usr.bin/dtc/input_buffer.cc

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2013 David Chisnall
   5  * All rights reserved.
   6  *
   7  * This software was developed by SRI International and the University of
   8  * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
   9  * ("CTSRD"), as part of the DARPA CRASH research programme.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD$
  33  */
  34
  35 #include "input_buffer.hh"
  36 #include <ctype.h>
  37 #include <errno.h>
  38 #include <limits.h>
  39 #include <stdint.h>
  40 #include <stdio.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <functional>
  44 #ifndef NDEBUG
  45 #include <iostream>
  46 #endif
  47
  48
  49 #include <sys/stat.h>
  50 #include <sys/mman.h>
  51 #include <assert.h>
  52 #include <fcntl.h>
  53 #include <unistd.h>
  54
  55 #ifndef MAP_PREFAULT_READ
  56 #define MAP_PREFAULT_READ 0
  57 #endif
  58
  59 using std::string;
  60
  61 namespace
  62 {
  63 /**
  64  * Subclass of input_buffer that mmap()s a file and owns the resulting memory.
  65  * When this object is destroyed, the memory is unmapped.
  66  */
  67 struct mmap_input_buffer : public dtc::input_buffer
  68 {
  69         string fn;
  70         const string &filename() const override
  71         {
  72                 return fn;
  73         }
  74         /**
  75          * Constructs a new buffer from the file passed in as a file
  76          * descriptor.
  77          */
  78         mmap_input_buffer(int fd, string &&filename);
  79         /**
  80          * Unmaps the buffer, if one exists.
  81          */
  82         virtual ~mmap_input_buffer();
  83 };
  84 /**
  85  * Input buffer read from standard input.  This is used for reading device tree
  86  * blobs and source from standard input.  It reads the entire input into
  87  * malloc'd memory, so will be very slow for large inputs.  DTS and DTB files
  88  * are very rarely more than 10KB though, so this is probably not a problem.
  89  */
  90 struct stream_input_buffer : public dtc::input_buffer
  91 {
  92         const string &filename() const override
  93         {
  94                 static string n = "<standard input>";
  95                 return n;
  96         }
  97         /**
  98          * The buffer that will store the data read from the standard input.
  99          */
 100         std::vector<char> b;
 101         /**
 102          * Constructs a new buffer from the standard input.
 103          */
 104         stream_input_buffer();
 105 };
 106
 107 mmap_input_buffer::mmap_input_buffer(int fd, string &&filename)
 108         : input_buffer(0, 0), fn(filename)
 109 {
 110         struct stat sb;
 111         if (fstat(fd, &sb))
 112         {
 113                 perror("Failed to stat file");
 114         }
 115         size = sb.st_size;
 116         buffer = (const char*)mmap(0, size, PROT_READ, MAP_PRIVATE |
 117                         MAP_PREFAULT_READ, fd, 0);
 118         if (buffer == MAP_FAILED)
 119         {
 120                 perror("Failed to mmap file");
 121                 exit(EXIT_FAILURE);
 122         }
 123 }
 124
 125 mmap_input_buffer::~mmap_input_buffer()
 126 {
 127         if (buffer != 0)
 128         {
 129                 munmap(const_cast<char*>(buffer), size);
 130         }
 131 }
 132
 133 stream_input_buffer::stream_input_buffer() : input_buffer(0, 0)
 134 {
 135         int c;
 136         while ((c = fgetc(stdin)) != EOF)
 137         {
 138                 b.push_back(c);
 139         }
 140         buffer = b.data();
 141         size = b.size();
 142 }
 143
 144 } // Anonymous namespace
 145
 146
 147 namespace dtc
 148 {
 149
 150 void
 151 input_buffer::skip_to(char c)
 152 {
 153         while ((cursor < size) && (buffer[cursor] != c))
 154         {
 155                 cursor++;
 156         }
 157 }
 158
 159 void
 160 text_input_buffer::skip_to(char c)
 161 {
 162         while (!finished() && (*(*this) != c))
 163         {
 164                 ++(*this);
 165         }
 166 }
 167
 168 void
 169 text_input_buffer::skip_spaces()
 170 {
 171         if (finished()) { return; }
 172         char c = *(*this);
 173         bool last_nl = false;
 174         while ((c == ' ') || (c == '\t') || (c == '\n') || (c == '\f')
 175                || (c == '\v') || (c == '\r'))
 176         {
 177                 last_nl = ((c == '\n') || (c == '\r'));
 178                 ++(*this);
 179                 if (finished())
 180                 {
 181                         c = '\0';
 182                 }
 183                 else
 184                 {
 185                         c = *(*this);
 186                 }
 187         }
 188         // Skip C preprocessor leftovers
 189         if ((c == '#') && ((cursor == 0) || last_nl))
 190         {
 191                 skip_to('\n');
 192                 skip_spaces();
 193         }
 194         if (consume("/include/"))
 195         {
