lib/Support/Windows/Program.inc - llvm-project/llvm - Git at Google

 //===- Win32/Program.cpp - Win32 Program Implementation ------- -*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file provides the Win32 specific implementation of the Program class.
 //
 //===----------------------------------------------------------------------===//

 #include "WindowsSupport.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/WindowsError.h"
 #include "llvm/Support/raw_ostream.h"
 #include <cstdio>
 #include <fcntl.h>
 #include <io.h>
 #include <malloc.h>

 //===----------------------------------------------------------------------===//
 //=== WARNING: Implementation here must contain only Win32 specific code
 //===          and must not be UNIX code
 //===----------------------------------------------------------------------===//

 namespace llvm {
 using namespace sys;

 ProcessInfo::ProcessInfo() : ProcessHandle(0), Pid(0), ReturnCode(0) {}

 ErrorOr<std::string> sys::findProgramByName(StringRef Name,
                                             ArrayRef<StringRef> Paths) {
   assert(!Name.empty() && "Must have a name!");

   if (Name.find_first_of("/\\") != StringRef::npos)
     return std::string(Name);

   const wchar_t *Path = nullptr;
   std::wstring PathStorage;
   if (!Paths.empty()) {
     PathStorage.reserve(Paths.size() * MAX_PATH);
     for (unsigned i = 0; i < Paths.size(); ++i) {
       if (i)
         PathStorage.push_back(L';');
       StringRef P = Paths[i];
       SmallVector<wchar_t, MAX_PATH> TmpPath;
       if (std::error_code EC = windows::UTF8ToUTF16(P, TmpPath))
         return EC;
       PathStorage.append(TmpPath.begin(), TmpPath.end());
     }
     Path = PathStorage.c_str();
   }

   SmallVector<wchar_t, MAX_PATH> U16Name;
   if (std::error_code EC = windows::UTF8ToUTF16(Name, U16Name))
     return EC;

   SmallVector<StringRef, 12> PathExts;
   PathExts.push_back("");
   PathExts.push_back(".exe"); // FIXME: This must be in %PATHEXT%.
   if (const char *PathExtEnv = std::getenv("PATHEXT"))
     SplitString(PathExtEnv, PathExts, ";");

   SmallVector<wchar_t, MAX_PATH> U16Result;
   DWORD Len = MAX_PATH;
   for (StringRef Ext : PathExts) {
     SmallVector<wchar_t, MAX_PATH> U16Ext;
     if (std::error_code EC = windows::UTF8ToUTF16(Ext, U16Ext))
       return EC;

     do {
       U16Result.reserve(Len);
       Len = ::SearchPathW(Path, c_str(U16Name),
                           U16Ext.empty() ? nullptr : c_str(U16Ext),
                           U16Result.capacity(), U16Result.data(), nullptr);
     } while (Len > U16Result.capacity());

     if (Len != 0)
       break; // Found it.
   }

   if (Len == 0)
     return mapWindowsError(::GetLastError());

   U16Result.set_size(Len);

   SmallVector<char, MAX_PATH> U8Result;
   if (std::error_code EC =
           windows::UTF16ToUTF8(U16Result.data(), U16Result.size(), U8Result))
     return EC;

   return std::string(U8Result.begin(), U8Result.end());
 }

 static HANDLE RedirectIO(const StringRef *path, int fd, std::string* ErrMsg) {
   HANDLE h;
   if (path == 0) {
     if (!DuplicateHandle(GetCurrentProcess(), (HANDLE)_get_osfhandle(fd),
                          GetCurrentProcess(), &h,
                          0, TRUE, DUPLICATE_SAME_ACCESS))
       return INVALID_HANDLE_VALUE;
     return h;
   }

   std::string fname;
   if (path->empty())
     fname = "NUL";
   else
     fname = *path;

   SECURITY_ATTRIBUTES sa;
   sa.nLength = sizeof(sa);
   sa.lpSecurityDescriptor = 0;
   sa.bInheritHandle = TRUE;

   SmallVector<wchar_t, 128> fnameUnicode;
   if (path->empty()) {
     // Don't play long-path tricks on "NUL".
     if (windows::UTF8ToUTF16(fname, fnameUnicode))
       return INVALID_HANDLE_VALUE;
   } else {
     if (path::widenPath(fname, fnameUnicode))
       return INVALID_HANDLE_VALUE;
   }
   h = CreateFileW(fnameUnicode.data(), fd ? GENERIC_WRITE : GENERIC_READ,
                   FILE_SHARE_READ, &sa, fd == 0 ? OPEN_EXISTING : CREATE_ALWAYS,
                   FILE_ATTRIBUTE_NORMAL, NULL);
   if (h == INVALID_HANDLE_VALUE) {
     MakeErrMsg(ErrMsg, fname + ": Can't open file for " +
         (fd ? "input: " : "output: "));
   }

   return h;
 }

 /// ArgNeedsQuotes - Check whether argument needs to be quoted when calling
 /// CreateProcess.
 static bool ArgNeedsQuotes(const char *Str) {
   return Str[0] == '\0' || strpbrk(Str, "\t \"&\'()*<>\\`^|") != 0;
 }

