The Tor Browser / file revision

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this file,

  * You can obtain one at http://mozilla.org/MPL/2.0/. */

 #include <cstring>

 #include <sys/mman.h>

 #include <vector>

 #include <dlfcn.h>

 #include "CustomElf.h"

 #include "Mappable.h"

 #include "Logging.h"

 using namespace Elf;

 using namespace mozilla;

 /* TODO: Fill ElfLoader::Singleton.lastError on errors. */

 /* Function used to report library mappings from the custom linker to Gecko

  * crash reporter */

 #ifdef ANDROID

 extern "C" {

   void report_mapping(char *name, void *base, uint32_t len, uint32_t offset);

 }

 #else

 #define report_mapping(...)

 #endif

 const Ehdr *Ehdr::validate(const void *buf)

 {

   if (!buf || buf == MAP_FAILED)

     return nullptr;

   const Ehdr *ehdr = reinterpret_cast<const Ehdr *>(buf);

   /* Only support ELF executables or libraries for the host system */

   if (memcmp(ELFMAG, &ehdr->e_ident, SELFMAG) ||

       ehdr->e_ident[EI_CLASS] != ELFCLASS ||

       ehdr->e_ident[EI_DATA] != ELFDATA ||

       ehdr->e_ident[EI_VERSION] != 1 ||

       (ehdr->e_ident[EI_OSABI] != ELFOSABI && ehdr->e_ident[EI_OSABI] != ELFOSABI_NONE) ||

 #ifdef EI_ABIVERSION

       ehdr->e_ident[EI_ABIVERSION] != ELFABIVERSION ||

 #endif

       (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) ||

       ehdr->e_machine != ELFMACHINE ||

       ehdr->e_version != 1 ||

       ehdr->e_phentsize != sizeof(Phdr))

     return nullptr;

   return ehdr;

 }

 namespace {

 void debug_phdr(const char *type, const Phdr *phdr)

 {

   DEBUG_LOG("%s @0x%08" PRIxAddr " ("

             "filesz: 0x%08" PRIxAddr ", "

             "memsz: 0x%08" PRIxAddr ", "

             "offset: 0x%08" PRIxAddr ", "

             "flags: %c%c%c)",

             type, phdr->p_vaddr, phdr->p_filesz, phdr->p_memsz,

             phdr->p_offset, phdr->p_flags & PF_R ? 'r' : '-',

             phdr->p_flags & PF_W ? 'w' : '-', phdr->p_flags & PF_X ? 'x' : '-');

 }

 static int p_flags_to_mprot(Word flags)

 {

   return ((flags & PF_X) ? PROT_EXEC : 0) |

          ((flags & PF_W) ? PROT_WRITE : 0) |

          ((flags & PF_R) ? PROT_READ : 0);

 }

 void

 __void_stub(void)

 {

 }

 } /* anonymous namespace */

 /**

  * RAII wrapper for a mapping of the first page off a Mappable object.

  * This calls Mappable::munmap instead of system munmap.

  */

 class Mappable1stPagePtr: public GenericMappedPtr<Mappable1stPagePtr> {

 public:

   Mappable1stPagePtr(Mappable *mappable)

   : GenericMappedPtr<Mappable1stPagePtr>(

       mappable->mmap(nullptr, PageSize(), PROT_READ, MAP_PRIVATE, 0))

   , mappable(mappable)

   {

     /* Ensure the content of this page */

     mappable->ensure(*this);

   }

 private:

   friend class GenericMappedPtr<Mappable1stPagePtr>;

   void munmap(void *buf, size_t length) {

     mappable->munmap(buf, length);

   }

   mozilla::RefPtr<Mappable> mappable;

 };

 TemporaryRef<LibHandle>

 CustomElf::Load(Mappable *mappable, const char *path, int flags)

 {

   DEBUG_LOG("CustomElf::Load(\"%s\", 0x%x) = ...", path, flags);

   if (!mappable)

     return nullptr;

   /* Keeping a RefPtr of the CustomElf is going to free the appropriate

    * resources when returning nullptr */

   RefPtr<CustomElf> elf = new CustomElf(mappable, path);