 196                 handle_include();
 197                 skip_spaces();
 198         }
 199 }
 200
 201 void
 202 text_input_buffer::handle_include()
 203 {
 204         bool reallyInclude = true;
 205         if (consume("if "))
 206         {
 207                 next_token();
 208                 string name = parse_property_name();
 209                 if (defines.count(name) == 0)
 210                 {
 211                         reallyInclude = false;
 212                 }
 213                 consume('/');
 214         }
 215         next_token();
 216         if (!consume('"'))
 217         {
 218                 parse_error("Expected quoted filename");
 219                 return;
 220         }
 221         auto loc = location();
 222         string file = parse_to('"');
 223         consume('"');
 224         if (!reallyInclude)
 225         {
 226                 return;
 227         }
 228         string include_file = dir + '/' + file;
 229         auto include_buffer = input_buffer::buffer_for_file(include_file, false);
 230         if (include_buffer == 0)
 231         {
 232                 for (auto i : include_paths)
 233                 {
 234                         include_file = i + '/' + file;
 235                         include_buffer = input_buffer::buffer_for_file(include_file, false);
 236                         if (include_buffer != 0)
 237                         {
 238                                 break;
 239                         }
 240                 }
 241         }
 242         if (depfile)
 243         {
 244                 putc(' ', depfile);
 245                 fputs(include_file.c_str(), depfile);
 246         }
 247         if (!include_buffer)
 248         {
 249                 loc.report_error("Unable to locate input file");
 250                 return;
 251         }
 252         input_stack.push(std::move(include_buffer));
 253 }
 254
 255 bool text_input_buffer::read_binary_file(const std::string &filename, byte_buffer &b)
 256 {
 257         bool try_include_paths = true;
 258         string include_file;
 259         if (filename[0] == '/')
 260         {
 261                 include_file = filename;
 262                 // Don't try include paths if we're given an absolute path.
 263                 // Failing is better so that we don't accidentally do the wrong thing,
 264                 // but make it seem like everything is alright.
 265                 try_include_paths = false;
 266         }
 267         else
 268         {
 269                 include_file = dir + '/' + filename;
 270         }
 271         auto include_buffer = input_buffer::buffer_for_file(include_file, false);
 272         if (include_buffer == 0 && try_include_paths)
 273         {
 274                 for (auto i : include_paths)
 275                 {
 276                         include_file = i + '/' + filename;
 277                         include_buffer = input_buffer::buffer_for_file(include_file, false);
 278                         if (include_buffer != 0)
 279                         {
 280                                 break;
 281                         }
 282                 }
 283         }
 284         if (!include_buffer)
 285         {
 286                 return false;
 287         }
 288         if (depfile)
 289         {
 290                 putc(' ', depfile);
 291                 fputs(include_file.c_str(), depfile);
 292         }
 293         b.insert(b.begin(), include_buffer->begin(), include_buffer->end());
 294         return true;
 295 }
 296
 297 input_buffer
 298 input_buffer::buffer_from_offset(int offset, int s)
 299 {
 300         if (offset < 0)
 301         {
 302                 return input_buffer();
 303         }
 304         if (s == 0)
 305         {
 306                 s = size - offset;
 307         }
 308         if (offset > size)
 309         {
 310                 return input_buffer();
 311         }
 312         if (s > (size-offset))
 313         {
 314                 return input_buffer();
 315         }
 316         return input_buffer(&buffer[offset], s);
 317 }
 318
 319 bool
 320 input_buffer::consume(const char *str)
 321 {
 322         int len = strlen(str);
 323         if (len > size - cursor)
 324         {
 325                 return false;
 326         }
 327         else
 328         {
 329                 for (int i=0 ; i<len ; ++i)
 330                 {
 331                         if (str[i] != (*this)[i])
 332                         {
 333                                 return false;
 334                         }
 335                 }
 336                 cursor += len;
 337                 return true;
 338         }
 339         return false;
 340 }
 341
 342 bool
 343 input_buffer::consume_integer(unsigned long long &outInt)
 344 {
 345         // The first character must be a digit.  Hex and octal strings
 346         // are prefixed by 0 and 0x, respectively.
