1998-10-28 16:10 -0500 Zack Weinberg <zack@rabi.phys.columbia.edu>

	 * c-lang.c: Declare extern char *yy_cur if USE_CPPLIB.
	   (lang_init): Call check_newline always.
	 * c-lex.c (init_parse) [USE_CPPLIB=1]: After calling
	   cpp_start_read, set yy_cur and yy_lim to read from
	   parse_in.token_buffer, so that we'll see the first #line
	   directive.
	 * cpplib.c (cpp_start_read): finclude the main input file
	   before processing -include/-imacros.	 Process -imacros and
	   -include separately, and handle -include by stacking a
	   buffer for the file in question as if it'd been #included.
	 * toplev.c (documented_lang_options) Recognize -H when
	   USE_CPPLIB is on.
1998-10-28 16:09 -0500	Zack Weinberg  <zack@rabi.phys.columbia.edu>
	 * cpplib.c: Merge do_once into do_pragma.  Break file handling
	   code out of do_include.
	   Move append_include_chain, deps_output,
	   file_cleanup, redundant_include_p, import_hash,
	   lookup_import, add_import, read_filename_string, read_name_map,
	   open_include_file, finclude, safe_read to cppfiles.c.
	   Move prototypes for deps_output, append_include_chain,
	   finclude to cpplib.h.  Move definition of struct
	   file_name_list there also.
	 * cppfiles.c: New file.  Contains all the above functions
	   broken out of cpplib.c; also hack_vms_include_specification
	   from cccp.c and find_include_file, a new function broken out of
	   do_include.
	 * Makefile.in (cppmain): Depend on cppfiles.o.
	   (fix-header): Likewise.
	   (cppfiles.o): New target.
	 * configure.in (--enable-c-cpplib): Add cppfiles.o to
	   extra_c_objs.  Add ../cppfiles.o to extra_cxx_objs.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@23424 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 1023 insertions, 0 deletions

diff --git a/gcc/cppfiles.c b/gcc/cppfiles.c
new file mode 100644
index 00000000000..559cc118985
--- /dev/null
+++ b/gcc/cppfiles.c
@@ -0,0 +1,1023 @@
+/* Part of CPP library.  (include file handling)
+   Copyright (C) 1986, 87, 89, 92 - 95, 1998 Free Software Foundation, Inc.
+   Written by Per Bothner, 1994.
+   Based on CCCP program by Paul Rubin, June 1986
+   Adapted to ANSI C, Richard Stallman, Jan 1987
+   Split out of cpplib.c, Zack Weinberg, Oct 1998
+
+This program 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 2, or (at your option) any
+later version.
+
+This program 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 this program; if not, write to the Free Software
+Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+ In other words, you are welcome to use, share and improve this program.
+ You are forbidden to forbid anyone else to use, share and improve
+ what you give them.   Help stamp out software-hoarding!  */
+
+#include "config.h"
+#include "system.h"
+#include "gansidecl.h"
+#include "cpplib.h"
+
+/* The entry points to this file are: find_include_file, finclude,
+   append_include_chain, deps_output, and file_cleanup.
+   file_cleanup is only called through CPP_BUFFER(pfile)->cleanup,
+   so it's static anyway. */
+
+static void add_import			PROTO ((cpp_reader *, int, char *));
+static int lookup_import		PROTO ((cpp_reader *, char *,
+						struct file_name_list *));
+static int redundant_include_p		PROTO ((cpp_reader *, char *));
+static struct file_name_map *read_name_map	PROTO ((cpp_reader *, char *));
+static char *read_filename_string	PROTO ((int, FILE *));
+static int open_include_file		PROTO ((cpp_reader *, char *,
+						struct file_name_list *));
+static int safe_read			PROTO ((int, char *, int));
+
+/* Not safe to prototype these. */
+extern char *xmalloc();
+extern char *xrealloc();
+
+/* Append a chain of `struct file_name_list's
+   to the end of the main include chain.
