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 // C
  27 #include <cstring>
  28 // OS
  29 #include <fcntl.h>
  30 #include <unistd.h>
  31 #if 0 // 1 for testing no mmap
  32 #define MAPPED_READING 0
  33 #else
  34 #ifdef IN_GCC
  35 #if HAVE_MMAP_FILE && _POSIX_MAPPED_FILES > 0
  36 #define MAPPED_READING 1
  37 #else
  38 #define MAPPED_READING 0
  39 #endif
  40 #else
  41 #ifdef HAVE_SYS_MMAN_H
  42 #include <sys/mman.h>
  43 #define MAPPED_READING 1
  44 #else
  45 #define MAPPED_READING 0
  46 #endif
  47 #endif
  48 #endif
  49
  50 #include <sys/types.h>
  51 #include <sys/stat.h>
  52
  53 #if !defined (IN_GCC) && !MAPPED_READING
  54 #define xmalloc(X) malloc(X)
  55 #endif
  56
  57 #if !HOST_HAS_O_CLOEXEC
  58 #define O_CLOEXEC 0
  59 #endif
  60
  61 #ifndef DIR_SEPARATOR
  62 #define DIR_SEPARATOR '/'
  63 #endif
  64
  65 module_resolver::module_resolver (bool map, bool xlate)
  66   : default_map (map), default_translate (xlate)
  67 {
  68 }
  69
  70 module_resolver::~module_resolver ()
  71 {
  72   if (fd_repo >= 0)
  73     close (fd_repo);
  74 }
  75
  76 bool
  77 module_resolver::set_repo (std::string &&r, bool force)
  78 {
  79   if (force || repo.empty ())
  80     {
  81       repo = std::move (r);
  82       force = true;
  83     }
  84   return force;
  85 }
  86
  87 bool
  88 module_resolver::add_mapping (std::string &&module, std::string &&file,
  89                               bool force)
  90 {
  91   auto res = map.emplace (std::move (module), std::move (file));
  92   if (res.second)
  93     force = true;
  94   else if (force)
  95     res.first->second = std::move (file);
  96
  97   return force;
  98 }
  99
 100 int
 101 module_resolver::read_tuple_file (int fd, char const *prefix, bool force)
 102 {
 103   struct stat stat;
 104   if (fstat (fd, &stat) < 0)
 105     return -errno;
 106
 107   if (!stat.st_size)
 108     return 0;
 109
 110   void *buffer = nullptr;
 111 #if MAPPED_READING
 112   // Just map the file, we're gonna read all of it, so no need for
 113   // line buffering
 114   buffer = mmap (nullptr, stat.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 115   if (buffer == MAP_FAILED)
 116     return -errno;
 117 #else
 118   buffer = xmalloc (stat.st_size);
 119   if (!buffer)
 120     return -errno;
 121   if (read (fd, buffer, stat.st_size) != stat.st_size)
 122     return -errno;
 123 #endif
 124
 125   size_t prefix_len = prefix ? strlen (prefix) : 0;
 126   unsigned lineno = 0;
 127
 128   for (char const *begin = reinterpret_cast <char const *> (buffer),
 129          *end = begin + stat.st_size, *eol;
 130        begin != end; begin = eol + 1)
 131     {
 132       lineno++;
 133       eol = std::find (begin, end, '\n');
 134       if (eol == end)
 135         // last line has no \n, ignore the line, you lose
 136         break;
 137
 138       auto *pos = begin;
 139       bool pfx_search = prefix_len != 0;
 140
 141     pfx_search:
 142       while (*pos == ' ' || *pos == '\t')
 143         pos++;
 144
 145       auto *space = pos;
 146       while (*space != '\n' && *space != ' ' && *space != '\t')
 147         space++;
 148
 149       if (pos == space)
 150         // at end of line, nothing here
 151         continue;
 152
 153       if (pfx_search)
 154         {
 155           if (size_t (space - pos) == prefix_len
 156               && std::equal (pos, space, prefix))
 157             pfx_search = false;
 158           pos = space;
 159           goto pfx_search;
 160         }
 161
 162       std::string module (pos, space);
 163       while (*space == ' ' || *space == '\t')
 164         space++;
 165       std::string file (space, eol);
 166
 167       if (module[0] == '$')
 168         {
 169           if (module == "$root")
 170             set_repo (std::move (file));
 171           else
 172             return lineno;
 173         }
 174       else
 175         {
 176           if (file.empty ())
 177             file = GetCMIName (module);
 178           add_mapping (std::move (module), std::move (file), force);
 179         }
 180     }
 181
 182 #if MAPPED_READING
 183   munmap (buffer, stat.st_size);
 184 #else
 185   free (buffer);
 186 #endif
 187
 188   return 0;
 189 }
 190
 191 char const *
 192 module_resolver::GetCMISuffix ()
 193 {
 194   return "gcm";
 195 }
 196
 197 module_resolver *
 198 module_resolver::ConnectRequest (Cody::Server *s, unsigned version,
 199                                  std::string &a, std::string &i)
 200 {
 201   if (!version || version > Cody::Version)
 202     s->ErrorResponse ("version mismatch");
 203   else if (a != "GCC")
 204     // Refuse anything but GCC
 205     ErrorResponse (s, std::string ("only GCC supported"));
 206   else if (!ident.empty () && ident != i)
 207     // Failed ident check
 208     ErrorResponse (s, std::string ("bad ident"));
 209   else
 210     // Success!