 347         if (!isdigit((*this)[0]))
 348         {
 349                 return false;
 350         }
 351         char *end= const_cast<char*>(&buffer[size]);
 352         outInt = strtoull(&buffer[cursor], &end, 0);
 353         if (end == &buffer[cursor])
 354         {
 355                 return false;
 356         }
 357         cursor = end - buffer;
 358         return true;
 359 }
 360
 361 namespace {
 362
 363 /**
 364  * Convenience typedef for the type that we use for all values.
 365  */
 366 typedef unsigned long long valty;
 367
 368 /**
 369  * Expression tree currently being parsed.
 370  */
 371 struct expression
 372 {
 373         typedef text_input_buffer::source_location source_location;
 374         /**
 375          * The type that is returned when computing the result.  The boolean value
 376          * indicates whether this is a valid expression.
 377          *
 378          * FIXME: Once we can use C++17, this should be `std::optional`.
 379          */
 380         typedef std::pair<valty, bool> result;
 381         /**
 382          * Evaluate this node, taking into account operator precedence.
 383          */
 384         virtual result operator()() = 0;
 385         /**
 386          * Returns the precedence of this node.  Lower values indicate higher
 387          * precedence.
 388          */
 389         virtual int precedence() = 0;
 390         /**
 391          * Constructs an expression, storing the location where it was created.
 392          */
 393         expression(source_location l) : loc(l) {}
 394         virtual ~expression() {}
 395 #ifndef NDEBUG
 396         /**
 397          * Dumps this expression to `std::cerr`, appending a newline if `nl` is
 398          * `true`.
 399          */
 400         void dump(bool nl=false)
 401         {
 402                 void *ptr = this;
 403                 if (ptr == nullptr)
 404                 {
 405                         std::cerr << "{nullptr}\n";
 406                         return;
 407                 }
 408                 dump_impl();
 409                 if (nl)
 410                 {
 411                         std::cerr << '\n';
 412                 }
 413         }
 414         private:
 415         /**
 416          * Method that sublcasses override to implement the behaviour of `dump()`.
 417          */
 418         virtual void dump_impl() = 0;
 419 #endif
 420         protected:
 421         source_location loc;
 422 };
 423
 424 /**
 425  * Expression wrapping a single integer.  Leaf nodes in the expression tree.
 426  */
 427 class terminal_expr : public expression
 428 {
 429         /**
 430          * The value that this wraps.
 431          */
 432         valty val;
 433         /**
 434          * Evaluate.  Trivially returns the value that this class wraps.
 435          */
 436         result operator()() override
 437         {
 438                 return {val, true};
 439         }
 440         int precedence() override
 441         {
 442                 return 0;
 443         }
 444         public:
 445         /**
 446          * Constructor.
 447          */
 448         terminal_expr(source_location l, valty v) : expression(l), val(v) {}
 449 #ifndef NDEBUG
 450         void dump_impl() override { std::cerr << val; }
 451 #endif
 452 };
 453
 454 /**
 455  * Parenthetical expression.  Exists to make the contents opaque.
 456  */
 457 struct paren_expression : public expression
 458 {
 459         /**
 460          * The expression within the parentheses.
 461          */
 462         expression_ptr subexpr;
 463         /**
 464          * Constructor.  Takes the child expression as the only argument.
 465          */
 466         paren_expression(source_location l, expression_ptr p) : expression(l),
 467         subexpr(std::move(p)) {}
 468         int precedence() override
 469         {
 470                 return 0;
 471         }
 472         /**
 473          * Evaluate - just forwards to the underlying expression.
 474          */
 475         result operator()() override
 476         {
 477                 return (*subexpr)();
 478         }
 479 #ifndef NDEBUG
 480         void dump_impl() override
 481         {
 482                 std::cerr << " (";
 483                 subexpr->dump();
 484                 std::cerr << ") ";
 485         }
 486 #endif
 487 };
 488
 489 /**
 490  * Template class for unary operators.  The `OpChar` template parameter is
 491  * solely for debugging and makes it easy to print the expression.  The `Op`
 492  * template parameter is a function object that implements the operator that
 493  * this class provides.  Most of these are provided by the `<functional>`
 494  * header.
 495  */
 496 template<char OpChar, class Op>
 497 class unary_operator : public expression
 498 {
 499         /**
 500          * The subexpression for this unary operator.
 501          */
 502         expression_ptr subexpr;
 503         result operator()() override
 504         {
 505                 Op op;
 506                 result s = (*subexpr)();
 507                 if (!s.second)
 508                 {
 509                         return s;
 510                 }
 511                 return {op(s.first), true};
 512         }
 513         /**
 514          * All unary operators have the same precedence.  They are all evaluated
 515          * before binary expressions, but after parentheses.
