19 #include "pthread_impl.h"
23 static char errbuf[128];
27 #if ULONG_MAX == 0xffffffff
28 typedef Elf32_Ehdr Ehdr;
29 typedef Elf32_Phdr Phdr;
30 typedef Elf32_Sym Sym;
31 #define R_TYPE(x) ((x)&255)
32 #define R_SYM(x) ((x)>>8)
34 typedef Elf64_Ehdr Ehdr;
35 typedef Elf64_Phdr Phdr;
36 typedef Elf64_Sym Sym;
37 #define R_TYPE(x) ((x)&0xffffffff)
38 #define R_SYM(x) ((x)>>32)
41 #define MAXP2(a,b) (-(-(a)&-(b)))
42 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
56 struct dso *next, *prev;
75 struct dso **deps, *needed_by;
76 char *rpath_orig, *rpath;
78 size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
79 size_t relro_start, relro_end;
81 unsigned char *new_tls;
82 int new_dtv_idx, new_tls_idx;
83 struct dso *fini_next;
103 REL_TLS, /* everything past here is TLS */
112 int __init_tp(void *);
113 void __init_libc(char **, char *);
115 const char *__libc_get_version(void);
117 static struct dso *head, *tail, *ldso, *fini_head;
118 static char *env_path, *sys_path;
119 static unsigned long long gencnt;
122 static int ldso_fail;
124 static jmp_buf *rtld_fail;
125 static pthread_rwlock_t lock;
126 static struct debug debug;
127 static size_t tls_cnt, tls_offset, tls_align = 4*sizeof(size_t);
128 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
129 static long long builtin_tls[(sizeof(struct pthread) + 64)/sizeof(long long)];
131 struct debug *_dl_debug_addr = &debug;
136 static void decode_vec(size_t *v, size_t *a, size_t cnt)
138 memset(a, 0, cnt*sizeof(size_t));
139 for (; v[0]; v+=2) if (v[0]<cnt) {
145 static int search_vec(size_t *v, size_t *r, size_t key)
147 for (; v[0]!=key; v+=2)
153 static void error(const char *fmt, ...)
157 vsnprintf(errbuf, sizeof errbuf, fmt, ap);
159 if (runtime) longjmp(*rtld_fail, 1);
160 dprintf(2, "%s\n", errbuf);
164 static uint32_t sysv_hash(const char *s0)
166 const unsigned char *s = (void *)s0;
172 return h & 0xfffffff;
175 static uint32_t gnu_hash(const char *s0)
177 const unsigned char *s = (void *)s0;
178 uint_fast32_t h = 5381;
184 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
187 Sym *syms = dso->syms;
188 uint32_t *hashtab = dso->hashtab;
189 char *strings = dso->strings;
190 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
191 if ((!dso->versym || dso->versym[i] >= 0)
192 && (!strcmp(s, strings+syms[i].st_name)))
198 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
200 Sym *syms = dso->syms;
201 char *strings = dso->strings;
202 uint32_t *hashtab = dso->ghashtab;
203 uint32_t nbuckets = hashtab[0];
204 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
207 uint32_t i = buckets[h1 % nbuckets];
211 hashval = buckets + nbuckets + (i - hashtab[1]);
213 for (h1 |= 1; ; i++) {
215 if ((!dso->versym || dso->versym[i] >= 0)
216 && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name))
224 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
225 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
227 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
229 uint32_t h = 0, gh = 0;
230 struct symdef def = {0};
231 for (; dso; dso=dso->next) {
233 if (!dso->global) continue;
235 if (!gh) gh = gnu_hash(s);
236 sym = gnu_lookup(s, gh, dso);
238 if (!h) h = sysv_hash(s);
239 sym = sysv_lookup(s, h, dso);
243 if (need_def || (sym->st_info&0xf) == STT_TLS)
246 if ((sym->st_info&0xf) != STT_TLS)
248 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
249 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
251 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
254 if (sym->st_info>>4 == STB_GLOBAL) break;
259 #define NO_INLINE_ADDEND (1<<REL_COPY | 1<<REL_GOT | 1<<REL_PLT)
261 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
263 unsigned char *base = dso->base;
264 Sym *syms = dso->syms;
265 char *strings = dso->strings;
277 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
278 astype = R_TYPE(rel[1]);
279 if (!astype) continue;
280 type = remap_rel(astype);
282 error(errbuf, sizeof errbuf,
283 "Error relocating %s: unsupported relocation type %d",
287 sym_index = R_SYM(rel[1]);
288 reloc_addr = (void *)(base + rel[0]);
290 sym = syms + sym_index;
291 name = strings + sym->st_name;
292 ctx = type==REL_COPY ? head->next : head;
293 def = find_sym(ctx, name, type==REL_PLT);
294 if (!def.sym && (sym->st_shndx != SHN_UNDEF
