nlist.c revision 90045 
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#include <sys/cdefs.h>
38__FBSDID("$FreeBSD: head/lib/libc/gen/nlist.c 90045 2002-02-01 01:32:19Z obrien $");
39
40#include "namespace.h"
41#include <sys/param.h>
42#include <sys/mman.h>
43#include <sys/stat.h>
44#include <sys/file.h>
45
46#include <errno.h>
47#include <a.out.h>
48#include <stdio.h>
49#include <string.h>
50#include <unistd.h>
51#include "un-namespace.h"
52
53#define _NLIST_DO_AOUT
54#define _NLIST_DO_ELF
55
56#ifdef _NLIST_DO_ELF
57#include <machine/elf.h>
58#include <elf-hints.h>
59#endif
60
61int __fdnlist(int, struct nlist *);
62int __aout_fdnlist(int, struct nlist *);
63int __elf_fdnlist(int, struct nlist *);
64
65int
66nlist(name, list)
67	const char *name;
68	struct nlist *list;
69{
70	int fd, n;
71
72	fd = _open(name, O_RDONLY, 0);
73	if (fd < 0)
74		return (-1);
75	n = __fdnlist(fd, list);
76	(void)_close(fd);
77	return (n);
78}
79
80static struct nlist_handlers {
81	int	(*fn)(int fd, struct nlist *list);
82} nlist_fn[] = {
83#ifdef _NLIST_DO_AOUT
84	{ __aout_fdnlist },
85#endif
86#ifdef _NLIST_DO_ELF
87	{ __elf_fdnlist },
88#endif
89};
90
91int
92__fdnlist(fd, list)
93	int fd;
94	struct nlist *list;
95{
96	int n = -1, i;
97
98	for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) {
99		n = (nlist_fn[i].fn)(fd, list);
100		if (n != -1)
101			break;
102	}
103	return (n);
104}
105
106#define	ISLAST(p)	(p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
107
108#ifdef _NLIST_DO_AOUT
109int
110__aout_fdnlist(fd, list)
111	int fd;
112	struct nlist *list;
113{
114	struct nlist *p, *symtab;
115	caddr_t strtab, a_out_mmap;
116	off_t stroff, symoff;
117	u_long symsize;
118	int nent;
119	struct exec * exec;
120	struct stat st;
121
122	/* check that file is at least as large as struct exec! */
123	if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
124		return (-1);
125
126	/* Check for files too large to mmap. */
127	if (st.st_size > SIZE_T_MAX) {
128		errno = EFBIG;
129		return (-1);
130	}
131
132	/*
133	 * Map the whole a.out file into our address space.
134	 * We then find the string table withing this area.
135	 * We do not just mmap the string table, as it probably
136	 * does not start at a page boundary - we save ourselves a
137	 * lot of nastiness by mmapping the whole file.
138	 *
139	 * This gives us an easy way to randomly access all the strings,
140	 * without making the memory allocation permanent as with
141	 * malloc/free (i.e., munmap will return it to the system).
142	 */
143	a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
144	if (a_out_mmap == MAP_FAILED)
145		return (-1);
146
147	exec = (struct exec *)a_out_mmap;
148	if (N_BADMAG(*exec)) {
149		munmap(a_out_mmap, (size_t)st.st_size);
150		return (-1);
151	}
152
153	symoff = N_SYMOFF(*exec);
154	symsize = exec->a_syms;
155	stroff = symoff + symsize;
156
157	/* find the string table in our mmapped area */
158	strtab = a_out_mmap + stroff;
159	symtab = (struct nlist *)(a_out_mmap + symoff);
160
161	/*
162	 * clean out any left-over information for all valid entries.
163	 * Type and value defined to be 0 if not found; historical
164	 * versions cleared other and desc as well.  Also figure out
165	 * the largest string length so don't read any more of the
166	 * string table than we have to.
167	 *
168	 * XXX clearing anything other than n_type and n_value violates
169	 * the semantics given in the man page.
170	 */
171	nent = 0;
172	for (p = list; !ISLAST(p); ++p) {
173		p->n_type = 0;
174		p->n_other = 0;
175		p->n_desc = 0;
176		p->n_value = 0;
177		++nent;
178	}
179
180	while (symsize > 0) {
181		int soff;
182
183		symsize-= sizeof(struct nlist);
184		soff = symtab->n_un.n_strx;
185
186
187		if (soff != 0 && (symtab->n_type & N_STAB) == 0)
188			for (p = list; !ISLAST(p); p++)
189				if (!strcmp(&strtab[soff], p->n_un.n_name)) {
190					p->n_value = symtab->n_value;
191					p->n_type = symtab->n_type;
192					p->n_desc = symtab->n_desc;
193					p->n_other = symtab->n_other;
194					if (--nent <= 0)
195						break;
196				}
197		symtab++;
198	}
199	munmap(a_out_mmap, (size_t)st.st_size);
200	return (nent);
201}
202#endif
203
204#ifdef _NLIST_DO_ELF
205static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);
206
207/*
208 * __elf_is_okay__ - Determine if ehdr really
209 * is ELF and valid for the target platform.
210 *
211 * WARNING:  This is NOT a ELF ABI function and
212 * as such it's use should be restricted.
213 */
214int
215__elf_is_okay__(ehdr)
216	Elf_Ehdr *ehdr;
217{
218	int retval = 0;
219	/*
220	 * We need to check magic, class size, endianess,
221	 * and version before we look at the rest of the
222	 * Elf_Ehdr structure.  These few elements are
223	 * represented in a machine independant fashion.
