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nlist.c revision 1.4 
      1 /*
      2  * Copyright (c) 1989, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 static char sccsid[] = "@(#)nlist.c	8.1 (Berkeley) 6/4/93";
     36 #endif /* LIBC_SCCS and not lint */
     37 
     38 #include <sys/param.h>
     39 #include <sys/mman.h>
     40 #include <sys/stat.h>
     41 #include <sys/file.h>
     42 
     43 #include <errno.h>
     44 #include <a.out.h>
     45 #include <stdio.h>
     46 #include <string.h>
     47 #include <unistd.h>
     48 
     49 int
     50 nlist(name, list)
     51 	const char *name;
     52 	struct nlist *list;
     53 {
     54 	int fd, n;
     55 
     56 	fd = open(name, O_RDONLY, 0);
     57 	if (fd < 0)
     58 		return (-1);
     59 	n = __fdnlist(fd, list);
     60 	(void)close(fd);
     61 	return (n);
     62 }
     63 
     64 #define	ISLAST(p)	(p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
     65 
     66 int
     67 __fdnlist(fd, list)
     68 	register int fd;
     69 	register struct nlist *list;
     70 {
     71 	register struct nlist *p, *s;
     72 	register caddr_t strtab;
     73 	register off_t stroff, symoff;
     74 	register u_long symsize;
     75 	register int nent, cc;
     76 	size_t strsize;
     77 	struct nlist nbuf[1024];
     78 	struct exec exec;
     79 	struct stat st;
     80 
     81 	if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
     82 	    read(fd, &exec, sizeof(exec)) != sizeof(exec) ||
     83 	    N_BADMAG(exec) || fstat(fd, &st) < 0)
     84 		return (-1);
     85 
     86 	symoff = N_SYMOFF(exec);
     87 	symsize = exec.a_syms;
     88 	stroff = symoff + symsize;
     89 
     90 	/* Check for files too large to mmap. */
     91 	if (st.st_size - stroff > SIZE_T_MAX) {
     92 		errno = EFBIG;
     93 		return (-1);
     94 	}
     95 	/*
     96 	 * Map string table into our address space.  This gives us
     97 	 * an easy way to randomly access all the strings, without
     98 	 * making the memory allocation permanent as with malloc/free
     99 	 * (i.e., munmap will return it to the system).
    100 	 */
    101 	strsize = st.st_size - stroff;
    102 	strtab = mmap(NULL, (size_t)strsize, PROT_READ, 0, fd, stroff);
    103 	if (strtab == (char *)-1)
    104 		return (-1);
    105 	/*
    106 	 * clean out any left-over information for all valid entries.
    107 	 * Type and value defined to be 0 if not found; historical
    108 	 * versions cleared other and desc as well.  Also figure out
    109 	 * the largest string length so don't read any more of the
    110 	 * string table than we have to.
    111 	 *
    112 	 * XXX clearing anything other than n_type and n_value violates
    113 	 * the semantics given in the man page.
    114 	 */
    115 	nent = 0;
    116 	for (p = list; !ISLAST(p); ++p) {
    117 		p->n_type = 0;
    118 		p->n_other = 0;
    119 		p->n_desc = 0;
    120 		p->n_value = 0;
    121 		++nent;
    122 	}
    123 	if (lseek(fd, symoff, SEEK_SET) == -1)
    124 		return (-1);
    125 
    126 	while (symsize > 0) {
    127 		cc = MIN(symsize, sizeof(nbuf));
    128 		if (read(fd, nbuf, cc) != cc)
    129 			break;
    130 		symsize -= cc;
    131 		for (s = nbuf; cc > 0; ++s, cc -= sizeof(*s)) {
    132 			register int soff = s->n_un.n_strx;
    133 
    134 			if (soff == 0 || (s->n_type & N_STAB) != 0)
    135 				continue;
    136 			for (p = list; !ISLAST(p); p++)
    137 				if (!strcmp(&strtab[soff], p->n_un.n_name)) {
    138 					p->n_value = s->n_value;
    139 					p->n_type = s->n_type;
    140 					p->n_desc = s->n_desc;
    141 					p->n_other = s->n_other;
    142 					if (--nent <= 0)
    143 						break;
    144 				}
    145 		}
    146 	}
    147 	munmap(strtab, strsize);
    148 	return (nent);
    149 }
    150