295 || sym->st_info>>4 != STB_WEAK)) {
296 error(errbuf, sizeof errbuf,
297 "Error relocating %s: %s: symbol not found",
307 addend = stride>2 ? rel[2]
308 : (1<<type & NO_INLINE_ADDEND) ? 0
311 sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0;
312 tls_val = def.sym ? def.sym->st_value : 0;
316 addend -= (size_t)reloc_addr;
320 *reloc_addr = sym_val + addend;
323 *reloc_addr = (size_t)base + addend;
326 if (sym) *reloc_addr = sym_val + addend;
327 else *reloc_addr = (size_t)base + addend;
330 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
333 *(uint32_t *)reloc_addr = sym_val + addend
334 - (size_t)reloc_addr;
337 *reloc_addr = def.dso->tls_id;
340 *reloc_addr = tls_val + addend;
344 *reloc_addr = tls_val + def.dso->tls_offset + TPOFF_K + addend;
348 *reloc_addr = tls_val - def.dso->tls_offset + addend;
351 *reloc_addr = def.dso->tls_offset - tls_val + addend;
358 /* A huge hack: to make up for the wastefulness of shared libraries
359 * needing at least a page of dirty memory even if they have no global
360 * data, we reclaim the gaps at the beginning and end of writable maps
361 * and "donate" them to the heap by setting up minimal malloc
362 * structures and then freeing them. */
364 static void reclaim(struct dso *dso, size_t start, size_t end)
367 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
368 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
369 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
370 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
371 if (start>end || end-start < 4*sizeof(size_t)) return;
372 a = (size_t *)(dso->base + start);
373 z = (size_t *)(dso->base + end);
375 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
380 static void reclaim_gaps(struct dso *dso)
382 Phdr *ph = dso->phdr;
383 size_t phcnt = dso->phnum;
385 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
386 if (ph->p_type!=PT_LOAD) continue;
387 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
388 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
389 reclaim(dso, ph->p_vaddr+ph->p_memsz,
390 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
394 static void *map_library(int fd, struct dso *dso)
396 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
397 void *allocated_buf=0;
399 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
400 size_t this_min, this_max;
405 unsigned char *map=MAP_FAILED, *base;
410 ssize_t l = read(fd, buf, sizeof buf);
413 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
415 phsize = eh->e_phentsize * eh->e_phnum;
416 if (phsize > sizeof buf - sizeof *eh) {
417 allocated_buf = malloc(phsize);
418 if (!allocated_buf) return 0;
419 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
420 if (l < 0) goto error;
421 if (l != phsize) goto noexec;
422 ph = ph0 = allocated_buf;
423 } else if (eh->e_phoff + phsize > l) {
424 l = pread(fd, buf+1, phsize, eh->e_phoff);
425 if (l < 0) goto error;
426 if (l != phsize) goto noexec;
427 ph = ph0 = (void *)(buf + 1);
429 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
431 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
432 if (ph->p_type == PT_DYNAMIC) {
434 } else if (ph->p_type == PT_TLS) {
435 tls_image = ph->p_vaddr;
436 dso->tls_align = ph->p_align;
437 dso->tls_len = ph->p_filesz;
438 dso->tls_size = ph->p_memsz;
439 } else if (ph->p_type == PT_GNU_RELRO) {
440 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
441 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
443 if (ph->p_type != PT_LOAD) continue;
444 if (ph->p_vaddr < addr_min) {
445 addr_min = ph->p_vaddr;
446 off_start = ph->p_offset;
447 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
448 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
449 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
451 if (ph->p_vaddr+ph->p_memsz > addr_max) {
452 addr_max = ph->p_vaddr+ph->p_memsz;
455 if (!dyn) goto noexec;
456 addr_max += PAGE_SIZE-1;
457 addr_max &= -PAGE_SIZE;
458 addr_min &= -PAGE_SIZE;
459 off_start &= -PAGE_SIZE;
460 map_len = addr_max - addr_min + off_start;
461 /* The first time, we map too much, possibly even more than
462 * the length of the file. This is okay because we will not
463 * use the invalid part; we just need to reserve the right
464 * amount of virtual address space to map over later. */
