/* Set up combined include path chain for the preprocessor.
   Copyright (C) 1986, 1987, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
   1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.

   Broken out of cppinit.c and cppfiles.c and rewritten Mar 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 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.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "cpplib.h"
#include "prefix.h"
#include "intl.h"
#include "c-incpath.h"
#include "cppdefault.h"

/* Windows does not natively support inodes, and neither does MSDOS.
   Cygwin's emulation can generate non-unique inodes, so don't use it.
   VMS has non-numeric inodes.  */
#ifdef VMS
# define INO_T_EQ(A, B) (!memcmp (&(A), &(B), sizeof (A)))
# define INO_T_COPY(DEST, SRC) memcpy(&(DEST), &(SRC), sizeof (SRC))
#else
# if (defined _WIN32 && ! defined (_UWIN)) || defined __MSDOS__
#  define INO_T_EQ(A, B) 0
# else
#  define INO_T_EQ(A, B) ((A) == (B))
# endif
# define INO_T_COPY(DEST, SRC) (DEST) = (SRC)
#endif

static void add_env_var_paths PARAMS ((const char *, int));
static void add_standard_paths PARAMS ((const char *, const char *, int));
static void free_path PARAMS ((struct cpp_path *, int));
static void merge_include_chains PARAMS ((cpp_reader *, int));
static int remove_component_p PARAMS ((const char *));
static struct cpp_path *
  remove_duplicates PARAMS ((cpp_reader *, struct cpp_path *,
			     struct cpp_path *, struct cpp_path *, int));

/* Include chains heads and tails.  */
static struct cpp_path *heads[4];
static struct cpp_path *tails[4];
static bool quote_ignores_source_dir;
enum { REASON_QUIET = 0, REASON_NOENT, REASON_DUP, REASON_DUP_SYS };

/* Free an element of the include chain, possibly giving a reason.  */
static void
free_path (path, reason)
     struct cpp_path *path;
     int reason;
{
  switch (reason)
    {
    case REASON_DUP:
    case REASON_DUP_SYS:
      fprintf (stderr, _("ignoring duplicate directory \"%s\"\n"), path->name);
      if (reason == REASON_DUP_SYS)
	fprintf (stderr,
 _("  as it is a non-system directory that duplicates a system directory\n"));
      break;

    case REASON_NOENT:
      fprintf (stderr, _("ignoring nonexistent directory \"%s\"\n"),
	       path->name);
      break;

    case REASON_QUIET:
    default:
      break;
    }

  free ((PTR) path->name);
  free (path);
}

/* Read ENV_VAR for a PATH_SEPARATOR-separated list of file names; and
   append all the names to the search path CHAIN.  */
static void
add_env_var_paths (env_var, chain)
     const char *env_var;
     int chain;
{
  char *p, *q, *path;

  GET_ENVIRONMENT (q, env_var);

  if (!q)
    return;

  for (p = q; *q; p = q + 1)
    {
      q = p;
      while (*q != 0 && *q != PATH_SEPARATOR)
	q++;

      if (p == q)
	path = xstrdup (".");
      else
	{
	  path = xmalloc (q - p + 1);
	  memcpy (path, p, q - p);
	  path[q - p] = '\0';
	}

      add_path (path, chain, chain == SYSTEM);
    }
}

/* Append the standard include chain defined in cppdefault.c.  */
static void
add_standard_paths (sysroot, iprefix, cxx_stdinc)
     const char *sysroot, *iprefix;
     int cxx_stdinc;
{
  const struct default_include *p;
  size_t len = 0;

  if (iprefix)
    len = cpp_GCC_INCLUDE_DIR_len;

  for (p = cpp_include_defaults; p->fname; p++)
    {
      if (!p->cplusplus || cxx_stdinc)
	{
	  char *str;

	  /* Should this directory start with the sysroot?  */
	  if (sysroot && p->add_sysroot)
	    str = concat (sysroot, p->fname, NULL);
	  /* Does this directory start with the prefix?  If so, search
	     "translated" versions of GNU directories.  These have
	     /usr/local/lib/gcc... replaced by iprefix.  */
	  else if (len && !strncmp (p->fname, cpp_GCC_INCLUDE_DIR, len))
	    str = concat (iprefix, p->fname + len, NULL);
	  else
	    str = update_path (p->fname, p->component);

	  add_path (str, SYSTEM, p->cxx_aware);
	}
    }
}

/* For each duplicate path in chain HEAD, keep just the first one.
   Remove each path in chain HEAD that also exists in chain SYSTEM.
   Set the NEXT pointer of the last path in the resulting chain to
   JOIN, unless it duplicates JOIN in which case the last path is
   removed.  Return the head of the resulting chain.  Any of HEAD,
   JOIN and SYSTEM can be NULL.  */
static struct cpp_path *
remove_duplicates (pfile, head, system, join, verbose)
     cpp_reader *pfile;
     struct cpp_path *head;
     struct cpp_path *system;
     struct cpp_path *join;
     int verbose;
{
  struct cpp_path **pcur, *tmp, *cur;
  struct stat st;

  for (pcur = &head; *pcur; )
    {
      int reason = REASON_QUIET;

      cur = *pcur;
      simplify_path (cur->name);

      if (stat (cur->name, &st))
	{
	  /* Dirs that don't exist are silently ignored, unless verbose.  */
	  if (errno != ENOENT)
	    cpp_errno (pfile, DL_ERROR, cur->name);
	  else
	    reason = REASON_NOENT;
	}
      else if (!S_ISDIR (st.st_mode))
	cpp_error_with_line (pfile, DL_ERROR, 0, 0,
			     "%s: not a directory", cur->name);
      else
	{
	  INO_T_COPY (cur->ino, st.st_ino);
	  cur->dev  = st.st_dev;