 211     s->ConnectResponse ("gcc");
 212
 213   return this;
 214 }
 215
 216 int
 217 module_resolver::ModuleRepoRequest (Cody::Server *s)
 218 {
 219   s->PathnameResponse (repo);
 220   return 0;
 221 }
 222
 223 int
 224 module_resolver::cmi_response (Cody::Server *s, std::string &module)
 225 {
 226   auto iter = map.find (module);
 227   if (iter == map.end ())
 228     {
 229       std::string file = default_map ? GetCMIName (module) : std::string ();
 230       auto res = map.emplace (module, file);
 231       iter = res.first;
 232     }
 233
 234   if (iter->second.empty ())
 235     s->ErrorResponse ("no such module");
 236   else
 237     s->PathnameResponse (iter->second);
 238
 239   return 0;
 240 }
 241
 242 int
 243 module_resolver::ModuleExportRequest (Cody::Server *s, Cody::Flags,
 244                                       std::string &module)
 245 {
 246   return cmi_response (s, module);
 247 }
 248
 249 int
 250 module_resolver::ModuleImportRequest (Cody::Server *s, Cody::Flags,
 251                                       std::string &module)
 252 {
 253   return cmi_response (s, module);
 254 }
 255
 256 int
 257 module_resolver::IncludeTranslateRequest (Cody::Server *s, Cody::Flags,
 258                                           std::string &include)
 259 {
 260   auto iter = map.find (include);
 261   if (iter == map.end () && default_translate)
 262     {
 263       // Not found, look for it
 264       auto file = GetCMIName (include);
 265       struct stat statbuf;
 266       bool ok = true;
 267
 268 #if HAVE_FSTATAT
 269       int fd_dir = AT_FDCWD;
 270       if (!repo.empty ())
 271         {
 272           if (fd_repo == -1)
 273             {
 274               fd_repo = open (repo.c_str (),
 275                               O_RDONLY | O_CLOEXEC | O_DIRECTORY);
 276               if (fd_repo < 0)
 277                 fd_repo = -2;
 278             }
 279           fd_dir = fd_repo;
 280         }
 281
 282       if (!repo.empty () && fd_repo < 0)
 283         ok = false;
 284       else if (fstatat (fd_dir, file.c_str (), &statbuf, 0) < 0
 285                || !S_ISREG (statbuf.st_mode))
 286         ok = false;
 287 #else
 288       auto append = repo;
 289       append.push_back (DIR_SEPARATOR);
 290       append.append (file);
 291       if (stat (append.c_str (), &statbuf) < 0
 292           || !S_ISREG (statbuf.st_mode))
 293         ok = false;
 294 #endif
 295       if (!ok)
 296         // Mark as not present
 297         file.clear ();
 298       auto res = map.emplace (include, file);
 299       iter = res.first;
 300     }
 301
 302   if (iter == map.end () || iter->second.empty ())
 303     s->BoolResponse (false);
 304   else
 305     s->PathnameResponse (iter->second);
 306
 307   return 0;
 308 }
 309