+   FIRST is the beginning of the chain to append, and LAST is the end.  */
+
+void
+append_include_chain (pfile, first, last)
+     cpp_reader *pfile;
+     struct file_name_list *first, *last;
+{
+  struct cpp_options *opts = CPP_OPTIONS (pfile);
+  struct file_name_list *dir;
+
+  if (!first || !last)
+    return;
+
+  if (opts->include == 0)
+    opts->include = first;
+  else
+    opts->last_include->next = first;
+
+  if (opts->first_bracket_include == 0)
+    opts->first_bracket_include = first;
+
+  for (dir = first; ; dir = dir->next) {
+    int len = strlen (dir->fname) + INCLUDE_LEN_FUDGE;
+    if (len > pfile->max_include_len)
+      pfile->max_include_len = len;
+    if (dir == last)
+      break;
+  }
+
+  last->next = NULL;
+  opts->last_include = last;
+}
+
+/* Add output to `deps_buffer' for the -M switch.
+   STRING points to the text to be output.
+   SPACER is ':' for targets, ' ' for dependencies, zero for text
+   to be inserted literally.  */
+
+void
+deps_output (pfile, string, spacer)
+     cpp_reader *pfile;
+     char *string;
+     int spacer;
+{
+  int size;
+
+  if (!*string)
+    return;
+
+#ifdef VMS
+  hack_vms_include_specification (string);
+#endif
+
+  size = strlen (string);
+
+#ifndef MAX_OUTPUT_COLUMNS
+#define MAX_OUTPUT_COLUMNS 72
+#endif
+  if (spacer
+      && pfile->deps_column > 0
+      && (pfile->deps_column + size) > MAX_OUTPUT_COLUMNS)
+    {
+      deps_output (pfile, " \\\n  ", 0);
+      pfile->deps_column = 0;
+    }
+
+  if (pfile->deps_size + size + 8 > pfile->deps_allocated_size)
+    {
+      pfile->deps_allocated_size = (pfile->deps_size + size + 50) * 2;
+      pfile->deps_buffer = (char *) xrealloc (pfile->deps_buffer,
+					      pfile->deps_allocated_size);
+    }
+  if (spacer == ' ' && pfile->deps_column > 0)
+    pfile->deps_buffer[pfile->deps_size++] = ' ';
+  bcopy (string, &pfile->deps_buffer[pfile->deps_size], size);
+  pfile->deps_size += size;
+  pfile->deps_column += size;
+  if (spacer == ':')
+    pfile->deps_buffer[pfile->deps_size++] = ':';
+  pfile->deps_buffer[pfile->deps_size] = 0;
+}
+
+static int
+file_cleanup (pbuf, pfile)
+     cpp_buffer *pbuf;
+     cpp_reader *pfile ATTRIBUTE_UNUSED;
+{
+  if (pbuf->buf)
+    {
+      free (pbuf->buf);
+      pbuf->buf = 0;
+    }
+  return 0;
+}
+
+int
+find_include_file (pfile, fbeg, flen, fname,
+		   importing, search_start, foundhere)
+     cpp_reader *pfile;
+     char *fbeg;
+     unsigned long flen;
+     char *fname;
+     int importing;
+     struct file_name_list *search_start;
+     struct file_name_list **foundhere;
+{
+  struct file_name_list *searchptr;
+  int f;
+    
+  /* If specified file name is absolute, just open it.  */
+
+  if (*fbeg == '/')
+  {
+    strcpy (fname, fbeg);
+#ifdef VMS
+    hack_vms_include_specification (fname);
+#endif
+    if (redundant_include_p (pfile, fname))
+      return -2;
+    if (importing)
+      f = lookup_import (pfile, fname, NULL_PTR);
+    else
+      f = open_include_file (pfile, fname, NULL_PTR);
+    if (f == -2)
+      return -2;	/* Already included this file */
+  }
+  else
+  {
+    /* Search directory path, trying to open the file.
+       Copy each filename tried into FNAME.  */
+
+    for (searchptr = search_start; searchptr; searchptr = searchptr->next)
+    {
+      unsigned int l = 0;
+      if (searchptr->fname)
+      {
+	/* The empty string in a search path is ignored.
