--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libcpp/files.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,1806 @@
+/* Part of CPP library.  File handling.
+   Copyright (C) 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1998,
+   1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+   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
+   Reimplemented, Neil Booth, Jul 2003
+
+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 3, 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; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "cpplib.h"
+#include "internal.h"
+#include "mkdeps.h"
+#include "obstack.h"
+#include "hashtab.h"
+#include "md5.h"
+#include <dirent.h>
+
+/* Variable length record files on VMS will have a stat size that includes
+   record control characters that won't be included in the read size.  */
+#ifdef VMS
+# define FAB_C_VAR 2 /* variable length records (see Starlet fabdef.h) */
+# define STAT_SIZE_RELIABLE(ST) ((ST).st_fab_rfm != FAB_C_VAR)
+#else
+# define STAT_SIZE_RELIABLE(ST) true
+#endif
+
+#ifdef __DJGPP__
+#include <io.h>
+  /* For DJGPP redirected input is opened in text mode.  */
+#  define set_stdin_to_binary_mode() \
+     if (! isatty (0)) setmode (0, O_BINARY)
+#else
+#  define set_stdin_to_binary_mode() /* Nothing */
+#endif
+
+/* This structure represents a file searched for by CPP, whether it
+   exists or not.  An instance may be pointed to by more than one
+   file_hash_entry; at present no reference count is kept.  */
+struct _cpp_file
+{
+  /* Filename as given to #include or command line switch.  */
+  const char *name;
+
+  /* The full path used to find the file.  */
+  const char *path;
+
+  /* The full path of the pch file.  */
+  const char *pchname;
+
+  /* The file's path with the basename stripped.  NULL if it hasn't
+     been calculated yet.  */
+  const char *dir_name;
+
+  /* Chain through all files.  */
+  struct _cpp_file *next_file;
+
+  /* The contents of NAME after calling read_file().  */
+  const uchar *buffer;
+
+  /* Pointer to the real start of BUFFER.  read_file() might increment
+     BUFFER; when freeing, this this pointer must be used instead.  */
+  const uchar *buffer_start;
+
+  /* The macro, if any, preventing re-inclusion.  */
+  const cpp_hashnode *cmacro;
+
+  /* The directory in the search path where FILE was found.  Used for
+     #include_next and determining whether a header is a system
+     header.  */
+  cpp_dir *dir;
+
+  /* As filled in by stat(2) for the file.  */
+  struct stat st;
+
+  /* File descriptor.  Invalid if -1, otherwise open.  */
+  int fd;
+
+  /* Zero if this file was successfully opened and stat()-ed,
+     otherwise errno obtained from failure.  */
+  int err_no;
+
+  /* Number of times the file has been stacked for preprocessing.  */
+  unsigned short stack_count;
+
+  /* If opened with #import or contains #pragma once.  */
+  bool once_only;
+
+  /* If read() failed before.  */
+  bool dont_read;
+
+  /* If this file is the main file.  */
+  bool main_file;
+
+  /* If BUFFER above contains the true contents of the file.  */
+  bool buffer_valid;
+};
+
+/* A singly-linked list for all searches for a given file name, with
+   its head pointed to by a slot in FILE_HASH.  The file name is what
+   appeared between the quotes in a #include directive; it can be
+   determined implicitly from the hash table location or explicitly
+   from FILE->name.
+
+   FILE is a structure containing details about the file that was
+   found with that search, or details of how the search failed.
+
+   START_DIR is the starting location of the search in the include
+   chain.  The current directories for "" includes are also hashed in
+   the hash table and therefore unique.  Files that are looked up
+   without using a search path, such as absolute filenames and file
+   names from the command line share a special starting directory so
+   they don't cause cache hits with normal include-chain lookups.
+
+   If START_DIR is NULL then the entry is for a directory, not a file,
+   and the directory is in DIR.  Since the starting point in a file
+   lookup chain is never NULL, this means that simple pointer
+   comparisons against START_DIR can be made to determine cache hits
+   in file lookups.
+
+   If a cache lookup fails because of e.g. an extra "./" in the path,
+   then nothing will break.  It is just less efficient as CPP will
+   have to do more work re-preprocessing the file, and/or comparing
+   its contents against earlier once-only files.
+*/
+struct file_hash_entry
+{
+  struct file_hash_entry *next;
+  cpp_dir *start_dir;
+  source_location location;
+  union
+  {
+    _cpp_file *file;
+    cpp_dir *dir;
+  } u;
+};
+
+/* Number of entries to put in a file_hash_entry pool.  */
+#define FILE_HASH_POOL_SIZE 127
+
+/* A file hash entry pool.  We allocate file_hash_entry object from
+   one of these.  */
+struct file_hash_entry_pool
+{
+  /* Number of entries used from this pool.  */
+  unsigned int file_hash_entries_used;
+  /* Next pool in the chain; used when freeing.  */
+  struct file_hash_entry_pool *next;
+  /* The memory pool.  */
+  struct file_hash_entry pool[FILE_HASH_POOL_SIZE];
+};
+
+static bool open_file (_cpp_file *file);
+static bool pch_open_file (cpp_reader *pfile, _cpp_file *file,
+			   bool *invalid_pch);
+static bool find_file_in_dir (cpp_reader *pfile, _cpp_file *file,
+			      bool *invalid_pch);
+static bool read_file_guts (cpp_reader *pfile, _cpp_file *file);
+static bool read_file (cpp_reader *pfile, _cpp_file *file);
+static bool should_stack_file (cpp_reader *, _cpp_file *file, bool import);
+static struct cpp_dir *search_path_head (cpp_reader *, const char *fname,
+				 int angle_brackets, enum include_type);
+static const char *dir_name_of_file (_cpp_file *file);
+static void open_file_failed (cpp_reader *pfile, _cpp_file *file, int);
+static struct file_hash_entry *search_cache (struct file_hash_entry *head,
+					     const cpp_dir *start_dir);
+static _cpp_file *make_cpp_file (cpp_reader *, cpp_dir *, const char *fname);
+static void destroy_cpp_file (_cpp_file *);
+static cpp_dir *make_cpp_dir (cpp_reader *, const char *dir_name, int sysp);
+static void allocate_file_hash_entries (cpp_reader *pfile);
+static struct file_hash_entry *new_file_hash_entry (cpp_reader *pfile);
+static int report_missing_guard (void **slot, void *b);
+static hashval_t file_hash_hash (const void *p);
+static int file_hash_eq (const void *p, const void *q);
+static char *read_filename_string (int ch, FILE *f);
+static void read_name_map (cpp_dir *dir);
+static char *remap_filename (cpp_reader *pfile, _cpp_file *file);
+static char *append_file_to_dir (const char *fname, cpp_dir *dir);
+static bool validate_pch (cpp_reader *, _cpp_file *file, const char *pchname);
+static int pchf_save_compare (const void *e1, const void *e2);
+static int pchf_compare (const void *d_p, const void *e_p);
+static bool check_file_against_entries (cpp_reader *, _cpp_file *, bool);
+
+/* Given a filename in FILE->PATH, with the empty string interpreted
+   as <stdin>, open it.
+
+   On success FILE contains an open file descriptor and stat
+   information for the file.  On failure the file descriptor is -1 and
+   the appropriate errno is also stored in FILE.  Returns TRUE iff
+   successful.