   /* Map the first page of the Elf object to access Elf and program headers */

   Mappable1stPagePtr ehdr_raw(mappable);

   if (ehdr_raw == MAP_FAILED)

     return nullptr;

   const Ehdr *ehdr = Ehdr::validate(ehdr_raw);

   if (!ehdr)

     return nullptr;

   /* Scan Elf Program Headers and gather some information about them */

   std::vector<const Phdr *> pt_loads;

   Addr min_vaddr = (Addr) -1; // We want to find the lowest and biggest

   Addr max_vaddr = 0;         // virtual address used by this Elf.

   const Phdr *dyn = nullptr;

   const Phdr *first_phdr = reinterpret_cast<const Phdr *>(

                            reinterpret_cast<const char *>(ehdr) + ehdr->e_phoff);

   const Phdr *end_phdr = &first_phdr[ehdr->e_phnum];

 #ifdef __ARM_EABI__

   const Phdr *arm_exidx_phdr = nullptr;

 #endif

   for (const Phdr *phdr = first_phdr; phdr < end_phdr; phdr++) {

     switch (phdr->p_type) {

       case PT_LOAD:

         debug_phdr("PT_LOAD", phdr);

         pt_loads.push_back(phdr);

         if (phdr->p_vaddr < min_vaddr)

           min_vaddr = phdr->p_vaddr;

         if (max_vaddr < phdr->p_vaddr + phdr->p_memsz)

           max_vaddr = phdr->p_vaddr + phdr->p_memsz;

         break;

       case PT_DYNAMIC:

         debug_phdr("PT_DYNAMIC", phdr);

         if (!dyn) {

           dyn = phdr;

         } else {

           LOG("%s: Multiple PT_DYNAMIC segments detected", elf->GetPath());

           return nullptr;

         }

         break;

       case PT_TLS:

         debug_phdr("PT_TLS", phdr);

         if (phdr->p_memsz) {

           LOG("%s: TLS is not supported", elf->GetPath());

           return nullptr;

         }

         break;

       case PT_GNU_STACK:

         debug_phdr("PT_GNU_STACK", phdr);

 // Skip on Android until bug 706116 is fixed

 #ifndef ANDROID

         if (phdr->p_flags & PF_X) {

           LOG("%s: Executable stack is not supported", elf->GetPath());

           return nullptr;

         }

 #endif

         break;

 #ifdef __ARM_EABI__

       case PT_ARM_EXIDX:

         /* We cannot initialize arm_exidx here

            because we don't have a base yet */

         arm_exidx_phdr = phdr;

         break;

 #endif

       default:

         DEBUG_LOG("%s: Warning: program header type #%d not handled",

                   elf->GetPath(), phdr->p_type);

     }

   }

   if (min_vaddr != 0) {

     LOG("%s: Unsupported minimal virtual address: 0x%08" PRIxAddr,

         elf->GetPath(), min_vaddr);

     return nullptr;

   }

   if (!dyn) {

     LOG("%s: No PT_DYNAMIC segment found", elf->GetPath());

     return nullptr;

   }

   /* Reserve enough memory to map the complete virtual address space for this

    * library.

    * As we are using the base address from here to mmap something else with

    * MAP_FIXED | MAP_SHARED, we need to make sure these mmaps will work. For

    * instance, on armv6, MAP_SHARED mappings require a 16k alignment, but mmap

    * MAP_PRIVATE only returns a 4k aligned address. So we first get a base

    * address with MAP_SHARED, which guarantees the kernel returns an address

    * that we'll be able to use with MAP_FIXED, and then remap MAP_PRIVATE at

    * the same address, because of some bad side effects of keeping it as

    * MAP_SHARED. */

   elf->base.Assign(MemoryRange::mmap(nullptr, max_vaddr, PROT_NONE,

                                      MAP_SHARED | MAP_ANONYMOUS, -1, 0));

   if ((elf->base == MAP_FAILED) ||

       (mmap(elf->base, max_vaddr, PROT_NONE,

             MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0) != elf->base)) {

     LOG("%s: Failed to mmap", elf->GetPath());

     return nullptr;

   }

   /* Load and initialize library */

   for (std::vector<const Phdr *>::iterator it = pt_loads.begin();

        it < pt_loads.end(); ++it)

     if (!elf->LoadSegment(*it))

       return nullptr;

   /* We're not going to mmap anymore */

   mappable->finalize();

   report_mapping(const_cast<char *>(elf->GetName()), elf->base,

                  (max_vaddr + PAGE_SIZE - 1) & PAGE_MASK, 0);

   elf->l_addr = elf->base;

   elf->l_name = elf->GetPath();

   elf->l_ld = elf->GetPtr<Dyn>(dyn->p_vaddr);

   ElfLoader::Singleton.Register(elf);

   if (!elf->InitDyn(dyn))

     return nullptr;

   if (elf->has_text_relocs) {

     for (std::vector<const Phdr *>::iterator it = pt_loads.begin();

          it < pt_loads.end(); ++it)

       mprotect(PageAlignedPtr(elf->GetPtr((*it)->p_vaddr)),

                PageAlignedEndPtr((*it)->p_memsz),

                p_flags_to_mprot((*it)->p_flags) | PROT_WRITE);

   }

   if (!elf->Relocate() || !elf->RelocateJumps())

     return nullptr;

   if (elf->has_text_relocs) {

     for (std::vector<const Phdr *>::iterator it = pt_loads.begin();

          it < pt_loads.end(); ++it)

       mprotect(PageAlignedPtr(elf->GetPtr((*it)->p_vaddr)),

                PageAlignedEndPtr((*it)->p_memsz),

                p_flags_to_mprot((*it)->p_flags));

   }

   if (!elf->CallInit())

     return nullptr;

 #ifdef __ARM_EABI__

   if (arm_exidx_phdr)

     elf->arm_exidx.InitSize(elf->GetPtr(arm_exidx_phdr->p_vaddr),

                             arm_exidx_phdr->p_memsz);

 #endif

   elf->stats("oneLibLoaded");

   DEBUG_LOG("CustomElf::Load(\"%s\", 0x%x) = %p", path, flags,

             static_cast<void *>(elf));

   return elf;

 }

 CustomElf::~CustomElf()

 {

   DEBUG_LOG("CustomElf::~CustomElf(%p [\"%s\"])",

             reinterpret_cast<void *>(this), GetPath());

   CallFini();

   /* Normally, __cxa_finalize is called by the .fini function. However,

    * Android NDK before r6b doesn't do that. Our wrapped cxa_finalize only

    * calls destructors once, so call it in all cases. */

   ElfLoader::__wrap_cxa_finalize(this);

   ElfLoader::Singleton.Forget(this);

 }

 namespace {

 /**

  * Hash function for symbol lookup, as defined in ELF standard for System V

  */

 unsigned long

 ElfHash(const char *symbol)

 {

   const unsigned char *sym = reinterpret_cast<const unsigned char *>(symbol);

   unsigned long h = 0, g;

   while (*sym) {

     h = (h << 4) + *sym++;

     if ((g = h & 0xf0000000))

       h ^= g >> 24;

     h &= ~g;

   }

   return h;

 }

 } /* anonymous namespace */

 void *

 CustomElf::GetSymbolPtr(const char *symbol) const

 {

   return GetSymbolPtr(symbol, ElfHash(symbol));

 }

 void *

 CustomElf::GetSymbolPtr(const char *symbol, unsigned long hash) const

 {

   const Sym *sym = GetSymbol(symbol, hash);

   void *ptr = nullptr;

   if (sym && sym->st_shndx != SHN_UNDEF)

     ptr = GetPtr(sym->st_value);

   DEBUG_LOG("CustomElf::GetSymbolPtr(%p [\"%s\"], \"%s\") = %p",

             reinterpret_cast<const void *>(this), GetPath(), symbol, ptr);

   return ptr;