 /// CountPrecedingBackslashes - Returns the number of backslashes preceding Cur
 /// in the C string Start.
 static unsigned int CountPrecedingBackslashes(const char *Start,
                                               const char *Cur) {
   unsigned int Count = 0;
   --Cur;
   while (Cur >= Start && *Cur == '\\') {
     ++Count;
     --Cur;
   }
   return Count;
 }

 /// EscapePrecedingEscapes - Append a backslash to Dst for every backslash
 /// preceding Cur in the Start string.  Assumes Dst has enough space.
 static char *EscapePrecedingEscapes(char *Dst, const char *Start,
                                     const char *Cur) {
   unsigned PrecedingEscapes = CountPrecedingBackslashes(Start, Cur);
   while (PrecedingEscapes > 0) {
     *Dst++ = '\\';
     --PrecedingEscapes;
   }
   return Dst;
 }

 /// ArgLenWithQuotes - Check whether argument needs to be quoted when calling
 /// CreateProcess and returns length of quoted arg with escaped quotes
 static unsigned int ArgLenWithQuotes(const char *Str) {
   const char *Start = Str;
   bool Quoted = ArgNeedsQuotes(Str);
   unsigned int len = Quoted ? 2 : 0;

   while (*Str != '\0') {
     if (*Str == '\"') {
       // We need to add a backslash, but ensure that it isn't escaped.
       unsigned PrecedingEscapes = CountPrecedingBackslashes(Start, Str);
       len += PrecedingEscapes + 1;
     }
     // Note that we *don't* need to escape runs of backslashes that don't
     // precede a double quote!  See MSDN:
     // http://msdn.microsoft.com/en-us/library/17w5ykft%28v=vs.85%29.aspx

     ++len;
     ++Str;
   }

   if (Quoted) {
     // Make sure the closing quote doesn't get escaped by a trailing backslash.
     unsigned PrecedingEscapes = CountPrecedingBackslashes(Start, Str);
     len += PrecedingEscapes + 1;
   }

   return len;
 }

 }

 static std::unique_ptr<char[]> flattenArgs(const char **args) {
   // First, determine the length of the command line.
   unsigned len = 0;
   for (unsigned i = 0; args[i]; i++) {
     len += ArgLenWithQuotes(args[i]) + 1;
   }

   // Now build the command line.
   std::unique_ptr<char[]> command(new char[len+1]);
   char *p = command.get();

   for (unsigned i = 0; args[i]; i++) {
     const char *arg = args[i];
     const char *start = arg;

     bool needsQuoting = ArgNeedsQuotes(arg);
     if (needsQuoting)
       *p++ = '"';

     while (*arg != '\0') {
       if (*arg == '\"') {
         // Escape all preceding escapes (if any), and then escape the quote.
         p = EscapePrecedingEscapes(p, start, arg);
         *p++ = '\\';
       }

       *p++ = *arg++;
     }

     if (needsQuoting) {
       // Make sure our quote doesn't get escaped by a trailing backslash.
       p = EscapePrecedingEscapes(p, start, arg);
       *p++ = '"';
     }
     *p++ = ' ';
   }

   *p = 0;
   return command;
 }

 static bool Execute(ProcessInfo &PI, StringRef Program, const char **args,
                     const char **envp, const StringRef **redirects,
                     unsigned memoryLimit, std::string *ErrMsg) {
   if (!sys::fs::can_execute(Program)) {
     if (ErrMsg)
       *ErrMsg = "program not executable";
     return false;
   }

   // Windows wants a command line, not an array of args, to pass to the new
   // process.  We have to concatenate them all, while quoting the args that
   // have embedded spaces (or are empty).
   std::unique_ptr<char[]> command = flattenArgs(args);

   // The pointer to the environment block for the new process.
   std::vector<wchar_t> EnvBlock;

   if (envp) {
     // An environment block consists of a null-terminated block of
     // null-terminated strings. Convert the array of environment variables to
     // an environment block by concatenating them.
     for (unsigned i = 0; envp[i]; ++i) {
       SmallVector<wchar_t, MAX_PATH> EnvString;
       if (std::error_code ec = windows::UTF8ToUTF16(envp[i], EnvString)) {
         SetLastError(ec.value());
         MakeErrMsg(ErrMsg, "Unable to convert environment variable to UTF-16");
         return false;
       }

       EnvBlock.insert(EnvBlock.end(), EnvString.begin(), EnvString.end());
       EnvBlock.push_back(0);
     }
     EnvBlock.push_back(0);
   }

