summaryrefslogtreecommitdiff
path: root/src/ldso/dynlink.c
blob: 1c181339d95a43964502c255c529e3d7449627d5 (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
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
#define _GNU_SOURCE
#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>

static int errflag;
static char errbuf[128];

#ifdef SHARED

#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 debug {
	int ver;
	void *head;
	void (*bp)(void);
	int state;
	void *base;
};

struct dso {
	unsigned char *base;
	char *name;
	size_t *dynv;
	struct dso *next, *prev;

	int refcnt;
	Sym *syms;
	uint32_t *hashtab;
	uint32_t *ghashtab;
	char *strings;
	unsigned char *map;
	size_t map_len;
	dev_t dev;
	ino_t ino;
	signed char global;
	char relocated;
	char constructed;
	struct dso **deps;
	char *shortname;
	char buf[];
};

#include "reloc.h"

void __init_ssp(size_t *);

static struct dso *head, *tail, *libc;
static char *env_path, *sys_path, *r_path;
static int rtld_used;
static int ssp_used;
static int runtime;
static int ldd_mode;
static int ldso_fail;
static jmp_buf rtld_fail;
static pthread_rwlock_t lock;
static struct debug debug;
static size_t *auxv;

struct debug *_dl_debug_addr = &debug;

#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 int search_vec(size_t *v, size_t *r, size_t key)
{
	for (; v[0]!=key; v+=2)
		if (!v[0]) return 0;
	*r = v[1];
	return 1;
}

static uint32_t sysv_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 uint32_t gnu_hash(const char *s0)
{
	const unsigned char *s = (void *)s0;
	uint_fast32_t h = 5381;
	for (; *s; s++)
		h = h*33 + *s;
	return h;
}

static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
{
	size_t i;
	Sym *syms = dso->syms;
	uint32_t *hashtab = dso->hashtab;
	char *strings = dso->strings;
	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;
}

static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
{
	Sym *sym;
	char *strings;
	uint32_t *hashtab = dso->ghashtab;
	uint32_t nbuckets = hashtab[0];
	uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
	uint32_t h2;
	uint32_t *hashval;
	uint32_t n = buckets[h1 % nbuckets];

	if (!n) return 0;

	strings = dso->strings;
	sym = dso->syms + n;
	hashval = buckets + nbuckets + (n - hashtab[1]);

	for (h1 |= 1; ; sym++) {
		h2 = *hashval++;
		if ((h1 == (h2|1)) && !strcmp(s, strings + sym->st_name))
			return sym;
		if (h2 & 1) break;
	}

	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 = 0, gh = 0;
	void *def = 0;
	if (dso->ghashtab) {
		gh = gnu_hash(s);
		if (gh == 0xf9040207 && !strcmp(s, "dlopen")) rtld_used = 1;
		if (gh == 0xf4dc4ae && !strcmp(s, "dlsym")) rtld_used = 1;
		if (gh == 0x1f4039c9 && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
	} else {
		h = sysv_hash(s);
		if (h == 0x6b366be && !strcmp(s, "dlopen")) rtld_used = 1;
		if (h == 0x6b3afd && !strcmp(s, "dlsym")) rtld_used = 1;
		if (h == 0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
	}
	for (; dso; dso=dso->next) {
		Sym *sym;
		if (!dso->global) continue;
		if (dso->ghashtab) {
			if (!gh) gh = gnu_hash(s);
			sym = gnu_lookup(s, gh, dso);
		} else {
			if (!h) h = sysv_hash(s);
			sym = sysv_lookup(s, h, dso);
		}
		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(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
{
	unsigned char *base = dso->base;
	Sym *syms = dso->syms;
	char *strings = dso->strings;
	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) ? head->next : head;
			sym_val = (size_t)find_sym(ctx, name, IS_PLT(type));
			if (!sym_val && sym->st_info>>4 != STB_WEAK) {
				snprintf(errbuf, sizeof errbuf,
					"Error relocating %s: %s: symbol not found",
					dso->name, name);
				if (runtime) longjmp(rtld_fail, 1);
				dprintf(2, "%s\n", errbuf);
				ldso_fail = 1;
				continue;
			}
			sym_size = sym->st_size;
		} else {
			sym_val = sym_size = 0;
		}
		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)
			goto error;
		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)
				goto error;
		}
	}
	for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
		if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
			if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
				goto error;
			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;
error:
	munmap(map, map_len);
	return 0;
}

