input-file.c revision 60484 
1/* input_file.c - Deal with Input Files -
2   Copyright (C) 1987, 90, 91, 92, 93, 94, 95, 98, 1999
3   Free Software Foundation, Inc.
4
5   This file is part of GAS, the GNU Assembler.
6
7   GAS is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 2, or (at your option)
10   any later version.
11
12   GAS is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with GAS; see the file COPYING.  If not, write to the Free
19   Software Foundation, 59 Temple Place - Suite 330, Boston, MA
20   02111-1307, USA.  */
21
22/*
23 * Confines all details of reading source bytes to this module.
24 * All O/S specific crocks should live here.
25 * What we lose in "efficiency" we gain in modularity.
26 * Note we don't need to #include the "as.h" file. No common coupling!
27 */
28
29#include <stdio.h>
30#include <string.h>
31
32#include "as.h"
33#include "input-file.h"
34
35static int input_file_get PARAMS ((char *, int));
36
37/* This variable is non-zero if the file currently being read should be
38   preprocessed by app.  It is zero if the file can be read straight in.
39   */
40int preprocess = 0;
41
42/*
43 * This code opens a file, then delivers BUFFER_SIZE character
44 * chunks of the file on demand.
45 * BUFFER_SIZE is supposed to be a number chosen for speed.
46 * The caller only asks once what BUFFER_SIZE is, and asks before
47 * the nature of the input files (if any) is known.
48 */
49
50#define BUFFER_SIZE (32 * 1024)
51
52/*
53 * We use static data: the data area is not sharable.
54 */
55
56static FILE *f_in;
57static char *file_name;
58
59/* Struct for saving the state of this module for file includes.  */
60struct saved_file
61  {
62    FILE *f_in;
63    char *file_name;
64    int preprocess;
65    char *app_save;
66  };
67
68/* These hooks accomodate most operating systems. */
69
70void
71input_file_begin ()
72{
73  f_in = (FILE *) 0;
74}
75
76void
77input_file_end ()
78{
79}
80
81/* Return BUFFER_SIZE. */
82unsigned int
83input_file_buffer_size ()
84{
85  return (BUFFER_SIZE);
86}
87
88int
89input_file_is_open ()
90{
91  return f_in != (FILE *) 0;
92}
93
94/* Push the state of our input, returning a pointer to saved info that
95   can be restored with input_file_pop ().  */
96char *
97input_file_push ()
98{
99  register struct saved_file *saved;
100
101  saved = (struct saved_file *) xmalloc (sizeof *saved);
102
103  saved->f_in = f_in;
104  saved->file_name = file_name;
105  saved->preprocess = preprocess;
106  if (preprocess)
107    saved->app_save = app_push ();
108
109  input_file_begin ();		/* Initialize for new file */
110
111  return (char *) saved;
112}
113
114void
115input_file_pop (arg)
116     char *arg;
117{
118  register struct saved_file *saved = (struct saved_file *) arg;
119
120  input_file_end ();		/* Close out old file */
121
122  f_in = saved->f_in;
123  file_name = saved->file_name;
124  preprocess = saved->preprocess;
125  if (preprocess)
126    app_pop (saved->app_save);
127
128  free (arg);
129}
130
131void
132input_file_open (filename, pre)
133     char *filename;		/* "" means use stdin. Must not be 0. */
134     int pre;
135{
136  int c;
137  char buf[80];
138
139  preprocess = pre;
140
141  assert (filename != 0);	/* Filename may not be NULL. */
142  if (filename[0])
143    {				/* We have a file name. Suck it and see. */
144      f_in = fopen (filename, "r");
145      file_name = filename;
146    }
147  else
148    {				/* use stdin for the input file. */
149      f_in = stdin;
150      file_name = _("{standard input}");	/* For error messages. */
151    }
152  if (f_in == (FILE *) 0)
153    {
154      as_bad (_("Can't open %s for reading."), file_name);
155      as_perror ("%s", file_name);
156      return;
157    }
158
159  c = getc (f_in);
160  if (c == '#')
161    {				/* Begins with comment, may not want to preprocess */
162      c = getc (f_in);
163      if (c == 'N')
164	{
165	  fgets (buf, 80, f_in);
166	  if (!strcmp (buf, "O_APP\n"))
167	    preprocess = 0;
168	  if (!strchr (buf, '\n'))
169	    ungetc ('#', f_in);	/* It was longer */
170	  else
171	    ungetc ('\n', f_in);
172	}
173      else if (c == '\n')
174	ungetc ('\n', f_in);
175      else
176	ungetc ('#', f_in);
177    }
178  else
179    ungetc (c, f_in);
180}
181
182/* Close input file.  */
183void
184input_file_close ()
185{
186  if (f_in != NULL)
187    {
188      fclose (f_in);
189    }				/* don't close a null file pointer */
190  f_in = 0;
191}				/* input_file_close() */
192
193/* This function is passed to do_scrub_chars.  */
194
195static int
196input_file_get (buf, buflen)
197     char *buf;
198     int buflen;
199{
200  int size;
201
202  size = fread (buf, sizeof (char), buflen, f_in);
203  if (size < 0)
204    {
205      as_perror (_("Can't read from %s"), file_name);
206      size = 0;
207    }
208  return size;
209}
210
211/* Read a buffer from the input file.  */
212
213char *
214input_file_give_next_buffer (where)
215     char *where;		/* Where to place 1st character of new buffer. */
216{
217  char *return_value;		/* -> Last char of what we read, + 1. */
218  register int size;
219
220  if (f_in == (FILE *) 0)
221    return 0;
222  /*
223   * fflush (stdin); could be done here if you want to synchronise
224   * stdin and stdout, for the case where our input file is stdin.
225   * Since the assembler shouldn't do any output to stdout, we
226   * don't bother to synch output and input.
227   */
228  if (preprocess)
229    size = do_scrub_chars (input_file_get, where, BUFFER_SIZE);
230  else
231    size = fread (where, sizeof (char), BUFFER_SIZE, f_in);
232  if (size < 0)
233    {
234      as_perror (_("Can't read from %s"), file_name);
235      size = 0;
236    }
237  if (size)
238    return_value = where + size;
239  else
240    {
241      if (fclose (f_in))
242	as_perror (_("Can't close %s"), file_name);
243      f_in = (FILE *) 0;
244      return_value = 0;
245    }
246  return (return_value);
247}
248
249/* end of input-file.c */
250