+
+   We used to open files in nonblocking mode, but that caused more
+   problems than it solved.  Do take care not to acquire a controlling
+   terminal by mistake (this can't happen on sane systems, but
+   paranoia is a virtue).
+
+   Use the three-argument form of open even though we aren't
+   specifying O_CREAT, to defend against broken system headers.
+
+   O_BINARY tells some runtime libraries (notably DJGPP) not to do
+   newline translation; we can handle DOS line breaks just fine
+   ourselves.  */
+static bool
+open_file (_cpp_file *file)
+{
+  if (file->path[0] == '\0')
+    {
+      file->fd = 0;
+      set_stdin_to_binary_mode ();
+    }
+  else
+    file->fd = open (file->path, O_RDONLY | O_NOCTTY | O_BINARY, 0666);
+
+  if (file->fd != -1)
+    {
+      if (fstat (file->fd, &file->st) == 0)
+	{
+	  if (!S_ISDIR (file->st.st_mode))
+	    {
+	      file->err_no = 0;
+	      return true;
+	    }
+
+	  /* Ignore a directory and continue the search.  The file we're
+	     looking for may be elsewhere in the search path.  */
+	  errno = ENOENT;
+	}
+
+      close (file->fd);
+      file->fd = -1;
+    }
+#if defined(_WIN32) && !defined(__CYGWIN__)
+  else if (errno == EACCES)
+    {
+      /* On most UNIX systems, open succeeds on a directory.  Above,
+         we check if we have opened a directory and if so, set errno
+         to ENOENT.  However, on Windows, opening a directory
+         fails with EACCES.  We want to return ENOENT in that
+         case too.  */
+      if (stat (file->path, &file->st) == 0
+          && S_ISDIR (file->st.st_mode))
+        errno = ENOENT;
+      else
+	/* The call to stat may have reset errno.  */
+	errno = EACCES;
+    }
+#endif    
+  else if (errno == ENOTDIR)
+    errno = ENOENT;
+
+  file->err_no = errno;
+
+  return false;
+}
+
+/* Temporary PCH intercept of opening a file.  Try to find a PCH file
+   based on FILE->name and FILE->dir, and test those found for
+   validity using PFILE->cb.valid_pch.  Return true iff a valid file is
+   found.  Set *INVALID_PCH if a PCH file is found but wasn't valid.  */
+
+static bool
+pch_open_file (cpp_reader *pfile, _cpp_file *file, bool *invalid_pch)
+{
+  static const char extension[] = ".gch";
+  const char *path = file->path;
+  size_t len, flen;
+  char *pchname;
+  struct stat st;
+  bool valid = false;
+
+  /* No PCH on <stdin> or if not requested.  */
+  if (file->name[0] == '\0' || !pfile->cb.valid_pch)
+    return false;
+
+  flen = strlen (path);
+  len = flen + sizeof (extension);
+  pchname = XNEWVEC (char, len);
+  memcpy (pchname, path, flen);
+  memcpy (pchname + flen, extension, sizeof (extension));
+
+  if (stat (pchname, &st) == 0)
+    {
+      DIR *pchdir;
+      struct dirent *d;
+      size_t dlen, plen = len;
+
+      if (!S_ISDIR (st.st_mode))
+	valid = validate_pch (pfile, file, pchname);
+      else if ((pchdir = opendir (pchname)) != NULL)
+	{
+	  pchname[plen - 1] = '/';
+	  while ((d = readdir (pchdir)) != NULL)
+	    {
+	      dlen = strlen (d->d_name) + 1;
+	      if ((strcmp (d->d_name, ".") == 0)
+		  || (strcmp (d->d_name, "..") == 0))
+		continue;
+	      if (dlen + plen > len)
+		{
+		  len += dlen + 64;
+		  pchname = XRESIZEVEC (char, pchname, len);
+		}
+	      memcpy (pchname + plen, d->d_name, dlen);
+	      valid = validate_pch (pfile, file, pchname);
+	      if (valid)
+		break;
+	    }
+	  closedir (pchdir);
+	}
+      if (!valid)
+	*invalid_pch = true;
+    }
+
+  if (valid)
+    file->pchname = pchname;
+  else
+    free (pchname);
+
+  return valid;
+}
+
+/* Try to open the path FILE->name appended to FILE->dir.  This is
+   where remap and PCH intercept the file lookup process.  Return true
+   if the file was found, whether or not the open was successful.
+   Set *INVALID_PCH to true if a PCH file is found but wasn't valid.  */
+
+static bool
+find_file_in_dir (cpp_reader *pfile, _cpp_file *file, bool *invalid_pch)
+{
+  char *path;
+
+  if (CPP_OPTION (pfile, remap) && (path = remap_filename (pfile, file)))
+    ;
+  else
+    if (file->dir->construct)
+      path = file->dir->construct (file->name, file->dir);
+    else
+      path = append_file_to_dir (file->name, file->dir);
+
+  if (path)
+    {
+      hashval_t hv = htab_hash_string (path);
+      char *copy;
+      void **pp;
+
+      if (htab_find_with_hash (pfile->nonexistent_file_hash, path, hv) != NULL)
+	{
+	  file->err_no = ENOENT;
+	  return false;
+	}
+
+      file->path = path;
+      if (pch_open_file (pfile, file, invalid_pch))
+	return true;
+
+      if (open_file (file))
+	return true;
+
+      if (file->err_no != ENOENT)
+	{
+	  open_file_failed (pfile, file, 0);
+	  return true;
+	}
+
+      /* We copy the path name onto an obstack partly so that we don't
+	 leak the memory, but mostly so that we don't fragment the
+	 heap.  */
+      copy = obstack_copy0 (&pfile->nonexistent_file_ob, path,
+			    strlen (path));
+      free (path);
+      pp = htab_find_slot_with_hash (pfile->nonexistent_file_hash,
+				     copy, hv, INSERT);
+      *pp = copy;
+
+      file->path = file->name;
+    }
+  else
+    {
+      file->err_no = ENOENT; 
+      file->path = NULL;
+    }
+
+  return false;
+}
+
+/* Return tue iff the missing_header callback found the given HEADER.  */
+static bool
+search_path_exhausted (cpp_reader *pfile, const char *header, _cpp_file *file)
+{
+  missing_header_cb func = pfile->cb.missing_header;
+
+  /* When the regular search path doesn't work, try context dependent
+     headers search paths.  */
+  if (func
+      && file->dir == NULL)
+    {
+      if ((file->path = func (pfile, header, &file->dir)) != NULL)
+	{
+	  if (open_file (file))
+	    return true;
+	  free ((void *)file->path);
+	}
+      file->path = file->name;
+    }
+
+  return false;
+}
+
+bool
+_cpp_find_failed (_cpp_file *file)
+{
+  return file->err_no != 0;
+}
+
+/* Given a filename FNAME search for such a file in the include path
+   starting from START_DIR.  If FNAME is the empty string it is
+   interpreted as STDIN if START_DIR is PFILE->no_search_path.
+
+   If the file is not found in the file cache fall back to the O/S and
+   add the result to our cache.
+
+   If the file was not found in the filesystem, or there was an error
+   opening it, then ERR_NO is nonzero and FD is -1.  If the file was
+   found, then ERR_NO is zero and FD could be -1 or an open file
+   descriptor.  FD can be -1 if the file was found in the cache and
+   had previously been closed.  To open it again pass the return value
+   to open_file().