static int path_open(const char *name, const char *search, char *buf, size_t buf_size)
{
	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, buf_size, "%.*s/%s", l, s, name);
		if ((fd = open(buf, O_RDONLY))>=0) return fd;
		s += l;
	}
}

static void decode_dyn(struct dso *p)
{
	size_t dyn[DYN_CNT] = {0};
	decode_vec(p->dynv, dyn, DYN_CNT);
	p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
	p->strings = (void *)(p->base + dyn[DT_STRTAB]);
	if (dyn[0]&(1<<DT_HASH))
		p->hashtab = (void *)(p->base + dyn[DT_HASH]);
	if (search_vec(p->dynv, dyn, DT_GNU_HASH))
		p->ghashtab = (void *)(p->base + *dyn);
}

static struct dso *load_library(const char *name)
{
	char buf[2*NAME_MAX+2];
	const char *pathname;
	unsigned char *base, *map;
	size_t dyno, map_len;
	struct dso *p;
	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;
			}
		}
	}
	if (strchr(name, '/')) {
		pathname = name;
		fd = open(name, O_RDONLY);
	} else {
		/* Search for the name to see if it's already loaded */
		for (p=head->next; p; p=p->next) {
			if (p->shortname && !strcmp(p->shortname, name)) {
				p->refcnt++;
				return p;
			}
		}
		if (strlen(name) > NAME_MAX) return 0;
		fd = -1;
		if (r_path) fd = path_open(name, r_path, buf, sizeof buf);
		if (fd < 0 && env_path) fd = path_open(name, env_path, buf, sizeof buf);
		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, buf, sizeof buf);
			else fd = path_open(name, "/lib:/usr/local/lib:/usr/lib", buf, sizeof buf);
		}
		pathname = buf;
	}
	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) {
			/* If this library was previously loaded with a
			 * pathname but a search found the same inode,
			 * setup its shortname so it can be found by name. */
			if (!p->shortname) p->shortname = strrchr(p->name, '/')+1;
			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(pathname) + 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_dyn(p);

	p->dev = st.st_dev;
	p->ino = st.st_ino;
	p->refcnt = 1;
	p->name = p->buf;
	strcpy(p->name, pathname);
	/* Add a shortname only if name arg was not an explicit pathname. */
	if (pathname != name) p->shortname = strrchr(p->name, '/')+1;

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

	if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, base);

	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) {
				snprintf(errbuf, sizeof errbuf,
					"Error loading shared library %s: %m (needed by %s)",
					p->strings + p->dynv[i+1], p->name);
				if (runtime) longjmp(rtld_fail, 1);
				dprintf(2, "%s\n", errbuf);
				ldso_fail = 1;
				continue;
			}
			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);
#ifdef NEED_ARCH_RELOCS
		do_arch_relocs(p, head);
#endif
		do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
			2+(dyn[DT_PLTREL]==DT_RELA));
		do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
		do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
		p->relocated = 1;
	}
}

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

static size_t find_dyn(Phdr *ph, size_t cnt, size_t stride)
{
	for (; cnt--; ph = (void *)((char *)ph + stride))
		if (ph->p_type == PT_DYNAMIC)
			return ph->p_vaddr;
	return 0;
}

static void find_map_range(Phdr *ph, size_t cnt, size_t stride, struct dso *p)
{
	size_t min_addr = -1, max_addr = 0;
	for (; cnt--; ph = (void *)((char *)ph + stride)) {
		if (ph->p_type != PT_LOAD) continue;
		if (ph->p_vaddr < min_addr)
			min_addr = ph->p_vaddr;
		if (ph->p_vaddr+ph->p_memsz > max_addr)
			max_addr = ph->p_vaddr+ph->p_memsz;
	}
	min_addr &= -PAGE_SIZE;
	max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
	p->map = p->base + min_addr;
	p->map_len = max_addr - min_addr;
}

static void do_init_fini(struct dso *p)
{
	size_t dyn[DYN_CNT] = {0};
	for (; p; p=p->prev) {
		if (p->constructed) return;
		decode_vec(p->dynv, dyn, DYN_CNT);
		if (dyn[0] & (1<<DT_FINI))
			atexit((void (*)(void))(p->base + dyn[DT_FINI]));
		if (dyn[0] & (1<<DT_INIT))
			((void (*)(void))(p->base + dyn[DT_INIT]))();
		p->constructed = 1;
	}
}

void _dl_debug_state(void)
{
}

void *__dynlink(int argc, char **argv)
{
	size_t aux[AUX_CNT] = {0};
	size_t i;
	Phdr *phdr;
	Ehdr *ehdr;
	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;
	char *env_preload=0;
	size_t vdso_base;

