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File: [cvs.NetBSD.org] / src / lib / libc / gen / getcap.c (download)

Revision 1.14, Mon Jul 21 14:07:03 1997 UTC (17 years ago) by jtc
Branch: MAIN
Changes since 1.13: +16 -3 lines

If port provides __weak_alias(), provide an Standard C and POSIX pure
identifier namespace by renaming non standard functions and variables
such that they have a leading underscore.  The library will use those
names internally.  Weak aliases are used to provide the original names
to the API.

This is only the first part of this change.  It is most of the functions
which are implemented in C for all NetBSD ports.  Subsequent changes are
to add the same support to the remaining C files, to assembly files, and
to the automagically generated assembly source used for system calls.
When all of the above is done, ports with weak alias support should add
a definition for __weak_alias to <sys/cdefs.h>.

/*	$NetBSD: getcap.c,v 1.14 1997/07/21 14:07:03 jtc 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)getcap.c	8.3 (Berkeley) 3/25/94";
#else
__RCSID("$NetBSD: getcap.c,v 1.14 1997/07/21 14:07:03 jtc Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include "namespace.h"
#include <sys/types.h>
#include <ctype.h>
#include <db.h>
#include <errno.h>	
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef __weak_alias
__weak_alias(cgetcap,_cgetcap);
__weak_alias(cgetclose,_cgetclose);
__weak_alias(cgetent,_cgetent);
__weak_alias(cgetfirst,_cgetfirst);
__weak_alias(cgetmatch,_cgetmatch);
__weak_alias(cgetnext,_cgetnext);
__weak_alias(cgetnum,_cgetnum);
__weak_alias(cgetset,_cgetset);
__weak_alias(cgetstr,_cgetstr);
__weak_alias(cgetustr,_cgetustr);
#endif

#define	BFRAG		1024
#define	BSIZE		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 */

static int	cdbget __P((DB *, char **, char *));
static int 	getent __P((char **, u_int *, char **, int, char *, int, char *));
static int	nfcmp __P((char *, char *));

/*
 * 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.
 */
int
cgetset(ent)
	char *ent;
{
	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;
        (void)strcpy(toprec, ent);	/* XXX: strcpy is safe */
        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.
 */
char *
cgetcap(buf, cap, type)
	char *buf, *cap;
	int type;
{
	register char *bp, *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.
 */
int
cgetent(buf, db_array, name)
	char **buf, **db_array, *name;
{
	u_int 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(cap, len, db_array, fd, name, depth, nfield)
	char **cap, **db_array, *name, *nfield;
	u_int *len;
	int fd, depth;
{
	DB *capdbp;
	register char *r_end, *rp = NULL, **db_p;	/* pacify gcc */
	int myfd = 0, eof, foundit, retval, clen;
	char *record, *cbuf;
	int tc_not_resolved;
	char pbuf[_POSIX_PATH_MAX];
	
	/*
	 * 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) {
		if ((record = malloc (topreclen + BFRAG)) == NULL) {
			errno = ENOMEM;
			return (-2);
		}
		(void)strcpy(record, toprec);	/* XXX: strcpy is safe */
		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, L_SET);
		} else {
			(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);
				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);
				memcpy(cbuf, record, clen + 1);
				if (capdbp->close(capdbp) < 0) {
					free(cbuf);
					return (-2);
				}
				*len = clen;
				*cap = cbuf;
				return (retval);
			} else {
				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];
		register char *b_end, *bp;
		register int c;

		/*
		 * 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.
		 */
		b_end = buf;
		bp = buf;
		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 (rp > record && *(rp-1) == '\\') {
						rp--;
						continue;
					} else
						break;
				}
				*rp++ = c;

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

					pos = rp - record;
					newsize = r_end - record + BFRAG;
					record = realloc(record, newsize);
					if (record == NULL) {
						errno = ENOMEM;
						if (myfd)
							(void)close(fd);
						return (-2);
					}
					r_end = record + newsize;
					rp = record + pos;
				}
			}
				/* loop invariant let's 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)
		return (-1);

	/*
	 * Got the capability record, but now we have to expand all tc=name
	 * references in it ...
	 */
tc_exp:	{
		register char *newicap, *s;
		register int newilen;
		u_int ilen;
		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;