	  /* Remove this one if it is in the system chain.  */
	  reason = REASON_DUP_SYS;
	  for (tmp = system; tmp; tmp = tmp->next)
	    if (INO_T_EQ (tmp->ino, cur->ino) && tmp->dev == cur->dev)
	      break;

	  if (!tmp)
	    {
	      /* Dupicate of something earlier in the same chain?  */
	      reason = REASON_DUP;
	      for (tmp = head; tmp != cur; tmp = tmp->next)
		if (INO_T_EQ (cur->ino, tmp->ino) && cur->dev == tmp->dev)
		  break;

	      if (tmp == cur
		  /* Last in the chain and duplicate of JOIN?  */
		  && !(cur->next == NULL && join
		       && INO_T_EQ (cur->ino, join->ino)
		       && cur->dev == join->dev))
		{
		  /* Unique, so keep this directory.  */
		  pcur = &cur->next;
		  continue;
		}
	    }
	}

      /* Remove this entry from the chain.  */
      *pcur = cur->next;
      free_path (cur, verbose ? reason: REASON_QUIET);
    }

  *pcur = join;
  return head;
}

/* Merge the four include chains together in the order quote, bracket,
   system, after.  Remove duplicate dirs (as determined by
   INO_T_EQ()).

   We can't just merge the lists and then uniquify them because then
   we may lose directories from the <> search path that should be
   there; consider -Ifoo -Ibar -I- -Ifoo -Iquux.  It is however safe
   to treat -Ibar -Ifoo -I- -Ifoo -Iquux as if written -Ibar -I- -Ifoo
   -Iquux.  */
static void
merge_include_chains (pfile, verbose)
     cpp_reader *pfile;
     int verbose;
{
  /* Join the SYSTEM and AFTER chains.  Remove duplicates in the
     resulting SYSTEM chain.  */
  if (heads[SYSTEM])
    tails[SYSTEM]->next = heads[AFTER];
  else
    heads[SYSTEM] = heads[AFTER];
  heads[SYSTEM] = remove_duplicates (pfile, heads[SYSTEM], 0, 0, verbose);

  /* Remove duplicates from BRACKET that are in itself or SYSTEM, and
     join it to SYSTEM.  */
  heads[BRACKET] = remove_duplicates (pfile, heads[BRACKET], heads[SYSTEM],
				      heads[SYSTEM], verbose);

  /* Remove duplicates from QUOTE that are in itself or SYSTEM, and
     join it to BRACKET.  */
  heads[QUOTE] = remove_duplicates (pfile, heads[QUOTE], heads[SYSTEM],
				    heads[BRACKET], verbose);

  /* If verbose, print the list of dirs to search.  */
  if (verbose)
    {
      struct cpp_path *p;

      fprintf (stderr, _("#include \"...\" search starts here:\n"));
      for (p = heads[QUOTE];; p = p->next)
	{
	  if (p == heads[BRACKET])
	    fprintf (stderr, _("#include <...> search starts here:\n"));
	  if (!p)
	    break;
	  fprintf (stderr, " %s\n", p->name);
	}
      fprintf (stderr, _("End of search list.\n"));
    }
}

/* Use given -I paths for #include "..." but not #include <...>, and
   don't search the directory of the present file for #include "...".
   (Note that -I. -I- is not the same as the default setup; -I. uses
   the compiler's working dir.)  */
void
split_quote_chain ()
{
  heads[QUOTE] = heads[BRACKET];
  tails[QUOTE] = tails[BRACKET];
  heads[BRACKET] = NULL;
  tails[BRACKET] = NULL;
  /* This is NOT redundant.  */
  quote_ignores_source_dir = true;
}

/* Add PATH to the include chain CHAIN. PATH must be malloc-ed and
   NUL-terminated.  */
void
add_path (path, chain, cxx_aware)
     char *path;
     int chain;
     int cxx_aware;
{
  struct cpp_path *p;

  p = (struct cpp_path *) xmalloc (sizeof (struct cpp_path));
  p->next = NULL;
  p->name = path;
  if (chain == SYSTEM || chain == AFTER)
    p->sysp = 1 + (cxx_aware != 0);
  else
    p->sysp = 0;

  if (tails[chain])
    tails[chain]->next = p;
  else
    heads[chain] = p;
  tails[chain] = p;
}

