Add support for hash-style=gnu
Change-Id: I171434a587420895feac8a9b1ad2342087197568
This commit is contained in:
@@ -35,6 +35,7 @@
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <unistd.h>
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#include <new>
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@@ -316,6 +317,7 @@ static void soinfo_free(soinfo* si) {
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}
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prev = trav;
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}
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if (trav == nullptr) {
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// si was not in solist
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DL_ERR("name \"%s\" is not in solist!", si->name);
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@@ -335,7 +337,6 @@ static void soinfo_free(soinfo* si) {
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g_soinfo_allocator.free(si);
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}
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static void parse_path(const char* path, const char* delimiters,
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const char** array, char* buf, size_t buf_size, size_t max_count) {
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if (path == nullptr) {
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@@ -415,39 +416,72 @@ int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void
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return rv;
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}
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static ElfW(Sym)* soinfo_elf_lookup(const soinfo* si, unsigned hash, const char* name) {
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ElfW(Sym)* symtab = si->symtab;
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ElfW(Sym)* soinfo::find_symbol_by_name(SymbolName& symbol_name) {
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return is_gnu_hash() ? gnu_lookup(symbol_name) : elf_lookup(symbol_name);
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}
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TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p %x %zd",
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name, si->name, reinterpret_cast<void*>(si->base), hash, hash % si->nbucket);
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static bool is_symbol_global_and_defined(const soinfo* si, const ElfW(Sym)* s) {
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if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
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ELF_ST_BIND(s->st_info) == STB_WEAK) {
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return s->st_shndx != SHN_UNDEF;
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} else if (ELF_ST_BIND(s->st_info) != STB_LOCAL) {
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DL_WARN("unexpected ST_BIND value: %d for '%s' in '%s'",
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ELF_ST_BIND(s->st_info), si->get_string(s->st_name), si->name);
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}
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for (unsigned n = si->bucket[hash % si->nbucket]; n != 0; n = si->chain[n]) {
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return false;
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}
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ElfW(Sym)* soinfo::gnu_lookup(SymbolName& symbol_name) {
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uint32_t hash = symbol_name.gnu_hash();
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uint32_t h2 = hash >> gnu_shift2;
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uint32_t bloom_mask_bits = sizeof(ElfW(Addr))*8;
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uint32_t word_num = (hash / bloom_mask_bits) & gnu_maskwords;
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ElfW(Addr) bloom_word = gnu_bloom_filter[word_num];
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// test against bloom filter
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if ((1 & (bloom_word >> (hash % bloom_mask_bits)) & (bloom_word >> (h2 % bloom_mask_bits))) == 0) {
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return nullptr;
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}
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// bloom test says "probably yes"...
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uint32_t n = bucket[hash % nbucket];
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if (n == 0) {
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return nullptr;
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}
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do {
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ElfW(Sym)* s = symtab + n;
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if (strcmp(si->get_string(s->st_name), name)) continue;
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if (((chain[n] ^ hash) >> 1) == 0 &&
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strcmp(get_string(s->st_name), symbol_name.get_name()) == 0 &&
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is_symbol_global_and_defined(this, s)) {
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return s;
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}
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} while ((chain[n++] & 1) == 0);
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// only concern ourselves with global and weak symbol definitions
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switch (ELF_ST_BIND(s->st_info)) {
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case STB_GLOBAL:
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case STB_WEAK:
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if (s->st_shndx == SHN_UNDEF) {
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continue;
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}
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return nullptr;
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}
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TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
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name, si->name, reinterpret_cast<void*>(s->st_value),
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static_cast<size_t>(s->st_size));
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return s;
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case STB_LOCAL:
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continue;
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default:
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__libc_fatal("ERROR: Unexpected ST_BIND value: %d for '%s' in '%s'",
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ELF_ST_BIND(s->st_info), name, si->name);
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ElfW(Sym)* soinfo::elf_lookup(SymbolName& symbol_name) {
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uint32_t hash = symbol_name.elf_hash();
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TRACE_TYPE(LOOKUP, "SEARCH %s in %s@%p h=%x(elf) %zd",
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symbol_name.get_name(), name, reinterpret_cast<void*>(base), hash, hash % nbucket);
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for (uint32_t n = bucket[hash % nbucket]; n != 0; n = chain[n]) {
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ElfW(Sym)* s = symtab + n;
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if (strcmp(get_string(s->st_name), symbol_name.get_name()) == 0 && is_symbol_global_and_defined(this, s)) {
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TRACE_TYPE(LOOKUP, "FOUND %s in %s (%p) %zd",
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symbol_name.get_name(), name, reinterpret_cast<void*>(s->st_value),
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static_cast<size_t>(s->st_size));
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return s;
