/* Preprocess only, using cpplib.
   Copyright (C) 1995-2021 Free Software Foundation, Inc.
   Written by Per Bothner, 1994-95.

   This program 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.

   This program 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; see the file COPYING3.  If not see
   <http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "c-common.h"		/* For flags.  */
#include "../libcpp/internal.h"
#include "langhooks.h"
#include "c-pragma.h"		/* For parse_in.  */
#include "file-prefix-map.h"    /* remap_macro_filename()  */

/* Encapsulates state used to convert a stream of tokens into a text
   file.  */
static struct
{
  FILE *outf;			/* Stream to write to.  */
  const cpp_token *prev;	/* Previous token.  */
  const cpp_token *source;	/* Source token for spacing.  */
  unsigned src_line;		/* Line number currently being written.  */
  bool printed;			/* True if something output at line.  */
  bool first_time;		/* pp_file_change hasn't been called yet.  */
  bool prev_was_system_token;	/* True if the previous token was a
				   system token.*/
  const char *src_file;		/* Current source file.  */
} print;

/* Defined and undefined macros being queued for output with -dU at
   the next newline.  */
struct macro_queue
{
  struct macro_queue *next;	/* Next macro in the list.  */
  char *macro;			/* The name of the macro if not
				   defined, the full definition if
				   defined.  */
};
static macro_queue *define_queue, *undef_queue;

/* General output routines.  */
static void scan_translation_unit (cpp_reader *);
static void scan_translation_unit_directives_only (cpp_reader *);
static void scan_translation_unit_trad (cpp_reader *);
static void account_for_newlines (const unsigned char *, size_t);
static int dump_macro (cpp_reader *, cpp_hashnode *, void *);
static void dump_queued_macros (cpp_reader *);

static bool print_line_1 (location_t, const char*, FILE *);
static bool print_line (location_t, const char *);
static bool maybe_print_line_1 (location_t, FILE *);
static bool maybe_print_line (location_t);
static bool do_line_change (cpp_reader *, const cpp_token *,
			    location_t, int);

/* Callback routines for the parser.   Most of these are active only
   in specific modes.  */
static void cb_line_change (cpp_reader *, const cpp_token *, int);
static void cb_define (cpp_reader *, location_t, cpp_hashnode *);
static void cb_undef (cpp_reader *, location_t, cpp_hashnode *);
static void cb_used_define (cpp_reader *, location_t, cpp_hashnode *);
static void cb_used_undef (cpp_reader *, location_t, cpp_hashnode *);
static void cb_include (cpp_reader *, location_t, const unsigned char *,
			const char *, int, const cpp_token **);
static void cb_ident (cpp_reader *, location_t, const cpp_string *);
static void cb_def_pragma (cpp_reader *, location_t);
static void cb_read_pch (cpp_reader *pfile, const char *name,
			 int fd, const char *orig_name);

/* Preprocess and output.  */
void
preprocess_file (cpp_reader *pfile)
{
  /* A successful cpp_read_main_file guarantees that we can call
     cpp_scan_nooutput or cpp_get_token next.  */
  if (flag_no_output && pfile->buffer)
    {
      /* Scan -included buffers, then the main file.  */
      while (pfile->buffer->prev)
	cpp_scan_nooutput (pfile);
      cpp_scan_nooutput (pfile);
    }
  else if (cpp_get_options (pfile)->traditional)
    scan_translation_unit_trad (pfile);
  else if (cpp_get_options (pfile)->directives_only
	   && !cpp_get_options (pfile)->preprocessed)
    scan_translation_unit_directives_only (pfile);
  else
    scan_translation_unit (pfile);

  /* -dM command line option.  Should this be elsewhere?  */
  if (flag_dump_macros == 'M')
    cpp_forall_identifiers (pfile, dump_macro, NULL);

  /* Flush any pending output.  */
  if (print.printed)
    putc ('\n', print.outf);
}

