/* input_scrub.c - Break up input buffers into whole numbers of lines.
   Copyright (C) 1987-2022 Free Software Foundation, Inc.

   This file is part of GAS, the GNU Assembler.

   GAS 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.

   GAS 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 GAS; see the file COPYING.  If not, write to the Free
   Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
   02110-1301, USA.  */

#include "as.h"
#include "filenames.h"
#include "input-file.h"
#include "sb.h"
#include "listing.h"

/*
 * O/S independent module to supply buffers of sanitised source code
 * to rest of assembler.  We get sanitised input data of arbitrary length.
 * We break these buffers on line boundaries, recombine pieces that
 * were broken across buffers, and return a buffer of full lines to
 * the caller.
 * The last partial line begins the next buffer we build and return to caller.
 * The buffer returned to caller is preceded by BEFORE_STRING and followed
 * by AFTER_STRING, as sentinels. The last character before AFTER_STRING
 * is a newline.
 * Also looks after line numbers, for e.g. error messages.
 */

/*
 * We don't care how filthy our buffers are, but our callers assume
 * that the following sanitation has already been done.
 *
 * No comments, reduce a comment to a space.
 * Reduce a tab to a space unless it is 1st char of line.
 * All multiple tabs and spaces collapsed into 1 char. Tab only
 *   legal if 1st char of line.
 * # line file statements converted to .line x;.file y; statements.
 * Escaped newlines at end of line: remove them but add as many newlines
 *   to end of statement as you removed in the middle, to synch line numbers.
 */

#define BEFORE_STRING ("\n")
#define AFTER_STRING ("\0")	/* memcpy of 0 chars might choke.  */
#define BEFORE_SIZE (1)
#define AFTER_SIZE  (1)

#ifndef TC_EOL_IN_INSN
#define TC_EOL_IN_INSN(P) 0
#endif

static char *buffer_start;	/*->1st char of full buffer area.  */
static char *partial_where;	/*->after last full line in buffer.  */
static size_t partial_size;	/* >=0. Number of chars in partial line in buffer.  */

/* Because we need AFTER_STRING just after last full line, it clobbers
   1st part of partial line. So we preserve 1st part of partial line
   here.  */
static char save_source[AFTER_SIZE];

/* The size of the input buffer we concatenate
   input_file_give_next_buffer chunks into.  Excludes the BEFORE and
   AFTER counts.  */
static size_t buffer_length;

/* The index into an sb structure we are reading from.  -1 if none.  */
static size_t sb_index = -1;

/* If we are reading from an sb structure, this is it.  */
static sb from_sb;

/* Should we do a conditional check on from_sb? */
static enum expansion from_sb_expansion = expanding_none;

/* The number of nested sb structures we have included.  */
int macro_nest;

/* We can have more than one source file open at once, though the info for all
   but the latest one are saved off in a struct input_save.  These files remain
   open, so we are limited by the number of open files allowed by the
   underlying OS. We may also sequentially read more than one source file in an
   assembly.  */

/* We must track the physical file and line number for error messages. We also
   track a "logical" file and line number corresponding to (C?)  compiler
   source line numbers.  Whenever we open a file we must fill in
   physical_input_file. So if it is NULL we have not opened any files yet.  */

static const char *physical_input_file;
static const char *logical_input_file;

/* 1-origin line number in a source file.  */
/* A line ends in '\n' or eof.  */
static unsigned int physical_input_line;
static unsigned int logical_input_line;

/* Struct used to save the state of the input handler during include files */
struct input_save {
  char *              buffer_start;
  char *              partial_where;
  size_t              partial_size;
  char                save_source[AFTER_SIZE];
  size_t              buffer_length;
  const char *        physical_input_file;
  const char *        logical_input_file;
  unsigned int        physical_input_line;
  unsigned int        logical_input_line;
  size_t              sb_index;
  sb                  from_sb;
  enum expansion      from_sb_expansion; /* Should we do a conditional check?  */
  struct input_save * next_saved_file;	/* Chain of input_saves.  */
  char *              input_file_save;	/* Saved state of input routines.  */
  char *              saved_position;	/* Caller's saved position in buf.  */
};

static struct input_save *input_scrub_push (char *saved_position);
static char *input_scrub_pop (struct input_save *arg);