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}
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}
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TRACE_TYPE(LOOKUP, "NOT FOUND %s in %s@%p %x %zd",
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name, si->name, reinterpret_cast<void*>(si->base), hash, hash % si->nbucket);
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symbol_name.get_name(), name, reinterpret_cast<void*>(base), hash, hash % nbucket);
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return nullptr;
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}
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@@ -468,22 +502,44 @@ soinfo::soinfo(const char* name, const struct stat* file_stat, off64_t file_offs
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this->rtld_flags = rtld_flags;
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}
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static unsigned elfhash(const char* _name) {
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const unsigned char* name = reinterpret_cast<const unsigned char*>(_name);
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unsigned h = 0, g;
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while (*name) {
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h = (h << 4) + *name++;
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g = h & 0xf0000000;
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h ^= g;
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h ^= g >> 24;
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uint32_t SymbolName::elf_hash() {
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if (!has_elf_hash_) {
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const unsigned char* name = reinterpret_cast<const unsigned char*>(name_);
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uint32_t h = 0, g;
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while (*name) {
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h = (h << 4) + *name++;
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g = h & 0xf0000000;
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h ^= g;
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h ^= g >> 24;
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}
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elf_hash_ = h;
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has_elf_hash_ = true;
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}
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return h;
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return elf_hash_;
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}
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uint32_t SymbolName::gnu_hash() {
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if (!has_gnu_hash_) {
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uint32_t h = 5381;
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const unsigned char* name = reinterpret_cast<const unsigned char*>(name_);
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while (*name != 0) {
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h += (h << 5) + *name++; // h*33 + c = h + h * 32 + c = h + h << 5 + c
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}
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gnu_hash_ = h;
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has_gnu_hash_ = true;
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}
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return gnu_hash_;
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}
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static ElfW(Sym)* soinfo_do_lookup(soinfo* si_from, const char* name, soinfo** si_found_in,
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const soinfo::soinfo_list_t& global_group, const soinfo::soinfo_list_t& local_group) {
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unsigned elf_hash = elfhash(name);
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SymbolName symbol_name(name);
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ElfW(Sym)* s = nullptr;
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/* "This element's presence in a shared object library alters the dynamic linker's
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@@ -499,7 +555,7 @@ static ElfW(Sym)* soinfo_do_lookup(soinfo* si_from, const char* name, soinfo** s
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*/
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if (si_from->has_DT_SYMBOLIC) {
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DEBUG("%s: looking up %s in local scope (DT_SYMBOLIC)", si_from->name, name);
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s = soinfo_elf_lookup(si_from, elf_hash, name);
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s = si_from->find_symbol_by_name(symbol_name);
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if (s != nullptr) {
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*si_found_in = si_from;
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}
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@@ -509,7 +565,7 @@ static ElfW(Sym)* soinfo_do_lookup(soinfo* si_from, const char* name, soinfo** s
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if (s == nullptr) {
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global_group.visit([&](soinfo* global_si) {
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DEBUG("%s: looking up %s in %s (from global group)", si_from->name, name, global_si->name);
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s = soinfo_elf_lookup(global_si, elf_hash, name);
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s = global_si->find_symbol_by_name(symbol_name);
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if (s != nullptr) {
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*si_found_in = global_si;
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return false;
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@@ -528,7 +584,7 @@ static ElfW(Sym)* soinfo_do_lookup(soinfo* si_from, const char* name, soinfo** s
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}
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DEBUG("%s: looking up %s in %s (from local group)", si_from->name, name, local_si->name);
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s = soinfo_elf_lookup(local_si, elf_hash, name);
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s = local_si->find_symbol_by_name(symbol_name);
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if (s != nullptr) {
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*si_found_in = local_si;
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return false;
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@@ -665,11 +721,11 @@ static bool walk_dependencies_tree(soinfo* root_soinfos[], size_t root_soinfos_s
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// specified soinfo object and its dependencies in breadth first order.
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ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name) {
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ElfW(Sym)* result = nullptr;
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uint32_t elf_hash = elfhash(name);
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SymbolName symbol_name(name);
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walk_dependencies_tree(&si, 1, [&](soinfo* current_soinfo) {
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result = soinfo_elf_lookup(current_soinfo, elf_hash, name);
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result = current_soinfo->find_symbol_by_name(symbol_name);
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if (result != nullptr) {
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*found = current_soinfo;
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return false;
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@@ -687,7 +743,7 @@ ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name) {
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specified soinfo (for RTLD_NEXT).