 }

 void *

 CustomElf::GetSymbolPtrInDeps(const char *symbol) const

 {

   /* Resolve dlopen and related functions to point to ours */

   if (symbol[0] == 'd' && symbol[1] == 'l') {

     if (strcmp(symbol + 2, "open") == 0)

       return FunctionPtr(__wrap_dlopen);

     if (strcmp(symbol + 2, "error") == 0)

       return FunctionPtr(__wrap_dlerror);

     if (strcmp(symbol + 2, "close") == 0)

       return FunctionPtr(__wrap_dlclose);

     if (strcmp(symbol + 2, "sym") == 0)

       return FunctionPtr(__wrap_dlsym);

     if (strcmp(symbol + 2, "addr") == 0)

       return FunctionPtr(__wrap_dladdr);

     if (strcmp(symbol + 2, "_iterate_phdr") == 0)

       return FunctionPtr(__wrap_dl_iterate_phdr);

   } else if (symbol[0] == '_' && symbol[1] == '_') {

   /* Resolve a few C++ ABI specific functions to point to ours */

 #ifdef __ARM_EABI__

     if (strcmp(symbol + 2, "aeabi_atexit") == 0)

       return FunctionPtr(&ElfLoader::__wrap_aeabi_atexit);

 #else

     if (strcmp(symbol + 2, "cxa_atexit") == 0)

       return FunctionPtr(&ElfLoader::__wrap_cxa_atexit);

 #endif

     if (strcmp(symbol + 2, "cxa_finalize") == 0)

       return FunctionPtr(&ElfLoader::__wrap_cxa_finalize);

     if (strcmp(symbol + 2, "dso_handle") == 0)

       return const_cast<CustomElf *>(this);

     if (strcmp(symbol + 2, "moz_linker_stats") == 0)

       return FunctionPtr(&ElfLoader::stats);

 #ifdef __ARM_EABI__

     if (strcmp(symbol + 2, "gnu_Unwind_Find_exidx") == 0)

       return FunctionPtr(__wrap___gnu_Unwind_Find_exidx);

 #endif

   }

 #define MISSING_FLASH_SYMNAME_START "_ZN7android10VectorImpl19reservedVectorImpl"

   // Android changed some symbols that Flash depended on in 4.4,

   // so stub those out here

   if (strncmp(symbol,

               MISSING_FLASH_SYMNAME_START,

               sizeof(MISSING_FLASH_SYMNAME_START) - 1) == 0) {

     return FunctionPtr(__void_stub);

   }

   void *sym;

   /* Search the symbol in the main program. Note this also tries all libraries

    * the system linker will have loaded RTLD_GLOBAL. Unfortunately, that doesn't

    * work with bionic, but its linker doesn't normally search the main binary

    * anyways. Moreover, on android, the main binary is dalvik. */

 #ifdef __GLIBC__

   sym = dlsym(RTLD_DEFAULT, symbol);

   DEBUG_LOG("dlsym(RTLD_DEFAULT, \"%s\") = %p", symbol, sym);

   if (sym)

     return sym;

 #endif

   /* Then search the symbol in our dependencies. Since we already searched in

    * libraries the system linker loaded, skip those (on glibc systems). We

    * also assume the symbol is to be found in one of the dependent libraries

    * directly, not in their own dependent libraries. Building libraries with

    * --no-allow-shlib-undefined ensures such indirect symbol dependency don't

    * happen. */

   unsigned long hash = ElfHash(symbol);

   for (std::vector<RefPtr<LibHandle> >::const_iterator it = dependencies.begin();

        it < dependencies.end(); ++it) {

     if (!(*it)->IsSystemElf()) {

       sym = reinterpret_cast<CustomElf *>((*it).get())->GetSymbolPtr(symbol, hash);

 #ifndef __GLIBC__

     } else {

       sym = (*it)->GetSymbolPtr(symbol);

 #endif

     }

     if (sym)

       return sym;

   }

   return nullptr;

 }

 const Sym *

 CustomElf::GetSymbol(const char *symbol, unsigned long hash) const

 {

   /* Search symbol with the buckets and chains tables.

    * The hash computed from the symbol name gives an index in the buckets

    * table. The corresponding value in the bucket table is an index in the

    * symbols table and in the chains table.

    * If the corresponding symbol in the symbols table matches, we're done.

