nlist.c revision 21786 
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)
35static 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
49int __fdnlist __P(( int, struct nlist * ));
50
51int
52nlist(name, list)
53	const char *name;
54	struct nlist *list;
55{
56	int fd, n;
57
58	fd = open(name, O_RDONLY, 0);
59	if (fd < 0)
60		return (-1);
61	n = __fdnlist(fd, list);
62	(void)close(fd);
63	return (n);
64}
65
66#define	ISLAST(p)	(p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
67
68int
69__fdnlist(fd, list)
70	register int fd;
71	register struct nlist *list;
72{
73	register struct nlist *p, *symtab;
74	register caddr_t strtab, a_out_mmap;
75	register off_t stroff, symoff;
76	register u_long symsize;
77	register int nent;
78	struct exec * exec;
79	struct stat st;
80
81	/* check that file is at least as large as struct exec! */
82	if ((fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
83		return (-1);
84
85	/* Check for files too large to mmap. */
86	if (st.st_size > SIZE_T_MAX) {
87		errno = EFBIG;
88		return (-1);
89	}
90
91	/*
92	 * Map the whole a.out file into our address space.
93	 * We then find the string table withing this area.
94	 * We do not just mmap the string table, as it probably
95	 * does not start at a page boundary - we save ourselves a
96	 * lot of nastiness by mmapping the whole file.
97	 *
98	 * This gives us an easy way to randomly access all the strings,
99	 * without making the memory allocation permanent as with
100	 * malloc/free (i.e., munmap will return it to the system).
101	 */
102	a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
103	if (a_out_mmap == MAP_FAILED)
104		return (-1);
105
106	exec = (struct exec *)a_out_mmap;
107	if (N_BADMAG(*exec)) {
108		munmap(a_out_mmap, (size_t)st.st_size);
109		return (-1);
110	}
111
112	symoff = N_SYMOFF(*exec);
113	symsize = exec->a_syms;
114	stroff = symoff + symsize;
115
116	/* find the string table in our mmapped area */
117	strtab = a_out_mmap + stroff;
118	symtab = (struct nlist *)(a_out_mmap + symoff);
119
120	/*
121	 * clean out any left-over information for all valid entries.
122	 * Type and value defined to be 0 if not found; historical
123	 * versions cleared other and desc as well.  Also figure out
124	 * the largest string length so don't read any more of the
125	 * string table than we have to.
126	 *
127	 * XXX clearing anything other than n_type and n_value violates
128	 * the semantics given in the man page.
129	 */
130	nent = 0;
131	for (p = list; !ISLAST(p); ++p) {
132		p->n_type = 0;
133		p->n_other = 0;
134		p->n_desc = 0;
135		p->n_value = 0;
136		++nent;
137	}
138
139	while (symsize > 0) {
140		register int soff;
141
142		symsize-= sizeof(struct nlist);
143		soff = symtab->n_un.n_strx;
144
145
146		if (soff != 0 && (symtab->n_type & N_STAB) == 0)
147			for (p = list; !ISLAST(p); p++)
148				if (!strcmp(&strtab[soff], p->n_un.n_name)) {
149					p->n_value = symtab->n_value;
150					p->n_type = symtab->n_type;
151					p->n_desc = symtab->n_desc;
152					p->n_other = symtab->n_other;
153					if (--nent <= 0)
154						break;
155				}
156		symtab++;
157	}
158	munmap(a_out_mmap, (size_t)st.st_size);
159	return (nent);
160}
161