summaryrefslogtreecommitdiffstats
path: root/lib/libc/gen/nlist.c
blob: 1361af3366c98a1edec5135c95ab73c37c9f234d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)nlist.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "namespace.h"
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <arpa/inet.h>

#include <errno.h>
#include <a.out.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"

#define _NLIST_DO_AOUT
#define _NLIST_DO_ELF

#ifdef _NLIST_DO_ELF
#include <machine/elf.h>
#include <elf-hints.h>
#endif

int __fdnlist(int, struct nlist *);
int __aout_fdnlist(int, struct nlist *);
int __elf_fdnlist(int, struct nlist *);

int
nlist(name, list)
	const char *name;
	struct nlist *list;
{
	int fd, n;

	fd = _open(name, O_RDONLY, 0);
	if (fd < 0)
		return (-1);
	n = __fdnlist(fd, list);
	(void)_close(fd);
	return (n);
}

static struct nlist_handlers {
	int	(*fn)(int fd, struct nlist *list);
} nlist_fn[] = {
#ifdef _NLIST_DO_AOUT
	{ __aout_fdnlist },
#endif
#ifdef _NLIST_DO_ELF
	{ __elf_fdnlist },
#endif
};

int
__fdnlist(fd, list)
	int fd;
	struct nlist *list;
{
	int n = -1, i;

	for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); i++) {
		n = (nlist_fn[i].fn)(fd, list);
		if (n != -1)
			break;
	}
	return (n);
}

#define	ISLAST(p)	(p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)

#ifdef _NLIST_DO_AOUT
int
__aout_fdnlist(fd, list)
	int fd;
	struct nlist *list;
{
	struct nlist *p, *symtab;
	caddr_t strtab, a_out_mmap;
	off_t stroff, symoff;
	u_long symsize;
	int nent;
	struct exec * exec;
	struct stat st;

	/* check that file is at least as large as struct exec! */
	if ((_fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
		return (-1);

	/* Check for files too large to mmap. */
	if (st.st_size > SIZE_T_MAX) {
		errno = EFBIG;
		return (-1);
	}

	/*
	 * Map the whole a.out file into our address space.
	 * We then find the string table withing this area.
	 * We do not just mmap the string table, as it probably
	 * does not start at a page boundary - we save ourselves a
	 * lot of nastiness by mmapping the whole file.
	 *
	 * This gives us an easy way to randomly access all the strings,
	 * without making the memory allocation permanent as with
	 * malloc/free (i.e., munmap will return it to the system).
	 */
	a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
	if (a_out_mmap == MAP_FAILED)
		return (-1);

	exec = (struct exec *)a_out_mmap;
	if (N_BADMAG(*exec)) {
		munmap(a_out_mmap, (size_t)st.st_size);
		return (-1);
	}

	symoff = N_SYMOFF(*exec);
	symsize = exec->a_syms;
	stroff = symoff + symsize;

	/* find the string table in our mmapped area */
	strtab = a_out_mmap + stroff;
	symtab = (struct nlist *)(a_out_mmap + symoff);

	/*
	 * 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.
	 *
	 * XXX clearing anything other than n_type and n_value violates
	 * the semantics given in the man page.
	 */
	nent = 0;
	for (p = list; !ISLAST(p); ++p) {
		p->n_type = 0;
		p->n_other = 0;
		p->n_desc = 0;
		p->n_value = 0;
		++nent;
	}

	while (symsize > 0) {
		int soff;

		symsize-= sizeof(struct nlist);
		soff = symtab->n_un.n_strx;


		if (soff != 0 && (symtab->n_type & N_STAB) == 0)
			for (p = list; !ISLAST(p); p++)
				if (!strcmp(&strtab[soff], p->n_un.n_name)) {
					p->n_value = symtab->n_value;
					p->n_type = symtab->n_type;
					p->n_desc = symtab->n_desc;
					p->n_other = symtab->n_other;
					if (--nent <= 0)
						break;
				}
		symtab++;
	}
	munmap(a_out_mmap, (size_t)st.st_size);
	return (nent);
}
#endif

#ifdef _NLIST_DO_ELF
static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);

/*
 * __elf_is_okay__ - Determine if ehdr really
 * is ELF and valid for the target platform.
 *
 * WARNING:  This is NOT an ELF ABI function and
 * as such its use should be restricted.
 */
int
__elf_is_okay__(Elf_Ehdr *ehdr)
{
	int retval = 0;
	/*
	 * We need to check magic, class size, endianess,
	 * and version before we look at the rest of the
	 * Elf_Ehdr structure.  These few elements are
	 * represented in a machine independant fashion.
	 */
	if (IS_ELF(*ehdr) &&
	    ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
	    ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
	    ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {

		/* Now check the machine dependant header */
		if (ehdr->e_machine == ELF_TARG_MACH &&
		    ehdr->e_version == ELF_TARG_VER)
			retval = 1;
	}
	return retval;
}

int
__elf_fdnlist(fd, list)
	int fd;
	struct nlist *list;
{
	struct nlist *p;
	Elf_Off symoff = 0, symstroff = 0;
	Elf_Size symsize = 0, symstrsize = 0;
	Elf_Ssize cc, i;
	int nent = -1;
	int errsave;
	Elf_Sym sbuf[1024];
	Elf_Sym *s;
	Elf_Ehdr ehdr;
	char *strtab = NULL;
	Elf_Shdr *shdr = NULL;
	Elf_Size shdr_size;
	void *base;
	struct stat st;

	/* Make sure obj is OK */
	if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
	    _read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
	    !__elf_is_okay__(&ehdr) ||
	    _fstat(fd, &st) < 0)
		return (-1);

	/* calculate section header table size */
	shdr_size = ehdr.e_shentsize * ehdr.e_shnum;

	/* Make sure it's not too big to mmap */
	if (shdr_size > SIZE_T_MAX) {
		errno = EFBIG;
		return (-1);
	}

	/* mmap section header table */
	base = mmap(NULL, (size_t)shdr_size, PROT_READ, 0, fd,
	    (off_t)ehdr.e_shoff);
	if (base == MAP_FAILED)
		return (-1);
	shdr = (Elf_Shdr *)base;

	/*
	 * Find the symbol table entry and it's corresponding
	 * string table entry.	Version 1.1 of the ABI states
	 * that there is only one symbol table but that this
	 * could change in the future.
	 */
	for (i = 0; i < ehdr.e_shnum; i++) {
		if (shdr[i].sh_type == SHT_SYMTAB) {
			symoff = shdr[i].sh_offset;
			symsize = shdr[i].sh_size;
			symstroff = shdr[shdr[i].sh_link].sh_offset;
			symstrsize = shdr[shdr[i].sh_link].sh_size;
			break;
		}
	}

	/* Check for files too large to mmap. */
	if (symstrsize > SIZE_T_MAX) {
		errno = EFBIG;
		goto done;
	}
	/*
	 * Map string table into our address space.  This gives us
	 * an easy way to randomly access all the strings, without
	 * making the memory allocation permanent as with malloc/free
	 * (i.e., munmap will return it to the system).
	 */
	base = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd,
	    (off_t)symstroff);
	if (base == MAP_FAILED)
		goto done;
	strtab = (char *)base;

	/*
	 * 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.
	 *
	 * XXX clearing anything other than n_type and n_value violates
	 * the semantics given in the man page.
	 */
	nent = 0;
	for (p = list; !ISLAST(p); ++p) {
		p->n_type = 0;
		p->n_other = 0;
		p->n_desc = 0;
		p->n_value = 0;
		++nent;
	}

	/* Don't process any further if object is stripped. */
	if (symoff == 0)
		goto done;
		
	if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
		nent = -1;
		goto done;
	}

	while (symsize > 0 && nent > 0) {
		cc = MIN(symsize, sizeof(sbuf));
		if (_read(fd, sbuf, cc) != cc)
			break;
		symsize -= cc;
		for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
			char *name;
			struct nlist *p;

			name = strtab + s->st_name;
			if (name[0] == '\0')
				continue;
			for (p = list; !ISLAST(p); p++) {
				if ((p->n_un.n_name[0] == '_' &&
				    strcmp(name, p->n_un.n_name+1) == 0)
				    || strcmp(name, p->n_un.n_name) == 0) {
					elf_sym_to_nlist(p, s, shdr,
					    ehdr.e_shnum);
					if (--nent <= 0)
						break;
				}
			}
		}
	}
  done:
	errsave = errno;
	if (strtab != NULL)
		munmap(strtab, symstrsize);
	if (shdr != NULL)
		munmap(shdr, shdr_size);
	errno = errsave;
	return (nent);
}

/*
 * Convert an Elf_Sym into an nlist structure.  This fills in only the
 * n_value and n_type members.
 */
static void
elf_sym_to_nlist(nl, s, shdr, shnum)
	struct nlist *nl;
	Elf_Sym *s;
	Elf_Shdr *shdr;
	int shnum;
{
	nl->n_value = s->st_value;

	switch (s->st_shndx) {
	case SHN_UNDEF:
	case SHN_COMMON:
		nl->n_type = N_UNDF;
		break;
	case SHN_ABS:
		nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
		    N_FN : N_ABS;
		break;
	default:
		if (s->st_shndx >= shnum)
			nl->n_type = N_UNDF;
		else {
			Elf_Shdr *sh = shdr + s->st_shndx;

			nl->n_type = sh->sh_type == SHT_PROGBITS ?
			    (sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
			    (sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
		}
		break;
	}

	if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
	    ELF_ST_BIND(s->st_info) == STB_WEAK)
		nl->n_type |= N_EXT;
}
#endif /* _NLIST_DO_ELF */
OpenPOWER on IntegriCloud