465 map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
466 if (map==MAP_FAILED) goto error;
467 /* If the loaded file is not relocatable and the requested address is
468 * not available, then the load operation must fail. */
469 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
473 base = map - addr_min;
476 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
477 if (ph->p_type != PT_LOAD) continue;
478 /* Check if the programs headers are in this load segment, and
479 * if so, record the address for use by dl_iterate_phdr. */
480 if (!dso->phdr && eh->e_phoff >= ph->p_offset
481 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
482 dso->phdr = (void *)(base + ph->p_vaddr
483 + (eh->e_phoff-ph->p_offset));
484 dso->phnum = eh->e_phnum;
485 dso->phentsize = eh->e_phentsize;
487 /* Reuse the existing mapping for the lowest-address LOAD */
488 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
489 this_min = ph->p_vaddr & -PAGE_SIZE;
490 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
491 off_start = ph->p_offset & -PAGE_SIZE;
492 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
493 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
494 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
495 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
497 if (ph->p_memsz > ph->p_filesz) {
498 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
499 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
500 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
501 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)
505 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
506 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
507 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
512 dso->map_len = map_len;
514 dso->dynv = (void *)(base+dyn);
515 if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
516 if (!runtime) reclaim_gaps(dso);
522 if (map!=MAP_FAILED) munmap(map, map_len);
527 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
532 s += strspn(s, ":\n");
533 l = strcspn(s, ":\n");
534 if (l-1 >= INT_MAX) return -1;
535 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) >= buf_size)
537 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
542 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
545 const char *s, *t, *origin;
547 if (p->rpath) return 0;
548 if (!p->rpath_orig) return -1;
549 if (!strchr(p->rpath_orig, '$')) {
550 p->rpath = p->rpath_orig;
555 while ((t=strchr(s, '$'))) {
556 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
561 if (n > SSIZE_MAX/PATH_MAX) return -1;
563 if (p->kernel_mapped) {
564 /* $ORIGIN searches cannot be performed for the main program
565 * when it is suid/sgid/AT_SECURE. This is because the
566 * pathname is under the control of the caller of execve.
567 * For libraries, however, $ORIGIN can be processed safely
568 * since the library's pathname came from a trusted source
569 * (either system paths or a call to dlopen). */
572 l = readlink("/proc/self/exe", buf, buf_size);
580 t = strrchr(origin, '/');
581 l = t ? t-origin : 0;
582 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
583 if (!p->rpath) return -1;
587 while ((t=strchr(s, '$'))) {
590 memcpy(d, origin, l);
592 /* It was determined previously that the '$' is followed
593 * either by "ORIGIN" or "{ORIGIN}". */
594 s = t + 7 + 2*(t[1]=='{');
600 static void decode_dyn(struct dso *p)
602 size_t dyn[DYN_CNT] = {0};
603 decode_vec(p->dynv, dyn, DYN_CNT);
604 p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
605 p->strings = (void *)(p->base + dyn[DT_STRTAB]);
606 if (dyn[0]&(1<<DT_HASH))
607 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
608 if (dyn[0]&(1<<DT_RPATH))
609 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
610 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
611 p->ghashtab = (void *)(p->base + *dyn);
612 if (search_vec(p->dynv, dyn, DT_VERSYM))
613 p->versym = (void *)(p->base + *dyn);
616 static struct dso *load_library(const char *name, struct dso *needed_by)
618 char buf[2*NAME_MAX+2];
619 const char *pathname;
621 struct dso *p, temp_dso = {0};
628 /* Catch and block attempts to reload the implementation itself */
629 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
630 static const char *rp, reserved[] =
631 "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