 516          */
 517         int precedence() override
 518         {
 519                 return 3;
 520         }
 521         public:
 522         unary_operator(source_location l, expression_ptr p) :
 523                 expression(l), subexpr(std::move(p)) {}
 524 #ifndef NDEBUG
 525         void dump_impl() override
 526         {
 527                 std::cerr << OpChar;
 528                 subexpr->dump();
 529         }
 530 #endif
 531 };
 532
 533 /**
 534  * Abstract base class for binary operators.  Allows the tree to be modified
 535  * without knowing what the operations actually are.
 536  */
 537 struct binary_operator_base : public expression
 538 {
 539         using expression::expression;
 540         /**
 541          * The left side of the expression.
 542          */
 543         expression_ptr lhs;
 544         /**
 545          * The right side of the expression.
 546          */
 547         expression_ptr rhs;
 548         /**
 549          * Insert a node somewhere down the path of left children, until it would
 550          * be preempting something that should execute first.
 551          */
 552         void insert_left(binary_operator_base *new_left)
 553         {
 554                 if (lhs->precedence() < new_left->precedence())
 555                 {
 556                         new_left->rhs = std::move(lhs);
 557                         lhs.reset(new_left);
 558                 }
 559                 else
 560                 {
 561                         static_cast<binary_operator_base*>(lhs.get())->insert_left(new_left);
 562                 }
 563         }
 564 };
 565
 566 /**
 567  * Template class for binary operators.  The precedence and the operation are
 568  * provided as template parameters.
 569  */
 570 template<int Precedence, class Op>
 571 struct binary_operator : public binary_operator_base
 572 {
 573         result operator()() override
 574         {
 575                 Op op;
 576                 result l = (*lhs)();
 577                 result r = (*rhs)();
 578                 if (!(l.second && r.second))
 579                 {
 580                         return {0, false};
 581                 }
 582                 return {op(l.first, r.first), true};
 583         }
 584         int precedence() override
 585         {
 586                 return Precedence;
 587         }
 588 #ifdef NDEBUG
 589         /**
 590          * Constructor.  Takes the name of the operator as an argument, for
 591          * debugging.  Only stores it in debug mode.
 592          */
 593         binary_operator(source_location l, const char *) :
 594                 binary_operator_base(l) {}
 595 #else
 596         const char *opName;
 597         binary_operator(source_location l, const char *o) :
 598                 binary_operator_base(l), opName(o) {}
 599         void dump_impl() override
 600         {
 601                 lhs->dump();
 602                 std::cerr << opName;
 603                 rhs->dump();
 604         }
 605 #endif
 606 };
 607
 608 /**
 609  * Ternary conditional operators (`cond ? true : false`) are a special case -
 610  * there are no other ternary operators.
 611  */
 612 class ternary_conditional_operator : public expression
 613 {
 614         /**
 615          * The condition for the clause.
 616          */
 617         expression_ptr cond;
 618         /**
 619          * The expression that this evaluates to if the condition is true.
 620          */
 621         expression_ptr lhs;
 622         /**
 623          * The expression that this evaluates to if the condition is false.
 624          */
 625         expression_ptr rhs;
 626         result operator()() override
 627         {
 628                 result c = (*cond)();
 629                 result l = (*lhs)();
 630                 result r = (*rhs)();
 631                 if (!(l.second && r.second && c.second))
 632                 {
 633                         return {0, false};
 634                 }
 635                 return c.first ? l : r;
 636         }
 637         int precedence() override
 638         {
 639                 // The actual precedence of a ternary conditional operator is 15, but
 640                 // its associativity is the opposite way around to the other operators,
 641                 // so we fudge it slightly.
 642                 return 3;
 643         }
 644 #ifndef NDEBUG
 645         void dump_impl() override
 646         {
 647                 cond->dump();
 648                 std::cerr << " ? ";
 649                 lhs->dump();
 650                 std::cerr << " : ";
 651                 rhs->dump();
 652         }
 653 #endif
 654         public:
 655         ternary_conditional_operator(source_location sl,
 656                                      expression_ptr c,
 657                                      expression_ptr l,
 658                                      expression_ptr r) :
 659                 expression(sl), cond(std::move(c)), lhs(std::move(l)),
 660                 rhs(std::move(r)) {}
 661 };
 662
 663 template<typename T>
 664 struct lshift
 665 {
 666         constexpr T operator()(const T &lhs, const T &rhs) const
 667         {
 668                 return lhs << rhs;
 669         }
 670 };
 671 template<typename T>
 672 struct rshift
 673 {
 674         constexpr T operator()(const T &lhs, const T &rhs) const
 675         {
 676                 return lhs >> rhs;
 677         }
 678 };
 679 template<typename T>
 680 struct unary_plus
 681 {
 682         constexpr T operator()(const T &val) const
 683         {
 684                 return +val;
 685         }
 686 };
 687 // TODO: Replace with std::bit_not once we can guarantee C++14 as a baseline.