    * Otherwise, the corresponding value in the chains table is a new index

    * in both tables, which corresponding symbol is tested and so on and so

    * forth */

   size_t bucket = hash % buckets.numElements();

   for (size_t y = buckets[bucket]; y != STN_UNDEF; y = chains[y]) {

     if (strcmp(symbol, strtab.GetStringAt(symtab[y].st_name)))

       continue;

     return &symtab[y];

   }

   return nullptr;

 }

 bool

 CustomElf::Contains(void *addr) const

 {

   return base.Contains(addr);

 }

 #ifdef __ARM_EABI__

 const void *

 CustomElf::FindExidx(int *pcount) const

 {

   if (arm_exidx) {

     *pcount = arm_exidx.numElements();

     return arm_exidx;

   }

   *pcount = 0;

   return nullptr;

 }

 #endif

 void

 CustomElf::stats(const char *when) const

 {

   mappable->stats(when, GetPath());

 }

 bool

 CustomElf::LoadSegment(const Phdr *pt_load) const

 {

   if (pt_load->p_type != PT_LOAD) {

     DEBUG_LOG("%s: Elf::LoadSegment only takes PT_LOAD program headers", GetPath());

     return false;;

   }

   int prot = p_flags_to_mprot(pt_load->p_flags);

   /* Mmap at page boundary */

   Addr align = PageSize();

   Addr align_offset;

   void *mapped, *where;

   do {

     align_offset = pt_load->p_vaddr - AlignedPtr(pt_load->p_vaddr, align);

     where = GetPtr(pt_load->p_vaddr - align_offset);

     DEBUG_LOG("%s: Loading segment @%p %c%c%c", GetPath(), where,

                                                 prot & PROT_READ ? 'r' : '-',

                                                 prot & PROT_WRITE ? 'w' : '-',

                                                 prot & PROT_EXEC ? 'x' : '-');

     mapped = mappable->mmap(where, pt_load->p_filesz + align_offset,

                             prot, MAP_PRIVATE | MAP_FIXED,

                             pt_load->p_offset - align_offset);

     if ((mapped != MAP_FAILED) || (pt_load->p_vaddr == 0) ||

         (pt_load->p_align == align))

       break;

     /* The virtual address space for the library is properly aligned at

      * 16k on ARMv6 (see CustomElf::Load), and so is the first segment

      * (p_vaddr == 0). But subsequent segments may not be 16k aligned

      * and fail to mmap. In such case, try to mmap again at the p_align

      * boundary instead of page boundary. */

     DEBUG_LOG("%s: Failed to mmap, retrying", GetPath());

     align = pt_load->p_align;

   } while (1);

   if (mapped != where) {

     if (mapped == MAP_FAILED) {

       LOG("%s: Failed to mmap", GetPath());

     } else {

       LOG("%s: Didn't map at the expected location (wanted: %p, got: %p)",

           GetPath(), where, mapped);

     }

     return false;

   }

   /* Ensure the availability of all pages within the mapping if on-demand

    * decompression is disabled (MOZ_LINKER_ONDEMAND=0 or signal handler not

    * registered). */

   const char *ondemand = getenv("MOZ_LINKER_ONDEMAND");

   if (!ElfLoader::Singleton.hasRegisteredHandler() ||

       (ondemand && !strncmp(ondemand, "0", 2 /* Including '\0' */))) {

     for (Addr off = 0; off < pt_load->p_filesz + align_offset;

          off += PageSize()) {

       mappable->ensure(reinterpret_cast<char *>(mapped) + off);

     }

   }

   /* When p_memsz is greater than p_filesz, we need to have nulled out memory

    * after p_filesz and before p_memsz.