632 char *z = strchr(name, '.');
635 for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
638 /* Track which names have been resolved
639 * and only report each one once. */
640 static unsigned reported;
641 unsigned mask = 1U<<(rp-reserved);
642 if (!(reported & mask)) {
644 dprintf(1, "\t%s => %s (%p)\n",
653 if (!strcmp(name, ldso->name)) is_self = 1;
658 tail = ldso->next ? ldso->next : ldso;
662 if (strchr(name, '/')) {
664 fd = open(name, O_RDONLY|O_CLOEXEC);
666 /* Search for the name to see if it's already loaded */
667 for (p=head->next; p; p=p->next) {
668 if (p->shortname && !strcmp(p->shortname, name)) {
673 if (strlen(name) > NAME_MAX) return 0;
675 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
676 for (p=needed_by; fd < 0 && p; p=p->needed_by)
677 if (!fixup_rpath(p, buf, sizeof buf))
678 fd = path_open(name, p->rpath, buf, sizeof buf);
683 if (ldso->name[0]=='/') {
685 for (s=t=z=ldso->name; *s; s++)
686 if (*s=='/') z=t, t=s;
687 prefix_len = z-ldso->name;
688 if (prefix_len < PATH_MAX)
695 char etc_ldso_path[prefix_len + 1
696 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
697 snprintf(etc_ldso_path, sizeof etc_ldso_path,
698 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
699 (int)prefix_len, prefix);
700 FILE *f = fopen(etc_ldso_path, "rbe");
702 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
707 } else if (errno != ENOENT) {
711 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
712 fd = path_open(name, sys_path, buf, sizeof buf);
716 if (fd < 0) return 0;
717 if (fstat(fd, &st) < 0) {
721 for (p=head->next; p; p=p->next) {
722 if (p->dev == st.st_dev && p->ino == st.st_ino) {
723 /* If this library was previously loaded with a
724 * pathname but a search found the same inode,
725 * setup its shortname so it can be found by name. */
726 if (!p->shortname && pathname != name)
727 p->shortname = strrchr(p->name, '/')+1;
733 map = noload ? 0 : map_library(fd, &temp_dso);
737 /* Allocate storage for the new DSO. When there is TLS, this
738 * storage must include a reservation for all pre-existing
739 * threads to obtain copies of both the new TLS, and an
740 * extended DTV capable of storing an additional slot for
741 * the newly-loaded DSO. */
742 alloc_size = sizeof *p + strlen(pathname) + 1;
743 if (runtime && temp_dso.tls_image) {
744 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
745 + sizeof(void *) * (tls_cnt+3);
746 n_th = libc.threads_minus_1 + 1;
747 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
748 else alloc_size += n_th * per_th;
750 p = calloc(1, alloc_size);
752 munmap(map, temp_dso.map_len);
755 memcpy(p, &temp_dso, sizeof temp_dso);
760 p->needed_by = needed_by;
762 strcpy(p->name, pathname);
763 /* Add a shortname only if name arg was not an explicit pathname. */
764 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
766 if (runtime && !libc.has_thread_pointer) {
767 munmap(map, p->map_len);
772 p->tls_id = ++tls_cnt;
773 tls_align = MAXP2(tls_align, p->tls_align);
775 p->tls_offset = tls_offset + ( (tls_align-1) &
776 -(tls_offset + (uintptr_t)p->tls_image) );
777 tls_offset += p->tls_size;
779 tls_offset += p->tls_size + p->tls_align - 1;
780 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
782 p->tls_offset = tls_offset;
784 p->new_dtv = (void *)(-sizeof(size_t) &
785 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
786 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
793 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
798 static void load_deps(struct dso *p)
801 struct dso ***deps = &p->deps, **tmp, *dep;
802 for (; p; p=p->next) {
803 for (i=0; p->dynv[i]; i+=2) {
804 if (p->dynv[i] != DT_NEEDED) continue;
805 dep = load_library(p->strings + p->dynv[i+1], p);
807 error(errbuf, sizeof errbuf,
808 "Error loading shared library %s: %m (needed by %s)",
809 p->strings + p->dynv[i+1], p->name);
813 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
814 if (!tmp) longjmp(*rtld_fail, 1);
823 static void load_preload(char *s)
828 for ( ; *s && isspace(*s); s++);
829 for (z=s; *z && !isspace(*z); z++);
837 static void make_global(struct dso *p)
839 for (; p; p=p->next) p->global = 1;
842 static void reloc_all(struct dso *p)
844 size_t dyn[DYN_CNT] = {0};
845 for (; p; p=p->next) {
846 if (p->relocated) continue;