+*/
+_cpp_file *
+_cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir, bool fake, int angle_brackets)
+{
+  struct file_hash_entry *entry, **hash_slot;
+  _cpp_file *file;
+  bool invalid_pch = false;
+  bool saw_bracket_include = false;
+  bool saw_quote_include = false;
+  struct cpp_dir *found_in_cache = NULL;
+
+  /* Ensure we get no confusion between cached files and directories.  */
+  if (start_dir == NULL)
+    cpp_error (pfile, CPP_DL_ICE, "NULL directory in find_file");
+
+  hash_slot = (struct file_hash_entry **)
+    htab_find_slot_with_hash (pfile->file_hash, fname,
+			      htab_hash_string (fname),
+			      INSERT);
+
+  /* First check the cache before we resort to memory allocation.  */
+  entry = search_cache (*hash_slot, start_dir);
+  if (entry)
+    return entry->u.file;
+
+  file = make_cpp_file (pfile, start_dir, fname);
+
+  /* Try each path in the include chain.  */
+  for (; !fake ;)
+    {
+      if (find_file_in_dir (pfile, file, &invalid_pch))
+	break;
+
+      file->dir = file->dir->next;
+      if (file->dir == NULL)
+	{
+	  if (search_path_exhausted (pfile, fname, file))
+	    {
+	      /* Although this file must not go in the cache, because
+		 the file found might depend on things (like the current file)
+		 that aren't represented in the cache, it still has to go in
+		 the list of all files so that #import works.  */
+	      file->next_file = pfile->all_files;
+	      pfile->all_files = file;
+	      return file;
+	    }
+
+	  open_file_failed (pfile, file, angle_brackets);
+	  if (invalid_pch)
+	    {
+	      cpp_error (pfile, CPP_DL_ERROR,
+	       "one or more PCH files were found, but they were invalid");
+	      if (!cpp_get_options (pfile)->warn_invalid_pch)
+		cpp_error (pfile, CPP_DL_ERROR,
+			   "use -Winvalid-pch for more information");
+	    }
+	  break;
+	}
+
+      /* Only check the cache for the starting location (done above)
+	 and the quote and bracket chain heads because there are no
+	 other possible starting points for searches.  */
+      if (file->dir == pfile->bracket_include)
+	saw_bracket_include = true;
+      else if (file->dir == pfile->quote_include)
+	saw_quote_include = true;
+      else
+	continue;
+
+      entry = search_cache (*hash_slot, file->dir);
+      if (entry)
+	{
+	  found_in_cache = file->dir;
+	  break;
+	}
+    }
+
+  if (entry)
+    {
+      /* Cache for START_DIR too, sharing the _cpp_file structure.  */
+      free ((char *) file->name);
+      free (file);
+      file = entry->u.file;
+    }
+  else
+    {
+      /* This is a new file; put it in the list.  */
+      file->next_file = pfile->all_files;
+      pfile->all_files = file;
+    }
+
+  /* Store this new result in the hash table.  */
+  entry = new_file_hash_entry (pfile);
+  entry->next = *hash_slot;
+  entry->start_dir = start_dir;
+  entry->location = pfile->line_table->highest_location;
+  entry->u.file = file;
+  *hash_slot = entry;
+
+  /* If we passed the quote or bracket chain heads, cache them also.
+     This speeds up processing if there are lots of -I options.  */
+  if (saw_bracket_include
+      && pfile->bracket_include != start_dir
+      && found_in_cache != pfile->bracket_include)
+    {
+      entry = new_file_hash_entry (pfile);
+      entry->next = *hash_slot;
+      entry->start_dir = pfile->bracket_include;
+      entry->location = pfile->line_table->highest_location;
+      entry->u.file = file;
+      *hash_slot = entry;
+    }
+  if (saw_quote_include
+      && pfile->quote_include != start_dir
+      && found_in_cache != pfile->quote_include)
+    {
+      entry = new_file_hash_entry (pfile);
+      entry->next = *hash_slot;
+      entry->start_dir = pfile->quote_include;
+      entry->location = pfile->line_table->highest_location;
+      entry->u.file = file;
+      *hash_slot = entry;
+    }
+
+  return file;
+}
+
+/* Read a file into FILE->buffer, returning true on success.
+
+   If FILE->fd is something weird, like a block device, we don't want
+   to read it at all.  Don't even try to figure out what something is,
+   except for plain files and block devices, since there is no
+   reliable portable way of doing this.
+
+   FIXME: Flush file cache and try again if we run out of memory.  */
+static bool
+read_file_guts (cpp_reader *pfile, _cpp_file *file)
+{
+  ssize_t size, total, count;
+  uchar *buf;
+  bool regular;
+
+  if (S_ISBLK (file->st.st_mode))
+    {
+      cpp_error (pfile, CPP_DL_ERROR, "%s is a block device", file->path);
+      return false;
+    }
+
+  regular = S_ISREG (file->st.st_mode);
+  if (regular)
+    {
+      /* off_t might have a wider range than ssize_t - in other words,
+	 the max size of a file might be bigger than the address
+	 space.  We can't handle a file that large.  (Anyone with
+	 a single source file bigger than 2GB needs to rethink
+	 their coding style.)  Some systems (e.g. AIX 4.1) define
+	 SSIZE_MAX to be much smaller than the actual range of the
+	 type.  Use INTTYPE_MAXIMUM unconditionally to ensure this
+	 does not bite us.  */
+      if (file->st.st_size > INTTYPE_MAXIMUM (ssize_t))
+	{
+	  cpp_error (pfile, CPP_DL_ERROR, "%s is too large", file->path);
+	  return false;
+	}
+
+      size = file->st.st_size;
+    }
+  else
+    /* 8 kilobytes is a sensible starting size.  It ought to be bigger
+       than the kernel pipe buffer, and it's definitely bigger than
+       the majority of C source files.  */
+    size = 8 * 1024;
+
+  buf = XNEWVEC (uchar, size + 1);
+  total = 0;
+  while ((count = read (file->fd, buf + total, size - total)) > 0)
+    {
+      total += count;
+
+      if (total == size)
+	{
+	  if (regular)
+	    break;
+	  size *= 2;
+	  buf = XRESIZEVEC (uchar, buf, size + 1);
+	}
+    }
+
+  if (count < 0)
+    {
+      cpp_errno (pfile, CPP_DL_ERROR, file->path);
+      return false;
+    }
+
+  if (regular && total != size && STAT_SIZE_RELIABLE (file->st))
+    cpp_error (pfile, CPP_DL_WARNING,
+	       "%s is shorter than expected", file->path);
+
+  file->buffer = _cpp_convert_input (pfile,
+				     CPP_OPTION (pfile, input_charset),
+				     buf, size, total,
+				     &file->buffer_start,
+				     &file->st.st_size);
+  file->buffer_valid = true;
+
+  return true;
+}
+
+/* Convenience wrapper around read_file_guts that opens the file if
+   necessary and closes the file descriptor after reading.  FILE must
+   have been passed through find_file() at some stage.  */
+static bool
+read_file (cpp_reader *pfile, _cpp_file *file)
+{
+  /* If we already have its contents in memory, succeed immediately.  */
+  if (file->buffer_valid)
+    return true;
+
+  /* If an earlier read failed for some reason don't try again.  */
+  if (file->dont_read || file->err_no)
+    return false;
+
+  if (file->fd == -1 && !open_file (file))
+    {
+      open_file_failed (pfile, file, 0);
+      return false;
+    }
+
+  file->dont_read = !read_file_guts (pfile, file);
+  close (file->fd);
+  file->fd = -1;
+
+  return !file->dont_read;
+}
+
+/* Returns TRUE if FILE's contents have been successfully placed in
+   FILE->buffer and the file should be stacked, otherwise false.  */
+static bool
+should_stack_file (cpp_reader *pfile, _cpp_file *file, bool import)
+{
+  _cpp_file *f;
+
+  /* Skip once-only files.  */
+  if (file->once_only)
+    return false;
+
+  /* We must mark the file once-only if #import now, before header
+     guard checks.  Otherwise, undefining the header guard might
+     cause the file to be re-stacked.  */
+  if (import)
+    {
+      _cpp_mark_file_once_only (pfile, file);
+
+      /* Don't stack files that have been stacked before.  */
+      if (file->stack_count)
+	return false;
+    }
+
+  /* Skip if the file had a header guard and the macro is defined.
