From d4048d49dbb02229af3ce28908083a95f5de8ecb Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Fri, 16 Oct 2020 16:38:03 +0900
Subject: [PATCH] temporary

---
 chibild.h          | 54 +++++++++++++++++++++++++++++++++++-----------
 input_files.cc     |  4 ++--
 input_sections.cc  |  4 +++-
 output_sections.cc | 48 ++++++++++++++---------------------------
 4 files changed, 63 insertions(+), 47 deletions(-)

diff --git a/chibild.h b/chibild.h
index 785cef7f..242027ce 100644
--- a/chibild.h
+++ b/chibild.h
@@ -128,7 +128,7 @@ private:
 class InputSection {
 public:
   InputSection(ObjectFile *file, const ELF64LE::Shdr *hdr, StringRef name);
-  void writeTo(uint8_t *buf);
+  void copy_to(uint8_t *buf);
   uint64_t get_size() const;
 
   StringRef name;
@@ -148,7 +148,7 @@ class OutputChunk {
 public:
   virtual ~OutputChunk() {}
 
-  virtual void writeTo(uint8_t *buf) = 0;
+  virtual void copy_to(uint8_t *buf) = 0;
   virtual void set_offset(uint64_t off) { offset = off; }
   uint64_t get_offset() const { return offset; }
   virtual uint64_t get_size() const = 0;
@@ -158,36 +158,65 @@ protected:
   int64_t size = -1;
 };
 
+// ELF header
 class OutputEhdr : public OutputChunk {
 public:
-  void writeTo(uint8_t *buf) override;
-  uint64_t get_size() const override;
+  OutputEhdr();
 
-  ELF64LE::Ehdr hdr;
+  void copy_to(uint8_t *buf) override {
+    memcpy(buf + offset, &hdr, sizeof(hdr));
+  }
+
+  uint64_t get_size() const override {
+    return sizeof(hdr);
+  }
+
+  ELF64LE::Ehdr hdr = {};
 };
 
+// Section header
 class OutputShdr : public OutputChunk {
 public:
-  void writeTo(uint8_t *buf) override;
-  uint64_t get_size() const override;
+  void copy_to(uint8_t *buf) override {
+    memcpy(buf + offset, &hdr[0], get_size());
+  }
+
+  uint64_t get_size() const override {
+    return hdr.size() * sizeof(hdr[0]);
+  }
 
   std::vector<ELF64LE::Shdr> hdr;
 };
 
+// Program header
 class OutputPhdr : public OutputChunk {
 public:
-  void writeTo(uint8_t *buf) override;
-  uint64_t get_size() const override;
+  void copy_to(uint8_t *buf) override {
+    memcpy(buf + offset, &hdr[0], get_size());
+  }
+
+  uint64_t get_size() const override {
+    return hdr.size() * sizeof(hdr[0]);
+  }
 
   std::vector<ELF64LE::Phdr> hdr;
 };
 
+// Sections
 class OutputSection : public OutputChunk {
 public:
-  OutputSection(StringRef name);
+  OutputSection(StringRef name) : name(name) {}
+
+  void copy_to(uint8_t *buf) override {
+    for (InputSection *sec : sections)
+      sec->copy_to(buf);
+  }
+
+  uint64_t get_size() const override {
+    assert(size >= 0);
+    return size;
+  }
 
-  void writeTo(uint8_t *buf) override;
-  uint64_t get_size() const override;
   void set_offset(uint64_t off) override;
 
   std::vector<InputSection *> sections;
@@ -216,6 +245,7 @@ public:
   int priority;
   bool is_alive = false;
   std::unordered_set<ObjectFile *> liveness_edges;
+  ELFFile<ELF64LE> obj;
 
 private:
   MemoryBufferRef mb;
diff --git a/input_files.cc b/input_files.cc
index b155de9f..b2eb3632 100644
--- a/input_files.cc
+++ b/input_files.cc
@@ -8,7 +8,8 @@ std::atomic_int num_undefined;
 std::atomic_int num_files;
 
