c++tools/resolver.cc

   1 /* C++ modules.  Experimental!  -*- c++ -*-
   2    Copyright (C) 2017-2021 Free Software Foundation, Inc.
   3    Written by Nathan Sidwell <nathan@acm.org> while at FaceBook
   4
   5    This file is part of GCC.
   6
   7    GCC is free software; you can redistribute it and/or modify it
   8    under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3, or (at your option)
  10    any later version.
  11
  12    GCC is distributed in the hope that it will be useful, but
  13    WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22
  23 #include "resolver.h"
  24 // C++
  25 #include <algorithm>
  26 #include <memory>
  27 // C
  28 #include <cstring>
  29 // OS
  30 #include <fcntl.h>
  31 #include <unistd.h>
  32 #if 0 // 1 for testing no mmap
  33 #define MAPPED_READING 0
  34 #else
  35 #ifdef IN_GCC
  36 #if HAVE_MMAP_FILE && _POSIX_MAPPED_FILES > 0
  37 #define MAPPED_READING 1
  38 #else
  39 #define MAPPED_READING 0
  40 #endif
  41 #else
  42 #ifdef HAVE_SYS_MMAN_H
  43 #include <sys/mman.h>
  44 #define MAPPED_READING 1
  45 #else
  46 #define MAPPED_READING 0
  47 #endif
  48 #endif
  49 #endif
  50
  51 #include <sys/types.h>
  52 #include <sys/stat.h>
  53
  54 #if !defined (IN_GCC) && !MAPPED_READING
  55 #define xmalloc(X) malloc(X)
  56 #endif
  57
  58 #if !HOST_HAS_O_CLOEXEC
  59 #define O_CLOEXEC 0
  60 #endif
  61
  62 #ifndef DIR_SEPARATOR
  63 #define DIR_SEPARATOR '/'
  64 #endif
  65
  66 module_resolver::module_resolver (bool map, bool xlate)
  67   : default_map (map), default_translate (xlate)
  68 {
  69 }
  70
  71 module_resolver::~module_resolver ()
  72 {
  73   if (fd_repo >= 0)
  74     close (fd_repo);
  75 }
  76
  77 bool
  78 module_resolver::set_repo (std::string &&r, bool force)
  79 {
  80   if (force || repo.empty ())
  81     {
  82       repo = std::move (r);
  83       force = true;
  84     }
  85   return force;
  86 }
  87
  88 bool
  89 module_resolver::add_mapping (std::string &&module, std::string &&file,
  90                               bool force)
  91 {
  92   auto res = map.emplace (std::move (module), std::move (file));
  93   if (res.second)
  94     force = true;
  95   else if (force)
  96     res.first->second = std::move (file);
  97
  98   return force;
  99 }
 100
 101 int
 102 module_resolver::read_tuple_file (int fd, char const *prefix, bool force)
 103 {
 104   struct stat stat;
 105   if (fstat (fd, &stat) < 0)
 106     return -errno;
 107
 108   if (!stat.st_size)
 109     return 0;
 110
 111   void *buffer = nullptr;
 112 #if MAPPED_READING
 113   // Just map the file, we're gonna read all of it, so no need for
 114   // line buffering
 115   buffer = mmap (nullptr, stat.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 116   if (buffer == MAP_FAILED)
 117     return -errno;
 118   struct Deleter {
 119     void operator()(void* p) const { munmap(p, size); }
 120     size_t size;
 121   };
 122   std::unique_ptr<void, Deleter> guard(buffer, Deleter{(size_t)stat.st_size});
 123 #else
 124   buffer = xmalloc (stat.st_size);
 125   if (!buffer)
 126     return -errno;
 127   struct Deleter { void operator()(void* p) const { free(p); } };
 128   std::unique_ptr<void, Deleter> guard(buffer);
 129   if (read (fd, buffer, stat.st_size) != stat.st_size)
 130     return -errno;
 131 #endif
 132
 133   size_t prefix_len = prefix ? strlen (prefix) : 0;
 134   unsigned lineno = 0;
 135
 136   for (char const *begin = reinterpret_cast <char const *> (buffer),
 137          *end = begin + stat.st_size, *eol;
 138        begin != end; begin = eol + 1)
 139     {
 140       lineno++;
 141       eol = std::find (begin, end, '\n');
 142       if (eol == end)
 143         // last line has no \n, ignore the line, you lose
 144         break;
 145
 146       auto *pos = begin;
 147       bool pfx_search = prefix_len != 0;
 148
 149     pfx_search:
 150       while (*pos == ' ' || *pos == '\t')
 151         pos++;
 152
 153       auto *space = pos;
 154       while (*space != '\n' && *space != ' ' && *space != '\t')
 155         space++;
 156
 157       if (pos == space)
 158         // at end of line, nothing here
 159         continue;
 160
 161       if (pfx_search)
 162         {
 163           if (size_t (space - pos) == prefix_len
 164               && std::equal (pos, space, prefix))
 165             pfx_search = false;
 166           pos = space;
 167           goto pfx_search;
 168         }
 169
