[lld] r330786 - [COFF] create MemoryBuffers without requiring NUL terminators

[Bob Haarman via llvm-commits]

Author: inglorion
Date: Tue Apr 24 16:16:39 2018
New Revision: 330786

URL: http://llvm.org/viewvc/llvm-project?rev=330786&view=rev
Log:
[COFF] create MemoryBuffers without requiring NUL terminators

Summary:
In a number of places in the COFF linker, we were calling
MemoryBuffer::getFile() with default parameters. This causes LLVM to
NUL-terminate the buffers, which can prevent them from being memory
mapped. Since we operate on binary and do not use NUL as an indicator
of the end of the file content, this change causes us to not require
the NUL terminator anymore.

Reviewers: ruiu, pcc

Reviewed By: ruiu

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D45909

Modified:
    lld/trunk/COFF/Driver.cpp

Modified: lld/trunk/COFF/Driver.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Driver.cpp?rev=330786&r1=330785&r2=330786&view=diff
==============================================================================
--- lld/trunk/COFF/Driver.cpp (original)
+++ lld/trunk/COFF/Driver.cpp Tue Apr 24 16:16:39 2018
@@ -105,7 +105,9 @@ static std::future<MBErrPair> createFutu
   auto Strategy = std::launch::deferred;
 #endif
   return std::async(Strategy, [=]() {
-    auto MBOrErr = MemoryBuffer::getFile(Path);
+    auto MBOrErr = MemoryBuffer::getFile(Path,
+                                         /*FileSize*/ -1,
+                                         /*RequiresNullTerminator*/ false);
     if (!MBOrErr)
       return MBErrPair{nullptr, MBOrErr.getError()};
     return MBErrPair{std::move(*MBOrErr), std::error_code()};
@@ -563,7 +565,8 @@ static void createImportLibrary(bool AsL
 
   // If the import library already exists, replace it only if the contents
   // have changed.
-  ErrorOr<std::unique_ptr<MemoryBuffer>> OldBuf = MemoryBuffer::getFile(Path);
+  ErrorOr<std::unique_ptr<MemoryBuffer>> OldBuf = MemoryBuffer::getFile(
+      Path, /*FileSize*/ -1, /*RequiresNullTerminator*/ false);
   if (!OldBuf) {
     HandleError(writeImportLibrary(LibName, Path, Exports, Config->Machine,
                                    false, Config->MinGW));
@@ -582,7 +585,8 @@ static void createImportLibrary(bool AsL
     return;
   }
 
-  std::unique_ptr<MemoryBuffer> NewBuf = check(MemoryBuffer::getFile(TmpName));
+  std::unique_ptr<MemoryBuffer> NewBuf = check(MemoryBuffer::getFile(
+      TmpName, /*FileSize*/ -1, /*RequiresNullTerminator*/ false));
   if ((*OldBuf)->getBuffer() != NewBuf->getBuffer()) {
     OldBuf->reset();
     HandleError(errorCodeToError(sys::fs::rename(TmpName, Path)));