+	   This makes it possible to turn off entirely
+	   a standard piece of the list.  */
+	if (searchptr->fname[0] == 0)
+	  continue;
+
+	l = strlen (searchptr->fname);
+
+	bcopy (searchptr->fname, fname, l);
+	fname[l++] = '/';
+      }
+
+      bcopy (fbeg, &fname[l], flen);
+      fname[flen+l] = '\0';
+#ifdef VMS
+      hack_vms_include_specification (fname);
+#endif /* VMS */
+      /* ??? There are currently 3 separate mechanisms for avoiding processing
+	 of redundant include files: #import, #pragma once, and
+	 redundant_include_p.  It would be nice if they were unified.  */
+      if (redundant_include_p (pfile, fname))
+	return -2;
+      if (importing)
+	f = lookup_import (pfile, fname, searchptr);
+      else
+	f = open_include_file (pfile, fname, searchptr);
+      if (f == -2)
+	return -2;			/* Already included this file */
+#ifdef EACCES
+      else if (f == -1 && errno == EACCES)
+	cpp_warning (pfile, "Header file %s exists, but is not readable",
+		     fname);
+#endif
+      if (f >= 0)
+	break;
+    }
+  }
+
+  if (f < 0)
+    {
+      /* A file that was not found.  */
+      bcopy (fbeg, fname, flen);
+      fname[flen] = 0;
+
+      return -1;
+    }
+  else
+    {
+      /* Check to see if this include file is a once-only include file.
+	 If so, give up.  */
+
+      struct file_name_list *ptr;
+
+      for (ptr = pfile->dont_repeat_files; ptr; ptr = ptr->next)
+	  if (!strcmp (ptr->fname, fname))
+	    {
+	      close (f);
+	      return -2;		/* This file was once'd.  */
+	    }
+    }
+
+    /* Record file on "seen" list for #import.  */
+    add_import (pfile, f, fname);
+
+    *foundhere = searchptr;
+    return f;
+}
+
+/* Return nonzero if there is no need to include file NAME
+   because it has already been included and it contains a conditional
+   to make a repeated include do nothing.  */
+
+static int
+redundant_include_p (pfile, name)
+     cpp_reader *pfile;
+     char *name;
+{
+  struct file_name_list *l = pfile->all_include_files;
+  for (; l; l = l->next)
+    if (! strcmp (name, l->fname)
+	&& l->control_macro
+	&& cpp_lookup (pfile, l->control_macro, -1, -1))
+      return 1;
+  return 0;
+}
+
+
+
+/* Maintain and search list of included files, for #import.  */
+
+/* Hash a file name for import_hash_table.  */
+
+static int 
+import_hash (f)
+     char *f;
+{
+  int val = 0;
+
+  while (*f) val += *f++;
+  return (val%IMPORT_HASH_SIZE);
+}
+
+/* Search for file FILENAME in import_hash_table.
+   Return -2 if found, either a matching name or a matching inode.
+   Otherwise, open the file and return a file descriptor if successful
+   or -1 if unsuccessful.  */
+
+static int
+lookup_import (pfile, filename, searchptr)
+     cpp_reader *pfile;
+     char *filename;
+     struct file_name_list *searchptr;
+{
+  struct import_file *i;
+  int h;
+  int hashval;
+  struct stat sb;
+  int fd;
+
+  hashval = import_hash (filename);
+
+  /* Attempt to find file in list of already included files */
+  i = pfile->import_hash_table[hashval];
+
+  while (i) {
+    if (!strcmp (filename, i->name))
+      return -2;		/* return found */
+    i = i->next;
+  }
+  /* Open it and try a match on inode/dev */
+  fd = open_include_file (pfile, filename, searchptr);
+  if (fd < 0)
+    return fd;
+  fstat (fd, &sb);
+  for (h = 0; h < IMPORT_HASH_SIZE; h++) {
+    i = pfile->import_hash_table[h];
+    while (i) {
+      /* Compare the inode and the device.
