summaryrefslogtreecommitdiff
path: root/src/ldso/dynlink.c
blob: b26992d38e705384008239152753d874957f0852 (plain) (blame)
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
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
#ifdef __PIC__
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <elf.h>
#include <sys/mman.h>
#include <limits.h>
#include <stdint.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#include <limits.h>
#include <elf.h>
#include <setjmp.h>
#include <pthread.h>
#include <ctype.h>
#include <dlfcn.h>

#include "reloc.h"

#if ULONG_MAX == 0xffffffff
typedef Elf32_Ehdr Ehdr;
typedef Elf32_Phdr Phdr;
typedef Elf32_Sym Sym;
#define R_TYPE(x) ((x)&255)
#define R_SYM(x) ((x)>>8)
#else
typedef Elf64_Ehdr Ehdr;
typedef Elf64_Phdr Phdr;
typedef Elf64_Sym Sym;
#define R_TYPE(x) ((x)&0xffffffff)
#define R_SYM(x) ((x)>>32)
#endif

struct dso
{
	struct dso *next, *prev;
	int refcnt;
	size_t *dynv;
	Sym *syms;
	uint32_t *hashtab;
	char *strings;
	unsigned char *base;
	unsigned char *map;
	size_t map_len;
	dev_t dev;
	ino_t ino;
	int global;
	int relocated;
	struct dso **deps;
	char *name;
	char buf[];
};

static struct dso *head, *tail, *libc;
static char *env_path, *sys_path, *r_path;
static int rtld_used;
static int runtime;
static jmp_buf rtld_fail;
static pthread_rwlock_t lock;

#define AUX_CNT 24
#define DYN_CNT 34

static void decode_vec(size_t *v, size_t *a, size_t cnt)
{
	memset(a, 0, cnt*sizeof(size_t));
	for (; v[0]; v+=2) if (v[0]<cnt) {
		a[0] |= 1ULL<<v[0];
		a[v[0]] = v[1];
	}
}

static uint32_t hash(const char *s0)
{
	const unsigned char *s = (void *)s0;
	uint_fast32_t h = 0;
	while (*s) {
		h = 16*h + *s++;
		h ^= h>>24 & 0xf0;
	}
	return h & 0xfffffff;
}

static Sym *lookup(const char *s, uint32_t h, Sym *syms, uint32_t *hashtab, char *strings)
{
	size_t i;
	for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
		if (!strcmp(s, strings+syms[i].st_name))
			return syms+i;
	}
	return 0;
}

#define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON)
#define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK)

static void *find_sym(struct dso *dso, const char *s, int need_def)
{
	uint32_t h = hash(s);
	void *def = 0;
	if (h==0x6b366be && !strcmp(s, "dlopen")) rtld_used = 1;
	if (h==0x6b3afd && !strcmp(s, "dlsym")) rtld_used = 1;
	for (; dso; dso=dso->next) {
		Sym *sym;
		if (!dso->global) continue;
		sym = lookup(s, h, dso->syms, dso->hashtab, dso->strings);
		if (sym && (!need_def || sym->st_shndx) && sym->st_value
		 && (1<<(sym->st_info&0xf) & OK_TYPES)
		 && (1<<(sym->st_info>>4) & OK_BINDS)) {
			if (def && sym->st_info>>4 == STB_WEAK) continue;
			def = dso->base + sym->st_value;
			if (sym->st_info>>4 == STB_GLOBAL) break;
		}
	}
	return def;
}

static void do_relocs(unsigned char *base, size_t *rel, size_t rel_size, size_t stride, Sym *syms, char *strings, struct dso *dso)
{
	Sym *sym;
	const char *name;
	size_t sym_val, sym_size;
	size_t *reloc_addr;
	void *ctx;
	int type;
	int sym_index;

	for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
		reloc_addr = (void *)(base + rel[0]);
		type = R_TYPE(rel[1]);
		sym_index = R_SYM(rel[1]);
		if (sym_index) {
			sym = syms + sym_index;
			name = strings + sym->st_name;
			ctx = IS_COPY(type) ? dso->next : dso;
			sym_val = (size_t)find_sym(ctx, name, IS_PLT(type));
			if (!sym_val && sym->st_info>>4 != STB_WEAK) {
				if (runtime) longjmp(rtld_fail, 1);
				dprintf(2, "%s: symbol not found\n", name);
				_exit(127);
			}
			sym_size = sym->st_size;
		}
		do_single_reloc(reloc_addr, type, sym_val, sym_size, base, rel[2]);
	}
}

