Libc-320.tar.gz

[apple/libc.git] / gen / FreeBSD / getcap.c

/*-
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getcap.c    8.3 (Berkeley) 3/25/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/gen/getcap.c,v 1.19 2003/01/02 10:19:43 thomas Exp $");

#include "namespace.h"
#include <sys/types.h>

#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"

#include <db.h>

#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(DB *, char **, const char *);
static int      getent(char **, u_int *, char **, int, const char *, int, char *);
static int      nfcmp(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(const 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);
        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(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.
 */
int
cgetent(char **buf, char **db_array, const char *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(char **cap, u_int *len, char **db_array, int fd, const char *name,
    int depth, char *nfield)
{
        DB *capdbp;
        char *r_end, *rp, **db_p;
        int myfd, 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);
                myfd = 0;
                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);
                        myfd = 0;
                } 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)
                                        continue;
                                myfd = 1;
                        }
                }
                /*
                 * Find the requested capability record ...
                 */
                {
                char buf[BUFSIZ];
                char *b_end, *bp;
                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 = reallocf(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) {
                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;
                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 = reallocf(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 =
                     reallocf(record, (size_t)(rp - record))) == NULL) {
                        errno = ENOMEM;
                        return (-2);
                }

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

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

        namebuf = strdup(name);
        if (namebuf == NULL)
                return (-2);
        key.data = namebuf;
        key.size = strlen(namebuf);

        for (;;) {
                /* Get the reference. */
                switch(capdbp->get(capdbp, &key, &data, 0)) {
                case -1:
                        free(namebuf);
                        return (-2);
                case 1:
                        free(namebuf);
                        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;
        free(namebuf);
        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(const char *buf, const char *name)
{
        const char *np, *bp;

        if (name == NULL || *name == '\0')
                return -1;

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

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

int
cgetclose(void)
{
        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(char **bp, char **db_array)
{
        size_t len;
        int done, hadreaderr, i, savederrno, status;
        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) {
                                hadreaderr = ferror(pfp);
                                if (hadreaderr)
                                        savederrno = errno;
                                fclose(pfp);
                                pfp = NULL;
                                if (hadreaderr) {
                                        cgetclose();
                                        errno = savederrno;
                                        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((unsigned char)*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) {
                                        /* Name extends beyond the EOF! */
                                        hadreaderr = ferror(pfp);
                                        if (hadreaderr)
                                                savederrno = errno;
                                        fclose(pfp);
                                        pfp = NULL;
                                        if (hadreaderr) {
                                                cgetclose();
                                                errno = savederrno;
                                                return (-1);
                                        } else {
                                                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(char *buf, const char *cap, char **str)
{
        u_int m_room;
        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 */
                        if (*bp == '?') {
                                *mp++ = '\177';
                                bp++;
                        } else
                                *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 ((mem = reallocf(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 = reallocf(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(char *buf, const char *cap, char **str)
{
        u_int m_room;
        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 = reallocf(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 = reallocf(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(char *buf, const char *cap, long *num)
{
        long n;
        int base, digit;
        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);
}