From e8437de727ed208cc4a8b7b36b6165dca89fafcb Mon Sep 17 00:00:00 2001
From: Jake Ehrlich <jakehehrlich@google.com>
Date: Tue, 19 Dec 2017 00:47:30 +0000
Subject: [llvm-objcopy] Add option to add a progbits section from a file

This change adds support for adding progbits sections with contents from a file

Differential Revision: https://reviews.llvm.org/D41212

llvm-svn: 321047
---
 llvm/tools/llvm-objcopy/Object.cpp       | 12 ++++++++++++
 llvm/tools/llvm-objcopy/Object.h         | 15 +++++++++++++++
 llvm/tools/llvm-objcopy/llvm-objcopy.cpp | 22 +++++++++++++++++++++-
 3 files changed, 48 insertions(+), 1 deletion(-)

(limited to 'llvm/tools/llvm-objcopy')

diff --git a/llvm/tools/llvm-objcopy/Object.cpp b/llvm/tools/llvm-objcopy/Object.cpp
index bd5bcd7fc18..d5dfcac40e4 100644
--- a/llvm/tools/llvm-objcopy/Object.cpp
+++ b/llvm/tools/llvm-objcopy/Object.cpp
@@ -81,6 +81,11 @@ void Section::writeSection(FileOutputBuffer &Out) const {
   std::copy(std::begin(Contents), std::end(Contents), Buf);
 }
 
+void OwnedDataSection::writeSection(FileOutputBuffer &Out) const {
+  uint8_t *Buf = Out.getBufferStart() + Offset;
+  std::copy(std::begin(Data), std::end(Data), Buf);
+}
+
 void StringTableSection::addString(StringRef Name) {
   StrTabBuilder.add(Name);
   Size = StrTabBuilder.getSize();
@@ -676,6 +681,13 @@ void Object<ELFT>::removeSections(
   Sections.erase(Iter, std::end(Sections));
 }
 
+template <class ELFT>
+void Object<ELFT>::addSection(StringRef SecName, ArrayRef<uint8_t> Data) {
+  auto Sec = llvm::make_unique<OwnedDataSection>(SecName, Data);
+  Sec->OriginalOffset = ~0ULL;
+  Sections.push_back(std::move(Sec));
+}
+
 template <class ELFT> void ELFObject<ELFT>::sortSections() {
   // Put all sections in offset order. Maintain the ordering as closely as
   // possible while meeting that demand however.
diff --git a/llvm/tools/llvm-objcopy/Object.h b/llvm/tools/llvm-objcopy/Object.h
index 9f98c04ad9b..b04b0c1a641 100644
--- a/llvm/tools/llvm-objcopy/Object.h
+++ b/llvm/tools/llvm-objcopy/Object.h
@@ -126,6 +126,20 @@ public:
   void writeSection(FileOutputBuffer &Out) const override;
 };
 
+class OwnedDataSection : public SectionBase {
+private:
+  std::vector<uint8_t> Data;
+
+public:
+  OwnedDataSection(StringRef SecName, ArrayRef<uint8_t> Data)
+      : Data(std::begin(Data), std::end(Data)) {
+    Name = SecName;
+    Type = ELF::SHT_PROGBITS;
+    Size = Data.size();
+  }
+  void writeSection(FileOutputBuffer &Out) const override;
+};
+
 // There are two types of string tables that can exist, dynamic and not dynamic.
 // In the dynamic case the string table is allocated. Changing a dynamic string
 // table would mean altering virtual addresses and thus the memory image. So
@@ -372,6 +386,7 @@ public:
   const SymbolTableSection *getSymTab() const { return SymbolTable; }
   const SectionBase *getSectionHeaderStrTab() const { return SectionNames; }
   void removeSections(std::function<bool(const SectionBase &)> ToRemove);
+  void addSection(StringRef SecName, ArrayRef<uint8_t> Data);
   virtual size_t totalSize() const = 0;
   virtual void finalize() = 0;
   virtual void write(FileOutputBuffer &Out) const = 0;
diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
index 9d60ae42639..20ce93bb40e 100644
--- a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
+++ b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
@@ -113,6 +113,10 @@ static cl::opt<std::string>
              cl::desc("Equivalent to extract-dwo on the input file to "
                       "<dwo-file>, then strip-dwo on the input file"),
              cl::value_desc("dwo-file"));
+static cl::list<std::string> AddSection(
+    "add-section",
+    cl::desc("Make a section named <section> with the contents of <file>."),
+    cl::value_desc("section=file"));
 
 using SectionPred = std::function<bool(const SectionBase &Sec)>;
 
@@ -174,7 +178,7 @@ template <class ELFT> void CopyBinary(const ELFObjectFile<ELFT> &ObjFile) {
     Obj = llvm::make_unique<ELFObject<ELFT>>(ObjFile);
 
   if (!SplitDWO.empty())
-    SplitDWOToFile<ELFT>(ObjFile, SplitDWO.getValue()); 
+    SplitDWOToFile<ELFT>(ObjFile, SplitDWO.getValue());
 
   SectionPred RemovePred = [](const SectionBase &) { return false; };
 
@@ -286,6 +290,22 @@ template <class ELFT> void CopyBinary(const ELFObjectFile<ELFT> &ObjFile) {
   }
 
   Obj->removeSections(RemovePred);
+
+  if (!AddSection.empty()) {
+    for (const auto &Flag : AddSection) {
+      auto SecPair = StringRef(Flag).split("=");
+      auto SecName = SecPair.first;
+      auto File = SecPair.second;
+      auto BufOrErr = MemoryBuffer::getFile(File);
+      if (!BufOrErr)
+        reportError(File, BufOrErr.getError());
+      auto Buf = std::move(*BufOrErr);
+      auto BufPtr = reinterpret_cast<const uint8_t *>(Buf->getBufferStart());
+      auto BufSize = Buf->getBufferSize();
+      Obj->addSection(SecName, ArrayRef<uint8_t>(BufPtr, BufSize));
+    }
+  }
+
   Obj->finalize();
   WriteObjectFile(*Obj, OutputFilename.getValue());
 }
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