Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 674 insertions, 0 deletions

diff --git a/mozglue/linker/CustomElf.cpp b/mozglue/linker/CustomElf.cpp
new file mode 100644
index 0000000000..fa7dffa395
--- /dev/null
+++ b/mozglue/linker/CustomElf.cpp
@@ -0,0 +1,674 @@
+/* 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 <signal.h>
+#include <string.h>
+#include "CustomElf.h"
+#include "BaseElf.h"
+#include "Mappable.h"
+#include "Logging.h"
+#include "mozilla/IntegerPrintfMacros.h"
+
+using namespace Elf;
+
+/* TODO: Fill ElfLoader::Singleton.lastError on errors. */
+
+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" PRIxPTR
+            " ("
+            "filesz: 0x%08" PRIxPTR
+            ", "
+            "memsz: 0x%08" PRIxPTR
+            ", "
+            "offset: 0x%08" PRIxPTR
+            ", "
+            "flags: %c%c%c)",
+            type, uintptr_t(phdr->p_vaddr), uintptr_t(phdr->p_filesz),
+            uintptr_t(phdr->p_memsz), uintptr_t(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);
+}
+
+} /* 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:
+  explicit Mappable1stPagePtr(Mappable* mappable)
+      : GenericMappedPtr<Mappable1stPagePtr>(
+            mappable->mmap(nullptr, PageSize(), PROT_READ, MAP_PRIVATE, 0)),
+        mappable(mappable) {}
+
+ private:
+  friend class GenericMappedPtr<Mappable1stPagePtr>;
+  void munmap(void* buf, size_t length) { mappable->munmap(buf, length); }
+
+  RefPtr<Mappable> mappable;
+};
+
+already_AddRefed<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 {
+          ERROR("%s: Multiple PT_DYNAMIC segments detected", elf->GetPath());
+          return nullptr;
+        }
+        break;
+      case PT_TLS:
+        debug_phdr("PT_TLS", phdr);
+        if (phdr->p_memsz) {
+          ERROR("%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) {
+          ERROR("%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: Program header type #%d not handled", elf->GetPath(),
+                  phdr->p_type);
+    }
+  }
+
+  if (min_vaddr != 0) {
+    ERROR("%s: Unsupported minimal virtual address: 0x%08" PRIxPTR,
+          elf->GetPath(), uintptr_t(min_vaddr));
+    return nullptr;
+  }
+  if (!dyn) {
+    ERROR("%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)) {
+    ERROR("%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();
+
+  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
+
+  DEBUG_LOG("CustomElf::Load(\"%s\", 0x%x) = %p", path, flags,
+            static_cast<void*>(elf));
+  return elf.forget();
+}
+
+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);
+}
+
+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);
+#ifdef __ARM_EABI__
+    if (strcmp(symbol + 2, "gnu_Unwind_Find_exidx") == 0)
+      return FunctionPtr(__wrap___gnu_Unwind_Find_exidx);
+#endif
+  } else if (symbol[0] == 's' && symbol[1] == 'i') {
+    if (strcmp(symbol + 2, "gnal") == 0) return FunctionPtr(signal);
+    if (strcmp(symbol + 2, "gaction") == 0) return FunctionPtr(sigaction);
+  }
+
+  void* sym;
+
+  unsigned long hash = Hash(symbol);
+
+  /* self_elf should never be NULL, but better safe than sorry. */
+  if (ElfLoader::Singleton.self_elf) {
+    /* We consider the library containing this code a permanent LD_PRELOAD,
+     * so, check if the symbol exists here first. */
+    sym = static_cast<BaseElf*>(ElfLoader::Singleton.self_elf.get())
+              ->GetSymbolPtr(symbol, hash);
+    if (sym) return sym;
+  }
+
+  /* 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. */
+  for (std::vector<RefPtr<LibHandle> >::const_iterator it =
+           dependencies.begin();
+       it < dependencies.end(); ++it) {
+    /* Skip if it's the library containing this code, since we've already
+     * looked at it above. */
+    if (*it == ElfLoader::Singleton.self_elf) continue;
+    if (BaseElf* be = (*it)->AsBaseElf()) {
+      sym = be->GetSymbolPtr(symbol, hash);
+    } else {
+      sym = (*it)->GetSymbolPtr(symbol);
+    }
+    if (sym) return sym;
+  }
+  return nullptr;
+}
+
+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) {
+      ERROR("%s: Failed to mmap", GetPath());
+    } else {
+      ERROR("%s: Didn't map at the expected location (wanted: %p, got: %p)",
+            GetPath(), where, mapped);
+    }
+    return false;
+  }
+
+  /* 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) {
+      void* ptr = GetPtr(file_end);
+      memset(ptr, 0, next_page - file_end);
+    }
+    if (mem_end > next_page) {
+      if (mprotect(GetPtr(next_page), mem_end - next_page, prot) < 0) {
+        ERROR("%s: Failed to mprotect", GetPath());
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+namespace {
+
+void debug_dyn(const char* type, const Dyn* dyn) {
+  DEBUG_LOG("%s 0x%08" PRIxPTR, type, uintptr_t(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)) {
+          ERROR("%s: Unsupported DT_SYMENT", GetPath());
+          return false;
+        }
+        break;
+      case DT_TEXTREL:
+        if (strcmp("libflashplayer.so", GetName()) == 0) {
+          has_text_relocs = true;
+        } else {
+          ERROR("%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):
+        ERROR("%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)) {
+          ERROR("%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()) {
+          ERROR("%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 {
+            ERROR("%s: Text relocations are not supported", GetPath());
+            return false;
+          }
+        }
+        /* we can treat this like having a DT_SYMBOLIC tag */
+        flags &= ~DF_SYMBOLIC;
+        if (flags)
+          WARN("%s: unhandled flags #%" PRIxPTR " not handled", GetPath(),
+               uintptr_t(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:
+        WARN("%s: dynamic header type #%" PRIxPTR " not handled", GetPath(),
+             uintptr_t(dyn->d_tag));
+    }
+  }
+
+  if (!buckets || !symnum) {
+    ERROR("%s: Missing or broken DT_HASH", GetPath());
+    return false;
+  }
+  if (!strtab) {
+    ERROR("%s: Missing DT_STRTAB", GetPath());
+    return false;
+  }
+  if (!symtab) {
+    ERROR("%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)
+      WARN("%s: Relocation to NULL @0x%08" PRIxPTR, GetPath(),
+           uintptr_t(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:
+        ERROR("%s: Unsupported relocation type: 0x%" PRIxPTR, GetPath(),
+              uintptr_t(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) {
+      ERROR("%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) {
+      if (ELF_ST_BIND(sym.st_info) == STB_WEAK) {
+        WARN("%s: Relocation to NULL @0x%08" PRIxPTR " for symbol \"%s\"",
+             GetPath(), uintptr_t(rel->r_offset),
+             strtab.GetStringAt(sym.st_name));
+      } else {
+        ERROR("%s: Relocation to NULL @0x%08" PRIxPTR " for symbol \"%s\"",
+              GetPath(), uintptr_t(rel->r_offset),
+              strtab.GetStringAt(sym.st_name));
+        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);
+}