+	 Supposedly on some systems the inode is not a scalar.  */
+      if (!bcmp ((char *) &i->inode, (char *) &sb.st_ino, sizeof (sb.st_ino))
+	  && i->dev == sb.st_dev) {
+        close (fd);
+        return -2;		/* return found */
+      }
+      i = i->next;
+    }
+  }
+  return fd;			/* Not found, return open file */
+}
+
+/* Add the file FNAME, open on descriptor FD, to import_hash_table.  */
+
+static void
+add_import (pfile, fd, fname)
+     cpp_reader *pfile;
+     int fd;
+     char *fname;
+{
+  struct import_file *i;
+  int hashval;
+  struct stat sb;
+
+  hashval = import_hash (fname);
+  fstat (fd, &sb);
+  i = (struct import_file *)xmalloc (sizeof (struct import_file));
+  i->name = (char *)xmalloc (strlen (fname)+1);
+  strcpy (i->name, fname);
+  bcopy ((char *) &sb.st_ino, (char *) &i->inode, sizeof (sb.st_ino));
+  i->dev = sb.st_dev;
+  i->next = pfile->import_hash_table[hashval];
+  pfile->import_hash_table[hashval] = i;
+}
+
+/* The file_name_map structure holds a mapping of file names for a
+   particular directory.  This mapping is read from the file named
+   FILE_NAME_MAP_FILE in that directory.  Such a file can be used to
+   map filenames on a file system with severe filename restrictions,
+   such as DOS.  The format of the file name map file is just a series
+   of lines with two tokens on each line.  The first token is the name
+   to map, and the second token is the actual name to use.  */
+
+struct file_name_map
+{
+  struct file_name_map *map_next;
+  char *map_from;
+  char *map_to;
+};
+
+#define FILE_NAME_MAP_FILE "header.gcc"
+
+/* Read a space delimited string of unlimited length from a stdio
+   file.  */
+
+static char *
+read_filename_string (ch, f)
+     int ch;
+     FILE *f;
+{
+  char *alloc, *set;
+  int len;
+
+  len = 20;
+  set = alloc = xmalloc (len + 1);
+  if (! is_space[ch])
+    {
+      *set++ = ch;
+      while ((ch = getc (f)) != EOF && ! is_space[ch])
+	{
+	  if (set - alloc == len)
+	    {
+	      len *= 2;
+	      alloc = xrealloc (alloc, len + 1);
+	      set = alloc + len / 2;
+	    }
+	  *set++ = ch;
+	}
+    }
+  *set = '\0';
+  ungetc (ch, f);
+  return alloc;
+}
+
+/* This structure holds a linked list of file name maps, one per directory.  */
+
+struct file_name_map_list
+{
+  struct file_name_map_list *map_list_next;
+  char *map_list_name;
+  struct file_name_map *map_list_map;
+};
+
+/* Read the file name map file for DIRNAME.  */
+
+static struct file_name_map *
+read_name_map (pfile, dirname)
+     cpp_reader *pfile;
+     char *dirname;
+{
+  register struct file_name_map_list *map_list_ptr;
+  char *name;
+  FILE *f;
+
+  for (map_list_ptr = CPP_OPTIONS (pfile)->map_list; map_list_ptr;
+       map_list_ptr = map_list_ptr->map_list_next)
+    if (! strcmp (map_list_ptr->map_list_name, dirname))
+      return map_list_ptr->map_list_map;
+
+  map_list_ptr = ((struct file_name_map_list *)
+		  xmalloc (sizeof (struct file_name_map_list)));
+  map_list_ptr->map_list_name = savestring (dirname);
+  map_list_ptr->map_list_map = NULL;
+
+  name = (char *) alloca (strlen (dirname) + strlen (FILE_NAME_MAP_FILE) + 2);
+  strcpy (name, dirname);
+  if (*dirname)
+    strcat (name, "/");
+  strcat (name, FILE_NAME_MAP_FILE);
+  f = fopen (name, "r");
+  if (!f)
+    map_list_ptr->map_list_map = NULL;
+  else
+    {
+      int ch;
+      int dirlen = strlen (dirname);
+
+      while ((ch = getc (f)) != EOF)
+	{
+	  char *from, *to;
+	  struct file_name_map *ptr;
+
+	  if (is_space[ch])
+	    continue;
+	  from = read_filename_string (ch, f);
+	  while ((ch = getc (f)) != EOF && is_hor_space[ch])
+	    ;
+	  to = read_filename_string (ch, f);
+
+	  ptr = ((struct file_name_map *)
+		 xmalloc (sizeof (struct file_name_map)));
+	  ptr->map_from = from;
+
+	  /* Make the real filename absolute.  */
+	  if (*to == '/')
+	    ptr->map_to = to;
+	  else
+	    {
+	      ptr->map_to = xmalloc (dirlen + strlen (to) + 2);
+	      strcpy (ptr->map_to, dirname);
+	      ptr->map_to[dirlen] = '/';
+	      strcpy (ptr->map_to + dirlen + 1, to);
+	      free (to);
+	    }	      
+
+	  ptr->map_next = map_list_ptr->map_list_map;
+	  map_list_ptr->map_list_map = ptr;
+
+	  while ((ch = getc (f)) != '\n')
+	    if (ch == EOF)
+	      break;
+	}
+      fclose (f);
+    }
+  