/* Set up the callbacks as appropriate.  */
void
init_pp_output (FILE *out_stream)
{
  cpp_callbacks *cb = cpp_get_callbacks (parse_in);

  if (!flag_no_output)
    {
      cb->line_change = cb_line_change;
      /* Don't emit #pragma or #ident directives if we are processing
	 assembly language; the assembler may choke on them.  */
      if (cpp_get_options (parse_in)->lang != CLK_ASM)
	{
	  cb->ident      = cb_ident;
	  cb->def_pragma = cb_def_pragma;
	}
    }

  if (flag_dump_includes)
    cb->include  = cb_include;

  if (flag_pch_preprocess)
    {
      cb->valid_pch = c_common_valid_pch;
      cb->read_pch = cb_read_pch;
    }

  if (flag_dump_macros == 'N' || flag_dump_macros == 'D')
    {
      cb->define = cb_define;
      cb->undef  = cb_undef;
    }

  if (flag_dump_macros == 'U')
    {
      cb->before_define = dump_queued_macros;
      cb->used_define = cb_used_define;
      cb->used_undef = cb_used_undef;
    }

  cb->has_attribute = c_common_has_attribute;
  cb->has_builtin = c_common_has_builtin;
  cb->get_source_date_epoch = cb_get_source_date_epoch;
  cb->remap_filename = remap_macro_filename;

  /* Initialize the print structure.  */
  print.src_line = 1;
  print.printed = false;
  print.prev = 0;
  print.outf = out_stream;
  print.first_time = 1;
  print.src_file = "";
  print.prev_was_system_token = false;
}

// FIXME: Ideally we'd just turn the entirety of the print struct into
// an encapsulated streamer ...

class token_streamer
{
  bool avoid_paste;
  bool do_line_adjustments;
  bool in_pragma;
  bool line_marker_emitted;

 public:
  token_streamer (cpp_reader *pfile)
    :avoid_paste (false),
    do_line_adjustments (cpp_get_options (pfile)->lang != CLK_ASM
			 && !flag_no_line_commands),
    in_pragma (false),
    line_marker_emitted (false)
    {
    }

  void begin_pragma () 
  {
    in_pragma = true;
  }

  void stream (cpp_reader *pfile, const cpp_token *tok, location_t);
};

void
token_streamer::stream (cpp_reader *pfile, const cpp_token *token,
			location_t loc)
{
  if (token->type == CPP_PADDING)
    {
      avoid_paste = true;
      if (print.source == NULL
	  || (!(print.source->flags & PREV_WHITE)
	      && token->val.source == NULL))
	print.source = token->val.source;
      return;
    }

  if (token->type == CPP_EOF)
    return;

  /* Subtle logic to output a space if and only if necessary.  */
  if (avoid_paste)
    {
      unsigned src_line = LOCATION_LINE (loc);

      if (print.source == NULL)
	print.source = token;

      if (src_line != print.src_line
	  && do_line_adjustments
	  && !in_pragma)
	{
	  line_marker_emitted = do_line_change (pfile, token, loc, false);
	  putc (' ', print.outf);
	  print.printed = true;
	}
      else if (print.source->flags & PREV_WHITE
	       || (print.prev
		   && cpp_avoid_paste (pfile, print.prev, token))
	       || (print.prev == NULL && token->type == CPP_HASH))
	{
	  putc (' ', print.outf);
	  print.printed = true;
	}
    }
  else if (token->flags & PREV_WHITE)
    {
      unsigned src_line = LOCATION_LINE (loc);

      if (src_line != print.src_line
	  && do_line_adjustments
	  && !in_pragma)
	line_marker_emitted = do_line_change (pfile, token, loc, false);
      putc (' ', print.outf);
      print.printed = true;
    }

  avoid_paste = false;
  print.source = NULL;
  print.prev = token;
  if (token->type == CPP_PRAGMA)
    {
      const char *space;
      const char *name;