 ObjectFile::ObjectFile(MemoryBufferRef mb, StringRef archive_name)
-  : mb(mb), archive_name(archive_name) {}
+  : mb(mb), archive_name(archive_name),
+    obj(check(ELFFile<ELF64LE>::create(mb.getBuffer()))) {}
 
 MemoryBufferRef readFile(StringRef path) {
   auto mbOrErr = MemoryBuffer::getFile(path, -1, false);
@@ -33,7 +34,6 @@ void ObjectFile::parse() {
   num_files++;
 
   // Initialize sections.
-  ELFFile<ELF64LE> obj = check(ELFFile<ELF64LE>::create(mb.getBuffer()));
   ArrayRef<ELF64LE::Shdr> sections = CHECK(obj.sections(), this);
   StringRef section_strtab = CHECK(obj.getSectionStringTable(sections), this);
 
diff --git a/input_sections.cc b/input_sections.cc
index f2c1a24f..a68fdc03 100644
--- a/input_sections.cc
+++ b/input_sections.cc
@@ -7,5 +7,7 @@ uint64_t InputSection::get_size() const {
   return hdr->sh_size;
 }
 
-void InputSection::writeTo(uint8_t *buf) {
+void InputSection::copy_to(uint8_t *buf) {
+  ArrayRef<uint8_t> data = check(file->obj.getSectionContents(*hdr));
+  memcpy(buf + offset, &data[0], data.size());
 }
diff --git a/output_sections.cc b/output_sections.cc
index 4b8ea493..5cb86019 100644
--- a/output_sections.cc
+++ b/output_sections.cc
@@ -1,34 +1,23 @@
 #include "chibild.h"
 
-void OutputEhdr::writeTo(uint8_t *buf) {
-  memcpy(buf + offset, &hdr, sizeof(hdr));
-}
+using namespace llvm::ELF;
 
-uint64_t OutputEhdr::get_size() const {
-  return sizeof(hdr);
-}
+OutputEhdr::OutputEhdr() {
+  memcpy(&hdr.e_ident, "\177ELF", 4);
 
-void OutputShdr::writeTo(uint8_t *buf) {
-  memcpy(buf + offset, &hdr[0], get_size());
-}
-
-uint64_t OutputShdr::get_size() const {
-  return hdr.size() * sizeof(hdr[0]);
-}
-
-void OutputPhdr::writeTo(uint8_t *buf) {
-  memcpy(buf + offset, &hdr[0], get_size());
-}
-
-uint64_t OutputPhdr::get_size() const {
-  return hdr.size() * sizeof(hdr[0]);
-}
-
-OutputSection::OutputSection(StringRef name) : name(name) {}
-
-uint64_t OutputSection::get_size() const {
-  assert(size >= 0);
-  return size;
+  hdr.e_ident[EI_CLASS] = ELFCLASS64;
+  hdr.e_ident[EI_DATA] = ELFDATA2LSB;
+  hdr.e_ident[EI_VERSION] = EV_CURRENT;
+  hdr.e_ident[EI_OSABI] = 0;
+  hdr.e_ident[EI_ABIVERSION] = 0;
+  hdr.e_machine = EM_X86_64;
+  hdr.e_version = EV_CURRENT;
+  hdr.e_flags = 0;
+  hdr.e_ehsize = sizeof(ELF64LE::Ehdr);
+  hdr.e_phnum = 0;
+  hdr.e_shentsize = sizeof(ELF64LE::Shdr);
+  hdr.e_phoff = sizeof(ELF64LE::Ehdr);
+  hdr.e_phentsize = sizeof(ELF64LE::Phdr);
 }
 
 void OutputSection::set_offset(uint64_t off) {
@@ -39,8 +28,3 @@ void OutputSection::set_offset(uint64_t off) {
   }
   size = off - offset;
 }
-
-void OutputSection::writeTo(uint8_t *buf) {
-  for (InputSection *sec : sections)
-    sec->writeTo(buf);
-}