/* input_file.c - Deal with Input Files -

   Copyright (C) 1987-2025 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.  */

/* Confines all details of reading source bytes to this module.

   All O/S specific crocks should live here.

   What we lose in "efficiency" we gain in modularity.

   Note we don't need to #include the "as.h" file. No common coupling!  */

#include "as.h"

#include "input-file.h"

#include "safe-ctype.h"

/* This variable is non-zero if the file currently being read should be

   preprocessed by app.  It is zero if the file can be read straight in.  */

int preprocess = 0;

/* This code opens a file, then delivers BUFFER_SIZE character

   chunks of the file on demand.

   BUFFER_SIZE is supposed to be a number chosen for speed.

   The caller only asks once what BUFFER_SIZE is, and asks before

   the nature of the input files (if any) is known.  */

#define BUFFER_SIZE (32 * 1024)

/* We use static data: the data area is not sharable.  */

static FILE *f_in;

static const char *file_name;

/* Struct for saving the state of this module for file includes.  */

struct saved_file

  {

    FILE * f_in;

    const char * file_name;

    int    preprocess;

    char * app_save;

  };

/* These hooks accommodate most operating systems.  */

void

input_file_begin (void)

{

  f_in = (FILE *) 0;

}

void

input_file_end (void)

{

}

/* Return BUFFER_SIZE.  */

size_t

input_file_buffer_size (void)

{

  return (BUFFER_SIZE);

}

/* Push the state of our input, returning a pointer to saved info that

   can be restored with input_file_pop ().  */

char *

input_file_push (void)

{

  struct saved_file *saved;

  saved = XNEW (struct saved_file);

  saved->f_in = f_in;

  saved->file_name = file_name;

  saved->preprocess = preprocess;

  if (preprocess)

    saved->app_save = app_push ();

  /* Initialize for new file.  */

  input_file_begin ();

  return (char *) saved;

}

void

input_file_pop (char *arg)

{

  struct saved_file *saved = (struct saved_file *) arg;

  input_file_end ();    /* Close out old file.  */

  f_in = saved->f_in;

  file_name = saved->file_name;

  preprocess = saved->preprocess;

  if (preprocess)

    app_pop (saved->app_save);

  free (arg);

}

/* Open the specified file, "" means stdin.  Filename must not be null.  */

void

input_file_open (const char *filename,

     int pre)

{

  int c;

  char buf[80];

  preprocess = pre;

  gas_assert (filename != 0); /* Filename may not be NULL.  */

  if (filename[0])

    {

      f_in = fopen (filename, FOPEN_RT);

      file_name = filename;

    }

  else

    {

      /* Use stdin for the input file.  */

      f_in = stdin;

      /* For error messages.  */

      file_name = _("{standard input}");

    }

  if (f_in == NULL)

    {

      as_bad (_("can't open %s for reading: %s"),

        file_name, xstrerror (errno));

      return;

    }

  c = getc (f_in);

  if (ferror (f_in))

    {

      as_bad (_("can't read from %s: %s"),

        file_name, xstrerror (errno));

      fclose (f_in);

      f_in = NULL;

      return;

    }

  /* Check for an empty input file.  */

  if (feof (f_in))

    {

      fclose (f_in);

      f_in = NULL;

      return;

    }

  gas_assert (c != EOF);

  if (strchr (line_comment_chars, '#')

      ? c == '#'

      : c && strchr (line_comment_chars, c))

    {

      /* Begins with comment, may not want to preprocess.  */

      int lead = c;

      c = getc (f_in);

      if (c == 'N')

  {

    char *p = fgets (buf, sizeof (buf), f_in);

    if (p && startswith (p, "O_APP") && is_end_of_line (p[5]))

      preprocess = 0;

    if (!p || !strchr (p, '\n'))

      ungetc (lead, f_in);

    else

      ungetc ('\n', f_in);

  }

      else if (c == 'A')

  {

    char *p = fgets (buf, sizeof (buf), f_in);

    if (p && startswith (p, "PP") && is_end_of_line (p[2]))

      preprocess = 1;

    if (!p || !strchr (p, '\n'))

      ungetc (lead, f_in);

    else

      ungetc ('\n', f_in);

  }

      else if (c == '\n')

  ungetc ('\n', f_in);

      else

  ungetc (lead, f_in);

    }

  else

    ungetc (c, f_in);

}

/* Close input file.  */

void

input_file_close (void)

{

  /* Don't close a null file pointer.  */

  if (f_in != NULL)

    fclose (f_in);

  f_in = 0;

}

/* This function is passed to do_scrub_chars.  */

static size_t

input_file_get (char *buf, size_t buflen)

{

  size_t size;

  if (feof (f_in))

    return 0;

  size = fread (buf, sizeof (char), buflen, f_in);

  if (ferror (f_in))

    as_bad (_("can't read from %s: %s"), file_name, xstrerror (errno));

  return size;

}

/* Read a buffer from the input file.  */

char *

input_file_give_next_buffer (char *where /* Where to place 1st character of new buffer.  */)

{

  char *return_value;   /* -> Last char of what we read, + 1.  */

  size_t size;

  if (f_in == (FILE *) 0)

    return 0;

  /* fflush (stdin); could be done here if you want to synchronise

     stdin and stdout, for the case where our input file is stdin.

     Since the assembler shouldn't do any output to stdout, we

     don't bother to synch output and input.  */

  if (preprocess)

    size = do_scrub_chars (input_file_get, where, BUFFER_SIZE,

                           multibyte_handling == multibyte_warn);

  else

    {

      size = input_file_get (where, BUFFER_SIZE);

      if (multibyte_handling == multibyte_warn)

  {

    const unsigned char *start = (const unsigned char *) where;

    (void) scan_for_multibyte_characters (start, start + size,

            true /* Generate warnings */);

  }

    }

  if (size)

    return_value = where + size;

  else

    {

      if (fclose (f_in))

  as_warn (_("can't close %s: %s"), file_name, xstrerror (errno));

      f_in = (FILE *) 0;

      return_value = 0;

    }

  return return_value;

}