/* A huge hack: to make up for the wastefulness of shared libraries
 * needing at least a page of dirty memory even if they have no global
 * data, we reclaim the gaps at the beginning and end of writable maps
 * and "donate" them to the heap by setting up minimal malloc
 * structures and then freeing them. */

static void reclaim(unsigned char *base, size_t start, size_t end)
{
	size_t *a, *z;
	start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
	end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
	if (start>end || end-start < 4*sizeof(size_t)) return;
	a = (size_t *)(base + start);
	z = (size_t *)(base + end);
	a[-2] = 1;
	a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
	z[1] = 1;
	free(a);
}

static void reclaim_gaps(unsigned char *base, Phdr *ph, size_t phent, size_t phcnt)
{
	for (; phcnt--; ph=(void *)((char *)ph+phent)) {
		if (ph->p_type!=PT_LOAD) continue;
		if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
		reclaim(base, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
		reclaim(base, ph->p_vaddr+ph->p_memsz,
			ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
	}
}

static void *map_library(int fd, size_t *lenp, unsigned char **basep, size_t *dynp)
{
	Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
	size_t phsize;
	size_t addr_min=SIZE_MAX, addr_max=0, map_len;
	size_t this_min, this_max;
	off_t off_start;
	Ehdr *eh;
	Phdr *ph;
	unsigned prot;
	unsigned char *map, *base;
	size_t dyn;
	size_t i;

	ssize_t l = read(fd, buf, sizeof buf);
	if (l<sizeof *eh) return 0;
	eh = buf;
	phsize = eh->e_phentsize * eh->e_phnum;
	if (phsize + sizeof *eh > l) return 0;
	if (eh->e_phoff + phsize > l) {
		l = pread(fd, buf+1, phsize, eh->e_phoff);
		if (l != phsize) return 0;
		eh->e_phoff = sizeof *eh;
	}
	ph = (void *)((char *)buf + eh->e_phoff);
	for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
		if (ph->p_type == PT_DYNAMIC)
			dyn = ph->p_vaddr;
		if (ph->p_type != PT_LOAD) continue;
		if (ph->p_vaddr < addr_min) {
			addr_min = ph->p_vaddr;
			off_start = ph->p_offset;
			prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
				((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
				((ph->p_flags&PF_X) ? PROT_EXEC : 0));
		}
		if (ph->p_vaddr+ph->p_memsz > addr_max) {
			addr_max = ph->p_vaddr+ph->p_memsz;
		}
	}
	if (!dyn) return 0;
	addr_max += PAGE_SIZE-1;
	addr_max &= -PAGE_SIZE;
	addr_min &= -PAGE_SIZE;
	off_start &= -PAGE_SIZE;
	map_len = addr_max - addr_min + off_start;
	/* The first time, we map too much, possibly even more than
	 * the length of the file. This is okay because we will not
	 * use the invalid part; we just need to reserve the right
	 * amount of virtual address space to map over later. */
	map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
	if (map==MAP_FAILED) return 0;
	base = map - addr_min;
	ph = (void *)((char *)buf + eh->e_phoff);
	for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
		if (ph->p_type != PT_LOAD) continue;
		/* Reuse the existing mapping for the lowest-address LOAD */
		if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
		this_min = ph->p_vaddr & -PAGE_SIZE;
		this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
		off_start = ph->p_offset & -PAGE_SIZE;
		prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
			((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
			((ph->p_flags&PF_X) ? PROT_EXEC : 0));
		if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED) {
			munmap(map, map_len);
			return 0;
		}
		if (ph->p_memsz > ph->p_filesz) {
			size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
			size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
			memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
			if (pgbrk-(size_t)base < this_max && mmap((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED) {
				munmap(map, map_len);
				return 0;
			}
		}
	}
	for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
		if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
			mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC);
			break;
		}
	if (!runtime) reclaim_gaps(base, (void *)((char *)buf + eh->e_phoff),
		eh->e_phentsize, eh->e_phnum);
	*lenp = map_len;
	*basep = base;
	*dynp = dyn;
	return map;
}

static int path_open(const char *name, const char *search)
{
	char buf[2*NAME_MAX+2];
	const char *s=search, *z;
	int l, fd;
	for (;;) {
		while (*s==':') s++;
		if (!*s) return -1;
		z = strchr(s, ':');
		l = z ? z-s : strlen(s);
		snprintf(buf, sizeof buf, "%.*s/%s", l, s, name);
		if ((fd = open(buf, O_RDONLY))>=0) return fd;
		s += l;
	}
}

static struct dso *load_library(const char *name)
{
	unsigned char *base, *map;
	size_t dyno, map_len;
	struct dso *p;
	size_t dyn[DYN_CNT] = {0};
	int fd;
	struct stat st;