+     PCH relies on this appearing before the PCH handler below.  */
+  if (file->cmacro && file->cmacro->type == NT_MACRO)
+    return false;
+
+  /* Handle PCH files immediately; don't stack them.  */
+  if (file->pchname)
+    {
+      pfile->cb.read_pch (pfile, file->pchname, file->fd, file->path);
+      file->fd = -1;
+      free ((void *) file->pchname);
+      file->pchname = NULL;
+      return false;
+    }
+
+  if (!read_file (pfile, file))
+    return false;
+
+  /* Check the file against the PCH file.  This is done before
+     checking against files we've already seen, since it may save on
+     I/O.  */
+  if (check_file_against_entries (pfile, file, import))
+    {
+      /* If this isn't a #import, but yet we can't include the file,
+	 that means that it was #import-ed in the PCH file,
+	 so we can never include it again.  */
+      if (! import)
+	_cpp_mark_file_once_only (pfile, file);
+      return false;
+    }
+
+  /* Now we've read the file's contents, we can stack it if there
+     are no once-only files.  */
+  if (!pfile->seen_once_only)
+    return true;
+
+  /* We may have read the file under a different name.  Look
+     for likely candidates and compare file contents to be sure.  */
+  for (f = pfile->all_files; f; f = f->next_file)
+    {
+      if (f == file)
+	continue;
+
+      if ((import || f->once_only)
+	  && f->err_no == 0
+	  && f->st.st_mtime == file->st.st_mtime
+	  && f->st.st_size == file->st.st_size)
+	{
+	  _cpp_file *ref_file;
+	  bool same_file_p = false;
+
+	  if (f->buffer && !f->buffer_valid)
+	    {
+	      /* We already have a buffer but it is not valid, because
+		 the file is still stacked.  Make a new one.  */
+	      ref_file = make_cpp_file (pfile, f->dir, f->name);
+	      ref_file->path = f->path;
+	    }
+	  else
+	    /* The file is not stacked anymore.  We can reuse it.  */
+	    ref_file = f;
+
+	  same_file_p = read_file (pfile, ref_file)
+			/* Size might have changed in read_file().  */
+			&& ref_file->st.st_size == file->st.st_size
+			&& !memcmp (ref_file->buffer,
+				    file->buffer,
+				    file->st.st_size);
+
+	  if (f->buffer && !f->buffer_valid)
+	    {
+	      ref_file->path = 0;
+	      destroy_cpp_file (ref_file);
+	    }
+
+	  if (same_file_p)
+	    break;
+	}
+    }
+
+  return f == NULL;
+}
+
+/* Place the file referenced by FILE into a new buffer on the buffer
+   stack if possible.  IMPORT is true if this stacking attempt is
+   because of a #import directive.  Returns true if a buffer is
+   stacked.  */
+bool
+_cpp_stack_file (cpp_reader *pfile, _cpp_file *file, bool import)
+{
+  cpp_buffer *buffer;
+  int sysp;
+
+  if (!should_stack_file (pfile, file, import))
+      return false;
+
+  if (pfile->buffer == NULL || file->dir == NULL)
+    sysp = 0;
+  else
+    sysp = MAX (pfile->buffer->sysp,  file->dir->sysp);
+
+  /* Add the file to the dependencies on its first inclusion.  */
+  if (CPP_OPTION (pfile, deps.style) > !!sysp && !file->stack_count)
+    {
+      if (!file->main_file || !CPP_OPTION (pfile, deps.ignore_main_file))
+	deps_add_dep (pfile->deps, file->path);
+    }
+
+  /* Clear buffer_valid since _cpp_clean_line messes it up.  */
+  file->buffer_valid = false;
+  file->stack_count++;
+
+  /* Stack the buffer.  */
+  buffer = cpp_push_buffer (pfile, file->buffer, file->st.st_size,
+			    CPP_OPTION (pfile, preprocessed)
+			    && !CPP_OPTION (pfile, directives_only));
+  buffer->file = file;
+  buffer->sysp = sysp;
+
+  /* Initialize controlling macro state.  */
+  pfile->mi_valid = true;
+  pfile->mi_cmacro = 0;
+
+  /* Generate the call back.  */
+  _cpp_do_file_change (pfile, LC_ENTER, file->path, 1, sysp);
+
+  return true;
+}
+
+/* Mark FILE to be included once only.  */
+void
+_cpp_mark_file_once_only (cpp_reader *pfile, _cpp_file *file)
+{
+  pfile->seen_once_only = true;
+  file->once_only = true;
+}
+
+/* Return the directory from which searching for FNAME should start,
+   considering the directive TYPE and ANGLE_BRACKETS.  If there is
+   nothing left in the path, returns NULL.  */
+static struct cpp_dir *
+search_path_head (cpp_reader *pfile, const char *fname, int angle_brackets,
+		  enum include_type type)
+{
+  cpp_dir *dir;
+  _cpp_file *file;
+
+  if (IS_ABSOLUTE_PATH (fname))
+    return &pfile->no_search_path;
+
+  /* pfile->buffer is NULL when processing an -include command-line flag.  */
+  file = pfile->buffer == NULL ? pfile->main_file : pfile->buffer->file;
+
+  /* For #include_next, skip in the search path past the dir in which
+     the current file was found, but if it was found via an absolute
+     path use the normal search logic.  */
+  if (type == IT_INCLUDE_NEXT && file->dir
+      && file->dir != &pfile->no_search_path)
+    dir = file->dir->next;
+  else if (angle_brackets)
+    dir = pfile->bracket_include;
+  else if (type == IT_CMDLINE)
+    /* -include and -imacros use the #include "" chain with the
+       preprocessor's cwd prepended.  */
+    return make_cpp_dir (pfile, "./", false);
+  else if (pfile->quote_ignores_source_dir)
+    dir = pfile->quote_include;
+  else
+    return make_cpp_dir (pfile, dir_name_of_file (file),
+			 pfile->buffer ? pfile->buffer->sysp : 0);
+
+  if (dir == NULL)
+    cpp_error (pfile, CPP_DL_ERROR,
+	       "no include path in which to search for %s", fname);
+
+  return dir;
+}
+
+/* Strip the basename from the file's path.  It ends with a slash if
+   of nonzero length.  Note that this procedure also works for
+   <stdin>, which is represented by the empty string.  */
+static const char *
+dir_name_of_file (_cpp_file *file)
+{
+  if (!file->dir_name)
+    {
+      size_t len = lbasename (file->path) - file->path;
+      char *dir_name = XNEWVEC (char, len + 1);
+
+      memcpy (dir_name, file->path, len);
+      dir_name[len] = '\0';
+      file->dir_name = dir_name;
+    }
+
+  return file->dir_name;
+}
+
+/* Handles #include-family directives (distinguished by TYPE),
+   including HEADER, and the command line -imacros and -include.