 688 template<typename T>
 689 struct bit_not
 690 {
 691         constexpr T operator()(const T &val) const
 692         {
 693                 return ~val;
 694         }
 695 };
 696
 697 template<typename T>
 698 struct divmod : public binary_operator<5, T>
 699 {
 700         using binary_operator<5, T>::binary_operator;
 701         using typename binary_operator_base::result;
 702         result operator()() override
 703         {
 704                 result r = (*binary_operator_base::rhs)();
 705                 if (r.second && (r.first == 0))
 706                 {
 707                         expression::loc.report_error("Division by zero");
 708                         return {0, false};
 709                 }
 710                 return binary_operator<5, T>::operator()();
 711         }
 712 };
 713
 714 } // anonymous namespace
 715
 716
 717 expression_ptr text_input_buffer::parse_binary_expression(expression_ptr lhs)
 718 {
 719         next_token();
 720         binary_operator_base *expr = nullptr;
 721         char op = *(*this);
 722         source_location l = location();
 723         switch (op)
 724         {
 725                 default:
 726                         return lhs;
 727                 case '+':
 728                         expr = new binary_operator<6, std::plus<valty>>(l, "+");
 729                         break;
 730                 case '-':
 731                         expr = new binary_operator<6, std::minus<valty>>(l, "-");
 732                         break;
 733                 case '%':
 734                         expr = new divmod<std::modulus<valty>>(l, "/");
 735                         break;
 736                 case '*':
 737                         expr = new binary_operator<5, std::multiplies<valty>>(l, "*");
 738                         break;
 739                 case '/':
 740                         expr = new divmod<std::divides<valty>>(l, "/");
 741                         break;
 742                 case '<':
 743                         switch (peek())
 744                         {
 745                                 default:
 746                                         parse_error("Invalid operator");
 747                                         return nullptr;
 748                                 case ' ':
 749                                 case '(':
 750                                 case '0'...'9':
 751                                         expr = new binary_operator<8, std::less<valty>>(l, "<");
 752                                         break;
 753                                 case '=':
 754                                         ++(*this);
 755                                         expr = new binary_operator<8, std::less_equal<valty>>(l, "<=");
 756                                         break;
 757                                 case '<':
 758                                         ++(*this);
 759                                         expr = new binary_operator<7, lshift<valty>>(l, "<<");
 760                                         break;
 761                         }
 762                         break;
 763                 case '>':
 764                         switch (peek())
 765                         {
 766                                 default:
 767                                         parse_error("Invalid operator");
 768                                         return nullptr;
 769                                 case '(':
 770                                 case ' ':
 771                                 case '0'...'9':
 772                                         expr = new binary_operator<8, std::greater<valty>>(l, ">");
 773                                         break;
 774                                 case '=':
 775                                         ++(*this);
 776                                         expr = new binary_operator<8, std::greater_equal<valty>>(l, ">=");
 777                                         break;
 778                                 case '>':
 779                                         ++(*this);
 780                                         expr = new binary_operator<7, rshift<valty>>(l, ">>");
 781                                         break;
 782                                         return lhs;
 783                         }
 784                         break;
 785                 case '=':
 786                         if (peek() != '=')
 787                         {
 788                                 parse_error("Invalid operator");
 789                                 return nullptr;
 790                         }
 791                         expr = new binary_operator<9, std::equal_to<valty>>(l, "==");
 792                         break;
 793                 case '!':
 794                         if (peek() != '=')
 795                         {
 796                                 parse_error("Invalid operator");
 797                                 return nullptr;
 798                         }
 799                         cursor++;
 800                         expr = new binary_operator<9, std::not_equal_to<valty>>(l, "!=");
 801                         break;
 802                 case '&':
 803                         if (peek() == '&')
 804                         {
 805                                 expr = new binary_operator<13, std::logical_and<valty>>(l, "&&");
 806                         }
 807                         else
 808                         {
 809                                 expr = new binary_operator<10, std::bit_and<valty>>(l, "&");
 810                         }
 811                         break;