      line_marker_emitted = maybe_print_line (token->src_loc);
      fputs ("#pragma ", print.outf);
      c_pp_lookup_pragma (token->val.pragma, &space, &name);
      if (space)
	fprintf (print.outf, "%s %s", space, name);
      else
	fprintf (print.outf, "%s", name);
      print.printed = true;
      in_pragma = true;
    }
  else if (token->type == CPP_PRAGMA_EOL)
    {
      maybe_print_line (UNKNOWN_LOCATION);
      in_pragma = false;
    }
  else
    {
      if (cpp_get_options (parse_in)->debug)
	linemap_dump_location (line_table, token->src_loc, print.outf);

      if (do_line_adjustments
	  && !in_pragma
	  && !line_marker_emitted
	  && print.prev_was_system_token != !!in_system_header_at (loc)
	  && !is_location_from_builtin_token (loc))
	/* The system-ness of this token is different from the one of
	   the previous token.  Let's emit a line change to mark the
	   new system-ness before we emit the token.  */
	{
	  do_line_change (pfile, token, loc, false);
	  print.prev_was_system_token = !!in_system_header_at (loc);
	}
      cpp_output_token (token, print.outf);
      line_marker_emitted = false;
      print.printed = true;
    }

  /* CPP_COMMENT tokens and raw-string literal tokens can have
     embedded new-line characters.  Rather than enumerating all the
     possible token types just check if token uses val.str union
     member.  */
  if (cpp_token_val_index (token) == CPP_TOKEN_FLD_STR)
    account_for_newlines (token->val.str.text, token->val.str.len);
}

/* Writes out the preprocessed file, handling spacing and paste
   avoidance issues.  */

static void
scan_translation_unit (cpp_reader *pfile)
{
  token_streamer streamer (pfile);
  uintptr_t filter = 0;

  if (lang_hooks.preprocess_token)
    filter = lang_hooks.preprocess_token (pfile, NULL, filter);

  print.source = NULL;
  for (;;)
    {
      location_t spelling_loc;
      const cpp_token *token
	= cpp_get_token_with_location (pfile, &spelling_loc);

      streamer.stream (pfile, token, spelling_loc);
      if (filter)
	{
	  unsigned flags = lang_hooks.preprocess_token (pfile, token, filter);
	  if (flags & lang_hooks::PT_begin_pragma)
	    streamer.begin_pragma ();
	}
      if (token->type == CPP_EOF)
	break;
    }

  if (filter)
    lang_hooks.preprocess_token (pfile, NULL, filter);
}

class do_streamer : public token_streamer
{
 public:
  uintptr_t filter;

  do_streamer (cpp_reader *pfile, uintptr_t filter)
    :token_streamer (pfile), filter (filter)
    {
    }
};

static void
directives_only_cb (cpp_reader *pfile, CPP_DO_task task, void *data_, ...)
{
  va_list args;
  va_start (args, data_);

  do_streamer *streamer = reinterpret_cast <do_streamer *> (data_);
  switch (task)
    {
    default:
      gcc_unreachable ();

    case CPP_DO_print:
      {
	print.src_line += va_arg (args, unsigned);

	const void *buf = va_arg (args, const void *);
	size_t size = va_arg (args, size_t);
	fwrite (buf, 1, size, print.outf);
      }
      break;

    case CPP_DO_location:
      maybe_print_line (va_arg (args, location_t));
      break;

    case CPP_DO_token:
      {
	const cpp_token *token = va_arg (args, const cpp_token *);
	location_t spelling_loc = va_arg (args, location_t);
	streamer->stream (pfile, token, spelling_loc);
	if (streamer->filter)
	  {
	    unsigned flags = lang_hooks.preprocess_token
	      (pfile, token, streamer->filter);
	    if (flags & lang_hooks::PT_begin_pragma)
	      streamer->begin_pragma ();
	  }
      }
      break;
    }

  va_end (args);
}

/* Writes out the preprocessed file, handling spacing and paste
   avoidance issues.  */
static void
scan_translation_unit_directives_only (cpp_reader *pfile)
{
  uintptr_t filter = 0;
  if (lang_hooks.preprocess_token)
    filter = lang_hooks.preprocess_token (pfile, NULL, filter);
  do_streamer streamer (pfile, filter);
  cpp_directive_only_process (pfile, &streamer, directives_only_cb);
  if (streamer.filter)
    lang_hooks.preprocess_token (pfile, NULL, streamer.filter);
}

