf.  A pointer to a decoded, NUL
 * terminated, malloc'd copy of the string is returned in the char *
 * pointed to by str.  The length of the string not including the trailing
 * NUL is returned on success, -1 if the requested string capability
 * couldn't be found, -2 if a system error was encountered (storage
 * allocation failure).
 */
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
cgetstr(char *buf, const char *cap, char **str)
{
    u_int m_room;
    const char *bp;
    char *mp;
    int len;
    char *mem, *nmem;

    *str = NULL;

    /*
     * Find string capability cap
     */
    bp = cgetcap(buf, cap, '=');
    if (bp == NULL)
	return (-1);

    /*
     * Conversion / storage allocation loop ...  Allocate memory in
     * chunks SFRAG in size.
     */
    if ((mem = malloc(SFRAG)) == NULL) {
	errno = ENOMEM;
	return (-2);	/* couldn't even allocate the first fragment */
    }
    m_room = SFRAG;
    mp = mem;

    while (*bp != ':' && *bp != '\0') {
	/*
	 * Loop invariants:
	 *	There is always room for one more character in mem.
	 *	Mp always points just past last character in mem.
	 *	Bp always points at next character in buf.
	 */
	if (*bp == '^') {
	    bp++;
	    if (*bp == ':' || *bp == '\0')
		break;	/* drop unfinished escape */
	    *mp++ = *bp++ & 037;
	} else if (*bp == '\\') {
	    bp++;
	    if (*bp == ':' || *bp == '\0')
		break;	/* drop unfinished escape */
	    if ('0' <= *bp && *bp <= '7') {
		int n, i;

		n = 0;
		i = 3;	/* maximum of three octal digits */
		do {
		    n = n * 8 + (*bp++ - '0');
		} while (--i && '0' <= *bp && *bp <= '7');
		*mp++ = n;
	    }
	    else switch (*bp++) {
	    case 'b': case 'B':
		*mp++ = '\b';
		break;
	    case 't': case 'T':
		*mp++ = '\t';
		break;
	    case 'n': case 'N':
		*mp++ = '\n';
		break;
	    case 'f': case 'F':
		*mp++ = '\f';
		break;
	    case 'r': case 'R':
		*mp++ = '\r';
		break;
	    case 'e': case 'E':
		*mp++ = ESC;
		break;
	    case 'c': case 'C':
		*mp++ = ':';
		break;
	    default:
		/*
		 * Catches '\', '^', and
		 *  everything else.
		 */
		*mp++ = *(bp-1);
		break;
	    }
	} else
	    *mp++ = *bp++;
	m_room--;

	/*
	 * Enforce loop invariant: if no room left in current
	 * buffer, try to get some more.
	 */
	if (m_room == 0) {
	    size_t size = mp - mem;

	    if ((nmem = realloc(mem, size + SFRAG)) == NULL) {
		free(mem);
		return (-2);
	    }
	    mem = nmem;
	    m_room = SFRAG;
	    mp = mem + size;
	}
    }
    *mp++ = '\0';	/* loop invariant let's us do this */
    m_room--;
    len = mp - mem - 1;

    /*
     * Give back any extra memory and return value and success.
     */
    if (m_room != 0) {
	if ((nmem = realloc(mem, (size_t)(mp - mem))) == NULL) {
	    free(mem);
	    return (-2);
	}
	mem = nmem;
    }
    *str = mem;
    return (len);
}

/*
 * Cgetustr retrieves the value of the string capability cap from the
 * capability record pointed to by buf.  The difference between cgetustr()
 * and cgetstr() is that cgetustr does not decode escapes but rather treats
 * all characters literally.  A pointer to a  NUL terminated malloc'd
 * copy of the string is returned in the char pointed to by str.  The
 * length of the string not including the trailing NUL is returned on success,
 * -1 if the requested string capability couldn't be found, -2 if a system
 * error was encountered (storage allocation failure).
 */
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
cgetustr(char *buf, const char *cap, char **str)
{
    u_int m_room;
    const char *bp;
    char *mp;
    int len;
    char *mem;

    /*
     * Find string capability cap
     */
    if ((bp = cgetcap(buf, cap, '=')) == NULL)
	return (-1);

    /*
     * Conversion / storage allocation loop ...  Allocate memory in
     * chunks SFRAG in size.
     */
    if ((mem = malloc(SFRAG)) == NULL) {
	errno = ENOMEM;
	return (-2);	/* couldn't even allocate the first fragment */
    }
    m_room = SFRAG;
    mp = mem;

    while (*bp != ':' && *bp != '\0') {
	/*
	 * Loop invariants:
	 *	There is always room for one more character in mem.
	 *	Mp always points just past last character in mem.
	 *	Bp always points at next character in buf.
	 */
	*mp++ = *bp++;
	m_room--;

	/*
	 * Enforce loop invariant: if no room left in current
	 * buffer, try to get some more.
	 */
	if (m_room == 0) {
	    size_t size = mp - mem;

	    if ((mem = realloc(mem, size + SFRAG)) == NULL)
		return (-2);
	    m_room = SFRAG;
	    mp = mem + size;
	}
    }
    *mp++ = '\0';	/* loop invariant let's us do this */
    m_room--;
    len = mp - mem - 1;

    /*
     * Give back any extra memory and return value and success.
     */
    if (m_room != 0) {
        char *tmp = realloc(mem, (size_t)(mp - mem));
	if (tmp == NULL) {
            free(mem);
	    return (-2);
        }
        mem = tmp;
    }
    *str = mem;
    return (len);
}

/*
 * Cgetnum retrieves the value of the numeric capability cap from the
 * capability record pointed to by buf.  The numeric value is returned in
 * the long pointed to by num.  0 is returned on success, -1 if the requested
 * numeric capability couldn't be found.
 */
ROKEN_LIB_FUNCTION int ROKEN_LIB_CALL
cgetnum(char *buf, const char *cap, long *num)
{
    long n;
    int base, digit;
    const char *bp;

    /*
     * Find numeric capability cap
     */
    bp = cgetcap(buf, cap, '#');
    if (bp == NULL)
	return (-1);

    /*
     * Look at value and determine numeric base:
     *	0x... or 0X...	hexadecimal,
     * else	0...		octal,
     * else			decimal.
     */
    if (*bp == '0') {
	bp++;
	if (*bp == 'x' || *bp == 'X') {
	    bp++;
	    base = 16;
	} else
	    base = 8;
    } else
	base = 10;

    /*
     * Conversion loop ...
     */
    n = 0;
    for (;;) {
	if ('0' <= *bp && *bp <= '9')
	    digit = *bp - '0';
	else if ('a' <= *bp && *bp <= 'f')
	    digit = 10 + *bp - 'a';
	else if ('A' <= *bp && *bp <= 'F')
	    digit = 10 + *bp - 'A';
	else
	    break;

	if (digit >= base)
	    break;

	n = n * base + digit;
	bp++;
    }

    /*
     * Return value and success.
     */
    *num = n;
    return (0);
}


/*
 * Compare name field of record.
 */
static int
nfcmp(char *nf, char *rec)
{
    char *cp, tmp;
    int ret;

    for (cp = rec; *cp != ':'; cp++)
	;

    tmp = *(cp + 1);
    *(cp + 1) = '\0';
    ret = strcmp(nf, rec);
    *(cp + 1) = tmp;

    return (ret);
}
