[Windows] Fix handling of \" in program name on cmd line.

Bugzilla #47579: if you invoke clang on Windows via a pathname in
which a quoted section closes just after a backslash, e.g.

  "C:\Program Files\Whatever\"clang.exe

then cmd.exe and CreateProcess will correctly find the binary, because
when they parse the program name at the start of the command line,
they don't regard the \ before the " as having any kind of escaping
effect. This is different from the behaviour of the Windows standard C
library when it parses the rest of the command line, which would
consider that \" not to close the quoted string.

But this confuses windows::GetCommandLineArguments, because the
Windows API function GetCommandLineW() will return a command line
containing that \" sequence, and cl::TokenizeWindowsCommandLine will
tokenize the whole string according to the C library's rules. So it
will misidentify where the program name stops and the arguments start.

To fix this, I've introduced a new variant function
cl::TokenizeWindowsCommandLineFull(), intended to be applied to the
string returned from GetCommandLineW(). It parses the first word of
the command line according to CreateProcess's rules, considering \ to
never be an escaping character; thereafter, it switches over to the C
library rules for the rest of the command line.

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D122914

1 files changed, 18 insertions, 0 deletions

diff --git a/llvm/unittests/Support/CommandLineTest.cpp b/llvm/unittests/Support/CommandLineTest.cpp
index 7f751e5..ec9901a 100644
--- a/llvm/unittests/Support/CommandLineTest.cpp
+++ b/llvm/unittests/Support/CommandLineTest.cpp
@@ -257,6 +257,24 @@ TEST(CommandLineTest, TokenizeWindowsCommandLineQuotedLastArgument) {
   testCommandLineTokenizer(cl::TokenizeWindowsCommandLine, Input3, Output3);
 }
 
+TEST(CommandLineTest, TokenizeWindowsCommandLineExeName) {
+  const char Input1[] =
+      R"("C:\Program Files\Whatever\"clang.exe z.c -DY=\"x\")";
+  const char *const Output1[] = {"C:\\Program Files\\Whatever\\clang.exe",
+                                 "z.c", "-DY=\"x\""};
+  testCommandLineTokenizer(cl::TokenizeWindowsCommandLineFull, Input1, Output1);
+
+  const char Input2[] = "\"a\\\"b c\\\"d\n\"e\\\"f g\\\"h\n";
+  const char *const Output2[] = {"a\\b", "c\"d", nullptr,
+                                 "e\\f", "g\"h", nullptr};
+  testCommandLineTokenizer(cl::TokenizeWindowsCommandLineFull, Input2, Output2,
+                           /*MarkEOLs=*/true);
+
+  const char Input3[] = R"(\\server\share\subdir\clang.exe)";
+  const char *const Output3[] = {"\\\\server\\share\\subdir\\clang.exe"};
+  testCommandLineTokenizer(cl::TokenizeWindowsCommandLineFull, Input3, Output3);
+}
+
 TEST(CommandLineTest, TokenizeAndMarkEOLs) {
   // Clang uses EOL marking in response files to support options that consume
   // the rest of the arguments on the current line, but do not consume arguments