am fe46030c: Merge changes I3bd27087,I0c9ec550,I3a0e5e86 into eclair
Merge commit 'fe46030cdd97f9cf810630541df367dd2b85cae9' into eclair-plus-aosp * commit 'fe46030cdd97f9cf810630541df367dd2b85cae9': bionic/linker: allow resolving of symbols from library back to executable bionic/linker: change lookup() to return soinfo, not base Revert "Revert "bionic/linker: fix symbol lookup during relocations""
This commit is contained in:
Iliyan Malchev
Android Git Automerger
commit
44e55ba8eb
@ -74,7 +74,7 @@ const char *dlerror(void)
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void *dlsym(void *handle, const char *symbol)
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{
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unsigned base;
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soinfo *found;
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Elf32_Sym *sym;
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unsigned bind;
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@ -90,19 +90,19 @@ void *dlsym(void *handle, const char *symbol)
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}
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if(handle == RTLD_DEFAULT) {
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sym = lookup(symbol, &base);
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sym = lookup(symbol, &found);
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} else if(handle == RTLD_NEXT) {
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sym = lookup(symbol, &base);
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sym = lookup(symbol, &found);
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} else {
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sym = lookup_in_library((soinfo*) handle, symbol);
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base = ((soinfo*) handle)->base;
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found = (soinfo*)handle;
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sym = lookup_in_library(found, symbol);
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}
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if(likely(sym != 0)) {
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bind = ELF32_ST_BIND(sym->st_info);
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if(likely((bind == STB_GLOBAL) && (sym->st_shndx != 0))) {
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unsigned ret = sym->st_value + base;
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unsigned ret = sym->st_value + found->base;
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pthread_mutex_unlock(&dl_lock);
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return (void*)ret;
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}
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143
linker/linker.c
143
linker/linker.c
@ -51,6 +51,7 @@
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#include "ba.h"
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#define ALLOW_SYMBOLS_FROM_MAIN 1
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#define SO_MAX 96
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/* Assume average path length of 64 and max 8 paths */
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@ -86,6 +87,15 @@ static soinfo sopool[SO_MAX];
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static soinfo *freelist = NULL;
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static soinfo *solist = &libdl_info;
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static soinfo *sonext = &libdl_info;
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#if ALLOW_SYMBOLS_FROM_MAIN
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static soinfo *somain; /* main process, always the one after libdl_info */
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#endif
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static inline int validate_soinfo(soinfo *si)
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{
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return (si >= sopool && si < sopool + SO_MAX) ||
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si == &libdl_info;
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}
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static char ldpaths_buf[LDPATH_BUFSIZE];
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static const char *ldpaths[LDPATH_MAX + 1];
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@ -421,53 +431,98 @@ _do_lookup_in_so(soinfo *si, const char *name, unsigned *elf_hash)
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return _elf_lookup (si, *elf_hash, name);
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}
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/* This is used by dl_sym() */
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Elf32_Sym *lookup_in_library(soinfo *si, const char *name)
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{
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unsigned unused = 0;
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return _do_lookup_in_so(si, name, &unused);
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}
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static Elf32_Sym *
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_do_lookup(soinfo *user_si, const char *name, unsigned *base)
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_do_lookup(soinfo *si, const char *name, unsigned *base)
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{
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unsigned elf_hash = 0;
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Elf32_Sym *s = NULL;
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soinfo *si;
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Elf32_Sym *s;
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unsigned *d;
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soinfo *lsi = si;
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/* Look for symbols in the local scope first (the object who is
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* searching). This happens with C++ templates on i386 for some
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* reason. */
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if (user_si) {
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s = _do_lookup_in_so(user_si, name, &elf_hash);
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if (s != NULL)
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*base = user_si->base;
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}
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s = _do_lookup_in_so(si, name, &elf_hash);
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if(s != NULL)
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goto done;
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for(si = solist; (s == NULL) && (si != NULL); si = si->next)
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{
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if((si->flags & FLAG_ERROR) || (si == user_si))
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continue;
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s = _do_lookup_in_so(si, name, &elf_hash);
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if (s != NULL) {
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*base = si->base;
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break;
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for(d = si->dynamic; *d; d += 2) {
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if(d[0] == DT_NEEDED){
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lsi = (soinfo *)d[1];
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if (!validate_soinfo(lsi)) {
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DL_ERR("%5d bad DT_NEEDED pointer in %s",
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pid, si->name);
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return 0;
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}
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DEBUG("%5d %s: looking up %s in %s\n",
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pid, si->name, name, lsi->name);
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s = _do_lookup_in_so(lsi, name, &elf_hash);
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if(s != NULL)
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goto done;
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}
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}
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if (s != NULL) {
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TRACE_TYPE(LOOKUP, "%5d %s s->st_value = 0x%08x, "
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"si->base = 0x%08x\n", pid, name, s->st_value, si->base);
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#if ALLOW_SYMBOLS_FROM_MAIN
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/* If we are resolving relocations while dlopen()ing a library, it's OK for
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* the library to resolve a symbol that's defined in the executable itself,
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* although this is rare and is generally a bad idea.
