/* GNU m4 -- A simple macro processor

   Copyright (C) 1989, 1990, 1991, 1992, 1993, 1994, 2006, 2007, 2008,
   2009, 2010 Free Software Foundation, Inc.

   This file is part of GNU M4.

   GNU M4 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 of the License, or
   (at your option) any later version.

   GNU M4 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 this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/* This module handles frozen files.  */

#include "m4.h"

/*-------------------------------------------------------------------.
| Destructively reverse a symbol list and return the reversed list.  |
`-------------------------------------------------------------------*/

static symbol *
reverse_symbol_list (symbol *sym)
{
  symbol *result;
  symbol *next;

  result = NULL;
  while (sym)
    {
      next = SYMBOL_NEXT (sym);
      SYMBOL_NEXT (sym) = result;
      result = sym;
      sym = next;
    }
  return result;
}

/*------------------------------------------------.
| Produce a frozen state to the given file NAME.  |
`------------------------------------------------*/

void
produce_frozen_state (const char *name)
{
  FILE *file;
  size_t h;
  symbol *sym;
  const builtin *bp;

  file = fopen (name, O_BINARY ? "wb" : "w");
  if (!file)
    {
      M4ERROR ((EXIT_FAILURE, errno, "cannot open `%s'", name));
      return;
    }

  /* Write a recognizable header.  */

  xfprintf (file, "# This is a frozen state file generated by %s\n",
           PACKAGE_STRING);
  xfprintf (file, "V1\n");

  /* Dump quote delimiters.  */

  if (strcmp (lquote.string, DEF_LQUOTE) || strcmp (rquote.string, DEF_RQUOTE))
    {
      xfprintf (file, "Q%d,%d\n", (int) lquote.length, (int) rquote.length);
      fputs (lquote.string, file);
      fputs (rquote.string, file);
      fputc ('\n', file);
    }

  /* Dump comment delimiters.  */

  if (strcmp (bcomm.string, DEF_BCOMM) || strcmp (ecomm.string, DEF_ECOMM))
    {
      xfprintf (file, "C%d,%d\n", (int) bcomm.length, (int) ecomm.length);
      fputs (bcomm.string, file);
      fputs (ecomm.string, file);
      fputc ('\n', file);
    }

  /* Dump all symbols.  */

  for (h = 0; h < hash_table_size; h++)
    {

      /* Process all entries in one bucket, from the last to the first.
         This order ensures that, at reload time, pushdef's will be
         executed with the oldest definitions first.  */

      symtab[h] = reverse_symbol_list (symtab[h]);
      for (sym = symtab[h]; sym; sym = SYMBOL_NEXT (sym))
        {
          switch (SYMBOL_TYPE (sym))
            {
            case TOKEN_TEXT:
              xfprintf (file, "T%d,%d\n",
                        (int) strlen (SYMBOL_NAME (sym)),
                        (int) strlen (SYMBOL_TEXT (sym)));
              fputs (SYMBOL_NAME (sym), file);
              fputs (SYMBOL_TEXT (sym), file);
              fputc ('\n', file);
              break;

            case TOKEN_FUNC:
              bp = find_builtin_by_addr (SYMBOL_FUNC (sym));
              if (bp == NULL)
                {
                  M4ERROR ((warning_status, 0, "\
INTERNAL ERROR: builtin not found in builtin table!"));
                  abort ();
                }
              xfprintf (file, "F%d,%d\n",
                        (int) strlen (SYMBOL_NAME (sym)),
                        (int) strlen (bp->name));
              fputs (SYMBOL_NAME (sym), file);
              fputs (bp->name, file);
              fputc ('\n', file);
              break;

            case TOKEN_VOID:
              /* Ignore placeholder tokens that exist due to traceon.  */
              break;

            default:
              M4ERROR ((warning_status, 0, "\
INTERNAL ERROR: bad token data type in freeze_one_symbol ()"));
              abort ();
              break;
            }
        }

      /* Reverse the bucket once more, putting it back as it was.  */

      symtab[h] = reverse_symbol_list (symtab[h]);
    }

  /* Let diversions be issued from output.c module, its cleaner to have this
     piece of code there.  */

  freeze_diversions (file);

  /* All done.  */

  fputs ("# End of frozen state file\n", file);
  if (close_stream (file) != 0)
    M4ERROR ((EXIT_FAILURE, errno, "unable to create frozen state"));
}

/*----------------------------------------------------------------------.
| Issue a message saying that some character is an EXPECTED character.  |
`----------------------------------------------------------------------*/

static void
issue_expect_message (int expected)
{
  if (expected == '\n')
    M4ERROR ((EXIT_FAILURE, 0, "expecting line feed in frozen file"));
  else
    M4ERROR ((EXIT_FAILURE, 0, "expecting character `%c' in frozen file",
              expected));
}

/*-------------------------------------------------.
| Reload a frozen state from the given file NAME.  |
`-------------------------------------------------*/

/* We are seeking speed, here.  */

void
reload_frozen_state (const char *name)
{
  FILE *file;
  int character;
  int operation;
  char *string[2];
  int allocated[2];
  int number[2];
  const builtin *bp;
  bool advance_line = true;

#define GET_CHARACTER                                           \
  do                                                            \
    {                                                           \
      if (advance_line)                                         \
        {                                                       \
          current_line++;                                       \
          advance_line = false;                                 \
        }                                                       \
      (character = getc (file));                                \
      if (character == '\n')                                    \
        advance_line = true;                                    \
    }                                                           \
  while (0)