+  map_list_ptr->map_list_next = CPP_OPTIONS (pfile)->map_list;
+  CPP_OPTIONS (pfile)->map_list = map_list_ptr;
+
+  return map_list_ptr->map_list_map;
+}  
+
+/* Try to open include file FILENAME.  SEARCHPTR is the directory
+   being tried from the include file search path.  This function maps
+   filenames on file systems based on information read by
+   read_name_map.  */
+
+static int
+open_include_file (pfile, filename, searchptr)
+     cpp_reader *pfile;
+     char *filename;
+     struct file_name_list *searchptr;
+{
+  if (CPP_OPTIONS (pfile)->remap)
+    {
+      register struct file_name_map *map;
+      register char *from;
+      char *p, *dir;
+
+      if (searchptr && ! searchptr->got_name_map)
+	{
+	  searchptr->name_map = read_name_map (pfile,
+					       searchptr->fname
+					       ? searchptr->fname : ".");
+	  searchptr->got_name_map = 1;
+	}
+
+      /* First check the mapping for the directory we are using.  */
+      if (searchptr && searchptr->name_map)
+	{
+	  from = filename;
+	  if (searchptr->fname)
+	    from += strlen (searchptr->fname) + 1;
+	  for (map = searchptr->name_map; map; map = map->map_next)
+	    {
+	      if (! strcmp (map->map_from, from))
+		{
+		  /* Found a match.  */
+		  return open (map->map_to, O_RDONLY, 0666);
+		}
+	    }
+	}
+
+      /* Try to find a mapping file for the particular directory we are
+	 looking in.  Thus #include <sys/types.h> will look up sys/types.h
+	 in /usr/include/header.gcc and look up types.h in
+	 /usr/include/sys/header.gcc.  */
+      p = rindex (filename, '/');
+      if (! p)
+	p = filename;
+      if (searchptr
+	  && searchptr->fname
+	  && strlen (searchptr->fname) == (size_t) (p - filename)
+	  && ! strncmp (searchptr->fname, filename, p - filename))
+	{
+	  /* FILENAME is in SEARCHPTR, which we've already checked.  */
+	  return open (filename, O_RDONLY, 0666);
+	}
+
+      if (p == filename)
+	{
+	  dir = ".";
+	  from = filename;
+	}
+      else
+	{
+	  dir = (char *) alloca (p - filename + 1);
+	  bcopy (filename, dir, p - filename);
+	  dir[p - filename] = '\0';
+	  from = p + 1;
+	}
+      for (map = read_name_map (pfile, dir); map; map = map->map_next)
+	if (! strcmp (map->map_from, from))
+	  return open (map->map_to, O_RDONLY, 0666);
+    }
+
+  return open (filename, O_RDONLY, 0666);
+}
+
+/* Process the contents of include file FNAME, already open on descriptor F,
+   with output to OP.
+   SYSTEM_HEADER_P is 1 if this file resides in any one of the known
+   "system" include directories (as decided by the `is_system_include'
+   function above).
+   DIRPTR is the link in the dir path through which this file was found,
+   or 0 if the file name was absolute or via the current directory.
+   Return 1 on success, 0 on failure.
+
+   The caller is responsible for the cpp_push_buffer.  */
+
+int
+finclude (pfile, f, fname, system_header_p, dirptr)
+     cpp_reader *pfile;
+     int f;
+     char *fname;
+     int system_header_p;
+     struct file_name_list *dirptr;
+{
+  struct stat st;
+  size_t st_size;
+  long i;
+  int length;
+  cpp_buffer *fp;			/* For input stack frame */
+#if 0
+  int missing_newline = 0;
+#endif
+
+  if (fstat (f, &st) < 0)
+    {
+      cpp_perror_with_name (pfile, fname);
+      close (f);
+      cpp_pop_buffer (pfile);
+      return 0;
+    }
+
+  fp = CPP_BUFFER (pfile);
+  fp->nominal_fname = fp->fname = fname;
+#if 0
+  fp->length = 0;
+#endif
+  fp->dir = dirptr;
+  fp->system_header_p = system_header_p;
+  fp->lineno = 1;
+  fp->colno = 1;
+  fp->cleanup = file_cleanup;
+
+  if (S_ISREG (st.st_mode)) {
+    st_size = (size_t) st.st_size;
+    if (st_size != st.st_size || st_size + 2 < st_size) {
+      cpp_error (pfile, "file `%s' too large", fname);
+      close (f);
+      return 0;
+    }
+    fp->buf = (U_CHAR *) xmalloc (st_size + 2);
+    fp->alimit = fp->buf + st_size + 2;
+    fp->cur = fp->buf;
+
+    /* Read the file contents, knowing that st_size is an upper bound
+       on the number of bytes we can read.  */
+    length = safe_read (f, fp->buf, st_size);
+    fp->rlimit = fp->buf + length;
+    if (length < 0) goto nope;
+  }
+  else if (S_ISDIR (st.st_mode)) {
+    cpp_error (pfile, "directory `%s' specified in #include", fname);
+    close (f);
+    return 0;
+  } else {
+    /* Cannot count its file size before reading.