    * Above the end of the last page, and up to p_memsz, we already have nulled

    * out memory because we mapped anonymous memory on the whole library virtual

    * address space. We just need to adjust this anonymous memory protection

    * flags. */

   if (pt_load->p_memsz > pt_load->p_filesz) {

     Addr file_end = pt_load->p_vaddr + pt_load->p_filesz;

     Addr mem_end = pt_load->p_vaddr + pt_load->p_memsz;

     Addr next_page = PageAlignedEndPtr(file_end);

     if (next_page > file_end) {

       /* The library is not registered at this point, so we can't rely on

        * on-demand decompression to handle missing pages here. */

       void *ptr = GetPtr(file_end);

       mappable->ensure(ptr);

       memset(ptr, 0, next_page - file_end);

     }

     if (mem_end > next_page) {

       if (mprotect(GetPtr(next_page), mem_end - next_page, prot) < 0) {

         LOG("%s: Failed to mprotect", GetPath());

         return false;

       }

     }

   }

   return true;

 }

 namespace {

 void debug_dyn(const char *type, const Dyn *dyn)

 {

   DEBUG_LOG("%s 0x%08" PRIxAddr, type, dyn->d_un.d_val);

 }

 } /* anonymous namespace */

 bool

 CustomElf::InitDyn(const Phdr *pt_dyn)

 {

   /* Scan PT_DYNAMIC segment and gather some information */

   const Dyn *first_dyn = GetPtr<Dyn>(pt_dyn->p_vaddr);

   const Dyn *end_dyn = GetPtr<Dyn>(pt_dyn->p_vaddr + pt_dyn->p_filesz);

   std::vector<Word> dt_needed;

   size_t symnum = 0;

   for (const Dyn *dyn = first_dyn; dyn < end_dyn && dyn->d_tag; dyn++) {

     switch (dyn->d_tag) {

       case DT_NEEDED:

         debug_dyn("DT_NEEDED", dyn);

         dt_needed.push_back(dyn->d_un.d_val);

         break;

       case DT_HASH:

         {

           debug_dyn("DT_HASH", dyn);

           const Word *hash_table_header = GetPtr<Word>(dyn->d_un.d_ptr);

           symnum = hash_table_header[1];

           buckets.Init(&hash_table_header[2], hash_table_header[0]);

           chains.Init(&*buckets.end());

         }

         break;

       case DT_STRTAB:

         debug_dyn("DT_STRTAB", dyn);

         strtab.Init(GetPtr(dyn->d_un.d_ptr));

         break;

       case DT_SYMTAB:

         debug_dyn("DT_SYMTAB", dyn);

         symtab.Init(GetPtr(dyn->d_un.d_ptr));

         break;

       case DT_SYMENT:

         debug_dyn("DT_SYMENT", dyn);

         if (dyn->d_un.d_val != sizeof(Sym)) {

           LOG("%s: Unsupported DT_SYMENT", GetPath());

           return false;

         }

         break;

       case DT_TEXTREL:

         if (strcmp("libflashplayer.so", GetName()) == 0) {

           has_text_relocs = true;

         } else {

           LOG("%s: Text relocations are not supported", GetPath());

           return false;

         }

         break;

       case DT_STRSZ: /* Ignored */

         debug_dyn("DT_STRSZ", dyn);

         break;

       case UNSUPPORTED_RELOC():

       case UNSUPPORTED_RELOC(SZ):

       case UNSUPPORTED_RELOC(ENT):

         LOG("%s: Unsupported relocations", GetPath());

         return false;

       case RELOC():

         debug_dyn(STR_RELOC(), dyn);

         relocations.Init(GetPtr(dyn->d_un.d_ptr));

         break;

       case RELOC(SZ):

         debug_dyn(STR_RELOC(SZ), dyn);

         relocations.InitSize(dyn->d_un.d_val);

         break;

       case RELOC(ENT):

         debug_dyn(STR_RELOC(ENT), dyn);

         if (dyn->d_un.d_val != sizeof(Reloc)) {

           LOG("%s: Unsupported DT_RELENT", GetPath());

           return false;

         }

         break;

       case DT_JMPREL:

         debug_dyn("DT_JMPREL", dyn);

         jumprels.Init(GetPtr(dyn->d_un.d_ptr));

         break;

       case DT_PLTRELSZ:

         debug_dyn("DT_PLTRELSZ", dyn);

         jumprels.InitSize(dyn->d_un.d_val);

         break;

       case DT_PLTGOT:

         debug_dyn("DT_PLTGOT", dyn);

         break;

       case DT_INIT:

         debug_dyn("DT_INIT", dyn);

         init = dyn->d_un.d_ptr;

         break;

       case DT_INIT_ARRAY:

