1 files changed, 90 insertions, 0 deletions
diff --git a/llvm/lib/Object/ELF.cpp b/llvm/lib/Object/ELF.cpp
index 130fb2d9ecc..2bb1fd56894 100644
--- a/llvm/lib/Object/ELF.cpp
+++ b/llvm/lib/Object/ELF.cpp
@@ -9,6 +9,7 @@
 
 #include "llvm/Object/ELF.h"
 #include "llvm/BinaryFormat/ELF.h"
+#include "llvm/Support/LEB128.h"
 
 using namespace llvm;
 using namespace object;
@@ -210,3 +211,92 @@ StringRef llvm::object::getELFSectionTypeName(uint32_t Machine, unsigned Type) {
     return "Unknown";
   }
 }
+
+template <class ELFT>
+Expected<std::vector<typename ELFT::Rela>>
+ELFFile<ELFT>::android_relas(const Elf_Shdr *Sec) const {
+  // This function reads relocations in Android's packed relocation format,
+  // which is based on SLEB128 and delta encoding.
+  Expected<ArrayRef<uint8_t>> ContentsOrErr = getSectionContents(Sec);
+  if (!ContentsOrErr)
+    return ContentsOrErr.takeError();
+  const uint8_t *Cur = ContentsOrErr->begin();
+  const uint8_t *End = ContentsOrErr->end();
+  if (ContentsOrErr->size() < 4 || Cur[0] != 'A' || Cur[1] != 'P' ||
+      Cur[2] != 'S' || Cur[3] != '2')
+    return createError("invalid packed relocation header");
+  Cur += 4;
+
+  const char *ErrStr = nullptr;
+  auto ReadSLEB = [&]() -> int64_t {
+    if (ErrStr)
+      return 0;
+    unsigned Len;
+    int64_t Result = decodeSLEB128(Cur, &Len, End, &ErrStr);
+    Cur += Len;
+    return Result;
+  };
+
+  uint64_t NumRelocs = ReadSLEB();
+  uint64_t Offset = ReadSLEB();
+  uint64_t Addend = 0;
+
+  if (ErrStr)
+    return createError(ErrStr);
+
+  std::vector<Elf_Rela> Relocs;
+  Relocs.reserve(NumRelocs);
+  while (NumRelocs) {
+    uint64_t NumRelocsInGroup = ReadSLEB();
+    if (NumRelocsInGroup > NumRelocs)
+      return createError("relocation group unexpectedly large");
+    NumRelocs -= NumRelocsInGroup;
+
+    uint64_t GroupFlags = ReadSLEB();
+    bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG;
+    bool GroupedByOffsetDelta = GroupFlags & ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG;
+    bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG;
+    bool GroupHasAddend = GroupFlags & ELF::RELOCATION_GROUP_HAS_ADDEND_FLAG;
+
+    uint64_t GroupOffsetDelta;
+    if (GroupedByOffsetDelta)
+      GroupOffsetDelta = ReadSLEB();
+
+    uint64_t GroupRInfo;
+    if (GroupedByInfo)
+      GroupRInfo = ReadSLEB();
+
+    if (GroupedByAddend && GroupHasAddend)
+      Addend += ReadSLEB();
+
+    for (uint64_t I = 0; I != NumRelocsInGroup; ++I) {
+      Elf_Rela R;
+      Offset += GroupedByOffsetDelta ? GroupOffsetDelta : ReadSLEB();
+      R.r_offset = Offset;
+      R.r_info = GroupedByInfo ? GroupRInfo : ReadSLEB();
+
+      if (GroupHasAddend) {
+        if (!GroupedByAddend)
+          Addend += ReadSLEB();
+        R.r_addend = Addend;
+      } else {
+        R.r_addend = 0;
+      }
+
+      Relocs.push_back(R);
+
+      if (ErrStr)
+        return createError(ErrStr);
+    }
+
+    if (ErrStr)
+      return createError(ErrStr);
+  }
+
+  return Relocs;
+}
+
+template class llvm::object::ELFFile<ELF32LE>;
+template class llvm::object::ELFFile<ELF32BE>;
+template class llvm::object::ELFFile<ELF64LE>;
+template class llvm::object::ELFFile<ELF64BE>;