+       First read the entire file into heap and
+       copy them into buffer on stack.  */
+
+    size_t bsize = 2000;
+
+    st_size = 0;
+    fp->buf = (U_CHAR *) xmalloc (bsize + 2);
+
+    for (;;) {
+      i = safe_read (f, fp->buf + st_size, bsize - st_size);
+      if (i < 0)
+	goto nope;      /* error! */
+      st_size += i;
+      if (st_size != bsize)
+	break;	/* End of file */
+      bsize *= 2;
+      fp->buf = (U_CHAR *) xrealloc (fp->buf, bsize + 2);
+    }
+    fp->cur = fp->buf;
+    length = st_size;
+  }
+
+  if ((length > 0 && fp->buf[length - 1] != '\n')
+      /* Backslash-newline at end is not good enough.  */
+      || (length > 1 && fp->buf[length - 2] == '\\')) {
+    fp->buf[length++] = '\n';
+#if 0
+    missing_newline = 1;
+#endif
+  }
+  fp->buf[length] = '\0';
+  fp->rlimit = fp->buf + length;
+
+  /* Close descriptor now, so nesting does not use lots of descriptors.  */
+  close (f);
+
+  /* Must do this before calling trigraph_pcp, so that the correct file name
+     will be printed in warning messages.  */
+
+  pfile->input_stack_listing_current = 0;
+
+#if 0
+  if (!no_trigraphs)
+    trigraph_pcp (fp);
+#endif
+
+#if 0
+  rescan (op, 0);
+
+  if (missing_newline)
+    fp->lineno--;
+
+  if (CPP_PEDANTIC (pfile) && missing_newline)
+    pedwarn ("file does not end in newline");
+
+  indepth--;
+  input_file_stack_tick++;
+  free (fp->buf);
+#endif
+  return 1;
+
+ nope:
+
+  cpp_perror_with_name (pfile, fname);
+  close (f);
+  free (fp->buf);
+  return 1;
+}
+
+/* Read LEN bytes at PTR from descriptor DESC, for file FILENAME,
+   retrying if necessary.  If MAX_READ_LEN is defined, read at most
+   that bytes at a time.  Return a negative value if an error occurs,
+   otherwise return the actual number of bytes read,
+   which must be LEN unless end-of-file was reached.  */
+
+static int
+safe_read (desc, ptr, len)
+     int desc;
+     char *ptr;
+     int len;
+{
+  int left, rcount, nchars;
+
+  left = len;
+  while (left > 0) {
+    rcount = left;
+#ifdef MAX_READ_LEN
+    if (rcount > MAX_READ_LEN)
+      rcount = MAX_READ_LEN;
+#endif
+    nchars = read (desc, ptr, rcount);
+    if (nchars < 0)
+      {
+#ifdef EINTR
+	if (errno == EINTR)
+	  continue;
+#endif
+	return nchars;
+      }
+    if (nchars == 0)
+      break;
+    ptr += nchars;
+    left -= nchars;
+  }
+  return len - left;
+}
+
+#ifdef VMS
+
+/* Under VMS we need to fix up the "include" specification filename.