   // Create a child process.
   STARTUPINFOW si;
   memset(&si, 0, sizeof(si));
   si.cb = sizeof(si);
   si.hStdInput = INVALID_HANDLE_VALUE;
   si.hStdOutput = INVALID_HANDLE_VALUE;
   si.hStdError = INVALID_HANDLE_VALUE;

   if (redirects) {
     si.dwFlags = STARTF_USESTDHANDLES;

     si.hStdInput = RedirectIO(redirects[0], 0, ErrMsg);
     if (si.hStdInput == INVALID_HANDLE_VALUE) {
       MakeErrMsg(ErrMsg, "can't redirect stdin");
       return false;
     }
     si.hStdOutput = RedirectIO(redirects[1], 1, ErrMsg);
     if (si.hStdOutput == INVALID_HANDLE_VALUE) {
       CloseHandle(si.hStdInput);
       MakeErrMsg(ErrMsg, "can't redirect stdout");
       return false;
     }
     if (redirects[1] && redirects[2] && *(redirects[1]) == *(redirects[2])) {
       // If stdout and stderr should go to the same place, redirect stderr
       // to the handle already open for stdout.
       if (!DuplicateHandle(GetCurrentProcess(), si.hStdOutput,
                            GetCurrentProcess(), &si.hStdError,
                            0, TRUE, DUPLICATE_SAME_ACCESS)) {
         CloseHandle(si.hStdInput);
         CloseHandle(si.hStdOutput);
         MakeErrMsg(ErrMsg, "can't dup stderr to stdout");
         return false;
       }
     } else {
       // Just redirect stderr
       si.hStdError = RedirectIO(redirects[2], 2, ErrMsg);
       if (si.hStdError == INVALID_HANDLE_VALUE) {
         CloseHandle(si.hStdInput);
         CloseHandle(si.hStdOutput);
         MakeErrMsg(ErrMsg, "can't redirect stderr");
         return false;
       }
     }
   }

   PROCESS_INFORMATION pi;
   memset(&pi, 0, sizeof(pi));

   fflush(stdout);
   fflush(stderr);

   SmallVector<wchar_t, MAX_PATH> ProgramUtf16;
   if (std::error_code ec = path::widenPath(Program, ProgramUtf16)) {
     SetLastError(ec.value());
     MakeErrMsg(ErrMsg,
                std::string("Unable to convert application name to UTF-16"));
     return false;
   }

   SmallVector<wchar_t, MAX_PATH> CommandUtf16;
   if (std::error_code ec = windows::UTF8ToUTF16(command.get(), CommandUtf16)) {
     SetLastError(ec.value());
     MakeErrMsg(ErrMsg,
                std::string("Unable to convert command-line to UTF-16"));
     return false;
   }

   BOOL rc = CreateProcessW(ProgramUtf16.data(), CommandUtf16.data(), 0, 0,
                            TRUE, CREATE_UNICODE_ENVIRONMENT,
                            EnvBlock.empty() ? 0 : EnvBlock.data(), 0, &si,
                            &pi);
   DWORD err = GetLastError();

   // Regardless of whether the process got created or not, we are done with
   // the handles we created for it to inherit.
   CloseHandle(si.hStdInput);
   CloseHandle(si.hStdOutput);
   CloseHandle(si.hStdError);

   // Now return an error if the process didn't get created.
   if (!rc) {
     SetLastError(err);
     MakeErrMsg(ErrMsg, std::string("Couldn't execute program '") +
                Program.str() + "'");
     return false;
   }

   PI.Pid = pi.dwProcessId;
   PI.ProcessHandle = pi.hProcess;

   // Make sure these get closed no matter what.
   ScopedCommonHandle hThread(pi.hThread);

   // Assign the process to a job if a memory limit is defined.
   ScopedJobHandle hJob;
   if (memoryLimit != 0) {
     hJob = CreateJobObjectW(0, 0);
     bool success = false;
     if (hJob) {
       JOBOBJECT_EXTENDED_LIMIT_INFORMATION jeli;
       memset(&jeli, 0, sizeof(jeli));
       jeli.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_PROCESS_MEMORY;
       jeli.ProcessMemoryLimit = uintptr_t(memoryLimit) * 1048576;
       if (SetInformationJobObject(hJob, JobObjectExtendedLimitInformation,
                                   &jeli, sizeof(jeli))) {
         if (AssignProcessToJobObject(hJob, pi.hProcess))
           success = true;
       }
     }
     if (!success) {
       SetLastError(GetLastError());
       MakeErrMsg(ErrMsg, std::string("Unable to set memory limit"));
       TerminateProcess(pi.hProcess, 1);
       WaitForSingleObject(pi.hProcess, INFINITE);
       return false;
     }
   }

   return true;
 }

 namespace llvm {
 ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
                       bool WaitUntilChildTerminates, std::string *ErrMsg) {
   assert(PI.Pid && "invalid pid to wait on, process not started?");
   assert(PI.ProcessHandle &&
          "invalid process handle to wait on, process not started?");
   DWORD milliSecondsToWait = 0;
   if (WaitUntilChildTerminates)
     milliSecondsToWait = INFINITE;
   else if (SecondsToWait > 0)
     milliSecondsToWait = SecondsToWait * 1000;