/* Exported function to handle include chain merging, duplicate
   removal, and registration with cpplib.  */
void
register_include_chains (pfile, sysroot, iprefix,
			 stdinc, cxx_stdinc, verbose)
     cpp_reader *pfile;
     const char *sysroot, *iprefix;
     int stdinc, cxx_stdinc, verbose;
{
  static const char *const lang_env_vars[] =
    { "C_INCLUDE_PATH", "CPLUS_INCLUDE_PATH",
      "OBJC_INCLUDE_PATH", "OBJCPLUS_INCLUDE_PATH" };
  cpp_options *cpp_opts = cpp_get_options (pfile);
  size_t idx = (cpp_opts->objc ? 2: 0);

  if (cpp_opts->cplusplus)
    idx++;
  else
    cxx_stdinc = false;

  /* CPATH and language-dependent environment variables may add to the
     include chain.  */
  add_env_var_paths ("CPATH", BRACKET);
  add_env_var_paths (lang_env_vars[idx], SYSTEM);

  /* Finally chain on the standard directories.  */
  if (stdinc)
    add_standard_paths (sysroot, iprefix, cxx_stdinc);

  merge_include_chains (pfile, verbose);

  cpp_set_include_chains (pfile, heads[QUOTE], heads[BRACKET],
			  quote_ignores_source_dir);
}

/* Returns true if it is safe to remove the final component of path,
   when it is followed by a ".." component.  We use lstat to avoid
   symlinks if we have it.  If not, we can still catch errors with
   stat ().  */
static int
remove_component_p (path)
     const char *path;
{
  struct stat s;
  int result;

#ifdef HAVE_LSTAT
  result = lstat (path, &s);
#else
  result = stat (path, &s);
#endif

  /* There's no guarantee that errno will be unchanged, even on
     success.  Cygwin's lstat(), for example, will often set errno to
     ENOSYS.  In case of success, reset errno to zero.  */
  if (result == 0)
    errno = 0;

  return result == 0 && S_ISDIR (s.st_mode);
}

/* Simplify a path name in place, deleting redundant components.  This
   reduces OS overhead and guarantees that equivalent paths compare
   the same (modulo symlinks).

   Transforms made:
   foo/bar/../quux	foo/quux
   foo/./bar		foo/bar
   foo//bar		foo/bar
   /../quux		/quux
   //quux		//quux  (POSIX allows leading // as a namespace escape)

   Guarantees no trailing slashes.  All transforms reduce the length
   of the string.  Returns PATH.  errno is 0 if no error occurred;
   nonzero if an error occurred when using stat () or lstat ().  */
void
simplify_path (path)
     char *path ATTRIBUTE_UNUSED;
{
#ifndef VMS
  char *from, *to;
  char *base, *orig_base;
  int absolute = 0;

  errno = 0;
  /* Don't overflow the empty path by putting a '.' in it below.  */
  if (*path == '\0')
    return;

#if defined (HAVE_DOS_BASED_FILE_SYSTEM)
  /* Convert all backslashes to slashes.  */
  for (from = path; *from; from++)
    if (*from == '\\') *from = '/';

  /* Skip over leading drive letter if present.  */
  if (ISALPHA (path[0]) && path[1] == ':')
    from = to = &path[2];
  else
    from = to = path;
#else
  from = to = path;
#endif

  /* Remove redundant leading /s.  */
  if (*from == '/')
    {
      absolute = 1;
      to++;
      from++;
      if (*from == '/')
	{
	  if (*++from == '/')
	    /* 3 or more initial /s are equivalent to 1 /.  */
	    while (*++from == '/');
	  else
	    /* On some hosts // differs from /; Posix allows this.  */
	    to++;
	}
    }

  base = orig_base = to;
  for (;;)
    {
      int move_base = 0;

      while (*from == '/')
	from++;

      if (*from == '\0')
	break;

      if (*from == '.')
	{
	  if (from[1] == '\0')
	    break;
	  if (from[1] == '/')
	    {
	      from += 2;
	      continue;
	    }
	  else if (from[1] == '.' && (from[2] == '/' || from[2] == '\0'))
	    {
	      /* Don't simplify if there was no previous component.  */
	      if (absolute && orig_base == to)
		{
		  from += 2;
		  continue;
		}
	      /* Don't simplify if the previous component was "../",
		 or if an error has already occurred with (l)stat.  */
	      if (base != to && errno == 0)
		{
		  /* We don't back up if it's a symlink.  */
		  *to = '\0';
		  if (remove_component_p (path))
		    {
		      while (to > base && *to != '/')
			to--;
		      from += 2;
		      continue;
		    }
		}
	      move_base = 1;
	    }
	}

      /* Add the component separator.  */
      if (to > orig_base)
	*to++ = '/';

      /* Copy this component until the trailing null or '/'.  */
      while (*from != '\0' && *from != '/')
	*to++ = *from++;

      if (move_base)
	base = to;
    }

  /* Change the empty string to "." so that it is not treated as stdin.
     Null terminate.  */
  if (to == path)
    *to++ = '.';
  *to = '\0';
#else  /* VMS */
  errno = 0;
#endif /* !VMS  */
}