	/* 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;
	}

	/* If the dynamic linker was invoked as a program itself, AT_BASE
	 * will not be set. In that case, we assume the base address is
	 * the start of the page containing the PHDRs; I don't know any
	 * better approach... */
	if (!aux[AT_BASE]) {
		aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
		aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
	}

	/* The dynamic linker load address is passed by the kernel
	 * in the AUX vector, so this is easy. */
	lib->base = (void *)aux[AT_BASE];
	lib->name = lib->shortname = "libc.so";
	lib->global = 1;
	ehdr = (void *)lib->base;
	find_map_range((void *)(aux[AT_BASE]+ehdr->e_phoff),
		ehdr->e_phnum, ehdr->e_phentsize, lib);
	lib->dynv = (void *)(lib->base + find_dyn(
		(void *)(aux[AT_BASE]+ehdr->e_phoff),
		ehdr->e_phnum, ehdr->e_phentsize));
	decode_dyn(lib);

	if (aux[AT_PHDR]) {
		size_t interp_off = 0;
		/* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
		phdr = (void *)aux[AT_PHDR];
		for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
			if (phdr->p_type == PT_PHDR)
				app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
			else if (phdr->p_type == PT_INTERP)
				interp_off = (size_t)phdr->p_vaddr;
		}
		if (interp_off) lib->name = (char *)app->base + interp_off;
		app->name = argv[0];
		app->dynv = (void *)(app->base + find_dyn(
			(void *)aux[AT_PHDR], aux[AT_PHNUM], aux[AT_PHENT]));
		find_map_range((void *)aux[AT_PHDR],
			aux[AT_PHNUM], aux[AT_PHENT], app);
	} else {
		int fd;
		char *ldname = argv[0];
		size_t dyno, l = strlen(ldname);
		if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
		*argv++ = (void *)-1;
		if (argv[0] && !strcmp(argv[0], "--")) *argv++ = (void *)-1;
		if (!argv[0]) {
			dprintf(2, "musl libc/dynamic program loader\n");
			dprintf(2, "usage: %s pathname%s\n", ldname,
				ldd_mode ? "" : " [args]");
			_exit(1);
		}
		fd = open(argv[0], O_RDONLY);
		if (fd < 0) {
			dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
			_exit(1);
		}
		runtime = 1;
		ehdr = (void *)map_library(fd, &app->map_len, &app->base, &dyno);
		if (!ehdr) {
			dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
			_exit(1);
		}
		runtime = 0;
		close(fd);
		lib->name = ldname;
		app->name = argv[0];
		app->dynv = (void *)(app->base + dyno);
		aux[AT_ENTRY] = ehdr->e_entry;
	}
	app->global = 1;
	app->constructed = 1;
	decode_dyn(app);

	/* Attach to vdso, if provided by the kernel */
	if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
		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);
		}
		vdso->name = vdso->shortname = "linux-gate.so.1";
		vdso->global = 1;
		decode_dyn(vdso);
		vdso->prev = lib;
		lib->next = vdso;
	}

	/* Initial dso chain consists only of the app. We temporarily
	 * append the dynamic linker/libc so we can relocate it, then
	 * restore the initial chain in preparation for loading third
	 * party libraries (preload/needed). */
	head = tail = app;
	libc = lib;
	app->next = lib;
	reloc_all(lib);
	app->next = 0;

	/* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */

	/* Donate unused parts of app and library mapping to malloc */
	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);

	/* Load preload/needed libraries, add their symbols to the global
	 * namespace, and perform all remaining relocations. The main
	 * program must be relocated LAST since it may contain copy
	 * relocations which depend on libraries' relocations. */
	if (env_preload) load_preload(env_preload);
	load_deps(app);
	make_global(app);
	reloc_all(app->next);
	reloc_all(app);

	if (ldso_fail) _exit(127);
	if (ldd_mode) _exit(0);