+   Returns true if a buffer was stacked.  */
+bool
+_cpp_stack_include (cpp_reader *pfile, const char *fname, int angle_brackets,
+		    enum include_type type)
+{
+  struct cpp_dir *dir;
+  _cpp_file *file;
+
+  dir = search_path_head (pfile, fname, angle_brackets, type);
+  if (!dir)
+    return false;
+
+  file = _cpp_find_file (pfile, fname, dir, false, angle_brackets);
+
+  /* Compensate for the increment in linemap_add.  In the case of a
+     normal #include, we're currently at the start of the line
+     *following* the #include.  A separate source_location for this
+     location makes no sense (until we do the LC_LEAVE), and
+     complicates LAST_SOURCE_LINE_LOCATION.  This does not apply if we
+     found a PCH file (in which case linemap_add is not called) or we
+     were included from the command-line.  */
+  if (file->pchname == NULL && file->err_no == 0 && type != IT_CMDLINE)
+    pfile->line_table->highest_location--;
+
+  return _cpp_stack_file (pfile, file, type == IT_IMPORT);
+}
+
+/* Could not open FILE.  The complication is dependency output.  */
+static void
+open_file_failed (cpp_reader *pfile, _cpp_file *file, int angle_brackets)
+{
+  int sysp = pfile->line_table->highest_line > 1 && pfile->buffer ? pfile->buffer->sysp : 0;
+  bool print_dep = CPP_OPTION (pfile, deps.style) > (angle_brackets || !!sysp);
+
+  errno = file->err_no;
+  if (print_dep && CPP_OPTION (pfile, deps.missing_files) && errno == ENOENT)
+    deps_add_dep (pfile->deps, file->name);
+  else
+    {
+      /* If we are outputting dependencies but not for this file then
+	 don't error because we can still produce correct output.  */
+      if (CPP_OPTION (pfile, deps.style) && ! print_dep)
+	cpp_errno (pfile, CPP_DL_WARNING, file->path);
+      else
+	cpp_errno (pfile, CPP_DL_ERROR, file->path);
+    }
+}
+
+/* Search in the chain beginning at HEAD for a file whose search path
+   started at START_DIR != NULL.  */
+static struct file_hash_entry *
+search_cache (struct file_hash_entry *head, const cpp_dir *start_dir)
+{
+  while (head && head->start_dir != start_dir)
+    head = head->next;
+
+  return head;
+}
+
+/* Allocate a new _cpp_file structure.  */
+static _cpp_file *
+make_cpp_file (cpp_reader *pfile, cpp_dir *dir, const char *fname)
+{
+  _cpp_file *file;
+
+  file = XCNEW (_cpp_file);
+  file->main_file = !pfile->buffer;
+  file->fd = -1;
+  file->dir = dir;
+  file->name = xstrdup (fname);
+
+  return file;
+}
+
+/* Release a _cpp_file structure.  */
+static void
+destroy_cpp_file (_cpp_file *file)
+{
+  if (file->buffer_start)
+    free ((void *) file->buffer_start);
+  free ((void *) file->name);
+  free (file);
+}
+
+/* Release all the files allocated by this reader.  */
+static void
+destroy_all_cpp_files (cpp_reader *pfile)
+{
+  _cpp_file *iter = pfile->all_files;
+  while (iter)
+    {
+      _cpp_file *next = iter->next_file;
+      destroy_cpp_file (iter);
+      iter = next;
+    }
+}
+
+/* A hash of directory names.  The directory names are the path names
+   of files which contain a #include "", the included file name is
+   appended to this directories.
+
+   To avoid duplicate entries we follow the convention that all
+   non-empty directory names should end in a '/'.  DIR_NAME must be
+   stored in permanently allocated memory.  */
+static cpp_dir *
+make_cpp_dir (cpp_reader *pfile, const char *dir_name, int sysp)
+{
+  struct file_hash_entry *entry, **hash_slot;
+  cpp_dir *dir;
+
+  hash_slot = (struct file_hash_entry **)
+    htab_find_slot_with_hash (pfile->dir_hash, dir_name,
+			      htab_hash_string (dir_name),
+			      INSERT);
+
+  /* Have we already hashed this directory?  */
+  for (entry = *hash_slot; entry; entry = entry->next)
+    if (entry->start_dir == NULL)
+      return entry->u.dir;
+
+  dir = XCNEW (cpp_dir);
+  dir->next = pfile->quote_include;
+  dir->name = (char *) dir_name;
+  dir->len = strlen (dir_name);
+  dir->sysp = sysp;
+  dir->construct = 0;
+
+  /* Store this new result in the hash table.  */
+  entry = new_file_hash_entry (pfile);
+  entry->next = *hash_slot;
+  entry->start_dir = NULL;
+  entry->location = pfile->line_table->highest_location;
+  entry->u.dir = dir;
+  *hash_slot = entry;
+
+  return dir;
+}
+
+/* Create a new block of memory for file hash entries.  */
+static void
+allocate_file_hash_entries (cpp_reader *pfile)
+{
+  struct file_hash_entry_pool *pool = XNEW (struct file_hash_entry_pool);
+  pool->file_hash_entries_used = 0;
+  pool->next = pfile->file_hash_entries;
+  pfile->file_hash_entries = pool;
+}
+
+/* Return a new file hash entry.  */
+static struct file_hash_entry *
+new_file_hash_entry (cpp_reader *pfile)
+{
+  unsigned int idx;
+  if (pfile->file_hash_entries->file_hash_entries_used == FILE_HASH_POOL_SIZE)
+    allocate_file_hash_entries (pfile);
+
+  idx = pfile->file_hash_entries->file_hash_entries_used++;
+  return &pfile->file_hash_entries->pool[idx];
+}
+
+/* Free the file hash entry pools.  */
+static void
+free_file_hash_entries (cpp_reader *pfile)
+{
+  struct file_hash_entry_pool *iter = pfile->file_hash_entries;
+  while (iter)
+    {
+      struct file_hash_entry_pool *next = iter->next;
+      free (iter);
+      iter = next;
+    }
+}
+
+/* Returns TRUE if a file FNAME has ever been successfully opened.