/* Adjust print.src_line for newlines embedded in output.  */
static void
account_for_newlines (const unsigned char *str, size_t len)
{
  while (len--)
    if (*str++ == '\n')
      print.src_line++;
}

/* Writes out a traditionally preprocessed file.  */
static void
scan_translation_unit_trad (cpp_reader *pfile)
{
  while (_cpp_read_logical_line_trad (pfile))
    {
      size_t len = pfile->out.cur - pfile->out.base;
      maybe_print_line (pfile->out.first_line);
      fwrite (pfile->out.base, 1, len, print.outf);
      print.printed = true;
      if (!CPP_OPTION (pfile, discard_comments))
	account_for_newlines (pfile->out.base, len);
    }
}

/* If the token read on logical line LINE needs to be output on a
   different line to the current one, output the required newlines or
   a line marker.  If a line marker was emitted, return TRUE otherwise
   return FALSE.  */

static bool
maybe_print_line_1 (location_t src_loc, FILE *stream)
{
  bool emitted_line_marker = false;
  unsigned src_line = LOCATION_LINE (src_loc);
  const char *src_file = LOCATION_FILE (src_loc);

  /* End the previous line of text.  */
  if (print.printed)
    {
      putc ('\n', stream);
      print.src_line++;
      print.printed = false;
    }

  if (!flag_no_line_commands
      && src_line >= print.src_line
      && src_line < print.src_line + 8
      && src_loc != UNKNOWN_LOCATION
      && strcmp (src_file, print.src_file) == 0)
    {
      while (src_line > print.src_line)
	{
	  putc ('\n', stream);
	  print.src_line++;
	}
    }
  else
    emitted_line_marker = print_line_1 (src_loc, "", stream);

  return emitted_line_marker;
}

/* If the token read on logical line LINE needs to be output on a
   different line to the current one, output the required newlines or
   a line marker.  If a line marker was emitted, return TRUE otherwise
   return FALSE.  */

static bool
maybe_print_line (location_t src_loc)
{
  if (cpp_get_options (parse_in)->debug)
    linemap_dump_location (line_table, src_loc,
			   print.outf);
  return maybe_print_line_1 (src_loc, print.outf);
}

/* Output a line marker for logical line LINE.  Special flags are "1"
   or "2" indicating entering or leaving a file.  If the line marker
   was effectively emitted, return TRUE otherwise return FALSE.  */

static bool
print_line_1 (location_t src_loc, const char *special_flags, FILE *stream)
{
  bool emitted_line_marker = false;

  /* End any previous line of text.  */
  if (print.printed)
    putc ('\n', stream);
  print.printed = false;

  if (src_loc != UNKNOWN_LOCATION && !flag_no_line_commands)
    {
      const char *file_path = LOCATION_FILE (src_loc);
      size_t to_file_len = strlen (file_path);
      unsigned char *to_file_quoted =
         (unsigned char *) alloca (to_file_len * 4 + 1);

      /* cpp_quote_string does not nul-terminate, so we have to do it
	 ourselves.  */
      unsigned char *p = cpp_quote_string (to_file_quoted,
					   (const unsigned char *) file_path,
					   to_file_len);
      *p = '\0';

      print.src_line = LOCATION_LINE (src_loc);
      print.src_file = file_path;

      fprintf (stream, "# %u \"%s\"%s",
	       print.src_line, to_file_quoted, special_flags);

      int sysp = in_system_header_at (src_loc);
      if (sysp == 2)
	fputs (" 3 4", stream);
      else if (sysp == 1)
	fputs (" 3", stream);

      putc ('\n', stream);
      emitted_line_marker = true;
    }

  return emitted_line_marker;
}

/* Output a line marker for logical line LINE.  Special flags are "1"
   or "2" indicating entering or leaving a file.  Return TRUE if a
   line marker was effectively emitted, FALSE otherwise.  */

static bool
print_line (location_t src_loc, const char *special_flags)
{
    if (cpp_get_options (parse_in)->debug)
      linemap_dump_location (line_table, src_loc,
			     print.outf);
    return print_line_1 (src_loc, special_flags, print.outf);
}