   ProcessInfo WaitResult = PI;
   DWORD WaitStatus = WaitForSingleObject(PI.ProcessHandle, milliSecondsToWait);
   if (WaitStatus == WAIT_TIMEOUT) {
     if (SecondsToWait) {
       if (!TerminateProcess(PI.ProcessHandle, 1)) {
         if (ErrMsg)
           MakeErrMsg(ErrMsg, "Failed to terminate timed-out program.");

         // -2 indicates a crash or timeout as opposed to failure to execute.
         WaitResult.ReturnCode = -2;
         CloseHandle(PI.ProcessHandle);
         return WaitResult;
       }
       WaitForSingleObject(PI.ProcessHandle, INFINITE);
       CloseHandle(PI.ProcessHandle);
     } else {
       // Non-blocking wait.
       return ProcessInfo();
     }
   }

   // Get its exit status.
   DWORD status;
   BOOL rc = GetExitCodeProcess(PI.ProcessHandle, &status);
   DWORD err = GetLastError();
   CloseHandle(PI.ProcessHandle);

   if (!rc) {
     SetLastError(err);
     if (ErrMsg)
       MakeErrMsg(ErrMsg, "Failed getting status for program.");

     // -2 indicates a crash or timeout as opposed to failure to execute.
     WaitResult.ReturnCode = -2;
     return WaitResult;
   }

   if (!status)
     return WaitResult;

   // Pass 10(Warning) and 11(Error) to the callee as negative value.
   if ((status & 0xBFFF0000U) == 0x80000000U)
     WaitResult.ReturnCode = static_cast<int>(status);
   else if (status & 0xFF)
     WaitResult.ReturnCode = status & 0x7FFFFFFF;
   else
     WaitResult.ReturnCode = 1;

   return WaitResult;
 }

 std::error_code sys::ChangeStdinToBinary() {
   int result = _setmode(_fileno(stdin), _O_BINARY);
   if (result == -1)
     return std::error_code(errno, std::generic_category());
   return std::error_code();
 }

 std::error_code sys::ChangeStdoutToBinary() {
   int result = _setmode(_fileno(stdout), _O_BINARY);
   if (result == -1)
     return std::error_code(errno, std::generic_category());
   return std::error_code();
 }

 std::error_code
 llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
                                  WindowsEncodingMethod Encoding) {
   std::error_code EC;
   llvm::raw_fd_ostream OS(FileName, EC, llvm::sys::fs::OpenFlags::F_Text);
   if (EC)
     return EC;

   if (Encoding == WEM_UTF8) {
     OS << Contents;
   } else if (Encoding == WEM_CurrentCodePage) {
     SmallVector<wchar_t, 1> ArgsUTF16;
     SmallVector<char, 1> ArgsCurCP;

     if ((EC = windows::UTF8ToUTF16(Contents, ArgsUTF16)))
       return EC;

     if ((EC = windows::UTF16ToCurCP(
              ArgsUTF16.data(), ArgsUTF16.size(), ArgsCurCP)))
       return EC;

     OS.write(ArgsCurCP.data(), ArgsCurCP.size());
   } else if (Encoding == WEM_UTF16) {
     SmallVector<wchar_t, 1> ArgsUTF16;

     if ((EC = windows::UTF8ToUTF16(Contents, ArgsUTF16)))
       return EC;

     // Endianness guessing
     char BOM[2];
     uint16_t src = UNI_UTF16_BYTE_ORDER_MARK_NATIVE;
     memcpy(BOM, &src, 2);
     OS.write(BOM, 2);
     OS.write((char *)ArgsUTF16.data(), ArgsUTF16.size() << 1);
   } else {
     llvm_unreachable("Unknown encoding");
   }

   if (OS.has_error())
     return std::make_error_code(std::errc::io_error);

   return EC;
 }

 bool llvm::sys::argumentsFitWithinSystemLimits(ArrayRef<const char*> Args) {
   // The documented max length of the command line passed to CreateProcess.
   static const size_t MaxCommandStringLength = 32768;
   size_t ArgLength = 0;
   for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
        I != E; ++I) {
     // Account for the trailing space for every arg but the last one and the
     // trailing NULL of the last argument.
     ArgLength += ArgLenWithQuotes(*I) + 1;
     if (ArgLength > MaxCommandStringLength) {
       return false;
     }
   }
   return true;
 }
 }
	//===- Win32/Program.cpp - Win32 Program Implementation ------- -- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file provides the Win32 specific implementation of the Program class.
	//
	//===----------------------------------------------------------------------===//