+   This routine is not intended to correctly handle filenames aliased
+   by links or redundant . or .. traversals etc.  */
+bool
+cpp_included (cpp_reader *pfile, const char *fname)
+{
+  struct file_hash_entry *entry;
+
+  entry = (struct file_hash_entry *)
+     htab_find_with_hash (pfile->file_hash, fname, htab_hash_string (fname));
+
+  while (entry && (entry->start_dir == NULL || entry->u.file->err_no))
+    entry = entry->next;
+
+  return entry != NULL;
+}
+
+/* Returns TRUE if a file FNAME has ever been successfully opened
+   before LOCATION.  This routine is not intended to correctly handle
+   filenames aliased by links or redundant . or .. traversals etc.  */
+bool
+cpp_included_before (cpp_reader *pfile, const char *fname,
+		     source_location location)
+{
+  struct file_hash_entry *entry;
+
+  entry = (struct file_hash_entry *)
+     htab_find_with_hash (pfile->file_hash, fname, htab_hash_string (fname));
+
+  while (entry && (entry->start_dir == NULL || entry->u.file->err_no
+		   || entry->location > location))
+    entry = entry->next;
+
+  return entry != NULL;
+}
+
+/* Calculate the hash value of a file hash entry P.  */
+
+static hashval_t
+file_hash_hash (const void *p)
+{
+  struct file_hash_entry *entry = (struct file_hash_entry *) p;
+  const char *hname;
+  if (entry->start_dir)
+    hname = entry->u.file->name;
+  else
+    hname = entry->u.dir->name;
+
+  return htab_hash_string (hname);
+}
+
+/* Compare a string Q against a file hash entry P.  */
+static int
+file_hash_eq (const void *p, const void *q)
+{
+  struct file_hash_entry *entry = (struct file_hash_entry *) p;
+  const char *fname = (const char *) q;
+  const char *hname;
+
+  if (entry->start_dir)
+    hname = entry->u.file->name;
+  else
+    hname = entry->u.dir->name;
+
+  return strcmp (hname, fname) == 0;
+}
+
+/* Compare entries in the nonexistent file hash table.  These are just
+   strings.  */
+static int
+nonexistent_file_hash_eq (const void *p, const void *q)
+{
+  return strcmp (p, q) == 0;
+}
+
+/* Initialize everything in this source file.  */
+void
+_cpp_init_files (cpp_reader *pfile)
+{
+  pfile->file_hash = htab_create_alloc (127, file_hash_hash, file_hash_eq,
+					NULL, xcalloc, free);
+  pfile->dir_hash = htab_create_alloc (127, file_hash_hash, file_hash_eq,
+					NULL, xcalloc, free);
+  allocate_file_hash_entries (pfile);
+  pfile->nonexistent_file_hash = htab_create_alloc (127, htab_hash_string,
+						    nonexistent_file_hash_eq,
+						    NULL, xcalloc, free);
+  _obstack_begin (&pfile->nonexistent_file_ob, 0, 0,
+		  (void *(*) (long)) xmalloc,
+		  (void (*) (void *)) free);
+}
+
+/* Finalize everything in this source file.  */
+void
+_cpp_cleanup_files (cpp_reader *pfile)
+{
+  htab_delete (pfile->file_hash);
+  htab_delete (pfile->dir_hash);
+  htab_delete (pfile->nonexistent_file_hash);
+  obstack_free (&pfile->nonexistent_file_ob, 0);
+  free_file_hash_entries (pfile);
+  destroy_all_cpp_files (pfile);
+}
+
+/* Make the parser forget about files it has seen.  This can be useful
+   for resetting the parser to start another run.  */
+void
+cpp_clear_file_cache (cpp_reader *pfile)
+{
+  _cpp_cleanup_files (pfile);
+  pfile->file_hash_entries = NULL;
+  pfile->all_files = NULL;
+  _cpp_init_files (pfile);
+}
+
+/* Enter a file name in the hash for the sake of cpp_included.  */
+void
+_cpp_fake_include (cpp_reader *pfile, const char *fname)
+{
+  _cpp_find_file (pfile, fname, pfile->buffer->file->dir, true, 0);
+}
+
+/* Not everyone who wants to set system-header-ness on a buffer can
+   see the details of a buffer.  This is an exported interface because
+   fix-header needs it.  */
+void
+cpp_make_system_header (cpp_reader *pfile, int syshdr, int externc)
+{
+  int flags = 0;
+  const struct line_maps *line_table = pfile->line_table;
+  const struct line_map *map = &line_table->maps[line_table->used-1];
+
+  /* 1 = system header, 2 = system header to be treated as C.  */
+  if (syshdr)
+    flags = 1 + (externc != 0);
+  pfile->buffer->sysp = flags;
+  _cpp_do_file_change (pfile, LC_RENAME, map->to_file,
+		       SOURCE_LINE (map, pfile->line_table->highest_line), flags);
+}
+
+/* Allow the client to change the current file.  Used by the front end
+   to achieve pseudo-file names like <built-in>.
+   If REASON is LC_LEAVE, then NEW_NAME must be NULL.  */
+void
+cpp_change_file (cpp_reader *pfile, enum lc_reason reason,
+		 const char *new_name)
+{
+  _cpp_do_file_change (pfile, reason, new_name, 1, 0);
+}
+
+struct report_missing_guard_data
+{
+  const char **paths;
+  size_t count;
+};
+
+/* Callback function for htab_traverse.  */
+static int
+report_missing_guard (void **slot, void *d)
+{
+  struct file_hash_entry *entry = (struct file_hash_entry *) *slot;
+  struct report_missing_guard_data *data
+    = (struct report_missing_guard_data *) d;
+
+  /* Skip directories.  */
+  if (entry->start_dir != NULL)
+    {
+      _cpp_file *file = entry->u.file;
+
+      /* We don't want MI guard advice for the main file.  */
+      if (file->cmacro == NULL && file->stack_count == 1 && !file->main_file)
+	{
+	  if (data->paths == NULL)
+	    {
+	      data->paths = XCNEWVEC (const char *, data->count);
+	      data->count = 0;
+	    }
+
+	  data->paths[data->count++] = file->path;
+	}
+    }
+
+  /* Keep traversing the hash table.  */
+  return 1;
+}
+
+/* Comparison function for qsort.  */
+static int
+report_missing_guard_cmp (const void *p1, const void *p2)
+{
+  return strcmp (*(const char *const *) p1, *(const char *const *) p2);
+}
+
+/* Report on all files that might benefit from a multiple include guard.
+   Triggered by -H.  */
+void
+_cpp_report_missing_guards (cpp_reader *pfile)
+{
+  struct report_missing_guard_data data;
+
+  data.paths = NULL;
+  data.count = htab_elements (pfile->file_hash);
+  htab_traverse (pfile->file_hash, report_missing_guard, &data);
+
+  if (data.paths != NULL)
+    {
+      size_t i;
+
+      /* Sort the paths to avoid outputting them in hash table
+	 order.  */
+      qsort (data.paths, data.count, sizeof (const char *),
+	     report_missing_guard_cmp);
+      fputs (_("Multiple include guards may be useful for:\n"),
+	     stderr);
+      for (i = 0; i < data.count; i++)
+	{
+	  fputs (data.paths[i], stderr);
+	  putc ('\n', stderr);
+	}
+      free (data.paths);
+    }
+}
+
+/* Locate HEADER, and determine whether it is newer than the current
+   file.  If it cannot be located or dated, return -1, if it is
+   newer, return 1, otherwise 0.  */
+int
+_cpp_compare_file_date (cpp_reader *pfile, const char *fname,
+			int angle_brackets)
+{
+  _cpp_file *file;
+  struct cpp_dir *dir;
+
+  dir = search_path_head (pfile, fname, angle_brackets, IT_INCLUDE);
+  if (!dir)
+    return -1;
+
+  file = _cpp_find_file (pfile, fname, dir, false, angle_brackets);
+  if (file->err_no)
+    return -1;
+
+  if (file->fd != -1)
+    {
+      close (file->fd);
+      file->fd = -1;
+    }
+
+  return file->st.st_mtime > pfile->buffer->file->st.st_mtime;
+}
+
+/* Pushes the given file onto the buffer stack.  Returns nonzero if
+   successful.  */
+bool
+cpp_push_include (cpp_reader *pfile, const char *fname)
+{
+  return _cpp_stack_include (pfile, fname, false, IT_CMDLINE);
+}
+
+/* Do appropriate cleanup when a file INC's buffer is popped off the
+   input stack.  */
+void
+_cpp_pop_file_buffer (cpp_reader *pfile, _cpp_file *file)
+{
+  /* Record the inclusion-preventing macro, which could be NULL
+     meaning no controlling macro.  */
+  if (pfile->mi_valid && file->cmacro == NULL)
+    file->cmacro = pfile->mi_cmacro;
+
+  /* Invalidate control macros in the #including file.  */
+  pfile->mi_valid = false;
+
+  if (file->buffer_start)
+    {
+      free ((void *) file->buffer_start);
+      file->buffer_start = NULL;
+      file->buffer = NULL;
+      file->buffer_valid = false;
+    }
+}
+
+/* Inteface to file statistics record in _cpp_file structure. */
+struct stat *
+_cpp_get_file_stat (_cpp_file *file)
+{
+    return &file->st;
+}
+
+/* Set the include chain for "" to QUOTE, for <> to BRACKET.  If
+   QUOTE_IGNORES_SOURCE_DIR, then "" includes do not look in the
+   directory of the including file.
