gas/input-file.c

   1 /* input_file.c - Deal with Input Files -
   2    Copyright (C) 1987-2014 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 3, 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 the Free
  18    Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
  19    02110-1301, USA.  */
  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 #include "as.h"
  27 #include "input-file.h"
  28 #include "safe-ctype.h"
  29
  30 /* This variable is non-zero if the file currently being read should be
  31    preprocessed by app.  It is zero if the file can be read straight in.  */
  32 int preprocess = 0;
  33
  34 /* This code opens a file, then delivers BUFFER_SIZE character
  35    chunks of the file on demand.
  36    BUFFER_SIZE is supposed to be a number chosen for speed.
  37    The caller only asks once what BUFFER_SIZE is, and asks before
  38    the nature of the input files (if any) is known.  */
  39
  40 #define BUFFER_SIZE (32 * 1024)
  41
  42 /* We use static data: the data area is not sharable.  */
  43
  44 static FILE *f_in;
  45 static char *file_name;
  46
  47 /* Struct for saving the state of this module for file includes.  */
  48 struct saved_file
  49   {
  50     FILE * f_in;
  51     char * file_name;
  52     int    preprocess;
  53     char * app_save;
  54   };
  55 \f
  56 /* These hooks accommodate most operating systems.  */
  57
  58 void
  59 input_file_begin (void)
  60 {
  61   f_in = (FILE *) 0;
  62 }
  63
  64 void
  65 input_file_end (void)
  66 {
  67 }
  68
  69 /* Return BUFFER_SIZE.  */
  70 size_t
  71 input_file_buffer_size (void)
  72 {
  73   return (BUFFER_SIZE);
  74 }
  75
  76 /* Push the state of our input, returning a pointer to saved info that
  77    can be restored with input_file_pop ().  */
  78
  79 char *
  80 input_file_push (void)
  81 {
  82   struct saved_file *saved;
  83
  84   saved = (struct saved_file *) xmalloc (sizeof *saved);
  85
  86   saved->f_in = f_in;
  87   saved->file_name = file_name;
  88   saved->preprocess = preprocess;
  89   if (preprocess)
  90     saved->app_save = app_push ();
  91
  92   /* Initialize for new file.  */
  93   input_file_begin ();
  94
  95   return (char *) saved;
  96 }
  97
  98 void
  99 input_file_pop (char *arg)
 100 {
 101   struct saved_file *saved = (struct saved_file *) arg;
 102
 103   input_file_end ();            /* Close out old file.  */
 104
 105   f_in = saved->f_in;
 106   file_name = saved->file_name;
 107   preprocess = saved->preprocess;
 108   if (preprocess)
 109     app_pop (saved->app_save);
 110
 111   free (arg);
 112 }
 113 \f
 114 void
 115 input_file_open (char *filename, /* "" means use stdin. Must not be 0.  */
 116                  int pre)
 117 {
 118   int c;
 119   char buf[80];
 120
 121   preprocess = pre;
 122
 123   gas_assert (filename != 0);   /* Filename may not be NULL.  */
 124   if (filename[0])
 125     {
 126       f_in = fopen (filename, FOPEN_RT);
 127       file_name = filename;
 128     }
 129   else
 130     {
 131       /* Use stdin for the input file.  */
 132       f_in = stdin;
 133       /* For error messages.  */
 134       file_name = _("{standard input}");
 135     }
 136
 137   if (f_in == NULL)
 138     {
 139       as_bad (_("can't open %s for reading: %s"),
 140               file_name, xstrerror (errno));
 141       return;
 142     }
 143
 144   c = getc (f_in);
 145
 146   if (ferror (f_in))
 147     {
 148       as_bad (_("can't read from %s: %s"),
 149               file_name, xstrerror (errno));
 150
 151       fclose (f_in);
 152       f_in = NULL;
 153       return;
 154     }
 155
 156   /* Check for an empty input file.  */
 157   if (feof (f_in))
 158     {
 159       fclose (f_in);
 160       f_in = NULL;
 161       return;
 162     }
 163   gas_assert (c != EOF);
 164
 165   if (c == '#')
 166     {
 167       /* Begins with comment, may not want to preprocess.  */
 168       c = getc (f_in);
 169       if (c == 'N')
 170         {
 171           if (fgets (buf, sizeof (buf), f_in)
 172               && !strncmp (buf, "O_APP", 5) && ISSPACE (buf[5]))
 173             preprocess = 0;
 174           if (!strchr (buf, '\n'))
 175             ungetc ('#', f_in); /* It was longer.  */
 176           else
 177             ungetc ('\n', f_in);
 178         }
 179       else if (c == 'A')
 180         {
 181           if (fgets (buf, sizeof (buf), f_in)
 182               && !strncmp (buf, "PP", 2) && ISSPACE (buf[2]))
 183             preprocess = 1;
 184           if (!strchr (buf, '\n'))
 185             ungetc ('#', f_in);
 186           else
 187             ungetc ('\n', f_in);
 188         }
 189       else if (c == '\n')
 190         ungetc ('\n', f_in);
 191       else
 192         ungetc ('#', f_in);
 193     }
 194   else
 195     ungetc (c, f_in);
 196 }
 197
 198 /* Close input file.  */
 199
 200 void
 201 input_file_close (void)
 202 {
 203   /* Don't close a null file pointer.  */
 204   if (f_in != NULL)
 205     fclose (f_in);
 206
 207   f_in = 0;
 208 }
 209
 210 /* This function is passed to do_scrub_chars.  */
 211
 212 static size_t
 213 input_file_get (char *buf, size_t buflen)
 214 {
 215   size_t size;
 216
 217   if (feof (f_in))
 218     return 0;
 219
 220   size = fread (buf, sizeof (char), buflen, f_in);
 221   if (ferror (f_in))
 222     as_bad (_("can't read from %s: %s"), file_name, xstrerror (errno));
 223   return size;
 224 }
 225
 226 /* Read a buffer from the input file.  */
 227
 228 char *
 229 input_file_give_next_buffer (char *where /* Where to place 1st character of new buffer.  */)
 230 {
 231   char *return_value;           /* -> Last char of what we read, + 1.  */
 232   size_t size;
 233
 234   if (f_in == (FILE *) 0)
 235     return 0;
 236   /* fflush (stdin); could be done here if you want to synchronise
 237      stdin and stdout, for the case where our input file is stdin.
 238      Since the assembler shouldn't do any output to stdout, we
 239      don't bother to synch output and input.  */
 240   if (preprocess)
 241     size = do_scrub_chars (input_file_get, where, BUFFER_SIZE);
 242   else
 243     size = input_file_get (where, BUFFER_SIZE);
 244
 245   if (size)
 246     return_value = where + size;
 247   else
 248     {
 249       if (fclose (f_in))
 250         as_warn (_("can't close %s: %s"), file_name, xstrerror (errno));
 251
 252       f_in = (FILE *) 0;
 253       return_value = 0;
 254     }
 255
 256   return return_value;
 257 }