	#include "WindowsSupport.h"
	#include "llvm/ADT/StringExtras.h"
	#include "llvm/Support/ConvertUTF.h"
	#include "llvm/Support/FileSystem.h"
	#include "llvm/Support/WindowsError.h"
	#include "llvm/Support/raw_ostream.h"
	#include <cstdio>
	#include <fcntl.h>
	#include <io.h>
	#include <malloc.h>

	//===----------------------------------------------------------------------===//
	//=== WARNING: Implementation here must contain only Win32 specific code
	//=== and must not be UNIX code
	//===----------------------------------------------------------------------===//

	namespace llvm {
	using namespace sys;

	ProcessInfo::ProcessInfo() : ProcessHandle(0), Pid(0), ReturnCode(0) {}

	ErrorOr<std::string> sys::findProgramByName(StringRef Name,
	ArrayRef<StringRef> Paths) {
	assert(!Name.empty() && "Must have a name!");

	if (Name.find_first_of("/\\") != StringRef::npos)
	return std::string(Name);

	const wchar_t *Path = nullptr;
	std::wstring PathStorage;
	if (!Paths.empty()) {
	PathStorage.reserve(Paths.size() * MAX_PATH);
	for (unsigned i = 0; i < Paths.size(); ++i) {
	if (i)
	PathStorage.push_back(L';');
	StringRef P = Paths[i];
	SmallVector<wchar_t, MAX_PATH> TmpPath;
	if (std::error_code EC = windows::UTF8ToUTF16(P, TmpPath))
	return EC;
	PathStorage.append(TmpPath.begin(), TmpPath.end());
	}
	Path = PathStorage.c_str();
	}

	SmallVector<wchar_t, MAX_PATH> U16Name;
	if (std::error_code EC = windows::UTF8ToUTF16(Name, U16Name))
	return EC;

	SmallVector<StringRef, 12> PathExts;
	PathExts.push_back("");
	PathExts.push_back(".exe"); // FIXME: This must be in %PATHEXT%.
	if (const char *PathExtEnv = std::getenv("PATHEXT"))
	SplitString(PathExtEnv, PathExts, ";");

	SmallVector<wchar_t, MAX_PATH> U16Result;
	DWORD Len = MAX_PATH;
	for (StringRef Ext : PathExts) {
	SmallVector<wchar_t, MAX_PATH> U16Ext;
	if (std::error_code EC = windows::UTF8ToUTF16(Ext, U16Ext))
	return EC;

	do {
	U16Result.reserve(Len);
	Len = ::SearchPathW(Path, c_str(U16Name),
	U16Ext.empty() ? nullptr : c_str(U16Ext),
	U16Result.capacity(), U16Result.data(), nullptr);
	} while (Len > U16Result.capacity());

	if (Len != 0)
	break; // Found it.
	}

	if (Len == 0)
	return mapWindowsError(::GetLastError());

	U16Result.set_size(Len);

	SmallVector<char, MAX_PATH> U8Result;
	if (std::error_code EC =
	windows::UTF16ToUTF8(U16Result.data(), U16Result.size(), U8Result))
	return EC;

	return std::string(U8Result.begin(), U8Result.end());
	}

	static HANDLE RedirectIO(const StringRef path, int fd, std::string ErrMsg) {
	HANDLE h;
	if (path == 0) {
	if (!DuplicateHandle(GetCurrentProcess(), (HANDLE)_get_osfhandle(fd),
	GetCurrentProcess(), &h,
	0, TRUE, DUPLICATE_SAME_ACCESS))
	return INVALID_HANDLE_VALUE;
	return h;
	}

	std::string fname;
	if (path->empty())
	fname = "NUL";
	else
	fname = *path;

	SECURITY_ATTRIBUTES sa;
	sa.nLength = sizeof(sa);
	sa.lpSecurityDescriptor = 0;
	sa.bInheritHandle = TRUE;

	SmallVector<wchar_t, 128> fnameUnicode;
	if (path->empty()) {
	// Don't play long-path tricks on "NUL".
	if (windows::UTF8ToUTF16(fname, fnameUnicode))
	return INVALID_HANDLE_VALUE;
	} else {
	if (path::widenPath(fname, fnameUnicode))
	return INVALID_HANDLE_VALUE;
	}
	h = CreateFileW(fnameUnicode.data(), fd ? GENERIC_WRITE : GENERIC_READ,
	FILE_SHARE_READ, &sa, fd == 0 ? OPEN_EXISTING : CREATE_ALWAYS,
	FILE_ATTRIBUTE_NORMAL, NULL);
	if (h == INVALID_HANDLE_VALUE) {
	MakeErrMsg(ErrMsg, fname + ": Can't open file for " +
	(fd ? "input: " : "output: "));
	}

	return h;
	}

	/// ArgNeedsQuotes - Check whether argument needs to be quoted when calling
	/// CreateProcess.
	static bool ArgNeedsQuotes(const char *Str) {
	return Str[0] == '\0' \|\| strpbrk(Str, "\t \"&\'()*<>\\`^\|") != 0;
	}