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*/
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ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start) {
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unsigned elf_hash = elfhash(name);
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SymbolName symbol_name(name);
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if (start == nullptr) {
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start = solist;
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@@ -699,7 +755,7 @@ ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* start)
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continue;
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}
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s = soinfo_elf_lookup(si, elf_hash, name);
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s = si->find_symbol_by_name(symbol_name);
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if (s != nullptr) {
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*found = si;
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break;
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@@ -724,16 +780,45 @@ soinfo* find_containing_library(const void* p) {
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return nullptr;
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}
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ElfW(Sym)* dladdr_find_symbol(soinfo* si, const void* addr) {
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ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - si->base;
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ElfW(Sym)* soinfo::find_symbol_by_address(const void* addr) {
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return is_gnu_hash() ? gnu_addr_lookup(addr) : elf_addr_lookup(addr);
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}
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static bool symbol_matches_soaddr(const ElfW(Sym)* sym, ElfW(Addr) soaddr) {
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return sym->st_shndx != SHN_UNDEF &&
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soaddr >= sym->st_value &&
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soaddr < sym->st_value + sym->st_size;
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}
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ElfW(Sym)* soinfo::gnu_addr_lookup(const void* addr) {
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ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - base;
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for (size_t i = 0; i < nbucket; ++i) {
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uint32_t n = bucket[i];
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if (n == 0) {
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continue;
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}
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do {
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ElfW(Sym)* sym = symtab + n;
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if (symbol_matches_soaddr(sym, soaddr)) {
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return sym;
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}
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} while ((chain[n++] & 1) == 0);
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}
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return nullptr;
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}
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ElfW(Sym)* soinfo::elf_addr_lookup(const void* addr) {
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ElfW(Addr) soaddr = reinterpret_cast<ElfW(Addr)>(addr) - base;
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// Search the library's symbol table for any defined symbol which
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// contains this address.
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for (size_t i = 0; i < si->nchain; ++i) {
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ElfW(Sym)* sym = &si->symtab[i];
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if (sym->st_shndx != SHN_UNDEF &&
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soaddr >= sym->st_value &&
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soaddr < sym->st_value + sym->st_size) {
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for (size_t i = 0; i < nchain; ++i) {
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ElfW(Sym)* sym = symtab + i;
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if (symbol_matches_soaddr(sym, soaddr)) {
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return sym;
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}
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}
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@@ -1898,6 +1983,10 @@ const char* soinfo::get_string(ElfW(Word) index) const {
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return strtab + index;
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}
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bool soinfo::is_gnu_hash() const {
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return (flags & FLAG_GNU_HASH) != 0;
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}
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bool soinfo::can_unload() const {
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return (get_rtld_flags() & (RTLD_NODELETE | RTLD_GLOBAL)) == 0;
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}
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@@ -2003,12 +2092,42 @@ bool soinfo::PrelinkImage() {
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break;
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case DT_HASH:
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if (nbucket != 0) {
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// in case of --hash-style=both, we prefer gnu
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break;
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}
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nbucket = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[0];
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nchain = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[1];
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bucket = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr + 8);
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chain = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr + 8 + nbucket * 4);
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break;
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case DT_GNU_HASH:
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if (nbucket != 0) {
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// in case of --hash-style=both, we prefer gnu
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nchain = 0;
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}
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nbucket = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[0];
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// skip symndx
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gnu_maskwords = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[2];
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gnu_shift2 = reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[3];
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gnu_bloom_filter = reinterpret_cast<ElfW(Addr)*>(load_bias + d->d_un.d_ptr + 16);
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bucket = reinterpret_cast<uint32_t*>(gnu_bloom_filter + gnu_maskwords);
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// amend chain for symndx = header[1]
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chain = bucket + nbucket - reinterpret_cast<uint32_t*>(load_bias + d->d_un.d_ptr)[1];
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if (!powerof2(gnu_maskwords)) {
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DL_ERR("invalid maskwords for gnu_hash = 0x%x, in \"%s\" expecting power to two", gnu_maskwords, name);
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return false;
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}
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--gnu_maskwords;
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flags |= FLAG_GNU_HASH;
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break;
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case DT_STRTAB:
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strtab = reinterpret_cast<const char*>(load_bias + d->d_un.d_ptr);
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break;
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@@ -2023,7 +2142,7 @@ bool soinfo::PrelinkImage() {
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case DT_SYMENT:
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if (d->d_un.d_val != sizeof(ElfW(Sym))) {
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DL_ERR("invalid DT_SYMENT: %zd", static_cast<size_t>(d->d_un.d_val));
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DL_ERR("invalid DT_SYMENT: %zd in \"%s\"", static_cast<size_t>(d->d_un.d_val), name);
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return false;
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}
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break;
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@@ -2263,7 +2382,7 @@ bool soinfo::PrelinkImage() {
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return false;
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}
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if (nbucket == 0) {
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DL_ERR("empty/missing DT_HASH in \"%s\" (built with --hash-style=gnu?)", name);
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DL_ERR("empty/missing DT_HASH/DT_GNU_HASH in \"%s\" (new hash type from the future?)", name);
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return false;
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}
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if (strtab == 0) {
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