	/* Switch to runtime mode: any further failures in the dynamic
	 * linker are a reportable failure rather than a fatal startup
	 * error. If the dynamic loader (dlopen) will not be used, free
	 * all memory used by the dynamic linker. */
	runtime = 1;

#ifndef DYNAMIC_IS_RO
	for (i=0; app->dynv[i]; i+=2)
		if (app->dynv[i]==DT_DEBUG)
			app->dynv[i+1] = (size_t)&debug;
#endif
	debug.ver = 1;
	debug.bp = _dl_debug_state;
	debug.head = head;
	debug.base = lib->base;
	debug.state = 0;
	_dl_debug_state();

	if (ssp_used) __init_ssp(auxv);

	do_init_fini(tail);

	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;
	int cs;

	if (!file) return head;

	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
	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;
		p = 0;
		errflag = 1;
		goto end;
	} else p = load_library(file);

	if (!p) {
		snprintf(errbuf, sizeof errbuf,
			"Error loading shared library %s: %m", file);
		errflag = 1;
		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;
	}

	if (ssp_used) __init_ssp(auxv);

	_dl_debug_state();

	do_init_fini(tail);
end:
	pthread_rwlock_unlock(&lock);
	pthread_setcancelstate(cs, 0);
	return p;
}

static void *do_dlsym(struct dso *p, const char *s, void *ra)
{
	size_t i;
	uint32_t h = 0, gh = 0;
	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;
		void *res = find_sym(p->next, s, 0);
		if (!res) goto failed;
		return res;
	}
	if (p == head || p == RTLD_DEFAULT) {
		void *res = find_sym(head, s, 0);
		if (!res) goto failed;
		return res;
	}
	if (p->ghashtab) {
		gh = gnu_hash(s);
		sym = gnu_lookup(s, gh, p);
	} else {
		h = sysv_hash(s);
		sym = sysv_lookup(s, h, p);
	}
	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++) {
		if (p->deps[i]->ghashtab) {
			if (!gh) gh = gnu_hash(s);
			sym = gnu_lookup(s, gh, p->deps[i]);
		} else {
			if (!h) h = sysv_hash(s);
			sym = sysv_lookup(s, h, p->deps[i]);
		}
		if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
			return p->deps[i]->base + sym->st_value;
	}
failed:
	errflag = 1;
	snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
	return 0;
}

int __dladdr(void *addr, Dl_info *info)
{
	struct dso *p;
	Sym *sym;
	uint32_t nsym;
	char *strings;
	size_t i;
	void *best = 0;
	char *bestname;

	pthread_rwlock_rdlock(&lock);
	for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
	pthread_rwlock_unlock(&lock);

	if (!p) return 0;

	sym = p->syms;
	strings = p->strings;
	if (p->hashtab) {
		nsym = p->hashtab[1];
	} else {
		uint32_t *buckets;
		uint32_t *hashval;
		buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
		sym += p->ghashtab[1];
		for (i = 0; i < p->ghashtab[0]; i++) {
			if (buckets[i] > nsym)
				nsym = buckets[i];
		}
		if (nsym) {
			nsym -= p->ghashtab[1];
			hashval = buckets + p->ghashtab[0] + nsym;
			do nsym++;
			while (!(*hashval++ & 1));
		}
	}

	for (; nsym; nsym--, sym++) {
		if (sym->st_shndx && sym->st_value
		 && (1<<(sym->st_info&0xf) & OK_TYPES)
		 && (1<<(sym->st_info>>4) & OK_BINDS)) {
			void *symaddr = p->base + sym->st_value;
			if (symaddr > addr || symaddr < best)
				continue;
			best = symaddr;
			bestname = strings + sym->st_name;
			if (addr == symaddr)
				break;
		}
	}

	if (!best) return 0;

	info->dli_fname = p->name;
	info->dli_fbase = p->base;
	info->dli_sname = bestname;
	info->dli_saddr = best;

	return 1;
}

void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
{
	void *res;
	pthread_rwlock_rdlock(&lock);
	res = do_dlsym(p, s, ra);
	pthread_rwlock_unlock(&lock);
	return res;
}
#else
void *dlopen(const char *file, int mode)
{
	return 0;
}
void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
{
	return 0;
}
int __dladdr (void *addr, Dl_info *info)
{
	return 0;
}
#endif

char *dlerror()
{
	if (!errflag) return 0;
	errflag = 0;
	return errbuf;
}

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