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

			/*
			 * Insert tc'ed record into our record.
			 */
			s = tcstart + newilen;
			bcopy(tcend, s, rp - tcend);
			bcopy(newicap, tcstart, 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)
		if ((record = 
		     realloc(record, (size_t)(rp - record))) == NULL) {
			errno = ENOMEM;
			return (-2);
		}
		
	*cap = record;
	if (tc_not_resolved)
		return (1);
	return (0);
}	

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

	key.data = 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);
}

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





int
cgetfirst(buf, db_array)
	char **buf, **db_array;
{
	(void)cgetclose();
	return (cgetnext(buf, db_array));
}

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

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

/*
 * Cgetnext() gets either the first or next entry in the logical database 
 * specified by db_array.  It returns 0 upon completion of the database, 1
 * upon returning an entry with more remaining, and -1 if an error occurs.
 */
int
cgetnext(bp, db_array)
        register char **bp;
	char **db_array;
{
	size_t len;
	int status, i, done;
	char *cp, *line, *rp, *np, buf[BSIZE], nbuf[BSIZE];
	u_int dummy;

	if (dbp == NULL)
		dbp = db_array;

	if (pfp == NULL && (pfp = fopen(*dbp, "r")) == NULL) {
		(void)cgetclose();
		return (-1);
	}
	for(;;) {
		if (toprec && !gottoprec) {
			gottoprec = 1;
			line = toprec;
		} else {
			line = fgetln(pfp, &len);
			if (line == NULL && pfp) {
				(void)fclose(pfp);
				if (ferror(pfp)) {
					(void)cgetclose();
					return (-1);
				} else {
					if (*++dbp == NULL) {
						(void)cgetclose();
						return (0);
					} else if ((pfp =
					    fopen(*dbp, "r")) == NULL) {
						(void)cgetclose();
						return (-1);
					} else
						continue;
				}
			} else
				line[len - 1] = '\0';
			if (len == 1) {
				slash = 0;
				continue;
			}
			if (isspace(*line) ||
			    *line == ':' || *line == '#' || slash) {
				if (line[len - 2] == '\\')
					slash = 1;
				else
					slash = 0;
				continue;
			}
			if (line[len - 2] == '\\')
				slash = 1;
			else
				slash = 0;
		}			


		/* 
		 * Line points to a name line.
		 */
		i = 0;
		done = 0;
		np = nbuf;
		for (;;) {
			for (cp = line; *cp != '\0'; cp++) {
				if (*cp == ':') {
					*np++ = ':';
					done = 1;
					break;
				}
				if (*cp == '\\')
					break;
				*np++ = *cp;
			}
			if (done) {
				*np = '\0';
				break;
			} else { /* name field extends beyond the line */
				line = fgetln(pfp, &len);
				if (line == NULL && pfp) {
					(void)fclose(pfp);
					if (ferror(pfp)) {
						(void)cgetclose();
						return (-1);
					}
				} else
					line[len - 1] = '\0';
			}
		}
		rp = buf;
		for(cp = nbuf; *cp != '\0'; cp++)
			if (*cp == '|' || *cp == ':')
				break;
			else
				*rp++ = *cp;

		*rp = '\0';
		/* 
		 * XXX 
		 * Last argument of getent here should be nbuf if we want true
		 * sequential access in the case of duplicates.  
		 * With NULL, getent will return the first entry found
		 * rather than the duplicate entry record.  This is a 
		 * matter of semantics that should be resolved.
		 */
		status = getent(bp, &dummy, db_array, -1, buf, 0, NULL);
		if (status == -2 || status == -3)
			(void)cgetclose();

		return (status + 1);
	}
	/* NOTREACHED */
}

/*
 * 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).
 */
int
cgetstr(buf, cap, str)
	char *buf, *cap;
	char **str;
{
	register u_int m_room;
	register char *bp, *mp;
	int len;
	char *mem;

	/*
	 * 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') {
				register 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 ((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)
		if ((mem = realloc(mem, (size_t)(mp - mem))) == NULL)
			return (-2);
	*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).
 */
int
cgetustr(buf, cap, str)
	char *buf, *cap, **str;
{
	register u_int m_room;
	register char *bp, *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)
		if ((mem = realloc(mem, (size_t)(mp - mem))) == NULL)
			return (-2);
	*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.
 */
int
cgetnum(buf, cap, num)
	char *buf, *cap;
	long *num;
{
	register long n;
	register int base, digit;
	register 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(nf, rec)
	char *nf, *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);
}