/* Helper function for cb_line_change and scan_translation_unit.
   Return TRUE if a line marker is emitted, FALSE otherwise.  */
static bool
do_line_change (cpp_reader *pfile, const cpp_token *token,
		location_t src_loc, int parsing_args)
{
  bool emitted_line_marker = false;
  if (define_queue || undef_queue)
    dump_queued_macros (pfile);

  if (token->type == CPP_EOF || parsing_args)
    return false;

  emitted_line_marker = maybe_print_line (src_loc);
  print.prev = 0;
  print.source = 0;

  /* Supply enough spaces to put this token in its original column,
     one space per column greater than 2, since scan_translation_unit
     will provide a space if PREV_WHITE.  Don't bother trying to
     reconstruct tabs; we can't get it right in general, and nothing
     ought to care.  Some things do care; the fault lies with them.  */
  if (!CPP_OPTION (pfile, traditional))
    {
      int spaces = LOCATION_COLUMN (src_loc) - 2;
      print.printed = true;

      while (-- spaces >= 0)
	putc (' ', print.outf);
    }

  return emitted_line_marker;
}

/* Called when a line of output is started.  TOKEN is the first token
   of the line, and at end of file will be CPP_EOF.  */
static void
cb_line_change (cpp_reader *pfile, const cpp_token *token,
		int parsing_args)
{
  do_line_change (pfile, token, token->src_loc, parsing_args);
}

static void
cb_ident (cpp_reader *pfile ATTRIBUTE_UNUSED, location_t line,
	  const cpp_string *str)
{
  maybe_print_line (line);
  fprintf (print.outf, "#ident %s\n", str->text);
  print.src_line++;
}

static void
cb_define (cpp_reader *pfile, location_t line, cpp_hashnode *node)
{
  const line_map_ordinary *map;

  maybe_print_line (line);
  fputs ("#define ", print.outf);

  /* 'D' is whole definition; 'N' is name only.  */
  if (flag_dump_macros == 'D')
    fputs ((const char *) cpp_macro_definition (pfile, node),
	   print.outf);
  else
    fputs ((const char *) NODE_NAME (node), print.outf);

  putc ('\n', print.outf);
  print.printed = false;
  linemap_resolve_location (line_table, line,
			    LRK_MACRO_DEFINITION_LOCATION,
			    &map);
  print.src_line++;
}

static void
cb_undef (cpp_reader *pfile, location_t line, cpp_hashnode *node)
{
  if (lang_hooks.preprocess_undef)
    lang_hooks.preprocess_undef (pfile, line, node);
  maybe_print_line (line);
  fprintf (print.outf, "#undef %s\n", NODE_NAME (node));
  print.src_line++;
}

static void
cb_used_define (cpp_reader *pfile, location_t line ATTRIBUTE_UNUSED,
		cpp_hashnode *node)
{
  if (cpp_user_macro_p (node))
    {
      macro_queue *q;
      q = XNEW (macro_queue);
      q->macro = xstrdup ((const char *) cpp_macro_definition (pfile, node));
      q->next = define_queue;
      define_queue = q;
    }
}

static void
cb_used_undef (cpp_reader *pfile ATTRIBUTE_UNUSED,
	       location_t line ATTRIBUTE_UNUSED,
	       cpp_hashnode *node)
{
  macro_queue *q;
  q = XNEW (macro_queue);
  q->macro = xstrdup ((const char *) NODE_NAME (node));
  q->next = undef_queue;
  undef_queue = q;
}

static void
dump_queued_macros (cpp_reader *pfile ATTRIBUTE_UNUSED)
{
  macro_queue *q;