 812                 case '|':
 813                         if (peek() == '|')
 814                         {
 815                                 expr = new binary_operator<12, std::logical_or<valty>>(l, "||");
 816                         }
 817                         else
 818                         {
 819                                 expr = new binary_operator<14, std::bit_or<valty>>(l, "|");
 820                         }
 821                         break;
 822                 case '?':
 823                 {
 824                         consume('?');
 825                         expression_ptr true_case = parse_expression();
 826                         next_token();
 827                         if (!true_case || !consume(':'))
 828                         {
 829                                 parse_error("Expected : in ternary conditional operator");
 830                                 return nullptr;
 831                         }
 832                         expression_ptr false_case = parse_expression();
 833                         if (!false_case)
 834                         {
 835                                 parse_error("Expected false condition for ternary operator");
 836                                 return nullptr;
 837                         }
 838                         return expression_ptr(new ternary_conditional_operator(l, std::move(lhs),
 839                                                 std::move(true_case), std::move(false_case)));
 840                 }
 841         }
 842         ++(*this);
 843         next_token();
 844         expression_ptr e(expr);
 845         expression_ptr rhs(parse_expression());
 846         if (!rhs)
 847         {
 848                 return nullptr;
 849         }
 850         expr->lhs = std::move(lhs);
 851         if (rhs->precedence() < expr->precedence())
 852         {
 853                 expr->rhs = std::move(rhs);
 854         }
 855         else
 856         {
 857                 // If we're a normal left-to-right expression, then we need to insert
 858                 // this as the far-left child node of the rhs expression
 859                 binary_operator_base *rhs_op =
 860                         static_cast<binary_operator_base*>(rhs.get());
 861                 rhs_op->insert_left(expr);
 862                 e.release();
 863                 return rhs;
 864         }
 865         return e;
 866 }
 867
 868 expression_ptr text_input_buffer::parse_expression(bool stopAtParen)
 869 {
 870         next_token();
 871         unsigned long long leftVal;
 872         expression_ptr lhs;
 873         source_location l = location();
 874         switch (*(*this))
 875         {
 876                 case '0'...'9':
 877                         if (!consume_integer(leftVal))
 878                         {
 879                                 return nullptr;
 880                         }
 881                         lhs.reset(new terminal_expr(l, leftVal));
 882                         break;
 883                 case '(':
 884                 {
 885                         consume('(');
 886                         expression_ptr &&subexpr = parse_expression();
 887                         if (!subexpr)
 888                         {
 889                                 return nullptr;
 890                         }
 891                         lhs.reset(new paren_expression(l, std::move(subexpr)));
 892                         if (!consume(')'))
 893                         {
 894                                 return nullptr;
 895                         }
 896                         if (stopAtParen)
 897                         {
 898                                 return lhs;
 899                         }
 900                         break;
 901                 }
 902                 case '+':
 903                 {
 904                         consume('+');
 905                         expression_ptr &&subexpr = parse_expression();
 906                         if (!subexpr)
 907                         {
 908                                 return nullptr;
 909                         }
 910                         lhs.reset(new unary_operator<'+', unary_plus<valty>>(l, std::move(subexpr)));
 911                         break;
 912                 }
 913                 case '-':
 914                 {
 915                         consume('-');
 916                         expression_ptr &&subexpr = parse_expression();
 917                         if (!subexpr)
 918                         {
 919                                 return nullptr;
 920                         }
 921                         lhs.reset(new unary_operator<'-', std::negate<valty>>(l, std::move(subexpr)));
 922                         break;
 923                 }
 924                 case '!':
 925                 {
 926                         consume('!');
 927                         expression_ptr &&subexpr = parse_expression();
 928                         if (!subexpr)
 929                         {
 930                                 return nullptr;
 931                         }
 932                         lhs.reset(new unary_operator<'!', std::logical_not<valty>>(l, std::move(subexpr)));
 933                         break;
 934                 }
 935                 case '~':
 936                 {
 937                         consume('~');
 938                         expression_ptr &&subexpr = parse_expression();
 939                         if (!subexpr)
 940                         {
 941                                 return nullptr;
 942                         }