+
+   If BRACKET does not lie in the QUOTE chain, it is set to QUOTE.  */
+void
+cpp_set_include_chains (cpp_reader *pfile, cpp_dir *quote, cpp_dir *bracket,
+			int quote_ignores_source_dir)
+{
+  pfile->quote_include = quote;
+  pfile->bracket_include = quote;
+  pfile->quote_ignores_source_dir = quote_ignores_source_dir;
+
+  for (; quote; quote = quote->next)
+    {
+      quote->name_map = NULL;
+      quote->len = strlen (quote->name);
+      if (quote == bracket)
+	pfile->bracket_include = bracket;
+    }
+}
+
+/* Append the file name to the directory to create the path, but don't
+   turn / into // or // into ///; // may be a namespace escape.  */
+static char *
+append_file_to_dir (const char *fname, cpp_dir *dir)
+{
+  size_t dlen, flen;
+  char *path;
+
+  dlen = dir->len;
+  flen = strlen (fname);
+  path = XNEWVEC (char, dlen + 1 + flen + 1);
+  memcpy (path, dir->name, dlen);
+  if (dlen && path[dlen - 1] != '/')
+    path[dlen++] = '/';
+  memcpy (&path[dlen], fname, flen + 1);
+
+  return path;
+}
+
+/* Read a space delimited string of unlimited length from a stdio
+   file F.  */
+static char *
+read_filename_string (int ch, FILE *f)
+{
+  char *alloc, *set;
+  int len;
+
+  len = 20;
+  set = alloc = XNEWVEC (char, len + 1);
+  if (! is_space (ch))
+    {
+      *set++ = ch;
+      while ((ch = getc (f)) != EOF && ! is_space (ch))
+	{
+	  if (set - alloc == len)
+	    {
+	      len *= 2;
+	      alloc = XRESIZEVEC (char, alloc, len + 1);
+	      set = alloc + len / 2;
+	    }
+	  *set++ = ch;
+	}
+    }
+  *set = '\0';
+  ungetc (ch, f);
+  return alloc;
+}
+
+/* Read the file name map file for DIR.  */
+static void
+read_name_map (cpp_dir *dir)
+{
+  static const char FILE_NAME_MAP_FILE[] = "header.gcc";
+  char *name;
+  FILE *f;
+  size_t len, count = 0, room = 9;
+
+  len = dir->len;
+  name = (char *) alloca (len + sizeof (FILE_NAME_MAP_FILE) + 1);
+  memcpy (name, dir->name, len);
+  if (len && name[len - 1] != '/')
+    name[len++] = '/';
+  strcpy (name + len, FILE_NAME_MAP_FILE);
+  f = fopen (name, "r");
+
+  dir->name_map = XNEWVEC (const char *, room);
+
+  /* Silently return NULL if we cannot open.  */
+  if (f)
+    {
+      int ch;
+
+      while ((ch = getc (f)) != EOF)
+	{
+	  char *to;
+
+	  if (is_space (ch))
+	    continue;
+
+	  if (count + 2 > room)
+	    {
+	      room += 8;
+	      dir->name_map = XRESIZEVEC (const char *, dir->name_map, room);
+	    }
+
+	  dir->name_map[count] = read_filename_string (ch, f);
+	  while ((ch = getc (f)) != EOF && is_hspace (ch))
+	    ;
+
+	  to = read_filename_string (ch, f);
+	  if (IS_ABSOLUTE_PATH (to))
+	    dir->name_map[count + 1] = to;
+	  else
+	    {
+	      dir->name_map[count + 1] = append_file_to_dir (to, dir);
+	      free (to);
+	    }
+
+	  count += 2;
+	  while ((ch = getc (f)) != '\n')
+	    if (ch == EOF)
+	      break;
+	}
+
+      fclose (f);
+    }
+
+  /* Terminate the list of maps.  */
+  dir->name_map[count] = NULL;
+}
+
+/* Remap a FILE's name based on the file_name_map, if any, for
+   FILE->dir.  If the file name has any directory separators,
+   recursively check those directories too.  */
+static char *
+remap_filename (cpp_reader *pfile, _cpp_file *file)
+{
+  const char *fname, *p;
+  char *new_dir;
+  cpp_dir *dir;
+  size_t index, len;
+
+  dir = file->dir;
+  fname = file->name;
+
+  for (;;)
+    {
+      if (!dir->name_map)
+	read_name_map (dir);
+
+      for (index = 0; dir->name_map[index]; index += 2)
+	if (!strcmp (dir->name_map[index], fname))
+	    return xstrdup (dir->name_map[index + 1]);
+
+      p = strchr (fname, '/');
+      if (!p || p == fname)
+	return NULL;
+
+      len = dir->len + (p - fname + 1);
+      new_dir = XNEWVEC (char, len + 1);
+      memcpy (new_dir, dir->name, dir->len);
+      memcpy (new_dir + dir->len, fname, p - fname + 1);
+      new_dir[len] = '\0';
+
+      dir = make_cpp_dir (pfile, new_dir, dir->sysp);
+      fname = p + 1;
+    }
+}
+
+/* Returns true if PCHNAME is a valid PCH file for FILE.  */
+static bool
+validate_pch (cpp_reader *pfile, _cpp_file *file, const char *pchname)
+{
+  const char *saved_path = file->path;
+  bool valid = false;
+
+  file->path = pchname;
+  if (open_file (file))
+    {
+      valid = 1 & pfile->cb.valid_pch (pfile, pchname, file->fd);
+
+      if (!valid)
+	{
+	  close (file->fd);
+	  file->fd = -1;
+	}
+
+      if (CPP_OPTION (pfile, print_include_names))
+	{
+	  unsigned int i;
+	  for (i = 1; i < pfile->line_table->depth; i++)
+	    putc ('.', stderr);
+	  fprintf (stderr, "%c %s\n",
+		   valid ? '!' : 'x', pchname);
+	}
+    }
+
+  file->path = saved_path;
+  return valid;
+}
+
+/* Get the path associated with the _cpp_file F.  The path includes
+   the base name from the include directive and the directory it was
+   found in via the search path.  */
+
+const char *
+cpp_get_path (struct _cpp_file *f)
+{
+  return f->path;
+}
+
+/* Get the directory associated with the _cpp_file F.  */
+
+cpp_dir *
+cpp_get_dir (struct _cpp_file *f)
+{
+  return f->dir;
+}
+
+/* Get the cpp_buffer currently associated with the cpp_reader
+   PFILE.  */
+
+cpp_buffer *
+cpp_get_buffer (cpp_reader *pfile)
+{
+  return pfile->buffer;
+}
+
+/* Get the _cpp_file associated with the cpp_buffer B.  */
+
+_cpp_file *
+cpp_get_file (cpp_buffer *b)
+{
+  return b->file;
+}
+
+/* Get the previous cpp_buffer given a cpp_buffer B.  The previous
+   buffer is the buffer that included the given buffer.  */
+
+cpp_buffer *
+cpp_get_prev (cpp_buffer *b)
+{
+  return b->prev;
+}
+
+/* This data structure holds the list of header files that were seen
+   while the PCH was being built.  The 'entries' field is kept sorted
+   in memcmp() order; yes, this means that on little-endian systems,
+   it's sorted initially by the least-significant byte of 'size', but
+   that's OK.  The code does rely on having entries with the same size
+   next to each other.  */
+
+struct pchf_entry {
+  /* The size of this file.  This is used to save running a MD5 checksum
+     if the sizes don't match.  */
+  off_t size;
+  /* The MD5 checksum of this file.  */
+  unsigned char sum[16];
+  /* Is this file to be included only once?  */
+  bool once_only;
+};
+
+struct pchf_data {
+  /* Number of pchf_entry structures.  */
+  size_t count;
+
+  /* Are there any values with once_only set?