847 decode_vec(p->dynv, dyn, DYN_CNT);
848 #ifdef NEED_ARCH_RELOCS
849 do_arch_relocs(p, head);
851 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
852 2+(dyn[DT_PLTREL]==DT_RELA));
853 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
854 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
856 if (p->relro_start != p->relro_end &&
857 mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
858 error(errbuf, sizeof errbuf,
859 "Error relocating %s: RELRO protection failed: %m",
867 static void kernel_mapped_dso(struct dso *p)
869 size_t min_addr = -1, max_addr = 0, cnt;
871 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
872 if (ph->p_type == PT_DYNAMIC) {
873 p->dynv = (void *)(p->base + ph->p_vaddr);
874 } else if (ph->p_type == PT_GNU_RELRO) {
875 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
876 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
878 if (ph->p_type != PT_LOAD) continue;
879 if (ph->p_vaddr < min_addr)
880 min_addr = ph->p_vaddr;
881 if (ph->p_vaddr+ph->p_memsz > max_addr)
882 max_addr = ph->p_vaddr+ph->p_memsz;
884 min_addr &= -PAGE_SIZE;
885 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
886 p->map = p->base + min_addr;
887 p->map_len = max_addr - min_addr;
888 p->kernel_mapped = 1;
891 static void do_fini()
894 size_t dyn[DYN_CNT] = {0};
895 for (p=fini_head; p; p=p->fini_next) {
896 if (!p->constructed) continue;
897 decode_vec(p->dynv, dyn, DYN_CNT);
898 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
899 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
900 size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
901 while (n--) ((void (*)(void))*--fn)();
903 #ifndef NO_LEGACY_INITFINI
904 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
905 ((void (*)(void))(p->base + dyn[DT_FINI]))();
910 static void do_init_fini(struct dso *p)
912 size_t dyn[DYN_CNT] = {0};
913 int need_locking = libc.threads_minus_1;
914 /* Allow recursive calls that arise when a library calls
915 * dlopen from one of its constructors, but block any
916 * other threads until all ctors have finished. */
917 if (need_locking) pthread_mutex_lock(&init_fini_lock);
918 for (; p; p=p->prev) {
919 if (p->constructed) continue;
921 decode_vec(p->dynv, dyn, DYN_CNT);
922 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
923 p->fini_next = fini_head;
926 #ifndef NO_LEGACY_INITFINI
927 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
928 ((void (*)(void))(p->base + dyn[DT_INIT]))();
930 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
931 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
932 size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
933 while (n--) ((void (*)(void))*fn++)();
935 if (!need_locking && libc.threads_minus_1) {
937 pthread_mutex_lock(&init_fini_lock);
940 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
943 void _dl_debug_state(void)
949 pthread_t self = __pthread_self();
951 for (p=head; p; p=p->next) {
952 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
953 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
954 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
955 p->tls_size - p->tls_len);
956 if (p->tls_id == (size_t)self->dtv[0]) break;
960 void *__copy_tls(unsigned char *mem)
965 void **dtv = (void *)mem;
966 dtv[0] = (void *)tls_cnt;
968 td = (void *)(dtv+1);
974 mem += sizeof(void *) * (tls_cnt+1);
975 mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
977 mem += sizeof(struct pthread);
979 for (p=head; p; p=p->next) {
980 if (!p->tls_id) continue;
981 dtv[p->tls_id] = mem + p->tls_offset;
982 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
985 mem += libc.tls_size - sizeof(struct pthread);
986 mem -= (uintptr_t)mem & (tls_align-1);
989 for (p=head; p; p=p->next) {
990 if (!p->tls_id) continue;
991 dtv[p->tls_id] = mem - p->tls_offset;
992 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
999 void *__tls_get_addr(size_t *v)
1001 pthread_t self = __pthread_self();
1002 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]])
1003 return (char *)self->dtv[v[0]]+v[1];
1005 /* Block signals to make accessing new TLS async-signal-safe */
1007 pthread_sigmask(SIG_BLOCK, SIGALL_SET, &set);
1008 if (v[0]<=(size_t)self->dtv[0] && self->dtv[v[0]]) {
1009 pthread_sigmask(SIG_SETMASK, &set, 0);