 943                         lhs.reset(new unary_operator<'~', bit_not<valty>>(l, std::move(subexpr)));
 944                         break;
 945                 }
 946         }
 947         if (!lhs)
 948         {
 949                 return nullptr;
 950         }
 951         return parse_binary_expression(std::move(lhs));
 952 }
 953
 954 bool
 955 text_input_buffer::consume_integer_expression(unsigned long long &outInt)
 956 {
 957         switch (*(*this))
 958         {
 959                 case '(':
 960                 {
 961                         expression_ptr e(parse_expression(true));
 962                         if (!e)
 963                         {
 964                                 return false;
 965                         }
 966                         auto r = (*e)();
 967                         if (r.second)
 968                         {
 969                                 outInt = r.first;
 970                                 return true;
 971                         }
 972                         return false;
 973                 }
 974                 case '0'...'9':
 975                         return consume_integer(outInt);
 976                 default:
 977                         return false;
 978         }
 979 }
 980
 981 bool
 982 input_buffer::consume_hex_byte(uint8_t &outByte)
 983 {
 984         if (!ishexdigit((*this)[0]) && !ishexdigit((*this)[1]))
 985         {
 986                 return false;
 987         }
 988         outByte = (digittoint((*this)[0]) << 4) | digittoint((*this)[1]);
 989         cursor += 2;
 990         return true;
 991 }
 992
 993 text_input_buffer&
 994 text_input_buffer::next_token()
 995 {
 996         auto &self = *this;
 997         int start;
 998         do {
 999                 start = cursor;
1000                 skip_spaces();
1001                 if (finished())
1002                 {
1003                         return self;
1004                 }
1005                 // Parse /* comments
1006                 if (*self == '/' && peek() == '*')
1007                 {
1008                         // eat the start of the comment
1009                         ++self;
1010                         ++self;
1011                         do {
1012                                 // Find the ending * of */
1013                                 while ((*self != '\0') && (*self != '*') && !finished())
1014                                 {
1015                                         ++self;
1016                                 }
1017                                 // Eat the *
1018                                 ++self;
1019                         } while ((*self != '\0') && (*self != '/') && !finished());
1020                         // Eat the /
1021                         ++self;
1022                 }
1023                 // Parse // comments
1024                 if ((*self == '/' && peek() == '/'))
1025                 {
1026                         // eat the start of the comment
1027                         ++self;
1028                         ++self;
1029                         // Find the ending of the line
1030                         while (*self != '\n' && !finished())
1031                         {
1032                                 ++self;
1033                         }
1034                         // Eat the \n
1035                         ++self;
1036                 }
1037         } while (start != cursor);
1038         return self;
1039 }
1040
1041 void
1042 text_input_buffer::parse_error(const char *msg)
1043 {
1044         if (input_stack.empty())
1045         {
1046                 fprintf(stderr, "Error: %s\n", msg);
1047                 return;
1048         }
1049         input_buffer &b = *input_stack.top();
1050         parse_error(msg, b, b.cursor);
1051 }
1052 void
1053 text_input_buffer::parse_error(const char *msg,
1054                                input_buffer &b,
1055                                int loc)
1056 {
1057         int line_count = 1;
1058         int line_start = 0;
1059         int line_end = loc;
1060         if (loc < 0 || loc > b.size)
1061         {
1062                 return;
1063         }
1064         for (int i=loc ; i>0 ; --i)
1065         {
1066                 if (b.buffer[i] == '\n')
1067                 {
1068                         line_count++;
1069                         if (line_start == 0)
1070                         {
1071                                 line_start = i+1;
1072                         }
1073                 }
1074         }
1075         for (int i=loc+1 ; i<b.size ; ++i)
1076         {
1077                 if (b.buffer[i] == '\n')
1078                 {
1079                         line_end = i;
1080                         break;
1081                 }
1082         }
1083         fprintf(stderr, "Error at %s:%d:%d: %s\n", b.filename().c_str(), line_count, loc - line_start, msg);
1084         fwrite(&b.buffer[line_start], line_end-line_start, 1, stderr);
1085         putc('\n', stderr);
1086         for (int i=0 ; i<(loc-line_start) ; ++i)
1087         {
1088                 char c = (b.buffer[i+line_start] == '\t') ? '\t' : ' ';
1089                 putc(c, stderr);
1090         }
1091         putc('^', stderr);
1092         putc('\n', stderr);
1093 }
1094 #ifndef NDEBUG
1095 void
1096 input_buffer::dump()
1097 {
1098         fprintf(stderr, "Current cursor: %d\n", cursor);
1099         fwrite(&buffer[cursor], size-cursor, 1, stderr);
1100 }
1101 #endif
1102
1103
1104 namespace
1105 {
1106 /**
1107  * The source files are ASCII, so we provide a non-locale-aware version of
1108  * isalpha.  This is a class so that it can be used with a template function
1109  * for parsing strings.