/* Saved information about the file that .include'd this one.  When we hit EOF,
   we automatically pop to that file.  */

static struct input_save *next_saved_file;

/* Initialize input buffering.  */

static void
input_scrub_reinit (void)
{
  input_file_begin ();		/* Reinitialize! */
  logical_input_line = -1u;
  logical_input_file = NULL;

  buffer_length = input_file_buffer_size () * 2;
  buffer_start = XNEWVEC (char, BEFORE_SIZE + AFTER_SIZE + 1 + buffer_length);
  memcpy (buffer_start, BEFORE_STRING, (int) BEFORE_SIZE);
}

/* Push the state of input reading and scrubbing so that we can #include.
   The return value is a 'void *' (fudged for old compilers) to a save
   area, which can be restored by passing it to input_scrub_pop().  */

static struct input_save *
input_scrub_push (char *saved_position)
{
  struct input_save *saved;

  saved = XNEW (struct input_save);

  saved->saved_position = saved_position;
  saved->buffer_start = buffer_start;
  saved->partial_where = partial_where;
  saved->partial_size = partial_size;
  saved->buffer_length = buffer_length;
  saved->physical_input_file = physical_input_file;
  saved->logical_input_file = logical_input_file;
  saved->physical_input_line = physical_input_line;
  saved->logical_input_line = logical_input_line;
  saved->sb_index = sb_index;
  saved->from_sb = from_sb;
  saved->from_sb_expansion = from_sb_expansion;
  memcpy (saved->save_source, save_source, sizeof (save_source));
  saved->next_saved_file = next_saved_file;
  saved->input_file_save = input_file_push ();

  sb_index = -1;

  input_scrub_reinit ();

  return saved;
}

static char *
input_scrub_pop (struct input_save *saved)
{
  char *saved_position;

  input_scrub_end ();		/* Finish off old buffer */

  input_file_pop (saved->input_file_save);
  saved_position = saved->saved_position;
  buffer_start = saved->buffer_start;
  buffer_length = saved->buffer_length;
  physical_input_file = saved->physical_input_file;
  logical_input_file = saved->logical_input_file;
  physical_input_line = saved->physical_input_line;
  logical_input_line = saved->logical_input_line;
  sb_index = saved->sb_index;
  from_sb = saved->from_sb;
  from_sb_expansion = saved->from_sb_expansion;
  partial_where = saved->partial_where;
  partial_size = saved->partial_size;
  next_saved_file = saved->next_saved_file;
  memcpy (save_source, saved->save_source, sizeof (save_source));

  free (saved);
  return saved_position;
}

void
input_scrub_begin (void)
{
  know (strlen (BEFORE_STRING) == BEFORE_SIZE);
  know (strlen (AFTER_STRING) == AFTER_SIZE
	|| (AFTER_STRING[0] == '\0' && AFTER_SIZE == 1));

  physical_input_file = NULL;	/* No file read yet.  */
  next_saved_file = NULL;	/* At EOF, don't pop to any other file */
  input_scrub_reinit ();
  do_scrub_begin (flag_m68k_mri);
}

void
input_scrub_end (void)
{
  if (buffer_start)
    {
      free (buffer_start);
      buffer_start = 0;
      input_file_end ();
    }
}

/* Start reading input from a new file.
   Return start of caller's part of buffer.  */

char *
input_scrub_new_file (const char *filename)
{
  input_file_open (filename, !flag_no_comments);
  physical_input_file = filename[0] ? filename : _("{standard input}");
  physical_input_line = 0;

  partial_size = 0;
  return (buffer_start + BEFORE_SIZE);
}

/* Include a file from the current file.  Save our state, cause it to
   be restored on EOF, and begin handling a new file.  Same result as
   input_scrub_new_file.  */

char *
input_scrub_include_file (const char *filename, char *position)
{
  next_saved_file = input_scrub_push (position);
  from_sb_expansion = expanding_none;
  return input_scrub_new_file (filename);
}