         debug_dyn("DT_INIT_ARRAY", dyn);

         init_array.Init(GetPtr(dyn->d_un.d_ptr));

         break;

       case DT_INIT_ARRAYSZ:

         debug_dyn("DT_INIT_ARRAYSZ", dyn);

         init_array.InitSize(dyn->d_un.d_val);

         break;

       case DT_FINI:

         debug_dyn("DT_FINI", dyn);

         fini = dyn->d_un.d_ptr;

         break;

       case DT_FINI_ARRAY:

         debug_dyn("DT_FINI_ARRAY", dyn);

         fini_array.Init(GetPtr(dyn->d_un.d_ptr));

         break;

       case DT_FINI_ARRAYSZ:

         debug_dyn("DT_FINI_ARRAYSZ", dyn);

         fini_array.InitSize(dyn->d_un.d_val);

         break;

       case DT_PLTREL:

         if (dyn->d_un.d_val != RELOC()) {

           LOG("%s: Error: DT_PLTREL is not " STR_RELOC(), GetPath());

           return false;

         }

         break;

       case DT_FLAGS:

         {

            Addr flags = dyn->d_un.d_val;

            /* Treat as a DT_TEXTREL tag */

            if (flags & DF_TEXTREL) {

              if (strcmp("libflashplayer.so", GetName()) == 0) {

                has_text_relocs = true;

              } else {

                LOG("%s: Text relocations are not supported", GetPath());

                return false;

              }

            }

            /* we can treat this like having a DT_SYMBOLIC tag */

            flags &= ~DF_SYMBOLIC;

            if (flags)

              LOG("%s: Warning: unhandled flags #%" PRIxAddr" not handled",

                  GetPath(), flags);

         }

         break;

       case DT_SONAME: /* Should match GetName(), but doesn't matter */

       case DT_SYMBOLIC: /* Indicates internal symbols should be looked up in

                          * the library itself first instead of the executable,

                          * which is actually what this linker does by default */

       case RELOC(COUNT): /* Indicates how many relocations are relative, which

                           * is usually used to skip relocations on prelinked

                           * libraries. They are not supported anyways. */

       case UNSUPPORTED_RELOC(COUNT): /* This should error out, but it doesn't

                                       * really matter. */

       case DT_FLAGS_1: /* Additional linker-internal flags that we don't care about. See

                         * DF_1_* values in src/include/elf/common.h in binutils. */

       case DT_VERSYM: /* DT_VER* entries are used for symbol versioning, which */

       case DT_VERDEF: /* this linker doesn't support yet. */

       case DT_VERDEFNUM:

       case DT_VERNEED:

       case DT_VERNEEDNUM:

         /* Ignored */

         break;

       default:

         LOG("%s: Warning: dynamic header type #%" PRIxAddr" not handled",

             GetPath(), dyn->d_tag);

     }

   }

   if (!buckets || !symnum) {

     LOG("%s: Missing or broken DT_HASH", GetPath());

     return false;

   }

   if (!strtab) {

     LOG("%s: Missing DT_STRTAB", GetPath());

     return false;

   }

   if (!symtab) {

     LOG("%s: Missing DT_SYMTAB", GetPath());

     return false;

   }

   /* Load dependent libraries */

   for (size_t i = 0; i < dt_needed.size(); i++) {

     const char *name = strtab.GetStringAt(dt_needed[i]);

     RefPtr<LibHandle> handle =

       ElfLoader::Singleton.Load(name, RTLD_GLOBAL | RTLD_LAZY, this);

     if (!handle)

       return false;

     dependencies.push_back(handle);

   }

   return true;

 }

 bool

 CustomElf::Relocate()

 {

   DEBUG_LOG("Relocate %s @%p", GetPath(), static_cast<void *>(base));

   uint32_t symtab_index = (uint32_t) -1;

   void *symptr = nullptr;

   for (Array<Reloc>::iterator rel = relocations.begin();

        rel < relocations.end(); ++rel) {

     /* Location of the relocation */

     void *ptr = GetPtr(rel->r_offset);