	/// CountPrecedingBackslashes - Returns the number of backslashes preceding Cur
	/// in the C string Start.
	static unsigned int CountPrecedingBackslashes(const char *Start,
	const char *Cur) {
	unsigned int Count = 0;
	--Cur;
	while (Cur >= Start && *Cur == '\\') {
	++Count;
	--Cur;
	}
	return Count;
	}

	/// EscapePrecedingEscapes - Append a backslash to Dst for every backslash
	/// preceding Cur in the Start string. Assumes Dst has enough space.
	static char EscapePrecedingEscapes(char Dst, const char *Start,
	const char *Cur) {
	unsigned PrecedingEscapes = CountPrecedingBackslashes(Start, Cur);
	while (PrecedingEscapes > 0) {
	*Dst++ = '\\';
	--PrecedingEscapes;
	}
	return Dst;
	}

	/// ArgLenWithQuotes - Check whether argument needs to be quoted when calling
	/// CreateProcess and returns length of quoted arg with escaped quotes
	static unsigned int ArgLenWithQuotes(const char *Str) {
	const char *Start = Str;
	bool Quoted = ArgNeedsQuotes(Str);
	unsigned int len = Quoted ? 2 : 0;

	while (*Str != '\0') {
	if (*Str == '\"') {
	// We need to add a backslash, but ensure that it isn't escaped.
	unsigned PrecedingEscapes = CountPrecedingBackslashes(Start, Str);
	len += PrecedingEscapes + 1;
	}
	// Note that we don't need to escape runs of backslashes that don't
	// precede a double quote! See MSDN:
	// http://msdn.microsoft.com/en-us/library/17w5ykft%28v=vs.85%29.aspx

	++len;
	++Str;
	}

	if (Quoted) {
	// Make sure the closing quote doesn't get escaped by a trailing backslash.
	unsigned PrecedingEscapes = CountPrecedingBackslashes(Start, Str);
	len += PrecedingEscapes + 1;
	}

	return len;
	}

	}

	static std::unique_ptr<char[]> flattenArgs(const char **args) {
	// First, determine the length of the command line.
	unsigned len = 0;
	for (unsigned i = 0; args[i]; i++) {
	len += ArgLenWithQuotes(args[i]) + 1;
	}

	// Now build the command line.
	std::unique_ptr<char[]> command(new char[len+1]);
	char *p = command.get();

	for (unsigned i = 0; args[i]; i++) {
	const char *arg = args[i];
	const char *start = arg;

	bool needsQuoting = ArgNeedsQuotes(arg);
	if (needsQuoting)
	*p++ = '"';

	while (*arg != '\0') {
	if (*arg == '\"') {
	// Escape all preceding escapes (if any), and then escape the quote.
	p = EscapePrecedingEscapes(p, start, arg);
	*p++ = '\\';
	}

	p++ = arg++;
	}

	if (needsQuoting) {
	// Make sure our quote doesn't get escaped by a trailing backslash.
	p = EscapePrecedingEscapes(p, start, arg);
	*p++ = '"';
	}
	*p++ = ' ';
	}

	*p = 0;
	return command;
	}

	static bool Execute(ProcessInfo &PI, StringRef Program, const char **args,
	const char envp, const StringRef redirects,
	unsigned memoryLimit, std::string *ErrMsg) {
	if (!sys::fs::can_execute(Program)) {
	if (ErrMsg)
	*ErrMsg = "program not executable";
	return false;
	}

	// Windows wants a command line, not an array of args, to pass to the new
	// process. We have to concatenate them all, while quoting the args that
	// have embedded spaces (or are empty).
	std::unique_ptr<char[]> command = flattenArgs(args);

	// The pointer to the environment block for the new process.
	std::vector<wchar_t> EnvBlock;

	if (envp) {
	// An environment block consists of a null-terminated block of
	// null-terminated strings. Convert the array of environment variables to
	// an environment block by concatenating them.
	for (unsigned i = 0; envp[i]; ++i) {
	SmallVector<wchar_t, MAX_PATH> EnvString;
	if (std::error_code ec = windows::UTF8ToUTF16(envp[i], EnvString)) {
	SetLastError(ec.value());
	MakeErrMsg(ErrMsg, "Unable to convert environment variable to UTF-16");
	return false;
	}

	EnvBlock.insert(EnvBlock.end(), EnvString.begin(), EnvString.end());
	EnvBlock.push_back(0);
	}
	EnvBlock.push_back(0);
	}

