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getcap.c

/*    $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. 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.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "roken.h"
RCSID("$Id: getcap.c,v 1.8 2003/04/16 16:23:36 lha Exp $");

#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
#if 0
#define     BSIZE       1024
#endif
#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 */

#if defined(HAVE_DBOPEN) && defined(HAVE_DB_H)
#define USE_DB
#endif

#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 *);


int cgetset(const char *ent);
char *cgetcap(char *buf, const char *cap, int type);
int cgetent(char **buf, char **db_array, const char *name);
int cgetmatch(const char *buf, const char *name);
int cgetclose(void);
#if 0
int cgetfirst(char **buf, char **db_array);
int cgetnext(char **bp, char **db_array);
#endif
int cgetstr(char *buf, const char *cap, char **str);
int cgetustr(char *buf, const char *cap, char **str);
int 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.
 */
int
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.
 */
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)
{
    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 len = topreclen + BFRAG;
      if ((record = malloc (len)) == NULL) {
          errno = ENOMEM;
          return (-2);
      }
      (void)strlcpy(record, toprec, len);
      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);
            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);
            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;
                  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;
                }
            }
            /* 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)
      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;

            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;
          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)
      if ((record = 
           realloc(record, (size_t)(rp - record))) == NULL) {
          errno = ENOMEM;
          return (-2);
      }
            
    *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 */
    }
}

#if 0
int
cgetfirst(char **buf, char **db_array)
{
    (void)cgetclose();
    return (cgetnext(buf, db_array));
}
#endif

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);
}

#if 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 status, done;
    char *cp, *line, *rp, *np, buf[BSIZE], nbuf[BSIZE];
    size_t 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) {
            if (ferror(pfp)) {
                (void)cgetclose();
                return (-1);
            } else {
                (void)fclose(pfp);
                pfp = NULL;
                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.
       */
      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) {
                if (ferror(pfp)) {
                  (void)cgetclose();
                  return (-1);
                }
                (void)fclose(pfp);
                pfp = NULL;
                *np = '\0';
                break;
            } 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 */
}
#endif

/*
 * 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;
    const char *bp;
    char *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') {
            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(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)
      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(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);
}

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