1010 return (char *)self->dtv[v[0]]+v[1];
1013 /* This is safe without any locks held because, if the caller
1014 * is able to request the Nth entry of the DTV, the DSO list
1015 * must be valid at least that far out and it was synchronized
1016 * at program startup or by an already-completed call to dlopen. */
1018 for (p=head; p->tls_id != v[0]; p=p->next);
1020 /* Get new DTV space from new DSO if needed */
1021 if (v[0] > (size_t)self->dtv[0]) {
1022 void **newdtv = p->new_dtv +
1023 (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
1024 memcpy(newdtv, self->dtv,
1025 ((size_t)self->dtv[0]+1) * sizeof(void *));
1026 newdtv[0] = (void *)v[0];
1030 /* Get new TLS memory from new DSO */
1031 unsigned char *mem = p->new_tls +
1032 (p->tls_size + p->tls_align) * a_fetch_add(&p->new_tls_idx,1);
1033 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem) & (p->tls_align-1);
1034 self->dtv[v[0]] = mem;
1035 memcpy(mem, p->tls_image, p->tls_len);
1036 pthread_sigmask(SIG_SETMASK, &set, 0);
1040 static void update_tls_size()
1042 libc.tls_size = ALIGN(
1043 (1+tls_cnt) * sizeof(void *) +
1045 sizeof(struct pthread) +
1050 void *__dynlink(int argc, char **argv)
1052 size_t aux[AUX_CNT] = {0};
1056 static struct dso builtin_dsos[3];
1057 struct dso *const app = builtin_dsos+0;
1058 struct dso *const lib = builtin_dsos+1;
1059 struct dso *const vdso = builtin_dsos+2;
1060 char *env_preload=0;
1063 char **envp = argv+argc+1;
1066 /* Find aux vector just past environ[] */
1067 for (i=argc+1; argv[i]; i++)
1068 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
1069 env_path = argv[i]+16;
1070 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
1071 env_preload = argv[i]+11;
1072 auxv = (void *)(argv+i+1);
1074 decode_vec(auxv, aux, AUX_CNT);
1076 /* Only trust user/env if kernel says we're not suid/sgid */
1077 if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1078 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
1083 libc.page_size = aux[AT_PAGESZ];
1085 /* If the dynamic linker was invoked as a program itself, AT_BASE
1086 * will not be set. In that case, we assume the base address is
1087 * the start of the page containing the PHDRs; I don't know any
1088 * better approach... */
1089 if (!aux[AT_BASE]) {
1090 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
1091 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
1094 /* The dynamic linker load address is passed by the kernel
1095 * in the AUX vector, so this is easy. */
1096 lib->base = (void *)aux[AT_BASE];
1097 lib->name = lib->shortname = "libc.so";
1099 ehdr = (void *)lib->base;
1100 lib->phnum = ehdr->e_phnum;
1101 lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
1102 lib->phentsize = ehdr->e_phentsize;
1103 kernel_mapped_dso(lib);
1107 size_t interp_off = 0;
1108 size_t tls_image = 0;
1109 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1110 app->phdr = phdr = (void *)aux[AT_PHDR];
1111 app->phnum = aux[AT_PHNUM];
1112 app->phentsize = aux[AT_PHENT];
1113 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1114 if (phdr->p_type == PT_PHDR)
1115 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1116 else if (phdr->p_type == PT_INTERP)
1117 interp_off = (size_t)phdr->p_vaddr;
1118 else if (phdr->p_type == PT_TLS) {
1119 tls_image = phdr->p_vaddr;
1120 app->tls_len = phdr->p_filesz;
1121 app->tls_size = phdr->p_memsz;
1122 app->tls_align = phdr->p_align;
1125 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
1126 if (interp_off) lib->name = (char *)app->base + interp_off;
1127 if ((aux[0] & (1UL<<AT_EXECFN))
1128 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1129 app->name = (char *)aux[AT_EXECFN];
1131 app->name = argv[0];
1132 kernel_mapped_dso(app);
1135 char *ldname = argv[0];
1136 size_t l = strlen(ldname);
1137 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1138 *argv++ = (void *)-1;
1139 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1140 char *opt = argv[0]+2;
1141 *argv++ = (void *)-1;
1144 } else if (!memcmp(opt, "list", 5)) {
1146 } else if (!memcmp(opt, "library-path", 12)) {
1147 if (opt[12]=='=') env_path = opt+13;
1148 else if (opt[12]) *argv = 0;
1149 else if (*argv) env_path = *argv++;
1150 } else if (!memcmp(opt, "preload", 7)) {
1151 if (opt[7]=='=') env_preload = opt+8;
1152 else if (opt[7]) *argv = 0;