+
+   Rules for possible conversions
+
+	fullname		tried paths
+
+	name			name
+	./dir/name		[.dir]name
+	/dir/name		dir:name
+	/name			[000000]name, name
+	dir/name		dir:[000000]name, dir:name, dir/name
+	dir1/dir2/name		dir1:[dir2]name, dir1:[000000.dir2]name
+	path:/name		path:[000000]name, path:name
+	path:/dir/name		path:[000000.dir]name, path:[dir]name
+	path:dir/name		path:[dir]name
+	[path]:[dir]name	[path.dir]name
+	path/[dir]name		[path.dir]name
+
+   The path:/name input is constructed when expanding <> includes. */
+
+
+static void
+hack_vms_include_specification (fullname)
+     char *fullname;
+{
+  register char *basename, *unixname, *local_ptr, *first_slash;
+  int f, check_filename_before_returning, must_revert;
+  char Local[512];
+
+  check_filename_before_returning = 0;
+  must_revert = 0;
+  /* See if we can find a 1st slash. If not, there's no path information.  */
+  first_slash = index (fullname, '/');
+  if (first_slash == 0)
+    return 0;				/* Nothing to do!!! */
+
+  /* construct device spec if none given.  */
+
+  if (index (fullname, ':') == 0)
+    {
+
+      /* If fullname has a slash, take it as device spec.  */
+
+      if (first_slash == fullname)
+	{
+	  first_slash = index (fullname+1, '/');	/* 2nd slash ? */
+	  if (first_slash)
+	    *first_slash = ':';				/* make device spec  */
+	  for (basename = fullname; *basename != 0; basename++)
+	    *basename = *(basename+1);			/* remove leading slash  */
+	}
+      else if ((first_slash[-1] != '.')		/* keep ':/', './' */
+	    && (first_slash[-1] != ':')
+	    && (first_slash[-1] != ']'))	/* or a vms path  */
+	{
+	  *first_slash = ':';
+	}
+      else if ((first_slash[1] == '[')		/* skip './' in './[dir'  */
+	    && (first_slash[-1] == '.'))
+	fullname += 2;
+    }
+
+  /* Get part after first ':' (basename[-1] == ':')
+     or last '/' (basename[-1] == '/').  */
+
+  basename = base_name (fullname);
+
+  local_ptr = Local;			/* initialize */
+
+  /* We are trying to do a number of things here.  First of all, we are
+     trying to hammer the filenames into a standard format, such that later
+     processing can handle them.
+     
+     If the file name contains something like [dir.], then it recognizes this
+     as a root, and strips the ".]".  Later processing will add whatever is
+     needed to get things working properly.
+     
+     If no device is specified, then the first directory name is taken to be
+     a device name (or a rooted logical).  */
+
+  /* Point to the UNIX filename part (which needs to be fixed!)
+     but skip vms path information.
+     [basename != fullname since first_slash != 0].  */
+
+  if ((basename[-1] == ':')		/* vms path spec.  */
+      || (basename[-1] == ']')
+      || (basename[-1] == '>'))
+    unixname = basename;
+  else
+    unixname = fullname;
+
+  if (*unixname == '/')
+    unixname++;
+
+  /* If the directory spec is not rooted, we can just copy
+     the UNIX filename part and we are done.  */
+
+  if (((basename - fullname) > 1)
+     && (  (basename[-1] == ']')
+        || (basename[-1] == '>')))
+    {
+      if (basename[-2] != '.')
+	{
+
+	/* The VMS part ends in a `]', and the preceding character is not a `.'.
+	   -> PATH]:/name (basename = '/name', unixname = 'name')
+	   We strip the `]', and then splice the two parts of the name in the
+	   usual way.  Given the default locations for include files in cccp.c,
+	   we will only use this code if the user specifies alternate locations
+	   with the /include (-I) switch on the command line.  */
+
+	  basename -= 1;	/* Strip "]" */
+	  unixname--;		/* backspace */
+	}
+      else
+	{
+
+	/* The VMS part has a ".]" at the end, and this will not do.  Later
+	   processing will add a second directory spec, and this would be a syntax
+	   error.  Thus we strip the ".]", and thus merge the directory specs.
+	   We also backspace unixname, so that it points to a '/'.  This inhibits the
+	   generation of the 000000 root directory spec (which does not belong here
+	   in this case).  */
+
+	  basename -= 2;	/* Strip ".]" */
+	  unixname--;		/* backspace */
+	}
+    }
+
+  else
+
+    {
+
+      /* We drop in here if there is no VMS style directory specification yet.
+         If there is no device specification either, we make the first dir a
+         device and try that.  If we do not do this, then we will be essentially
+         searching the users default directory (as if they did a #include "asdf.h").
