gas/input-file.c

   1 /* input_file.c - Deal with Input Files -
   2    Copyright (C) 1987-2020 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 const 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     const 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 = XNEW (struct saved_file);
  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 /* Open the specified file, "" means stdin.  Filename must not be null.  */
 115
 116 void
 117 input_file_open (const char *filename,
 118                  int pre)
 119 {
 120   int c;
 121   char buf[80];
 122
 123   preprocess = pre;
 124
 125   gas_assert (filename != 0);   /* Filename may not be NULL.  */
 126   if (filename[0])
 127     {
 128       f_in = fopen (filename, FOPEN_RT);
 129       file_name = filename;
 130     }
 131   else
 132     {
 133       /* Use stdin for the input file.  */
 134       f_in = stdin;
 135       /* For error messages.  */
 136       file_name = _("{standard input}");
 137     }
 138
 139   if (f_in == NULL)
 140     {
 141       as_bad (_("can't open %s for reading: %s"),
 142               file_name, xstrerror (errno));
 143       return;
 144     }
 145
 146   c = getc (f_in);
 147
 148   if (ferror (f_in))
 149     {
 150       as_bad (_("can't read from %s: %s"),
 151               file_name, xstrerror (errno));
 152
 153       fclose (f_in);
 154       f_in = NULL;
 155       return;
 156     }
 157
 158   /* Check for an empty input file.  */
 159   if (feof (f_in))
 160     {
 161       fclose (f_in);
 162       f_in = NULL;
 163       return;
 164     }
 165   gas_assert (c != EOF);
 166
 167   if (c == '#')
 168     {
 169       /* Begins with comment, may not want to preprocess.  */
 170       c = getc (f_in);
 171       if (c == 'N')
 172         {
 173           if (fgets (buf, sizeof (buf), f_in)
 174               && !strncmp (buf, "O_APP", 5) && ISSPACE (buf[5]))
 175             preprocess = 0;
 176           if (!strchr (buf, '\n'))
 177             ungetc ('#', f_in); /* It was longer.  */
 178           else
 179             ungetc ('\n', f_in);
 180         }
 181       else if (c == 'A')
 182         {
 183           if (fgets (buf, sizeof (buf), f_in)
 184               && !strncmp (buf, "PP", 2) && ISSPACE (buf[2]))
 185             preprocess = 1;
 186           if (!strchr (buf, '\n'))
 187             ungetc ('#', f_in);
 188           else
 189             ungetc ('\n', f_in);
 190         }
 191       else if (c == '\n')
 192         ungetc ('\n', f_in);
 193       else
 194         ungetc ('#', f_in);
 195     }
 196   else
 197     ungetc (c, f_in);
 198 }
 199
 200 /* Close input file.  */
 201
 202 void
 203 input_file_close (void)
 204 {
 205   /* Don't close a null file pointer.  */
 206   if (f_in != NULL)
 207     fclose (f_in);
 208
 209   f_in = 0;
 210 }
 211
 212 /* This function is passed to do_scrub_chars.  */
 213
 214 static size_t
 215 input_file_get (char *buf, size_t buflen)
 216 {
 217   size_t size;
 218
 219   if (feof (f_in))
 220     return 0;
 221
 222   size = fread (buf, sizeof (char), buflen, f_in);
 223   if (ferror (f_in))
 224     as_bad (_("can't read from %s: %s"), file_name, xstrerror (errno));
 225   return size;
 226 }
 227
 228 /* Read a buffer from the input file.  */
 229
 230 char *
 231 input_file_give_next_buffer (char *where /* Where to place 1st character of new buffer.  */)
 232 {
 233   char *return_value;           /* -> Last char of what we read, + 1.  */
 234   size_t size;
 235
 236   if (f_in == (FILE *) 0)
 237     return 0;
 238   /* fflush (stdin); could be done here if you want to synchronise
 239      stdin and stdout, for the case where our input file is stdin.
 240      Since the assembler shouldn't do any output to stdout, we
 241      don't bother to synch output and input.  */
 242   if (preprocess)
 243     size = do_scrub_chars (input_file_get, where, BUFFER_SIZE);
 244   else
 245     size = input_file_get (where, BUFFER_SIZE);
 246
 247   if (size)
 248     return_value = where + size;
 249   else
 250     {
 251       if (fclose (f_in))
 252         as_warn (_("can't close %s: %s"), file_name, xstrerror (errno));
 253
 254       f_in = (FILE *) 0;
 255       return_value = 0;
 256     }
 257
 258   return return_value;
 259 }