1153 else if (*argv) env_preload = *argv++;
1157 argv[-1] = (void *)-1;
1160 dprintf(2, "musl libc\n"
1162 "Dynamic Program Loader\n"
1163 "Usage: %s [options] [--] pathname%s\n",
1164 __libc_get_version(), ldname,
1165 ldd_mode ? "" : " [args]");
1168 fd = open(argv[0], O_RDONLY);
1170 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1174 ehdr = (void *)map_library(fd, app);
1176 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1182 app->name = argv[0];
1183 aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry;
1184 /* Find the name that would have been used for the dynamic
1185 * linker had ldd not taken its place. */
1187 for (i=0; i<app->phnum; i++) {
1188 if (app->phdr[i].p_type == PT_INTERP)
1189 lib->name = (void *)(app->base
1190 + app->phdr[i].p_vaddr);
1192 dprintf(1, "\t%s (%p)\n", lib->name, lib->base);
1195 if (app->tls_size) {
1196 app->tls_id = tls_cnt = 1;
1198 app->tls_offset = 0;
1199 tls_offset = app->tls_size
1200 + ( -((uintptr_t)app->tls_image + app->tls_size)
1201 & (app->tls_align-1) );
1203 tls_offset = app->tls_offset = app->tls_size
1204 + ( -((uintptr_t)app->tls_image + app->tls_size)
1205 & (app->tls_align-1) );
1207 tls_align = MAXP2(tls_align, app->tls_align);
1212 /* Attach to vdso, if provided by the kernel */
1213 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1214 ehdr = (void *)vdso_base;
1215 vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
1216 vdso->phnum = ehdr->e_phnum;
1217 vdso->phentsize = ehdr->e_phentsize;
1218 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1219 if (phdr->p_type == PT_DYNAMIC)
1220 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
1221 if (phdr->p_type == PT_LOAD)
1222 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1225 vdso->shortname = "linux-gate.so.1";
1232 /* Initial dso chain consists only of the app. We temporarily
1233 * append the dynamic linker/libc so we can relocate it, then
1234 * restore the initial chain in preparation for loading third
1235 * party libraries (preload/needed). */
1242 /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
1244 /* Donate unused parts of app and library mapping to malloc */
1248 /* Load preload/needed libraries, add their symbols to the global
1249 * namespace, and perform all remaining relocations. The main
1250 * program must be relocated LAST since it may contain copy
1251 * relocations which depend on libraries' relocations. */
1252 if (env_preload) load_preload(env_preload);
1256 #ifndef DYNAMIC_IS_RO
1257 for (i=0; app->dynv[i]; i+=2)
1258 if (app->dynv[i]==DT_DEBUG)
1259 app->dynv[i+1] = (size_t)&debug;
1262 reloc_all(app->next);
1266 if (libc.tls_size > sizeof builtin_tls) {
1267 initial_tls = calloc(libc.tls_size, 1);
1269 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1270 argv[0], libc.tls_size);
1274 initial_tls = builtin_tls;
1276 if (__init_tp(__copy_tls(initial_tls)) < 0 && tls_cnt) {
1277 dprintf(2, "%s: Thread-local storage not supported by kernel.\n", argv[0]);
1281 if (ldso_fail) _exit(127);
1282 if (ldd_mode) _exit(0);
1284 /* Switch to runtime mode: any further failures in the dynamic
1285 * linker are a reportable failure rather than a fatal startup
1286 * error. If the dynamic loader (dlopen) will not be used, free
1287 * all memory used by the dynamic linker. */
1291 debug.bp = _dl_debug_state;
1293 debug.base = lib->base;
1297 __init_libc(envp, argv[0]);
1302 return (void *)aux[AT_ENTRY];
1305 void *dlopen(const char *file, int mode)
1307 struct dso *volatile p, *orig_tail, *next;
1308 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1313 if (!file) return head;
1315 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1316 pthread_rwlock_wrlock(&lock);
1320 orig_tls_cnt = tls_cnt;
1321 orig_tls_offset = tls_offset;
1322 orig_tls_align = tls_align;
1324 noload = mode & RTLD_NOLOAD;
1327 if (setjmp(*rtld_fail)) {
1328 /* Clean up anything new that was (partially) loaded */
1329 if (p && p->deps) for (i=0; p->deps[i]; i++)
1330 if (p->deps[i]->global < 0)
1331 p->deps[i]->global = 0;
1332 for (p=orig_tail->next; p; p=next) {
1334 munmap(p->map, p->map_len);
1338 tls_cnt = orig_tls_cnt;
1339 tls_offset = orig_tls_offset;
1340 tls_align = orig_tls_align;
1346 } else p = load_library(file, head);
1349 snprintf(errbuf, sizeof errbuf, noload ?