     /* R_*_RELATIVE relocations apply directly at the given location */

     if (ELF_R_TYPE(rel->r_info) == R_RELATIVE) {

       *(void **) ptr = GetPtr(rel->GetAddend(base));

       continue;

     }

     /* Other relocation types need a symbol resolution */

     /* Avoid symbol resolution when it's the same symbol as last iteration */

     if (symtab_index != ELF_R_SYM(rel->r_info)) {

       symtab_index = ELF_R_SYM(rel->r_info);

       const Sym sym = symtab[symtab_index];

       if (sym.st_shndx != SHN_UNDEF) {

         symptr = GetPtr(sym.st_value);

       } else {

         /* TODO: handle symbol resolving to nullptr vs. being undefined. */

         symptr = GetSymbolPtrInDeps(strtab.GetStringAt(sym.st_name));

       }

     }

     if (symptr == nullptr)

       LOG("%s: Warning: relocation to NULL @0x%08" PRIxAddr,

           GetPath(), rel->r_offset);

     /* Apply relocation */

     switch (ELF_R_TYPE(rel->r_info)) {

     case R_GLOB_DAT:

       /* R_*_GLOB_DAT relocations simply use the symbol value */

       *(void **) ptr = symptr;

       break;

     case R_ABS:

       /* R_*_ABS* relocations add the relocation added to the symbol value */

       *(const char **) ptr = (const char *)symptr + rel->GetAddend(base);

       break;

     default:

       LOG("%s: Unsupported relocation type: 0x%" PRIxAddr,

           GetPath(), ELF_R_TYPE(rel->r_info));

       return false;

     }

   }

   return true;

 }

 bool

 CustomElf::RelocateJumps()

 {

   /* TODO: Dynamic symbol resolution */

   for (Array<Reloc>::iterator rel = jumprels.begin();

        rel < jumprels.end(); ++rel) {

     /* Location of the relocation */

     void *ptr = GetPtr(rel->r_offset);

     /* Only R_*_JMP_SLOT relocations are expected */

     if (ELF_R_TYPE(rel->r_info) != R_JMP_SLOT) {

       LOG("%s: Jump relocation type mismatch", GetPath());

       return false;

     }

     /* TODO: Avoid code duplication with the relocations above */

     const Sym sym = symtab[ELF_R_SYM(rel->r_info)];

     void *symptr;

     if (sym.st_shndx != SHN_UNDEF)

       symptr = GetPtr(sym.st_value);

     else

       symptr = GetSymbolPtrInDeps(strtab.GetStringAt(sym.st_name));

     if (symptr == nullptr) {

       LOG("%s: %s: relocation to NULL @0x%08" PRIxAddr " for symbol \"%s\"",

           GetPath(),

           (ELF_ST_BIND(sym.st_info) == STB_WEAK) ? "Warning" : "Error",

           rel->r_offset, strtab.GetStringAt(sym.st_name));

       if (ELF_ST_BIND(sym.st_info) != STB_WEAK)

         return false;

     }

     /* Apply relocation */

     *(void **) ptr = symptr;

   }

   return true;

 }

 bool

 CustomElf::CallInit()

 {

   if (init)

     CallFunction(init);

   for (Array<void *>::iterator it = init_array.begin();

        it < init_array.end(); ++it) {

     /* Android x86 NDK wrongly puts 0xffffffff in INIT_ARRAY */

     if (*it && *it != reinterpret_cast<void *>(-1))

       CallFunction(*it);

   }

   initialized = true;

   return true;

 }

 void

 CustomElf::CallFini()

 {

   if (!initialized)

     return;

   for (Array<void *>::reverse_iterator it = fini_array.rbegin();

        it < fini_array.rend(); ++it) {

     /* Android x86 NDK wrongly puts 0xffffffff in FINI_ARRAY */

     if (*it && *it != reinterpret_cast<void *>(-1))

       CallFunction(*it);

   }

   if (fini)

     CallFunction(fini);

 }

 Mappable *

 CustomElf::GetMappable() const

 {

   if (!mappable)

     return nullptr;

   if (mappable->GetKind() == Mappable::MAPPABLE_EXTRACT_FILE)

     return mappable;

   return ElfLoader::GetMappableFromPath(GetPath());

 }