+     This is used as an optimisation, it means we don't have to search
+     the structure if we're processing a regular #include.  */
+  bool have_once_only;
+
+  struct pchf_entry entries[1];
+};
+
+static struct pchf_data *pchf;
+
+/* A qsort ordering function for pchf_entry structures.  */
+
+static int
+pchf_save_compare (const void *e1, const void *e2)
+{
+  return memcmp (e1, e2, sizeof (struct pchf_entry));
+}
+
+/* Create and write to F a pchf_data structure.  */
+
+bool
+_cpp_save_file_entries (cpp_reader *pfile, FILE *fp)
+{
+  size_t count = 0;
+  struct pchf_data *result;
+  size_t result_size;
+  _cpp_file *f;
+
+  for (f = pfile->all_files; f; f = f->next_file)
+    ++count;
+
+  result_size = (sizeof (struct pchf_data)
+		 + sizeof (struct pchf_entry) * (count - 1));
+  result = XCNEWVAR (struct pchf_data, result_size);
+
+  result->count = 0;
+  result->have_once_only = false;
+
+  for (f = pfile->all_files; f; f = f->next_file)
+    {
+      size_t count;
+
+      /* This should probably never happen, since if a read error occurred
+	 the PCH file shouldn't be written...  */
+      if (f->dont_read || f->err_no)
+	continue;
+
+      if (f->stack_count == 0)
+	continue;
+
+      count = result->count++;
+
+      result->entries[count].once_only = f->once_only;
+      /* |= is avoided in the next line because of an HP C compiler bug */
+      result->have_once_only = result->have_once_only | f->once_only;
+      if (f->buffer_valid)
+	md5_buffer ((const char *)f->buffer,
+		    f->st.st_size, result->entries[count].sum);
+      else
+	{
+	  FILE *ff;
+	  int oldfd = f->fd;
+
+	  if (!open_file (f))
+	    {
+	      open_file_failed (pfile, f, 0);
+	      return false;
+	    }
+	  ff = fdopen (f->fd, "rb");
+	  md5_stream (ff, result->entries[count].sum);
+	  fclose (ff);
+	  f->fd = oldfd;
+	}
+      result->entries[count].size = f->st.st_size;
+    }
+
+  result_size = (sizeof (struct pchf_data)
+                 + sizeof (struct pchf_entry) * (result->count - 1));
+
+  qsort (result->entries, result->count, sizeof (struct pchf_entry),
+	 pchf_save_compare);
+
+  return fwrite (result, result_size, 1, fp) == 1;
+}
+
+/* Read the pchf_data structure from F.  */
+
+bool
+_cpp_read_file_entries (cpp_reader *pfile ATTRIBUTE_UNUSED, FILE *f)
+{
+  struct pchf_data d;
+
+  if (fread (&d, sizeof (struct pchf_data) - sizeof (struct pchf_entry), 1, f)
+       != 1)
+    return false;
+
+  pchf = XNEWVAR (struct pchf_data, sizeof (struct pchf_data)
+		  + sizeof (struct pchf_entry) * (d.count - 1));
+  memcpy (pchf, &d, sizeof (struct pchf_data) - sizeof (struct pchf_entry));
+  if (fread (pchf->entries, sizeof (struct pchf_entry), d.count, f)
+      != d.count)
+    return false;
+  return true;
+}
+
+/* The parameters for pchf_compare.  */
+
+struct pchf_compare_data
+{
+  /* The size of the file we're looking for.  */
+  off_t size;
+
+  /* The MD5 checksum of the file, if it's been computed.  */
+  unsigned char sum[16];
+
+  /* Is SUM valid?  */
+  bool sum_computed;
+
+  /* Do we need to worry about entries that don't have ONCE_ONLY set?  */
+  bool check_included;
+
+  /* The file that we're searching for.  */
+  _cpp_file *f;
+};
+
+/* bsearch comparison function; look for D_P in E_P.  */
+
+static int
+pchf_compare (const void *d_p, const void *e_p)
+{
+  const struct pchf_entry *e = (const struct pchf_entry *)e_p;
+  struct pchf_compare_data *d = (struct pchf_compare_data *)d_p;
+  int result;
+
+  result = memcmp (&d->size, &e->size, sizeof (off_t));
+  if (result != 0)
+    return result;
+
+  if (! d->sum_computed)
+    {
+      _cpp_file *const f = d->f;
+
+      md5_buffer ((const char *)f->buffer, f->st.st_size, d->sum);
+      d->sum_computed = true;
+    }
+
+  result = memcmp (d->sum, e->sum, 16);
+  if (result != 0)
+    return result;
+
+  if (d->check_included || e->once_only)
+    return 0;
+  else
+    return 1;
+}
+
+/* Check that F is not in a list read from a PCH file (if any).
+   Assumes that f->buffer_valid is true.  Return TRUE if the file
+   should not be read.  */
+
+static bool
+check_file_against_entries (cpp_reader *pfile ATTRIBUTE_UNUSED,
+			    _cpp_file *f,
+			    bool check_included)
+{
+  struct pchf_compare_data d;
+
+  if (pchf == NULL
+      || (! check_included && ! pchf->have_once_only))
+    return false;
+
+  d.size = f->st.st_size;
+  d.sum_computed = false;
+  d.f = f;
+  d.check_included = check_included;
+  return bsearch (&d, pchf->entries, pchf->count, sizeof (struct pchf_entry),
+		  pchf_compare) != NULL;
+}