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			120 lines
		
	
	
		
			3.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			120 lines
		
	
	
		
			3.6 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| //===- FileOutputBuffer.cpp - File Output Buffer ----------------*- C++ -*-===//
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| //
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| //                     The LLVM Compiler Infrastructure
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| //
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| // This file is distributed under the University of Illinois Open Source
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| // License. See LICENSE.TXT for details.
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| //
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| //===----------------------------------------------------------------------===//
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| //
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| // Utility for creating a in-memory buffer that will be written to a file.
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| //
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| //===----------------------------------------------------------------------===//
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| 
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| #include "llvm/Support/FileOutputBuffer.h"
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| #include "llvm/ADT/OwningPtr.h"
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| #include "llvm/ADT/SmallVector.h"
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| #include "llvm/Support/raw_ostream.h"
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| #include "llvm/Support/system_error.h"
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| 
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| using llvm::sys::fs::mapped_file_region;
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| 
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| namespace llvm {
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| FileOutputBuffer::FileOutputBuffer(mapped_file_region * R,
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|                                    StringRef Path, StringRef TmpPath)
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|   : Region(R)
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|   , FinalPath(Path)
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|   , TempPath(TmpPath) {
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| }
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| 
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| FileOutputBuffer::~FileOutputBuffer() {
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|   bool Existed;
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|   sys::fs::remove(Twine(TempPath), Existed);
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| }
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| 
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| error_code FileOutputBuffer::create(StringRef FilePath,
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|                                     size_t Size,
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|                                     OwningPtr<FileOutputBuffer> &Result,
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|                                     unsigned Flags) {
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|   // If file already exists, it must be a regular file (to be mappable).
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|   sys::fs::file_status Stat;
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|   error_code EC = sys::fs::status(FilePath, Stat);
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|   switch (Stat.type()) {
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|     case sys::fs::file_type::file_not_found:
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|       // If file does not exist, we'll create one.
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|       break;
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|     case sys::fs::file_type::regular_file: {
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|         // If file is not currently writable, error out.
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|         // FIXME: There is no sys::fs:: api for checking this.
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|         // FIXME: In posix, you use the access() call to check this.
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|       }
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|       break;
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|     default:
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|       if (EC)
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|         return EC;
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|       else
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|         return make_error_code(errc::operation_not_permitted);
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|   }
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| 
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|   // Delete target file.
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|   bool Existed;
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|   EC = sys::fs::remove(FilePath, Existed);
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|   if (EC)
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|     return EC;
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| 
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|   // Create new file in same directory but with random name.
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|   SmallString<128> TempFilePath;
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|   int FD;
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|   EC = sys::fs::unique_file(Twine(FilePath) + ".tmp%%%%%%%",
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|                             FD, TempFilePath, false, 0644);
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|   if (EC)
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|     return EC;
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| 
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|   OwningPtr<mapped_file_region> MappedFile(
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|     new mapped_file_region(FD, mapped_file_region::readwrite, Size, 0, EC));
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|   if (EC)
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|     return EC;
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| 
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|   // If requested, make the output file executable.
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|   if ( Flags & F_executable ) {
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|     sys::fs::file_status Stat2;
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|     EC = sys::fs::status(Twine(TempFilePath), Stat2);
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|     if (EC)
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|       return EC;
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| 
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|     sys::fs::perms new_perms = Stat2.permissions();
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|     if ( new_perms & sys::fs::owner_read )
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|       new_perms |= sys::fs::owner_exe;
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|     if ( new_perms & sys::fs::group_read )
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|       new_perms |= sys::fs::group_exe;
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|     if ( new_perms & sys::fs::others_read )
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|       new_perms |= sys::fs::others_exe;
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|     new_perms |= sys::fs::add_perms;
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|     EC = sys::fs::permissions(Twine(TempFilePath), new_perms);
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|     if (EC)
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|       return EC;
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|   }
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| 
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|   Result.reset(new FileOutputBuffer(MappedFile.get(), FilePath, TempFilePath));
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|   if (Result)
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|     MappedFile.take();
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| 
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|   return error_code::success();
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| }
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| 
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| error_code FileOutputBuffer::commit(int64_t NewSmallerSize) {
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|   // Unmap buffer, letting OS flush dirty pages to file on disk.
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|   Region.reset(0);
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| 
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|   // If requested, resize file as part of commit.
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|   if ( NewSmallerSize != -1 ) {
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|     error_code EC = sys::fs::resize_file(Twine(TempPath), NewSmallerSize);
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|     if (EC)
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|       return EC;
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|   }
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| 
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|   // Rename file to final name.
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|   return sys::fs::rename(Twine(TempPath), Twine(FinalPath));
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| }
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| } // namespace
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