	/* Catch and block attempts to reload the implementation itself */
	if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
		static const char *rp, reserved[] =
			"c\0pthread\0rt\0m\0dl\0util\0xnet\0";
		char *z = strchr(name, '.');
		if (z) {
			size_t l = z-name;
			for (rp=reserved; *rp && memcmp(name+3, rp, l-3); rp+=strlen(rp)+1);
			if (*rp) {
				if (!libc->prev) {
					tail->next = libc;
					libc->prev = tail;
					tail = libc->next ? libc->next : libc;
				}
				return libc;
			}
		}
	}
	/* Search for the name to see if it's already loaded */
	for (p=head->next; p; p=p->next) {
		if (!strcmp(p->name, name)) {
			p->refcnt++;
			return p;
		}
	}
	if (strchr(name, '/')) {
		fd = open(name, O_RDONLY);
	} else {
		if (strlen(name) > NAME_MAX) return 0;
		fd = -1;
		if (r_path) fd = path_open(name, r_path);
		if (fd < 0 && env_path) fd = path_open(name, env_path);
		if (fd < 0) {
			if (!sys_path) {
				FILE *f = fopen(ETC_LDSO_PATH, "r");
				if (f) {
					if (getline(&sys_path, (size_t[1]){0}, f) > 0)
						sys_path[strlen(sys_path)-1]=0;
					fclose(f);
				}
			}
			if (sys_path) fd = path_open(name, sys_path);
			else fd = path_open(name, "/lib:/usr/local/lib:/usr/lib");
		}
	}
	if (fd < 0) return 0;
	if (fstat(fd, &st) < 0) {
		close(fd);
		return 0;
	}
	for (p=head->next; p; p=p->next) {
		if (p->dev == st.st_dev && p->ino == st.st_ino) {
			close(fd);
			p->refcnt++;
			return p;
		}
	}
	map = map_library(fd, &map_len, &base, &dyno);
	close(fd);
	if (!map) return 0;
	p = calloc(1, sizeof *p + strlen(name) + 1);
	if (!p) {
		munmap(map, map_len);
		return 0;
	}

	p->map = map;
	p->map_len = map_len;
	p->base = base;
	p->dynv = (void *)(base + dyno);
	decode_vec(p->dynv, dyn, DYN_CNT);

	p->syms = (void *)(base + dyn[DT_SYMTAB]);
	p->hashtab = (void *)(base + dyn[DT_HASH]);
	p->strings = (void *)(base + dyn[DT_STRTAB]);
	p->dev = st.st_dev;
	p->ino = st.st_ino;
	p->refcnt = 1;
	p->name = p->buf;
	strcpy(p->name, name);

	tail->next = p;
	p->prev = tail;
	tail = p;

	return p;
}

static void load_deps(struct dso *p)
{
	size_t i, ndeps=0;
	struct dso ***deps = &p->deps, **tmp, *dep;
	for (; p; p=p->next) {
		for (i=0; p->dynv[i]; i+=2) {
			if (p->dynv[i] != DT_RPATH) continue;
			r_path = (void *)(p->strings + p->dynv[i+1]);
		}
		for (i=0; p->dynv[i]; i+=2) {
			if (p->dynv[i] != DT_NEEDED) continue;
			dep = load_library(p->strings + p->dynv[i+1]);
			if (!dep) {
				if (runtime) longjmp(rtld_fail, 1);
				dprintf(2, "%s: %m (needed by %s)\n",
					p->strings + p->dynv[i+1], p->name);
				_exit(127);
			}
			if (runtime) {
				tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
				if (!tmp) longjmp(rtld_fail, 1);
				tmp[ndeps++] = dep;
				tmp[ndeps] = 0;
				*deps = tmp;
			}
		}
		r_path = 0;
	}
}