+        
+         Then all we need to do is to push a '[' into the output string. Later
+         processing will fill this in, and close the bracket.  */
+
+      if ((unixname != fullname)	/* vms path spec found.  */
+	 && (basename[-1] != ':'))
+	*local_ptr++ = ':';		/* dev not in spec.  take first dir */
+
+      *local_ptr++ = '[';		/* Open the directory specification */
+    }
+
+    if (unixname == fullname)		/* no vms dir spec.  */
+      {
+	must_revert = 1;
+	if ((first_slash != 0)		/* unix dir spec.  */
+	    && (*unixname != '/')	/* not beginning with '/'  */
+	    && (*unixname != '.'))	/* or './' or '../'  */
+	  *local_ptr++ = '.';		/* dir is local !  */
+      }
+
+  /* at this point we assume that we have the device spec, and (at least
+     the opening "[" for a directory specification.  We may have directories
+     specified already.
+
+     If there are no other slashes then the filename will be
+     in the "root" directory.  Otherwise, we need to add
+     directory specifications.  */
+
+  if (index (unixname, '/') == 0)
+    {
+      /* if no directories specified yet and none are following.  */
+      if (local_ptr[-1] == '[')
+	{
+	  /* Just add "000000]" as the directory string */
+	  strcpy (local_ptr, "000000]");
+	  local_ptr += strlen (local_ptr);
+	  check_filename_before_returning = 1; /* we might need to fool with this later */
+	}
+    }
+  else
+    {
+
+      /* As long as there are still subdirectories to add, do them.  */
+      while (index (unixname, '/') != 0)
+	{
+	  /* If this token is "." we can ignore it
+	       if it's not at the beginning of a path.  */
+	  if ((unixname[0] == '.') && (unixname[1] == '/'))
+	    {
+	      /* remove it at beginning of path.  */
+	      if (  ((unixname == fullname)		/* no device spec  */
+		    && (fullname+2 != basename))	/* starts with ./ */
+							/* or  */
+		 || ((basename[-1] == ':')		/* device spec  */
+		    && (unixname-1 == basename)))	/* and ./ afterwards  */
+		*local_ptr++ = '.';		 	/* make '[.' start of path.  */
+	      unixname += 2;
+	      continue;
+	    }
+
+	  /* Add a subdirectory spec. Do not duplicate "." */
+	  if (  local_ptr[-1] != '.'
+	     && local_ptr[-1] != '['
+	     && local_ptr[-1] != '<')
+	    *local_ptr++ = '.';
+
+	  /* If this is ".." then the spec becomes "-" */
+	  if (  (unixname[0] == '.')
+	     && (unixname[1] == '.')
+	     && (unixname[2] == '/'))
+	    {
+	      /* Add "-" and skip the ".." */
+	      if ((local_ptr[-1] == '.')
+		  && (local_ptr[-2] == '['))
+		local_ptr--;			/* prevent [.-  */
+	      *local_ptr++ = '-';
+	      unixname += 3;
+	      continue;
+	    }
+
+	  /* Copy the subdirectory */
+	  while (*unixname != '/')
+	    *local_ptr++= *unixname++;
+
+	  unixname++;			/* Skip the "/" */
+	}
+
+      /* Close the directory specification */
+      if (local_ptr[-1] == '.')		/* no trailing periods */
+	local_ptr--;
+
+      if (local_ptr[-1] == '[')		/* no dir needed */
+	local_ptr--;
+      else
+	*local_ptr++ = ']';
+    }
+
+  /* Now add the filename.  */
+
+  while (*unixname)
+    *local_ptr++ = *unixname++;
+  *local_ptr = 0;
+
+  /* Now append it to the original VMS spec.  */
+
+  strcpy ((must_revert==1)?fullname:basename, Local);
+
+  /* If we put a [000000] in the filename, try to open it first. If this fails,
+     remove the [000000], and return that name.  This provides flexibility
+     to the user in that they can use both rooted and non-rooted logical names
+     to point to the location of the file.  */
+
+  if (check_filename_before_returning)
+    {
+      f = open (fullname, O_RDONLY, 0666);
+      if (f >= 0)
+	{
+	  /* The file name is OK as it is, so return it as is.  */
+	  close (f);
+	  return 1;
+	}
+
+      /* The filename did not work.  Try to remove the [000000] from the name,
+	 and return it.  */
+
+      basename = index (fullname, '[');
+      local_ptr = index (fullname, ']') + 1;
+      strcpy (basename, local_ptr);		/* this gets rid of it */
+
+    }
+
+  return 1;
+}
+#endif	/* VMS */