Add c++tools

Part of our module implementation adds a sample mapper server, the
guts of which are used by the default in-process mapping of cc1plus.
Rather than add another executable to gcc/cp/, this creates a new
c++tools directory where this and any other c++ tools might live.
The toplevel changes are a subsequent commit, because ... git.

c++tools/ChangeLog:

	* Makefile.in: New.
	* config.h.in: New.
	* configure: New.
	* configure.ac: New.
	* resolver.cc: New.
	* resolver.h: New.
	* server.cc: New.

1 files changed, 272 insertions, 0 deletions

diff --git a/c++tools/resolver.cc b/c++tools/resolver.cc
new file mode 100644
index 0000000..5028d2a
--- /dev/null
+++ b/c++tools/resolver.cc
@@ -0,0 +1,272 @@
+/* C++ modules.  Experimental!	-*- c++ -*-
+   Copyright (C) 2017-2020 Free Software Foundation, Inc.
+   Written by Nathan Sidwell <nathan@acm.org> while at FaceBook
+
+   This file is part of GCC.
+
+   GCC is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   GCC is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+
+#include "resolver.h"
+// C++
+#include <algorithm>
+// C
+#include <cstring>
+// OS
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#ifndef DIR_SEPARATOR
+#define DIR_SEPARATOR '/'
+#endif
+
+module_resolver::module_resolver (bool map, bool xlate)
+  : default_map (map), default_translate (xlate)
+{
+}
+
+module_resolver::~module_resolver ()
+{
+  if (fd_repo >= 0)
+    close (fd_repo);
+}
+
+bool
+module_resolver::set_repo (std::string &&r, bool force)
+{
+  if (force || repo.empty ())
+    {
+      repo = std::move (r);
+      force = true;
+    }
+  return force;
+}
+
+bool
+module_resolver::add_mapping (std::string &&module, std::string &&file,
+			      bool force)
+{
+  auto res = map.emplace (std::move (module), std::move (file));
+  if (res.second)
+    force = true;
+  else if (force)
+    res.first->second = std::move (file);
+
+  return force;
+}
+
+int
+module_resolver::read_tuple_file (int fd, char const *prefix, bool force)
+{
+  struct stat stat;
+  if (fstat (fd, &stat) < 0)
+    return -errno;
+
+  if (!stat.st_size)
+    return 0;
+
+  // Just map the file, we're gonna read all of it, so no need for
+  // line buffering
+  void *buffer = mmap (nullptr, stat.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+  if (buffer == MAP_FAILED)
+    return -errno;
+
+  size_t prefix_len = prefix ? strlen (prefix) : 0;
+  unsigned lineno = 0;
+
+  for (char const *begin = reinterpret_cast <char const *> (buffer),
+	 *end = begin + stat.st_size, *eol;
+       begin != end; begin = eol + 1)
+    {
+      lineno++;
+      eol = std::find (begin, end, '\n');
+      if (eol == end)
+	// last line has no \n, ignore the line, you lose
+	break;
+
+      auto *pos = begin;
+      bool pfx_search = prefix_len != 0;
+
+    pfx_search:
+      while (*pos == ' ' || *pos == '\t')
+	pos++;
+
+      auto *space = pos;
+      while (*space != '\n' && *space != ' ' && *space != '\t')
+	space++;
+
+      if (pos == space)
+	// at end of line, nothing here	
+	continue;
+
+      if (pfx_search)
+	{
+	  if (size_t (space - pos) == prefix_len
+	      && std::equal (pos, space, prefix))
+	    pfx_search = false;
+	  pos = space;
+	  goto pfx_search;
+	}
+
+      std::string module (pos, space);
+      while (*space == ' ' || *space == '\t')
+	space++;
+      std::string file (space, eol);
+
+      if (module[0] == '$')
+	{
+	  if (module == "$root")
+	    set_repo (std::move (file));
+	  else
+	    return lineno;
+	}
+      else
+	{
+	  if (file.empty ())
+	    file = GetCMIName (module);
+	  add_mapping (std::move (module), std::move (file), force);
+	}
+    }
+
+  munmap (buffer, stat.st_size);
+
+  return 0;
+}
+
+char const *
+module_resolver::GetCMISuffix ()
+{
+  return "gcm";
+}
+
+module_resolver *
+module_resolver::ConnectRequest (Cody::Server *s, unsigned version,
+				 std::string &a, std::string &i)
+{
+  if (!version || version > Cody::Version)
+    s->ErrorResponse ("version mismatch");
+  else if (a != "GCC")
+    // Refuse anything but GCC
+    ErrorResponse (s, std::string ("only GCC supported"));
+  else if (!ident.empty () && ident != i)
+    // Failed ident check
+    ErrorResponse (s, std::string ("bad ident"));
+  else
+    // Success!
+    s->ConnectResponse ("gcc");
+
+  return this;
+}
+
+int
+module_resolver::ModuleRepoRequest (Cody::Server *s)
+{
+  s->PathnameResponse (repo);
+  return 0;
+}
+
+int
+module_resolver::cmi_response (Cody::Server *s, std::string &module)
+{
+  auto iter = map.find (module);
+  if (iter == map.end ())
+    {
+      std::string file;
+      if (default_map)
+	file = std::move (GetCMIName (module));
+      auto res = map.emplace (module, file);
+      iter = res.first;
+    }
+
+  if (iter->second.empty ())
+    s->ErrorResponse ("no such module");
+  else
+    s->PathnameResponse (iter->second);
+
+  return 0;
+}
+
+int
+module_resolver::ModuleExportRequest (Cody::Server *s, Cody::Flags,
+				      std::string &module)
+{
+  return cmi_response (s, module);
+}
+
+int
+module_resolver::ModuleImportRequest (Cody::Server *s, Cody::Flags,
+				      std::string &module)
+{
+  return cmi_response (s, module);
+}
+
+int
+module_resolver::IncludeTranslateRequest (Cody::Server *s, Cody::Flags,
+					  std::string &include)
+{
+  auto iter = map.find (include);
+  if (iter == map.end () && default_translate)
+    {
+      // Not found, look for it
+      auto file = GetCMIName (include);
+      struct stat statbuf;
+      bool ok = true;
+
+#if HAVE_FSTATAT
+      int fd_dir = AT_FDCWD;
+      if (!repo.empty ())
+	{
+	  if (fd_repo == -1)
+	    {
+	      fd_repo = open (repo.c_str (),
+			      O_RDONLY | O_CLOEXEC | O_DIRECTORY);
+	      if (fd_repo < 0)
+		fd_repo = -2;
+	    }
+	  fd_dir = fd_repo;
+	}
+
+      if (!repo.empty () && fd_repo < 0)
+	ok = false;
+      else if (fstatat (fd_dir, file.c_str (), &statbuf, 0) < 0
+	       || !S_ISREG (statbuf.st_mode))
+	ok = false;
+#else
+      auto append = repo;
+      append.push_back (DIR_SEPARATOR);
+      append.append (file);
+      if (stat (append.c_str (), &statbuf) < 0
+	  || !S_ISREG (statbuf.st_mode))
+	ok = false;
+#endif
+      if (!ok)
+	// Mark as not present
+	file.clear ();
+      auto res = map.emplace (include, file);
+      iter = res.first;
+    }
+
+  if (iter == map.end () || iter->second.empty ())
+    s->BoolResponse (false);
+  else
+    s->PathnameResponse (iter->second);
+
+  return 0;
+}
+