	// Create a child process.
	STARTUPINFOW si;
	memset(&si, 0, sizeof(si));
	si.cb = sizeof(si);
	si.hStdInput = INVALID_HANDLE_VALUE;
	si.hStdOutput = INVALID_HANDLE_VALUE;
	si.hStdError = INVALID_HANDLE_VALUE;

	if (redirects) {
	si.dwFlags = STARTF_USESTDHANDLES;

	si.hStdInput = RedirectIO(redirects[0], 0, ErrMsg);
	if (si.hStdInput == INVALID_HANDLE_VALUE) {
	MakeErrMsg(ErrMsg, "can't redirect stdin");
	return false;
	}
	si.hStdOutput = RedirectIO(redirects[1], 1, ErrMsg);
	if (si.hStdOutput == INVALID_HANDLE_VALUE) {
	CloseHandle(si.hStdInput);
	MakeErrMsg(ErrMsg, "can't redirect stdout");
	return false;
	}
	if (redirects[1] && redirects[2] && (redirects[1]) == (redirects[2])) {
	// If stdout and stderr should go to the same place, redirect stderr
	// to the handle already open for stdout.
	if (!DuplicateHandle(GetCurrentProcess(), si.hStdOutput,
	GetCurrentProcess(), &si.hStdError,
	0, TRUE, DUPLICATE_SAME_ACCESS)) {
	CloseHandle(si.hStdInput);
	CloseHandle(si.hStdOutput);
	MakeErrMsg(ErrMsg, "can't dup stderr to stdout");
	return false;
	}
	} else {
	// Just redirect stderr
	si.hStdError = RedirectIO(redirects[2], 2, ErrMsg);
	if (si.hStdError == INVALID_HANDLE_VALUE) {
	CloseHandle(si.hStdInput);
	CloseHandle(si.hStdOutput);
	MakeErrMsg(ErrMsg, "can't redirect stderr");
	return false;
	}
	}
	}

	PROCESS_INFORMATION pi;
	memset(&pi, 0, sizeof(pi));

	fflush(stdout);
	fflush(stderr);

	SmallVector<wchar_t, MAX_PATH> ProgramUtf16;
	if (std::error_code ec = path::widenPath(Program, ProgramUtf16)) {
	SetLastError(ec.value());
	MakeErrMsg(ErrMsg,
	std::string("Unable to convert application name to UTF-16"));
	return false;
	}

	SmallVector<wchar_t, MAX_PATH> CommandUtf16;
	if (std::error_code ec = windows::UTF8ToUTF16(command.get(), CommandUtf16)) {
	SetLastError(ec.value());
	MakeErrMsg(ErrMsg,
	std::string("Unable to convert command-line to UTF-16"));
	return false;
	}

	BOOL rc = CreateProcessW(ProgramUtf16.data(), CommandUtf16.data(), 0, 0,
	TRUE, CREATE_UNICODE_ENVIRONMENT,
	EnvBlock.empty() ? 0 : EnvBlock.data(), 0, &si,
	&pi);
	DWORD err = GetLastError();

	// Regardless of whether the process got created or not, we are done with
	// the handles we created for it to inherit.
	CloseHandle(si.hStdInput);
	CloseHandle(si.hStdOutput);
	CloseHandle(si.hStdError);

	// Now return an error if the process didn't get created.
	if (!rc) {
	SetLastError(err);
	MakeErrMsg(ErrMsg, std::string("Couldn't execute program '") +
	Program.str() + "'");
	return false;
	}

	PI.Pid = pi.dwProcessId;
	PI.ProcessHandle = pi.hProcess;

	// Make sure these get closed no matter what.
	ScopedCommonHandle hThread(pi.hThread);

	// Assign the process to a job if a memory limit is defined.
	ScopedJobHandle hJob;
	if (memoryLimit != 0) {
	hJob = CreateJobObjectW(0, 0);
	bool success = false;
	if (hJob) {
	JOBOBJECT_EXTENDED_LIMIT_INFORMATION jeli;
	memset(&jeli, 0, sizeof(jeli));
	jeli.BasicLimitInformation.LimitFlags = JOB_OBJECT_LIMIT_PROCESS_MEMORY;
	jeli.ProcessMemoryLimit = uintptr_t(memoryLimit) * 1048576;
	if (SetInformationJobObject(hJob, JobObjectExtendedLimitInformation,
	&jeli, sizeof(jeli))) {
	if (AssignProcessToJobObject(hJob, pi.hProcess))
	success = true;
	}
	}
	if (!success) {
	SetLastError(GetLastError());
	MakeErrMsg(ErrMsg, std::string("Unable to set memory limit"));
	TerminateProcess(pi.hProcess, 1);
	WaitForSingleObject(pi.hProcess, INFINITE);
	return false;
	}
	}

	return true;
	}

	namespace llvm {
	ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
	bool WaitUntilChildTerminates, std::string *ErrMsg) {
	assert(PI.Pid && "invalid pid to wait on, process not started?");
	assert(PI.ProcessHandle &&
	"invalid process handle to wait on, process not started?");
	DWORD milliSecondsToWait = 0;
	if (WaitUntilChildTerminates)
	milliSecondsToWait = INFINITE;
	else if (SecondsToWait > 0)
	milliSecondsToWait = SecondsToWait * 1000;