static void load_preload(char *s)
{
	int tmp;
	char *z;
	for (z=s; *z; s=z) {
		for (   ; *s && isspace(*s); s++);
		for (z=s; *z && !isspace(*z); z++);
		tmp = *z;
		*z = 0;
		load_library(s);
		*z = tmp;
	}
}

static void make_global(struct dso *p)
{
	for (; p; p=p->next) p->global = 1;
}

static void reloc_all(struct dso *p)
{
	size_t dyn[DYN_CNT] = {0};
	for (; p; p=p->next) {
		if (p->relocated) continue;
		decode_vec(p->dynv, dyn, DYN_CNT);
		do_relocs(p->base, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
			2+(dyn[DT_PLTREL]==DT_RELA), p->syms, p->strings, head);
		do_relocs(p->base, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ],
			2, p->syms, p->strings, head);
		do_relocs(p->base, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ],
			3, p->syms, p->strings, head);
		p->relocated = 1;
	}
}

static void free_all(struct dso *p)
{
	struct dso *n;
	while (p) {
		n = p->next;
		if (p->map) free(p);
		p = n;
	}
}

void *__dynlink(int argc, char **argv, size_t *got)
{
	size_t *auxv, aux[AUX_CNT] = {0};
	size_t app_dyn[DYN_CNT] = {0};
	size_t lib_dyn[DYN_CNT] = {0};
	size_t vdso_dyn[DYN_CNT] = {0};
	size_t i;
	Phdr *phdr;
	Ehdr *ehdr;
	size_t *lib_dynv;
	static struct dso builtin_dsos[3];
	struct dso *const app = builtin_dsos+0;
	struct dso *const lib = builtin_dsos+1;
	struct dso *const vdso = builtin_dsos+2;
	size_t vdso_base=0;
	char *env_preload=0;

	/* Find aux vector just past environ[] */
	for (i=argc+1; argv[i]; i++)
		if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
			env_path = argv[i]+16;
		else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
			env_preload = argv[i]+11;
	auxv = (void *)(argv+i+1);

	decode_vec(auxv, aux, AUX_CNT);

	/* Only trust user/env if kernel says we're not suid/sgid */
	if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
	  || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
		env_path = 0;
		env_preload = 0;
	}

	for (i=0; auxv[i]; i+=2) {
		if (auxv[i]==AT_SYSINFO_EHDR) {
			vdso_base = auxv[i+1];
			break;
		}
	}

	/* Find the dynamic linker's DYNAMIC section and decode it */
	ehdr = (void *)aux[AT_BASE];
	phdr = (void *)(aux[AT_BASE] + ehdr->e_phoff);
	for (i=ehdr->e_phnum; i--; phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
		if (phdr->p_type == PT_DYNAMIC) {
			lib_dynv = (void *)(aux[AT_BASE] + phdr->p_vaddr);
			decode_vec(lib_dynv, lib_dyn, DYN_CNT);
			break;
		}
	}

	/* Find the program image's DYNAMIC section and decode it */
	phdr = (void *)aux[AT_PHDR];
	for (i=aux[AT_PHNUM]; i--; phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
		if (phdr->p_type == PT_DYNAMIC) {
			decode_vec((void *)phdr->p_vaddr, app_dyn, DYN_CNT);
			break;
		}
	}

	*app = (struct dso){
		.base = 0,
		.strings = (void *)(app_dyn[DT_STRTAB]),
		.hashtab = (void *)(app_dyn[DT_HASH]),
		.syms = (void *)(app_dyn[DT_SYMTAB]),
		.dynv = (void *)(phdr->p_vaddr),
		.name = argv[0],
		.global = 1,
		.next = lib
	};

	*lib = (struct dso){
		.base = (void *)aux[AT_BASE],
		.strings = (void *)(aux[AT_BASE]+lib_dyn[DT_STRTAB]),
		.hashtab = (void *)(aux[AT_BASE]+lib_dyn[DT_HASH]),
		.syms = (void *)(aux[AT_BASE]+lib_dyn[DT_SYMTAB]),
		.dynv = lib_dynv,
		.name = "libc.so",
		.global = 1,
		.relocated = 1
	};

