Revert "Resubmit "[Support] Expose flattenWindowsCommandLine.""

This reverts commit 65243b6d19143cb7a03f68df0169dcb63e8b4632.

Seems like it's not a flake.  It might have something to do with
the '*' character being in a command line.

llvm-svn: 334356

2 files changed, 116 insertions, 73 deletions

diff --git a/llvm/lib/Support/Windows/Path.inc b/llvm/lib/Support/Windows/Path.inc
index 7ef7468867d..9173206d816 100644
--- a/llvm/lib/Support/Windows/Path.inc
+++ b/llvm/lib/Support/Windows/Path.inc
@@ -1197,7 +1197,7 @@ Expected<file_t> openNativeFileForRead(const Twine &Name, OpenFlags Flags,
   if (Result && RealPath)
     realPathFromHandle(*Result, *RealPath);
 
-  return Result;
+  return std::move(Result);
 }
 
 void closeFile(file_t &F) {
diff --git a/llvm/lib/Support/Windows/Program.inc b/llvm/lib/Support/Windows/Program.inc
index ef1da602897..183b66ce2c0 100644
--- a/llvm/lib/Support/Windows/Program.inc
+++ b/llvm/lib/Support/Windows/Program.inc
@@ -23,7 +23,6 @@
 #include <fcntl.h>
 #include <io.h>
 #include <malloc.h>
-#include <numeric>
 
 //===----------------------------------------------------------------------===//
 //=== WARNING: Implementation here must contain only Win32 specific code
@@ -32,7 +31,7 @@
 
 namespace llvm {
 
-ProcessInfo::ProcessInfo() : Pid(0), Process(0), ReturnCode(0) {}
+ProcessInfo::ProcessInfo() : Process(0), Pid(0), ReturnCode(0) {}
 
 ErrorOr<std::string> sys::findProgramByName(StringRef Name,
                                             ArrayRef<StringRef> Paths) {
@@ -147,13 +146,108 @@ static HANDLE RedirectIO(Optional<StringRef> Path, int fd,
   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;
 }
 
-static SmallVector<StringRef, 8> buildArgVector(const char **Args) {
-  SmallVector<StringRef, 8> Result;
-  for (unsigned I = 0; Args[I]; ++I)
-    Result.push_back(StringRef(Args[I]));
-  return Result;
+/// 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,
@@ -176,8 +270,7 @@ static bool Execute(ProcessInfo &PI, StringRef Program, const char **Args,
   // 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).
-  auto ArgVector = buildArgVector(Args);
-  std::string Command = flattenWindowsCommandLine(ArgVector);
+  std::unique_ptr<char[]> command = flattenArgs(Args);
 
   // The pointer to the environment block for the new process.
   std::vector<wchar_t> EnvBlock;
@@ -260,7 +353,7 @@ static bool Execute(ProcessInfo &PI, StringRef Program, const char **Args,
   }
 
   SmallVector<wchar_t, MAX_PATH> CommandUtf16;
-  if (std::error_code ec = windows::UTF8ToUTF16(Command, 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"));
@@ -321,63 +414,7 @@ static bool Execute(ProcessInfo &PI, StringRef Program, const char **Args,
   return true;
 }
 
-static bool argNeedsQuotes(StringRef Arg) {
-  if (Arg.empty())
-    return true;
-  return StringRef::npos != Arg.find_first_of(" \t\n\v\"");
-}
-
-static std::string quoteSingleArg(StringRef Arg) {
-  std::string Result;
-  Result.push_back('"');
-
-  while (!Arg.empty()) {
-    size_t FirstNonBackslash = Arg.find_first_not_of('\\');
-    size_t BackslashCount = FirstNonBackslash;
-    if (FirstNonBackslash == StringRef::npos) {
-      // The entire remainder of the argument is backslashes.  Escape all of
-      // them and just early out.
-      BackslashCount = Arg.size();
-      Result.append(BackslashCount * 2, '\\');
-      break;
-    }
-
-    if (Arg[FirstNonBackslash] == '\"') {
-      // This is an embedded quote.  Escape all preceding backslashes, then
-      // add one additional backslash to escape the quote.
-      Result.append(BackslashCount * 2 + 1, '\\');
-      Result.push_back('\"');
-    } else {
-      // This is just a normal character.  Don't escape any of the preceding
-      // backslashes, just append them as they are and then append the
-      // character.
-      Result.append(BackslashCount, '\\');
-      Result.push_back(Arg[FirstNonBackslash]);
-    }
-
-    // Drop all the backslashes, plus the following character.
-    Arg = Arg.drop_front(FirstNonBackslash + 1);
-  }
-
-  Result.push_back('"');
-  return Result;
-}
-
 namespace llvm {
-std::string sys::flattenWindowsCommandLine(ArrayRef<StringRef> Args) {
-  std::string Command;
-  for (StringRef Arg : Args) {
-    if (argNeedsQuotes(Arg))
-      Command += quoteSingleArg(Arg);
-    else
-      Command += Arg;
-
-    Command.push_back(' ');
-  }
-
-  return Command;
-}
-
 ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
                       bool WaitUntilChildTerminates, std::string *ErrMsg) {
   assert(PI.Pid && "invalid pid to wait on, process not started?");
@@ -500,13 +537,19 @@ llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
 }
 
 bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program,
-                                                  ArrayRef<StringRef> Args) {
+                                                  ArrayRef<const char *> Args) {
   // The documented max length of the command line passed to CreateProcess.
   static const size_t MaxCommandStringLength = 32768;
-  SmallVector<StringRef, 8> FullArgs;
-  FullArgs.push_back(Program);
-  FullArgs.append(Args.begin(), Args.end());
-  std::string Result = flattenWindowsCommandLine(FullArgs);
-  return (Result.size() + 1) <= MaxCommandStringLength;
+  // Account for the trailing space for the program path and the
+  // trailing NULL of the last argument.
+  size_t ArgLength = ArgLenWithQuotes(Program.str().c_str()) + 2;
+  for (const char* Arg : Args) {
+    // Account for the trailing space for every arg
+    ArgLength += ArgLenWithQuotes(Arg) + 1;
+    if (ArgLength > MaxCommandStringLength) {
+      return false;
+    }
+  }
+  return true;
 }
 }