input-file.c revision 33965 
1/* input_file.c - Deal with Input Files -
2   Copyright (C) 1987, 1990, 1991, 1992 Free Software Foundation, Inc.
3
4   This file is part of GAS, the GNU Assembler.
5
6   GAS is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 2, or (at your option)
9   any later version.
10
11   GAS is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   You should have received a copy of the GNU General Public License
17   along with GAS; see the file COPYING.  If not, write to
18   the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
19
20/*
21 * Confines all details of reading source bytes to this module.
22 * All O/S specific crocks should live here.
23 * What we lose in "efficiency" we gain in modularity.
24 * Note we don't need to #include the "as.h" file. No common coupling!
25 */
26
27#include <stdio.h>
28#include <string.h>
29
30#include "as.h"
31#include "input-file.h"
32
33static int input_file_get PARAMS ((char **));
34
35/* This variable is non-zero if the file currently being read should be
36   preprocessed by app.  It is zero if the file can be read straight in.
37   */
38int preprocess = 0;
39
40/*
41 * This code opens a file, then delivers BUFFER_SIZE character
42 * chunks of the file on demand.
43 * BUFFER_SIZE is supposed to be a number chosen for speed.
44 * The caller only asks once what BUFFER_SIZE is, and asks before
45 * the nature of the input files (if any) is known.
46 */
47
48#define BUFFER_SIZE (32 * 1024)
49
50/*
51 * We use static data: the data area is not sharable.
52 */
53
54static FILE *f_in;
55static char *file_name;
56
57/* Struct for saving the state of this module for file includes.  */
58struct saved_file
59  {
60    FILE *f_in;
61    char *file_name;
62    int preprocess;
63    char *app_save;
64  };
65
66/* These hooks accomodate most operating systems. */
67
68void
69input_file_begin ()
70{
71  f_in = (FILE *) 0;
72}
73
74void
75input_file_end ()
76{
77}
78
79/* Return BUFFER_SIZE. */
80unsigned int
81input_file_buffer_size ()
82{
83  return (BUFFER_SIZE);
84}
85
86int
87input_file_is_open ()
88{
89  return f_in != (FILE *) 0;
90}
91
92/* Push the state of our input, returning a pointer to saved info that
93   can be restored with input_file_pop ().  */
94char *
95input_file_push ()
96{
97  register struct saved_file *saved;
98
99  saved = (struct saved_file *) xmalloc (sizeof *saved);
100
101  saved->f_in = f_in;
102  saved->file_name = file_name;
103  saved->preprocess = preprocess;
104  if (preprocess)
105    saved->app_save = app_push ();
106
107  input_file_begin ();		/* Initialize for new file */
108
109  return (char *) saved;
110}
111
112void
113input_file_pop (arg)
114     char *arg;
115{
116  register struct saved_file *saved = (struct saved_file *) arg;
117
118  input_file_end ();		/* Close out old file */
119
120  f_in = saved->f_in;
121  file_name = saved->file_name;
122  preprocess = saved->preprocess;
123  if (preprocess)
124    app_pop (saved->app_save);
125
126  free (arg);
127}
128
129void
130input_file_open (filename, pre)
131     char *filename;		/* "" means use stdin. Must not be 0. */
132     int pre;
133{
134  int c;
135  char buf[80];
136
137  preprocess = pre;
138
139  assert (filename != 0);	/* Filename may not be NULL. */
140  if (filename[0])
141    {				/* We have a file name. Suck it and see. */
142      f_in = fopen (filename, "r");
143      file_name = filename;
144    }
145  else
146    {				/* use stdin for the input file. */
147      f_in = stdin;
148      file_name = "{standard input}";	/* For error messages. */
149    }
150  if (f_in == (FILE *) 0)
151    {
152      as_bad ("Can't open %s for reading.", file_name);
153      as_perror ("%s", file_name);
154      return;
155    }
156
157  c = getc (f_in);
158  if (c == '#')
159    {				/* Begins with comment, may not want to preprocess */
160      c = getc (f_in);
161      if (c == 'N')
162	{
163	  fgets (buf, 80, f_in);
164	  if (!strcmp (buf, "O_APP\n"))
165	    preprocess = 0;
166	  if (!strchr (buf, '\n'))
167	    ungetc ('#', f_in);	/* It was longer */
168	  else
169	    ungetc ('\n', f_in);
170	}
171      else if (c == '\n')
172	ungetc ('\n', f_in);
173      else
174	ungetc ('#', f_in);
175    }
176  else
177    ungetc (c, f_in);
178}
179
180/* Close input file.  */
181void
182input_file_close ()
183{
184  if (f_in != NULL)
185    {
186      fclose (f_in);
187    }				/* don't close a null file pointer */
188  f_in = 0;
189}				/* input_file_close() */
190
191/* This function is passed to do_scrub_chars.  */
192
193static int
194input_file_get (from)
195     char **from;
196{
197  static char buf[BUFFER_SIZE];
198  int size;
199
200  size = fread (buf, sizeof (char), sizeof buf, f_in);
201  if (size < 0)
202    {
203      as_perror ("Can't read from %s", file_name);
204      size = 0;
205    }
206  *from = buf;
207  return size;
208}
209
210/* Read a buffer from the input file.  */
211
212char *
213input_file_give_next_buffer (where)
214     char *where;		/* Where to place 1st character of new buffer. */
215{
216  char *return_value;		/* -> Last char of what we read, + 1. */
217  register int size;
218
219  if (f_in == (FILE *) 0)
220    return 0;
221  /*
222   * fflush (stdin); could be done here if you want to synchronise
223   * stdin and stdout, for the case where our input file is stdin.
224   * Since the assembler shouldn't do any output to stdout, we
225   * don't bother to synch output and input.
226   */
227  if (preprocess)
228    size = do_scrub_chars (input_file_get, where, BUFFER_SIZE);
229  else
230    size = fread (where, sizeof (char), BUFFER_SIZE, f_in);
231  if (size < 0)
232    {
233      as_perror ("Can't read from %s", file_name);
234      size = 0;
235    }
236  if (size)
237    return_value = where + size;
238  else
239    {
240      if (fclose (f_in))
241	as_perror ("Can't close %s", file_name);
242      f_in = (FILE *) 0;
243      return_value = 0;
244    }
245  return (return_value);
246}
247
248/* end of input-file.c */
249