/* Start getting input from an sb structure.  This is used when
   expanding a macro.  */

void
input_scrub_include_sb (sb *from, char *position, enum expansion expansion)
{
  int newline;

  if (macro_nest > max_macro_nest)
    as_fatal (_("macros nested too deeply"));
  ++macro_nest;

  gas_assert (expansion < expanding_nested);

#ifdef md_macro_start
  if (expansion == expanding_macro)
    {
      md_macro_start ();
    }
#endif

  next_saved_file = input_scrub_push (position);

  /* Allocate sufficient space: from->len + optional newline.  */
  newline = from->len >= 1 && from->ptr[0] != '\n';
  sb_build (&from_sb, from->len + newline);
  if (expansion == expanding_repeat && from_sb_expansion >= expanding_macro)
    expansion = expanding_nested;
  from_sb_expansion = expansion;
  if (newline)
    {
      /* Add the sentinel required by read.c.  */
      sb_add_char (&from_sb, '\n');
    }
  sb_scrub_and_add_sb (&from_sb, from);

  /* Make sure the parser looks at defined contents when it scans for
     e.g. end-of-line at the end of a macro.  */
  sb_terminate (&from_sb);

  sb_index = 1;

  /* These variables are reset by input_scrub_push.  Restore them
     since we are, after all, still at the same point in the file.  */
  logical_input_line = next_saved_file->logical_input_line;
  logical_input_file = next_saved_file->logical_input_file;
}

void
input_scrub_close (void)
{
  input_file_close ();
  physical_input_line = 0;
  logical_input_line = -1u;
}

char *
input_scrub_next_buffer (char **bufp)
{
  char *limit;		/*->just after last char of buffer.  */

  if (sb_index != (size_t) -1)
    {
      if (sb_index >= from_sb.len)
	{
	  sb_kill (&from_sb);
	  if (from_sb_expansion == expanding_macro)
	    {
	      cond_finish_check (macro_nest);
#ifdef md_macro_end
	      /* Allow the target to clean up per-macro expansion
	         data.  */
	      md_macro_end ();
#endif
	    }
	  --macro_nest;
	  partial_where = NULL;
	  partial_size = 0;
	  if (next_saved_file != NULL)
	    *bufp = input_scrub_pop (next_saved_file);
	  return partial_where;
	}

      partial_where = from_sb.ptr + from_sb.len;
      partial_size = 0;
      *bufp = from_sb.ptr + sb_index;
      sb_index = from_sb.len;
      return partial_where;
    }

  if (partial_size)
    {
      memmove (buffer_start + BEFORE_SIZE, partial_where, partial_size);
      memcpy (buffer_start + BEFORE_SIZE, save_source, AFTER_SIZE);
    }

  while (1)
    {
      char *p;
      char *start = buffer_start + BEFORE_SIZE + partial_size;

      *bufp = buffer_start + BEFORE_SIZE;
      limit = input_file_give_next_buffer (start);
      if (!limit)
	{
	  if (!partial_size)
	    /* End of this file.  */
	    break;

	  as_warn (_("end of file not at end of a line; newline inserted"));
	  p = buffer_start + BEFORE_SIZE + partial_size;
	  *p++ = '\n';
	  limit = p;
	}
      else
	{
	  /* Terminate the buffer to avoid confusing TC_EOL_IN_INSN.  */
	  *limit = '\0';

	  /* Find last newline.  */
	  for (p = limit - 1; *p != '\n' || TC_EOL_IN_INSN (p); --p)
	    if (p < start)
	      goto read_more;
	  ++p;
	}

      if (multibyte_handling == multibyte_warn)
	(void) scan_for_multibyte_characters ((const unsigned char *) p,
					      (const unsigned char *) limit,
					      true /* Generate warnings */);

      /* We found a newline in the newly read chars.  */
      partial_where = p;
      partial_size = limit - p;