	if (vdso_base) {
		ehdr = (void *)vdso_base;
		phdr = (void *)(vdso_base + ehdr->e_phoff);
		for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
			if (phdr->p_type == PT_DYNAMIC)
				vdso->dynv = (void *)(vdso_base + phdr->p_offset);
			if (phdr->p_type == PT_LOAD)
				vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
		}
		decode_vec(vdso->dynv, vdso_dyn, DYN_CNT);
		vdso->syms = (void *)(vdso->base + vdso_dyn[DT_SYMTAB]);
		vdso->hashtab = (void *)(vdso->base + vdso_dyn[DT_HASH]);
		vdso->strings = (void *)(vdso->base + vdso_dyn[DT_STRTAB]);
		vdso->name = "linux-gate.so.1";
		vdso->global = 1;

		vdso->prev = lib;
		lib->next = vdso;
	}

	/* Relocate the dynamic linker/libc */
	do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_REL]),
		lib_dyn[DT_RELSZ], 2, lib->syms, lib->strings, app);
	do_relocs((void *)aux[AT_BASE], (void *)(aux[AT_BASE]+lib_dyn[DT_RELA]),
		lib_dyn[DT_RELASZ], 3, lib->syms, lib->strings, app);

	/* At this point the standard library is fully functional */

	reclaim_gaps(app->base, (void *)aux[AT_PHDR], aux[AT_PHENT], aux[AT_PHNUM]);
	ehdr = (void *)lib->base;
	reclaim_gaps(lib->base, (void *)(lib->base+ehdr->e_phoff),
		ehdr->e_phentsize, ehdr->e_phnum);

	head = tail = app;
	libc = lib;
	app->next = 0;
	if (env_preload) load_preload(env_preload);
	load_deps(head);

	make_global(head);
	reloc_all(head->next);
	reloc_all(head);

	runtime = 1;
	if (!rtld_used) {
		free_all(head);
		free(sys_path);
		reclaim((void *)builtin_dsos, 0, sizeof builtin_dsos);
	}

	errno = 0;
	return (void *)aux[AT_ENTRY];
}

void *dlopen(const char *file, int mode)
{
	struct dso *volatile p, *orig_tail = tail, *next;
	size_t i;

	if (!file) return head;

	pthread_rwlock_wrlock(&lock);

	if (setjmp(rtld_fail)) {
		/* Clean up anything new that was (partially) loaded */
		if (p->deps) for (i=0; p->deps[i]; i++)
			if (p->deps[i]->global < 0)
				p->deps[i]->global = 0;
		for (p=orig_tail->next; p; p=next) {
			next = p->next;
			munmap(p->map, p->map_len);
			free(p->deps);
			free(p);
		}
		tail = orig_tail;
		tail->next = 0;
		pthread_rwlock_unlock(&lock);
		return 0;
	}

	p = load_library(file);
	if (!p) goto end;

	/* First load handling */
	if (!p->deps) {
		load_deps(p);
		if (p->deps) for (i=0; p->deps[i]; i++)
			if (!p->deps[i]->global)
				p->deps[i]->global = -1;
		if (!p->global) p->global = -1;
		reloc_all(p);
		if (p->deps) for (i=0; p->deps[i]; i++)
			if (p->deps[i]->global < 0)
				p->deps[i]->global = 0;
		if (p->global < 0) p->global = 0;
	}

	if (mode & RTLD_GLOBAL) {
		if (p->deps) for (i=0; p->deps[i]; i++)
			p->deps[i]->global = 1;
		p->global = 1;
	}

end:
	pthread_rwlock_unlock(&lock);
	return p;
}

static void *do_dlsym(struct dso *p, const char *s, void *ra)
{
	size_t i;
	uint32_t h;
	Sym *sym;
	if (p == RTLD_NEXT) {
		for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
		if (!p) p=head;
		p=p->next;
	}
	if (p == head || p == RTLD_DEFAULT)
		return find_sym(head, s, 0);
	h = hash(s);
	sym = lookup(s, h, p->syms, p->hashtab, p->strings);
	if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
		return p->base + sym->st_value;
	if (p->deps) for (i=0; p->deps[i]; i++) {
		sym = lookup(s, h, p->deps[i]->syms,
			p->deps[i]->hashtab, p->deps[i]->strings);
		if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
			return p->deps[i]->base + sym->st_value;
	}
	return 0;
}

void *__dlsym(void *p, const char *s, void *ra)
{
	void *res;
	pthread_rwlock_rdlock(&lock);
	res = do_dlsym(p, s, ra);
	pthread_rwlock_unlock(&lock);
	return res;
}

char *dlerror()
{
	return "unknown error";
}

int dlclose(void *p)
{
	return 0;
}
#endif