224	 */
225	if (IS_ELF(*ehdr) &&
226	    ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
227	    ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
228	    ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
229
230		/* Now check the machine dependant header */
231		if (ehdr->e_machine == ELF_TARG_MACH &&
232		    ehdr->e_version == ELF_TARG_VER)
233			retval = 1;
234	}
235	return retval;
236}
237
238int
239__elf_fdnlist(fd, list)
240	int fd;
241	struct nlist *list;
242{
243	struct nlist *p;
244	Elf_Off symoff = 0, symstroff = 0;
245	Elf_Word symsize = 0, symstrsize = 0;
246	Elf_Sword cc, i;
247	int nent = -1;
248	int errsave;
249	Elf_Sym sbuf[1024];
250	Elf_Sym *s;
251	Elf_Ehdr ehdr;
252	char *strtab = NULL;
253	Elf_Shdr *shdr = NULL;
254	Elf_Shdr *sh;
255	Elf_Word shdr_size;
256	void *base;
257	struct stat st;
258
259	/* Make sure obj is OK */
260	if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
261	    _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
262	    !__elf_is_okay__(&ehdr) ||
263	    _fstat(fd, &st) < 0)
264		return (-1);
265
266	/* calculate section header table size */
267	shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
268
269	/* Make sure it's not too big to mmap */
270	if (shdr_size > SIZE_T_MAX) {
271		errno = EFBIG;
272		return (-1);
273	}
274
275	/* mmap section header table */
276	base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd,
277	    (off_t)ehdr.e_shoff);
278	if (base == MAP_FAILED)
279		return (-1);
280	shdr = (Elf_Shdr *)base;
281
282	/*
283	 * Find the symbol table entry and it's corresponding
284	 * string table entry.	Version 1.1 of the ABI states
285	 * that there is only one symbol table but that this
286	 * could change in the future.
287	 */
288	for (i = 0; i < ehdr.e_shnum; i++) {
289		if (shdr[i].sh_type == SHT_SYMTAB) {
290			symoff = shdr[i].sh_offset;
291			symsize = shdr[i].sh_size;
292			symstroff = shdr[shdr[i].sh_link].sh_offset;
293			symstrsize = shdr[shdr[i].sh_link].sh_size;
294			break;
295		}
296	}
297
298	/* Check for files too large to mmap. */
299	if (symstrsize > SIZE_T_MAX) {
300		errno = EFBIG;
301		goto done;
302	}
303	/*
304	 * Map string table into our address space.  This gives us
305	 * an easy way to randomly access all the strings, without
306	 * making the memory allocation permanent as with malloc/free
307	 * (i.e., munmap will return it to the system).
308	 */
309	base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd,
310	    (off_t)symstroff);
311	if (base == MAP_FAILED)
312		goto done;
313	strtab = (char *)base;
314
315	/*
316	 * clean out any left-over information for all valid entries.
317	 * Type and value defined to be 0 if not found; historical
318	 * versions cleared other and desc as well.  Also figure out
319	 * the largest string length so don't read any more of the
320	 * string table than we have to.
321	 *
322	 * XXX clearing anything other than n_type and n_value violates
323	 * the semantics given in the man page.
324	 */
325	nent = 0;
326	for (p = list; !ISLAST(p); ++p) {
327		p->n_type = 0;
328		p->n_other = 0;
329		p->n_desc = 0;
330		p->n_value = 0;
331		++nent;
332	}
333
334	/* Don't process any further if object is stripped. */
335	if (symoff == 0)
336		goto done;
337
338	if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
339		nent = -1;
340		goto done;
341	}
342
343	while (symsize > 0 && nent > 0) {
344		cc = MIN(symsize, sizeof(sbuf));
345		if (_read(fd, sbuf, cc) != cc)
346			break;
347		symsize -= cc;
348		for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
349			char *name;
350			struct nlist *p;
351
352			name = strtab + s->st_name;
353			if (name[0] == '\0')
354				continue;
355			for (p = list; !ISLAST(p); p++) {
356				if ((p->n_un.n_name[0] == '_' &&
357				    strcmp(name, p->n_un.n_name+1) == 0)
358				    || strcmp(name, p->n_un.n_name) == 0) {
359					elf_sym_to_nlist(p, s, shdr,
360					    ehdr.e_shnum);
361					if (--nent <= 0)
362						break;
363				}
364			}
365		}
366	}
367  done:
368	errsave = errno;
369	if (strtab != NULL)
370		munmap(strtab, symstrsize);
371	if (shdr != NULL)
372		munmap(shdr, shdr_size);
373	errno = errsave;
374	return (nent);
375}
376
377/*
378 * Convert an Elf_Sym into an nlist structure.  This fills in only the
379 * n_value and n_type members.
380 */
381static void
382elf_sym_to_nlist(nl, s, shdr, shnum)
383	struct nlist *nl;
384	Elf_Sym *s;
385	Elf_Shdr *shdr;
386	int shnum;
387{
388	nl->n_value = s->st_value;
389
390	switch (s->st_shndx) {
391	case SHN_UNDEF:
392	case SHN_COMMON:
393		nl->n_type = N_UNDF;
394		break;
395	case SHN_ABS:
396		nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
397		    N_FN : N_ABS;
398		break;
399	default:
400		if (s->st_shndx >= shnum)
401			nl->n_type = N_UNDF;
402		else {
403			Elf_Shdr *sh = shdr + s->st_shndx;
404
405			nl->n_type = sh->sh_type == SHT_PROGBITS ?
406			    (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
407			    (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
408		}
409		break;
410	}
411
412	if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
413	    ELF_ST_BIND(s->st_info) == STB_WEAK)
414		nl->n_type |= N_EXT;
415}
416#endif /* _NLIST_DO_ELF */
417