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*/
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if (somain) {
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lsi = somain;
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DEBUG("%5d %s: looking up %s in executable %s\n",
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pid, si->name, name, lsi->name);
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s = _do_lookup_in_so(lsi, name, &elf_hash);
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}
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#endif
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done:
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if(s != NULL) {
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TRACE_TYPE(LOOKUP, "%5d si %s sym %s s->st_value = 0x%08x, "
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"found in %s, base = 0x%08x\n",
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pid, si->name, name, s->st_value, lsi->name, lsi->base);
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*base = lsi->base;
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return s;
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}
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return 0;
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}
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/* This is used by dl_sym() */
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Elf32_Sym *lookup(const char *name, unsigned *base)
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/* This is used by dl_sym(). It performs symbol lookup only within the
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specified soinfo object and not in any of its dependencies.
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*/
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Elf32_Sym *lookup_in_library(soinfo *si, const char *name)
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{
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return _do_lookup(NULL, name, base);
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unsigned unused = 0;
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return _do_lookup_in_so(si, name, &unused);
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}
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/* This is used by dl_sym(). It performs a global symbol lookup.
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*/
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Elf32_Sym *lookup(const char *name, soinfo **found)
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{
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unsigned elf_hash = 0;
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Elf32_Sym *s = NULL;
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soinfo *si;
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for(si = solist; (s == NULL) && (si != NULL); si = si->next)
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{
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if(si->flags & FLAG_ERROR)
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continue;
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s = _do_lookup_in_so(si, name, &elf_hash);
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if (s != NULL) {
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*found = si;
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break;
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}
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}
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if(s != NULL) {
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TRACE_TYPE(LOOKUP, "%5d %s s->st_value = 0x%08x, "
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"si->base = 0x%08x\n", pid, name, s->st_value, si->base);
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return s;
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}
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return 0;
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}
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#if 0
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@ -1116,14 +1171,16 @@ unsigned unload_library(soinfo *si)
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for(d = si->dynamic; *d; d += 2) {
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if(d[0] == DT_NEEDED){
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TRACE("%5d %s needs to unload %s\n", pid,
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si->name, si->strtab + d[1]);
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soinfo *lsi = find_library(si->strtab + d[1]);
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if(lsi)
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soinfo *lsi = (soinfo *)d[1];
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d[1] = 0;
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if (validate_soinfo(lsi)) {
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TRACE("%5d %s needs to unload %s\n", pid,
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si->name, lsi->name);
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unload_library(lsi);
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}
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else
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DL_ERR("%5d could not unload '%s'",
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pid, si->strtab + d[1]);
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DL_ERR("%5d %s: could not unload dependent library",
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pid, si->name);
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}
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}
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@ -1641,6 +1698,14 @@ static int link_image(soinfo *si, unsigned wr_offset)
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pid, si->strtab + d[1], si->name, tmp_err_buf);
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goto fail;
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}
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/* Save the soinfo of the loaded DT_NEEDED library in the payload
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of the DT_NEEDED entry itself, so that we can retrieve the
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soinfo directly later from the dynamic segment. This is a hack,
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but it allows us to map from DT_NEEDED to soinfo efficiently
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later on when we resolve relocations, trying to look up a symgol
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with dlsym().
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*/
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d[1] = (unsigned)lsi;
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lsi->refcount++;
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}
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}
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@ -1846,6 +1911,14 @@ unsigned __linker_init(unsigned **elfdata)
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exit(-1);
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}
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#if ALLOW_SYMBOLS_FROM_MAIN
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/* Set somain after we've loaded all the libraries in order to prevent
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* linking of symbols back to the main image, which is not set up at that
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* point yet.
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*/
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somain = si;
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#endif
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#if TIMING
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gettimeofday(&t1,NULL);
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PRINT("LINKER TIME: %s: %d microseconds\n", argv[0], (int) (
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@ -203,7 +203,7 @@ extern soinfo libdl_info;
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soinfo *find_library(const char *name);
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unsigned unload_library(soinfo *si);
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Elf32_Sym *lookup_in_library(soinfo *si, const char *name);
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Elf32_Sym *lookup(const char *name, unsigned *base);
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Elf32_Sym *lookup(const char *name, soinfo **found);
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const char *linker_get_error(void);
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#ifdef ANDROID_ARM_LINKER
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