	ProcessInfo WaitResult = PI;
	DWORD WaitStatus = WaitForSingleObject(PI.ProcessHandle, milliSecondsToWait);
	if (WaitStatus == WAIT_TIMEOUT) {
	if (SecondsToWait) {
	if (!TerminateProcess(PI.ProcessHandle, 1)) {
	if (ErrMsg)
	MakeErrMsg(ErrMsg, "Failed to terminate timed-out program.");

	// -2 indicates a crash or timeout as opposed to failure to execute.
	WaitResult.ReturnCode = -2;
	CloseHandle(PI.ProcessHandle);
	return WaitResult;
	}
	WaitForSingleObject(PI.ProcessHandle, INFINITE);
	CloseHandle(PI.ProcessHandle);
	} else {
	// Non-blocking wait.
	return ProcessInfo();
	}
	}

	// Get its exit status.
	DWORD status;
	BOOL rc = GetExitCodeProcess(PI.ProcessHandle, &status);
	DWORD err = GetLastError();
	CloseHandle(PI.ProcessHandle);

	if (!rc) {
	SetLastError(err);
	if (ErrMsg)
	MakeErrMsg(ErrMsg, "Failed getting status for program.");

	// -2 indicates a crash or timeout as opposed to failure to execute.
	WaitResult.ReturnCode = -2;
	return WaitResult;
	}

	if (!status)
	return WaitResult;

	// Pass 10(Warning) and 11(Error) to the callee as negative value.
	if ((status & 0xBFFF0000U) == 0x80000000U)
	WaitResult.ReturnCode = static_cast<int>(status);
	else if (status & 0xFF)
	WaitResult.ReturnCode = status & 0x7FFFFFFF;
	else
	WaitResult.ReturnCode = 1;

	return WaitResult;
	}

	std::error_code sys::ChangeStdinToBinary() {
	int result = _setmode(_fileno(stdin), _O_BINARY);
	if (result == -1)
	return std::error_code(errno, std::generic_category());
	return std::error_code();
	}

	std::error_code sys::ChangeStdoutToBinary() {
	int result = _setmode(_fileno(stdout), _O_BINARY);
	if (result == -1)
	return std::error_code(errno, std::generic_category());
	return std::error_code();
	}

	std::error_code
	llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
	WindowsEncodingMethod Encoding) {
	std::error_code EC;
	llvm::raw_fd_ostream OS(FileName, EC, llvm::sys::fs::OpenFlags::F_Text);
	if (EC)
	return EC;

	if (Encoding == WEM_UTF8) {
	OS << Contents;
	} else if (Encoding == WEM_CurrentCodePage) {
	SmallVector<wchar_t, 1> ArgsUTF16;
	SmallVector<char, 1> ArgsCurCP;

	if ((EC = windows::UTF8ToUTF16(Contents, ArgsUTF16)))
	return EC;

	if ((EC = windows::UTF16ToCurCP(
	ArgsUTF16.data(), ArgsUTF16.size(), ArgsCurCP)))
	return EC;

	OS.write(ArgsCurCP.data(), ArgsCurCP.size());
	} else if (Encoding == WEM_UTF16) {
	SmallVector<wchar_t, 1> ArgsUTF16;

	if ((EC = windows::UTF8ToUTF16(Contents, ArgsUTF16)))
	return EC;

	// Endianness guessing
	char BOM[2];
	uint16_t src = UNI_UTF16_BYTE_ORDER_MARK_NATIVE;
	memcpy(BOM, &src, 2);
	OS.write(BOM, 2);
	OS.write((char *)ArgsUTF16.data(), ArgsUTF16.size() << 1);
	} else {
	llvm_unreachable("Unknown encoding");
	}

	if (OS.has_error())
	return std::make_error_code(std::errc::io_error);

	return EC;
	}

	bool llvm::sys::argumentsFitWithinSystemLimits(ArrayRef<const char*> Args) {
	// The documented max length of the command line passed to CreateProcess.
	static const size_t MaxCommandStringLength = 32768;
	size_t ArgLength = 0;
	for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
	I != E; ++I) {
	// Account for the trailing space for every arg but the last one and the
	// trailing NULL of the last argument.
	ArgLength += ArgLenWithQuotes(*I) + 1;
	if (ArgLength > MaxCommandStringLength) {
	return false;
	}
	}
	return true;
	}
	}