 170       std::string module (pos, space);
 171       while (*space == ' ' || *space == '\t')
 172         space++;
 173       std::string file (space, eol);
 174
 175       if (module[0] == '$')
 176         {
 177           if (module == "$root")
 178             set_repo (std::move (file));
 179           else
 180             return lineno;
 181         }
 182       else
 183         {
 184           if (file.empty ())
 185             file = GetCMIName (module);
 186           add_mapping (std::move (module), std::move (file), force);
 187         }
 188     }
 189
 190   return 0;
 191 }
 192
 193 char const *
 194 module_resolver::GetCMISuffix ()
 195 {
 196   return "gcm";
 197 }
 198
 199 module_resolver *
 200 module_resolver::ConnectRequest (Cody::Server *s, unsigned version,
 201                                  std::string &a, std::string &i)
 202 {
 203   if (!version || version > Cody::Version)
 204     s->ErrorResponse ("version mismatch");
 205   else if (a != "GCC")
 206     // Refuse anything but GCC
 207     ErrorResponse (s, std::string ("only GCC supported"));
 208   else if (!ident.empty () && ident != i)
 209     // Failed ident check
 210     ErrorResponse (s, std::string ("bad ident"));
 211   else
 212     // Success!
 213     s->ConnectResponse ("gcc");
 214
 215   return this;
 216 }
 217
 218 int
 219 module_resolver::ModuleRepoRequest (Cody::Server *s)
 220 {
 221   s->PathnameResponse (repo);
 222   return 0;
 223 }
 224
 225 int
 226 module_resolver::cmi_response (Cody::Server *s, std::string &module)
 227 {
 228   auto iter = map.find (module);
 229   if (iter == map.end ())
 230     {
 231       std::string file = default_map ? GetCMIName (module) : std::string ();
 232       auto res = map.emplace (module, file);
 233       iter = res.first;
 234     }
 235
 236   if (iter->second.empty ())
 237     s->ErrorResponse ("no such module");
 238   else
 239     s->PathnameResponse (iter->second);
 240
 241   return 0;
 242 }
 243
 244 int
 245 module_resolver::ModuleExportRequest (Cody::Server *s, Cody::Flags,
 246                                       std::string &module)
 247 {
 248   return cmi_response (s, module);
 249 }
 250
 251 int
 252 module_resolver::ModuleImportRequest (Cody::Server *s, Cody::Flags,
 253                                       std::string &module)
 254 {
 255   return cmi_response (s, module);
 256 }
 257
 258 int
 259 module_resolver::IncludeTranslateRequest (Cody::Server *s, Cody::Flags,
 260                                           std::string &include)
 261 {
 262   auto iter = map.find (include);
 263   if (iter == map.end () && default_translate)
 264     {
 265       // Not found, look for it
 266       auto file = GetCMIName (include);
 267       struct stat statbuf;
 268       bool ok = true;
 269
 270 #if HAVE_FSTATAT
 271       int fd_dir = AT_FDCWD;
 272       if (!repo.empty ())
 273         {
 274           if (fd_repo == -1)
 275             {
 276               fd_repo = open (repo.c_str (),
 277                               O_RDONLY | O_CLOEXEC | O_DIRECTORY);
 278               if (fd_repo < 0)
 279                 fd_repo = -2;
 280             }
 281           fd_dir = fd_repo;
 282         }
 283
 284       if (!repo.empty () && fd_repo < 0)
 285         ok = false;
 286       else if (fstatat (fd_dir, file.c_str (), &statbuf, 0) < 0
 287                || !S_ISREG (statbuf.st_mode))
 288         ok = false;
 289 #else
 290       auto append = repo;
 291       append.push_back (DIR_SEPARATOR);
 292       append.append (file);
 293       if (stat (append.c_str (), &statbuf) < 0
 294           || !S_ISREG (statbuf.st_mode))
 295         ok = false;
 296 #endif
 297       if (!ok)
 298         // Mark as not present
 299         file.clear ();
 300       auto res = map.emplace (include, file);
 301       iter = res.first;
 302     }
 303
 304   if (iter == map.end () || iter->second.empty ())
 305     s->BoolResponse (false);
 306   else
 307     s->PathnameResponse (iter->second);
 308
 309   return 0;
 310 }
 311
 312 /* This handles a client notification to the server that a CMI has been
 313    produced for a module.  For this simplified server, we just accept
 314    the transaction and respond with "OK".  */
 315
 316 int
 317 module_resolver::ModuleCompiledRequest (Cody::Server *s, Cody::Flags,
 318                                       std::string &)
 319 {
 320   s->OKResponse();
 321   return 0;
 322 }