1350 "Library %s is not already loaded" :
1351 "Error loading shared library %s: %m",
1357 /* First load handling */
1360 if (p->deps) for (i=0; p->deps[i]; i++)
1361 if (!p->deps[i]->global)
1362 p->deps[i]->global = -1;
1363 if (!p->global) p->global = -1;
1365 if (p->deps) for (i=0; p->deps[i]; i++)
1366 if (p->deps[i]->global < 0)
1367 p->deps[i]->global = 0;
1368 if (p->global < 0) p->global = 0;
1371 if (mode & RTLD_GLOBAL) {
1372 if (p->deps) for (i=0; p->deps[i]; i++)
1373 p->deps[i]->global = 1;
1383 pthread_rwlock_unlock(&lock);
1384 if (p) do_init_fini(orig_tail);
1385 pthread_setcancelstate(cs, 0);
1389 static int invalid_dso_handle(void *h)
1392 for (p=head; p; p=p->next) if (h==p) return 0;
1393 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1398 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1401 uint32_t h = 0, gh = 0;
1403 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1404 if (p == RTLD_DEFAULT) {
1406 } else if (p == RTLD_NEXT) {
1407 for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1411 struct symdef def = find_sym(p, s, 0);
1412 if (!def.sym) goto failed;
1413 if ((def.sym->st_info&0xf) == STT_TLS)
1414 return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1415 return def.dso->base + def.sym->st_value;
1417 if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p))
1421 sym = gnu_lookup(s, gh, p);
1424 sym = sysv_lookup(s, h, p);
1426 if (sym && (sym->st_info&0xf) == STT_TLS)
1427 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1428 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1429 return p->base + sym->st_value;
1430 if (p->deps) for (i=0; p->deps[i]; i++) {
1431 if (p->deps[i]->ghashtab) {
1432 if (!gh) gh = gnu_hash(s);
1433 sym = gnu_lookup(s, gh, p->deps[i]);
1435 if (!h) h = sysv_hash(s);
1436 sym = sysv_lookup(s, h, p->deps[i]);
1438 if (sym && (sym->st_info&0xf) == STT_TLS)
1439 return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1440 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1441 return p->deps[i]->base + sym->st_value;
1445 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1449 int __dladdr(const void *addr, Dl_info *info)
1459 pthread_rwlock_rdlock(&lock);
1460 for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1461 pthread_rwlock_unlock(&lock);
1466 strings = p->strings;
1468 nsym = p->hashtab[1];
1472 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1473 sym += p->ghashtab[1];
1474 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1475 if (buckets[i] > nsym)
1479 nsym -= p->ghashtab[1];
1480 hashval = buckets + p->ghashtab[0] + nsym;
1482 while (!(*hashval++ & 1));
1486 for (; nsym; nsym--, sym++) {
1488 && (1<<(sym->st_info&0xf) & OK_TYPES)
1489 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1490 void *symaddr = p->base + sym->st_value;
1491 if (symaddr > addr || symaddr < best)
1494 bestname = strings + sym->st_name;
1495 if (addr == symaddr)
1500 if (!best) return 0;
1502 info->dli_fname = p->name;
1503 info->dli_fbase = p->base;
1504 info->dli_sname = bestname;
1505 info->dli_saddr = best;
1510 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1513 pthread_rwlock_rdlock(&lock);
1514 res = do_dlsym(p, s, ra);
1515 pthread_rwlock_unlock(&lock);
1519 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1521 struct dso *current;
1522 struct dl_phdr_info info;
1524 for(current = head; current;) {
1525 info.dlpi_addr = (uintptr_t)current->base;
1526 info.dlpi_name = current->name;
1527 info.dlpi_phdr = current->phdr;
1528 info.dlpi_phnum = current->phnum;
1529 info.dlpi_adds = gencnt;
1531 info.dlpi_tls_modid = current->tls_id;
1532 info.dlpi_tls_data = current->tls_image;
1534 ret = (callback)(&info, sizeof (info), data);
1536 if (ret != 0) break;
1538 pthread_rwlock_rdlock(&lock);
1539 current = current->next;
1540 pthread_rwlock_unlock(&lock);
1545 static int invalid_dso_handle(void *h)
1547 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1551 void *dlopen(const char *file, int mode)
1555 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1559 int __dladdr (const void *addr, Dl_info *info)
1565 int __dlinfo(void *dso, int req, void *res)
1567 if (invalid_dso_handle(dso)) return -1;
1568 if (req != RTLD_DI_LINKMAP) {
1569 snprintf(errbuf, sizeof errbuf, "Unsupported request %d", req);
1573 *(struct link_map **)res = dso;
1579 if (!errflag) return 0;
1584 int dlclose(void *p)
1586 return invalid_dso_handle(p);