[Zucchini] ZTF (text) disassembler

A Zucchini text format (ZTF) disassembler for validating and
debugging Zucchini using special text files.

This is intended to be primarily used for easier validation of the
core Zucchini algorithm. It is also useful for fuzzing reference
projection as it is a lighter weight disassembler than other
executable formats. References are encoded in an ASCII plain-text
format to be human-readable and easier to debug.

See the disassembler_ztf.h file for a complete outline of the file
format. Which is referred to as Zucchini Text Format (ZTF) throughout
the code.

The design is meant to be highly flexible and non-redundant so a fair
amount of templating/overloading is used. The overall design is:

Shared:
- ZtfConfig: To handle metadata for different types of references.
- ZtfTranslator: Translate text references into offsets and back.

Read:
- ZtfParser: Find references in the file.
- ZtfReferenceReader: Drive ZtfParser through the file and use it
  with ZtfTranslator to translate between offsets and references.

Write:
- ZtfWriter: The counterpart to parser for writing a reference to a
  location.
- ZtfReferenceWriter: Compose ZtfWriter and ZtfTranslator
  together and write references to an image.

Bug: 834904
Change-Id: Iec62c67eab6bd3e7e95b79798417035a4873360a
Reviewed-on: https://chromium-review.googlesource.com/1056147
Commit-Queue: Calder Kitagawa <ckitagawa@google.com>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Reviewed-by: Greg Thompson <grt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561140}
NOKEYCHECK=True
GitOrigin-RevId: d2c5be5844c12d2585bde53ba891154ffed2ca62

1 files changed, 24 insertions, 1 deletions

diff --git a/element_detection.cc b/element_detection.cc
index a826f54..6b31f61 100644
--- a/element_detection.cc
+++ b/element_detection.cc
@@ -9,9 +9,19 @@
 #include "base/logging.h"
 #include "components/zucchini/buildflags.h"
 #include "components/zucchini/disassembler.h"
-#include "components/zucchini/disassembler_dex.h"
 #include "components/zucchini/disassembler_no_op.h"
+
+#if BUILDFLAG(ENABLE_DEX)
+#include "components/zucchini/disassembler_dex.h"
+#endif  // BUILDFLAG(ENABLE_DEX)
+
+#if BUILDFLAG(ENABLE_WIN)
 #include "components/zucchini/disassembler_win32.h"
+#endif  // BUILDFLAG(ENABLE_WIN)
+
+#if BUILDFLAG(ENABLE_ZTF)
+#include "components/zucchini/disassembler_ztf.h"
+#endif  // BUILDFLAG(ENABLE_ZTF)
 
 namespace zucchini {
 
@@ -48,6 +58,15 @@ std::unique_ptr<Disassembler> MakeDisassemblerWithoutFallback(
   }
 #endif  // BUILDFLAG(ENABLE_DEX)
 
+#if BUILDFLAG(ENABLE_ZTF)
+  if (DisassemblerZtf::QuickDetect(image)) {
+    // This disallows very short examples like "ZTxtxtZ\n" in ensemble patching.
+    auto disasm = Disassembler::Make<DisassemblerZtf>(image);
+    if (disasm && disasm->size() >= kMinProgramSize)
+      return disasm;
+  }
+#endif  // BUILDFLAG(ENABLE_ZTF)
+
   return nullptr;
 }
 
@@ -64,6 +83,10 @@ std::unique_ptr<Disassembler> MakeDisassemblerOfType(ConstBufferView image,
     case kExeTypeDex:
       return Disassembler::Make<DisassemblerDex>(image);
 #endif  // BUILDFLAG(ENABLE_DEX)
+#if BUILDFLAG(ENABLE_ZTF)
+    case kExeTypeZtf:
+      return Disassembler::Make<DisassemblerZtf>(image);
+#endif  // BUILDFLAG(ENABLE_ZTF)
     case kExeTypeNoOp:
       return Disassembler::Make<DisassemblerNoOp>(image);
     default: