Split .oat_patches to multiple sections.

.oat_patches section currently contains encoded patch locations for
several other sections. Split it to several sections - one for each
of the destination sections. For example, .text.oat_patches section
contains patch locations for the .text section.

This ensures that if we strip some the sections using standard
tools, we strip the corresponding .oat_patches section as well.

It also makes the overall design simpler.
I should have done it this way in the first place.

Since ApplyOatPatches has been simplified and uses unaligned memory
access, this also fixes bug 21403573.

Bug:20556771
Bug:21403573
Change-Id: Iae7c423911507b524eec500e8d61744046fcd3ba

1 files changed, 10 insertions, 4 deletions

diff --git a/compiler/elf_builder.h b/compiler/elf_builder.h
index 8a63a4882f..730d780f6b 100644
--- a/compiler/elf_builder.h
+++ b/compiler/elf_builder.h
@@ -168,6 +168,10 @@ class ElfBuilder FINAL {
           patched_(false), patch_(patch), patch_base_section_(patch_base_section) {
     }
 
+    RawSection(const std::string& name, Elf_Word type)
+        : RawSection(name, type, 0, nullptr, 0, 1, 0, nullptr, nullptr) {
+    }
+
     Elf_Word GetSize() const OVERRIDE {
       return buffer_.size();
     }
@@ -779,10 +783,12 @@ class ElfBuilder FINAL {
 
   template<typename T>
   static bool WriteArray(File* elf_file, const T* data, size_t count) {
-    DCHECK(data != nullptr);
-    if (!elf_file->WriteFully(data, count * sizeof(T))) {
-      PLOG(ERROR) << "Failed to write to file " << elf_file->GetPath();
-      return false;
+    if (count != 0) {
+      DCHECK(data != nullptr);
+      if (!elf_file->WriteFully(data, count * sizeof(T))) {
+        PLOG(ERROR) << "Failed to write to file " << elf_file->GetPath();
+        return false;
+      }
     }
     return true;
   }