1110  */
1111 struct is_alpha
1112 {
1113         static inline bool check(const char c)
1114         {
1115                 return ((c >= 'a') && (c <= 'z')) || ((c >= 'A') &&
1116                         (c <= 'Z'));
1117         }
1118 };
1119 /**
1120  * Check whether a character is in the set allowed for node names.  This is a
1121  * class so that it can be used with a template function for parsing strings.
1122  */
1123 struct is_node_name_character
1124 {
1125         static inline bool check(const char c)
1126         {
1127                 switch(c)
1128                 {
1129                         default:
1130                                 return false;
1131                         case 'a'...'z': case 'A'...'Z': case '0'...'9':
1132                         case ',': case '.': case '+': case '-':
1133                         case '_':
1134                                 return true;
1135                 }
1136         }
1137 };
1138 /**
1139  * Check whether a character is in the set allowed for property names.  This is
1140  * a class so that it can be used with a template function for parsing strings.
1141  */
1142 struct is_property_name_character
1143 {
1144         static inline bool check(const char c)
1145         {
1146                 switch(c)
1147                 {
1148                         default:
1149                                 return false;
1150                         case 'a'...'z': case 'A'...'Z': case '0'...'9':
1151                         case ',': case '.': case '+': case '-':
1152                         case '_': case '#':
1153                                 return true;
1154                 }
1155         }
1156 };
1157
1158 template<class T>
1159 string parse(text_input_buffer &s)
1160 {
1161         std::vector<char> bytes;
1162         for (char c=*s ; T::check(c) ; c=*(++s))
1163         {
1164                 bytes.push_back(c);
1165         }
1166         return string(bytes.begin(), bytes.end());
1167 }
1168
1169 }
1170
1171 string
1172 text_input_buffer::parse_node_name()
1173 {
1174         return parse<is_node_name_character>(*this);
1175 }
1176
1177 string
1178 text_input_buffer::parse_property_name()
1179 {
1180         return parse<is_property_name_character>(*this);
1181 }
1182
1183 string
1184 text_input_buffer::parse_node_or_property_name(bool &is_property)
1185 {
1186         if (is_property)
1187         {
1188                 return parse_property_name();
1189         }
1190         std::vector<char> bytes;
1191         for (char c=*(*this) ; is_node_name_character::check(c) ; c=*(++(*this)))
1192         {
1193                 bytes.push_back(c);
1194         }
1195         for (char c=*(*this) ; is_property_name_character::check(c) ; c=*(++(*this)))
1196         {
1197                 bytes.push_back(c);
1198                 is_property = true;
1199         }
1200         return string(bytes.begin(), bytes.end());
1201 }
1202
1203 string
1204 input_buffer::parse_to(char stop)
1205 {
1206         std::vector<char> bytes;
1207         for (char c=*(*this) ; c != stop ; c=*(++(*this)))
1208         {
1209                 bytes.push_back(c);
1210         }
1211         return string(bytes.begin(), bytes.end());
1212 }
1213
1214 string
1215 text_input_buffer::parse_to(char stop)
1216 {
1217         std::vector<char> bytes;
1218         for (char c=*(*this) ; c != stop ; c=*(++(*this)))
1219         {
1220                 if (finished())
1221                 {
1222                         break;
1223                 }
1224                 bytes.push_back(c);
1225         }
1226         return string(bytes.begin(), bytes.end());
1227 }
1228
1229 char
1230 text_input_buffer::peek()
1231 {
1232         return (*input_stack.top())[1];
1233 }
1234
1235 std::unique_ptr<input_buffer>
1236 input_buffer::buffer_for_file(const string &path, bool warn)
1237 {
1238         if (path == "-")
1239         {
1240                 std::unique_ptr<input_buffer> b(new stream_input_buffer());
1241                 return b;
1242         }
1243         int source = open(path.c_str(), O_RDONLY);
1244         if (source == -1)
1245         {
1246                 if (warn)
1247                 {
1248                         fprintf(stderr, "Unable to open file '%s'.  %s\n", path.c_str(), strerror(errno));
1249                 }
1250                 return 0;
1251         }
1252         struct stat st;
1253         if (fstat(source, &st) == 0 && S_ISDIR(st.st_mode))
1254         {
1255                 if (warn)
1256                 {
1257                         fprintf(stderr, "File %s is a directory\n", path.c_str());
1258                 }
1259                 close(source);
1260                 return 0;
1261         }
1262         std::unique_ptr<input_buffer> b(new mmap_input_buffer(source, string(path)));
1263         close(source);
1264         return b;
1265 }
1266
1267 } // namespace dtc
1268