      /* Save the fragment after that last newline.  */
      memcpy (save_source, partial_where, (int) AFTER_SIZE);
      memcpy (partial_where, AFTER_STRING, (int) AFTER_SIZE);
      return partial_where;

    read_more:
      /* Didn't find a newline.  Read more text.  */
      partial_size = limit - (buffer_start + BEFORE_SIZE);
      if (buffer_length - input_file_buffer_size () < partial_size)
	{
	  /* Increase the buffer when it doesn't have room for the
	     next block of input.  */
	  buffer_length *= 2;
	  buffer_start = XRESIZEVEC (char, buffer_start,
				     (buffer_length
				      + BEFORE_SIZE + AFTER_SIZE + 1));
	}
    }

  /* Tell the listing we've finished the file.  */
  LISTING_EOF ();

  /* If we should pop to another file at EOF, do it.  */
  partial_where = NULL;
  if (next_saved_file)
    *bufp = input_scrub_pop (next_saved_file);

  return partial_where;
}

/* The remaining part of this file deals with line numbers, error
   messages and so on.  Return TRUE if we opened any file.  */

int
seen_at_least_1_file (void)
{
  return (physical_input_file != NULL);
}

void
bump_line_counters (void)
{
  if (sb_index == (size_t) -1)
    ++physical_input_line;

  /* PR gas/16908 workaround: Don't bump logical line numbers while
     expanding macros, unless file (and maybe line; see as_where()) are
     used inside the macro.  */
  if (logical_input_line != -1u && from_sb_expansion < expanding_macro)
    ++logical_input_line;
}

/* Tells us what the new logical line number and file are.
   If the line_number is -1, we don't change the current logical line
   number.
   If fname is NULL, we don't change the current logical file name, unless
   bit 3 of flags is set.
   Returns nonzero if the filename actually changes.  */

void
new_logical_line_flags (const char *fname, /* DON'T destroy it!  We point to it!  */
			int line_number,
			int flags)
{
  switch (flags)
    {
    case 0:
      break;
    case 1:
      if (line_number != -1)
	abort ();
      break;
    case 1 << 1:
    case 1 << 2:
      /* FIXME: we could check that include nesting is correct.  */
      break;
    case 1 << 3:
      if (line_number < 0 || fname != NULL || next_saved_file == NULL)
	abort ();
      /* PR gas/16908 workaround: Ignore updates when nested inside a macro
	 expansion.  */
      if (from_sb_expansion == expanding_nested)
	return;
      if (next_saved_file->logical_input_file)
	fname = next_saved_file->logical_input_file;
      else
	fname = next_saved_file->physical_input_file;
      break;
    default:
      abort ();
    }

  if (line_number >= 0)
    logical_input_line = line_number;
  else if (line_number == -1 && fname && !*fname && (flags & (1 << 2)))
    {
      logical_input_file = physical_input_file;
      logical_input_line = physical_input_line;
      fname = NULL;
    }

  if (fname
      && (logical_input_file == NULL
	  || filename_cmp (logical_input_file, fname)))
    logical_input_file = fname;

  /* When encountering file or line changes inside a macro, arrange for
     bump_line_counters() to henceforth increment the logical line number
     again, just like it does when expanding repeats.  See as_where() for
     why changing file or line alone doesn't alter expansion mode.  */
  if (from_sb_expansion == expanding_macro
      && logical_input_file != NULL
      && logical_input_line != -1u)
    from_sb_expansion = expanding_repeat;
}

void
new_logical_line (const char *fname, int line_number)
{
  new_logical_line_flags (fname, line_number, 0);
}


/* Return the current physical input file name and line number, if known  */

const char *
as_where_physical (unsigned int *linep)
{
  if (physical_input_file != NULL)
    {
      if (linep != NULL)
	*linep = physical_input_line;
      return physical_input_file;
    }

  if (linep != NULL)
    *linep = 0;
  return NULL;
}

/* Return the current file name and line number.  */

const char *
as_where (unsigned int *linep)
{
  if (logical_input_file != NULL
      && (linep == NULL || logical_input_line != -1u))
    {
      if (linep != NULL)
	*linep = logical_input_line;
      return logical_input_file;
    }

  return as_where_physical (linep);
}