  /* End the previous line of text.  */
  if (print.printed)
    {
      putc ('\n', print.outf);
      print.src_line++;
      print.printed = false;
    }

  for (q = define_queue; q;)
    {
      macro_queue *oq;
      fputs ("#define ", print.outf);
      fputs (q->macro, print.outf);
      putc ('\n', print.outf);
      print.printed = false;
      print.src_line++;
      oq = q;
      q = q->next;
      free (oq->macro);
      free (oq);
    }
  define_queue = NULL;
  for (q = undef_queue; q;)
    {
      macro_queue *oq;
      fprintf (print.outf, "#undef %s\n", q->macro);
      print.src_line++;
      oq = q;
      q = q->next;
      free (oq->macro);
      free (oq);
    }
  undef_queue = NULL;
}

static void
cb_include (cpp_reader *pfile ATTRIBUTE_UNUSED, location_t line,
	    const unsigned char *dir, const char *header, int angle_brackets,
	    const cpp_token **comments)
{
  maybe_print_line (line);
  if (angle_brackets)
    fprintf (print.outf, "#%s <%s>", dir, header);
  else
    fprintf (print.outf, "#%s \"%s\"", dir, header);

  if (comments != NULL)
    {
      while (*comments != NULL)
	{
	  if ((*comments)->flags & PREV_WHITE)
	    putc (' ', print.outf);
	  cpp_output_token (*comments, print.outf);
	  ++comments;
	}
    }

  putc ('\n', print.outf);
  print.printed = false;
  print.src_line++;
}

/* Callback called when -fworking-director and -E to emit working
   directory in cpp output file.  */

void
pp_dir_change (cpp_reader *pfile ATTRIBUTE_UNUSED, const char *dir)
{
  size_t to_file_len = strlen (dir);
  unsigned char *to_file_quoted =
     (unsigned char *) alloca (to_file_len * 4 + 1);
  unsigned char *p;

  /* cpp_quote_string does not nul-terminate, so we have to do it ourselves.  */
  p = cpp_quote_string (to_file_quoted, (const unsigned char *) dir, to_file_len);
  *p = '\0';
  fprintf (print.outf, "# 1 \"%s//\"\n", to_file_quoted);
}

/* The file name, line number or system header flags have changed, as
   described in MAP.  */

void
pp_file_change (const line_map_ordinary *map)
{
  const char *flags = "";

  if (flag_no_line_commands)
    return;

  if (map != NULL)
    {
      input_location = map->start_location;
      if (print.first_time)
	{
	  /* Avoid printing foo.i when the main file is foo.c.  */
	  if (!cpp_get_options (parse_in)->preprocessed)
	    print_line (map->start_location, flags);
	  print.first_time = 0;
	}
      else
	{
	  /* Bring current file to correct line when entering a new file.  */
	  if (map->reason == LC_ENTER)
	    {
	      maybe_print_line (linemap_included_from (map));
	      flags = " 1";
	    }
	  else if (map->reason == LC_LEAVE)
	    flags = " 2";
	  print_line (map->start_location, flags);
	}
    }
}

/* Copy a #pragma directive to the preprocessed output.  */
static void
cb_def_pragma (cpp_reader *pfile, location_t line)
{
  maybe_print_line (line);
  fputs ("#pragma ", print.outf);
  cpp_output_line (pfile, print.outf);
  print.printed = false;
  print.src_line++;
}

/* Dump out the hash table.  */
static int
dump_macro (cpp_reader *pfile, cpp_hashnode *node, void *v ATTRIBUTE_UNUSED)
{
  if (cpp_user_macro_p (node))
    {
      fputs ("#define ", print.outf);
      fputs ((const char *) cpp_macro_definition (pfile, node),
	     print.outf);
      putc ('\n', print.outf);
      print.printed = false;
      print.src_line++;
    }

  return 1;
}

/* Load in the PCH file NAME, open on FD.  It was originally searched for
   by ORIG_NAME.  Also, print out a #include command so that the PCH
   file can be loaded when the preprocessed output is compiled.  */

static void
cb_read_pch (cpp_reader *pfile, const char *name,
	     int fd, const char *orig_name ATTRIBUTE_UNUSED)
{
  c_common_read_pch (pfile, name, fd, orig_name);

  fprintf (print.outf, "#pragma GCC pch_preprocess \"%s\"\n", name);
  print.src_line++;
}