new version from scratch; this version uses relative offsets from the

[unix-history] / usr / src / lib / libc / gen / nlist.c

/*
* Copyright (c) 1989 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)nlist.c     5.3 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/file.h>
#include <a.out.h>
#include <stdio.h>
#include <unistd.h>

typedef struct nlist NLIST;
#define _strx   n_un.n_strx
#define _name   n_un.n_name
#define ISVALID(p)      (p->_name && p->_name[0])

nlist(name, list)
       char *name;
       NLIST *list;
{
       register NLIST *p, *s;
       struct exec ebuf;
       FILE *fstr, *fsym;
       NLIST nbuf;
       off_t curoff, strings_offset, symbol_offset, symbol_size, lseek();
       int entries, len, maxlen;
       char sbuf[256];

       entries = -1;

       if (!(fsym = fopen(name, "r")))
               return(-1);
       if (fread((char *)&ebuf, sizeof(struct exec), 1, fsym) != 1 ||
           N_BADMAG(ebuf))
               goto done1;

       symbol_offset = N_SYMOFF(ebuf);
       symbol_size = ebuf.a_syms;
       strings_offset = symbol_offset + symbol_size;
       if (fseek(fsym, symbol_offset, SEEK_SET))
               goto done1;

       /*
        * some versions of stdio do lseek's on every fseek call relative
        * to the beginning of the file.  For this reason, all string seeks
        * are made relative to the beginning of the symbol table.
        */
       curoff = 0;
       if (!(fstr = fopen(name, "r")))
               goto done1;
       if (fseek(fstr, strings_offset, SEEK_SET))
               goto done2;

       /*
        * clean out any left-over information for all valid entries.
        * Type and value defined to be 0 if not found; historical
        * versions cleared other and desc as well.  Also figure out
        * the largest string length so don't read any more of the
        * string table than we have to.
        */
       for (p = list, entries = maxlen = 0; ISVALID(p); ++p, ++entries) {
               p->n_type = 0;
               p->n_other = 0;
               p->n_desc = 0;
               p->n_value = 0;
               if ((len = strlen(p->_name)) > maxlen)
                       maxlen = len;
       }
       if (++maxlen > sizeof(sbuf)) {          /* for the NULL */
               (void)fprintf(stderr, "nlist: symbol too large.\n");
               entries = -1;
               goto done2;
       }

       for (s = &nbuf; symbol_size--;) {
               if (fread((char *)s, sizeof(NLIST), 1, fsym) != 1)
                       goto done2;
               if (!s->_strx || s->n_type&N_STAB)
                       continue;
               if (fseek(fstr, s->_strx - curoff, SEEK_CUR))
                       goto done2;
               curoff = s->_strx +
                   fread(sbuf, sizeof(sbuf[0]), maxlen, fstr);
               for (p = list; ISVALID(p); p++)
                       if (!strcmp(p->_name, sbuf)) {
                               p->n_value = s->n_value;
                               p->n_type = s->n_type;
                               p->n_desc = s->n_desc;
                               p->n_other = s->n_other;
                               if (!--entries)
                                       goto done2;
                       }
       }
done2:  (void)fclose(fstr);
done1:  (void)fclose(fsym);
       return(entries);
}