#define GET_NUMBER(Number, AllowNeg)                            \
  do                                                            \
    {                                                           \
      unsigned int n = 0;                                       \
      while (isdigit (character) && n <= INT_MAX / 10U)         \
        {                                                       \
          n = 10 * n + character - '0';                         \
          GET_CHARACTER;                                        \
        }                                                       \
      if (((AllowNeg) ? INT_MIN : INT_MAX) + 0U < n             \
          || isdigit (character))                               \
        m4_error (EXIT_FAILURE, 0,                              \
                  _("integer overflow in frozen file"));        \
      (Number) = n;                                             \
    }                                                           \
  while (0)

#define VALIDATE(Expected)                                      \
  do                                                            \
    {                                                           \
      if (character != (Expected))                              \
        issue_expect_message (Expected);                        \
    }                                                           \
  while (0)

  /* Skip comments (`#' at beginning of line) and blank lines, setting
     character to the next directive or to EOF.  */

#define GET_DIRECTIVE                                           \
  do                                                            \
    {                                                           \
      GET_CHARACTER;                                            \
      if (character == '#')                                     \
        {                                                       \
          while (character != EOF && character != '\n')         \
            GET_CHARACTER;                                      \
          VALIDATE ('\n');                                      \
        }                                                       \
    }                                                           \
  while (character == '\n')

#define GET_STRING(i)                                                   \
  do                                                                    \
    {                                                                   \
      void *tmp;                                                        \
      char *p;                                                          \
      if (number[(i)] + 1 > allocated[(i)])                             \
        {                                                               \
          free (string[(i)]);                                           \
          allocated[(i)] = number[(i)] + 1;                             \
          string[(i)] = xcharalloc ((size_t) allocated[(i)]);           \
        }                                                               \
      if (number[(i)] > 0                                               \
          && !fread (string[(i)], (size_t) number[(i)], 1, file))       \
        m4_error (EXIT_FAILURE, 0,                                      \
                  _("premature end of frozen file"));                   \
      string[(i)][number[(i)]] = '\0';                                  \
      p = string[(i)];                                                  \
      while ((tmp = memchr(p, '\n', number[(i)] - (p - string[(i)]))))  \
        {                                                               \
          current_line++;                                               \
          p = (char *) tmp + 1;                                         \
        }                                                               \
    }                                                                   \
  while (0)

  file = m4_path_search (name, NULL);
  if (file == NULL)
    M4ERROR ((EXIT_FAILURE, errno, "cannot open %s", name));
  current_file = name;

  allocated[0] = 100;
  string[0] = xcharalloc ((size_t) allocated[0]);
  allocated[1] = 100;
  string[1] = xcharalloc ((size_t) allocated[1]);

  /* Validate format version.  Only `1' is acceptable for now.  */
  GET_DIRECTIVE;
  VALIDATE ('V');
  GET_CHARACTER;
  GET_NUMBER (number[0], false);
  if (number[0] > 1)
    M4ERROR ((EXIT_MISMATCH, 0,
              "frozen file version %d greater than max supported of 1",
              number[0]));
  else if (number[0] < 1)
    M4ERROR ((EXIT_FAILURE, 0,
              "ill-formed frozen file, version directive expected"));
  VALIDATE ('\n');

  GET_DIRECTIVE;
  while (character != EOF)
    {
      switch (character)
        {
        default:
          M4ERROR ((EXIT_FAILURE, 0, "ill-formed frozen file"));

        case 'C':
        case 'D':
        case 'F':
        case 'T':
        case 'Q':
          operation = character;
          GET_CHARACTER;

          /* Get string lengths.  Accept a negative diversion number.  */

          if (operation == 'D' && character == '-')
            {
              GET_CHARACTER;
              GET_NUMBER (number[0], true);
              number[0] = -number[0];
            }
          else
            GET_NUMBER (number[0], false);
          VALIDATE (',');
          GET_CHARACTER;
          GET_NUMBER (number[1], false);
          VALIDATE ('\n');

          if (operation != 'D')
            GET_STRING (0);
          GET_STRING (1);
          GET_CHARACTER;
          VALIDATE ('\n');

          /* Act according to operation letter.  */

          switch (operation)
            {
            case 'C':

              /* Change comment strings.  */

              set_comment (string[0], string[1]);
              break;

            case 'D':

              /* Select a diversion and add a string to it.  */

              make_diversion (number[0]);
              if (number[1] > 0)
                output_text (string[1], number[1]);
              break;

            case 'F':

              /* Enter a macro having a builtin function as a definition.  */

              bp = find_builtin_by_name (string[1]);
              define_builtin (string[0], bp, SYMBOL_PUSHDEF);
              break;

            case 'T':

              /* Enter a macro having an expansion text as a definition.  */

              define_user_macro (string[0], string[1], SYMBOL_PUSHDEF);
              break;

            case 'Q':

              /* Change quote strings.  */

              set_quotes (string[0], string[1]);
              break;

            default:

              /* Cannot happen.  */

              break;
            }
          break;

        }
      GET_DIRECTIVE;
    }

  free (string[0]);
  free (string[1]);
  if (close_stream (file) != 0)
    m4_error (EXIT_FAILURE, errno, _("unable to read frozen state"));
  current_file = NULL;
  current_line = 0;

#undef GET_CHARACTER
#undef GET_DIRECTIVE
#undef GET_NUMBER
#undef VALIDATE
#undef GET_STRING
}