path: root/gcc/prefix.c

/* Utility to update paths from internal to external forms.
   Copyright (C) 1997-2019 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU Library General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at
your option) any later version.

GCC 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

/* This file contains routines to update a path, both to canonicalize
   the directory format and to handle any prefix translation.

   This file must be compiled with -DPREFIX= to specify the "prefix"
   value used by configure.  If a filename does not begin with this
   prefix, it will not be affected other than by directory canonicalization.

   Each caller of 'update_path' may specify both a filename and
   a translation prefix and consist of the name of the package that contains
   the file ("@GCC", "@BINUTIL", "@GNU", etc).

   If the prefix is not specified, the filename will only undergo
   directory canonicalization.

   If it is specified, the string given by PREFIX will be replaced
   by the specified prefix (with a '@' in front unless the prefix begins
   with a '$') and further translation will be done as follows
   until none of the two conditions below are met:

   1) If the filename begins with '@', the string between the '@' and
   the end of the name or the first '/' or directory separator will
   be considered a "key" and looked up as follows:

   -- If this is a Win32 OS, then the Registry will be examined for
      an entry of "key" in

      HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<KEY>

      if found, that value will be used. <KEY> defaults to GCC version
      string, but can be overridden at configuration time.

   -- If not found (or not a Win32 OS), the environment variable
      key_ROOT (the value of "key" concatenated with the constant "_ROOT")
      is tried.  If that fails, then PREFIX (see above) is used.

   2) If the filename begins with a '$', the rest of the string up
   to the end or the first '/' or directory separator will be used
   as an environment variable, whose value will be returned.

   Once all this is done, any '/' will be converted to DIR_SEPARATOR,
   if they are different.

   NOTE:  using resolve_keyed_path under Win32 requires linking with
   advapi32.dll.  */


#include "config.h"
#include "system.h"
#include "coretypes.h"
#if defined(_WIN32) && defined(ENABLE_WIN32_REGISTRY)
#include <windows.h>
#endif
#include "prefix.h"
#include "common/common-target.h"

static const char *std_prefix = PREFIX;

static const char *get_key_value (char *);
static char *translate_name (char *);
static char *save_string (const char *, int);
static void tr (char *, int, int);

#if defined(_WIN32) && defined(ENABLE_WIN32_REGISTRY)
static char *lookup_key (char *);
static HKEY reg_key = (HKEY) INVALID_HANDLE_VALUE;
#endif

/* Given KEY, as above, return its value.  */

static const char *
get_key_value (char *key)
{
  const char *prefix = 0;
  char *temp = 0;

#if defined(_WIN32) && defined(ENABLE_WIN32_REGISTRY)
  prefix = lookup_key (key);
#endif

  if (prefix == 0)
    prefix = getenv (temp = concat (key, "_ROOT", NULL));

  if (prefix == 0)
    prefix = std_prefix;

  free (temp);

  return prefix;
}

/* Return a copy of a string that has been placed in the heap.  */

static char *
save_string (const char *s, int len)
{
  char *result = XNEWVEC (char, len + 1);

  memcpy (result, s, len);
  result[len] = 0;
  return result;
}

#if defined(_WIN32) && defined(ENABLE_WIN32_REGISTRY)

#ifndef WIN32_REGISTRY_KEY
# define WIN32_REGISTRY_KEY BASEVER
#endif

/* Look up "key" in the registry, as above.  */

static char *
lookup_key (char *key)
{
  char *dst;
  DWORD size;
  DWORD type;
  LONG res;

  if (reg_key == (HKEY) INVALID_HANDLE_VALUE)
    {
      res = RegOpenKeyExA (HKEY_LOCAL_MACHINE, "SOFTWARE", 0,
			   KEY_READ, &reg_key);

      if (res == ERROR_SUCCESS)
	res = RegOpenKeyExA (reg_key, "Free Software Foundation", 0,
			     KEY_READ, &reg_key);

      if (res == ERROR_SUCCESS)
	res = RegOpenKeyExA (reg_key, WIN32_REGISTRY_KEY, 0,
			     KEY_READ, &reg_key);

      if (res != ERROR_SUCCESS)
	{
	  reg_key = (HKEY) INVALID_HANDLE_VALUE;
	  return 0;
	}
    }

  size = 32;
  dst = XNEWVEC (char, size);

  res = RegQueryValueExA (reg_key, key, 0, &type, (LPBYTE) dst, &size);
  if (res == ERROR_MORE_DATA && type == REG_SZ)
    {
      dst = XRESIZEVEC (char, dst, size);
      res = RegQueryValueExA (reg_key, key, 0, &type, (LPBYTE) dst, &size);
    }

  if (type != REG_SZ || res != ERROR_SUCCESS)
    {
      free (dst);
      dst = 0;
    }

  return dst;
}
#endif

/* If NAME, a malloc-ed string, starts with a '@' or '$', apply the
   translation rules above and return a newly malloc-ed name.
   Otherwise, return the given name.  */

static char *
translate_name (char *name)
{
  char code;
  char *key, *old_name;
  const char *prefix;
  int keylen;

  for (;;)
    {
      code = name[0];
      if (code != '@' && code != '$')
	break;

      for (keylen = 0;
	   (name[keylen + 1] != 0 && !IS_DIR_SEPARATOR (name[keylen + 1]));
	   keylen++)
	;

      key = (char *) alloca (keylen + 1);
      memcpy (key, &name[1], keylen);
      key[keylen] = 0;

      if (code == '@')
	{
	  prefix = get_key_value (key);
	  if (prefix == 0)
	    prefix = std_prefix;
	}
      else
	prefix = getenv (key);

      if (prefix == 0)
	prefix = PREFIX;

      /* We used to strip trailing DIR_SEPARATORs here, but that can
	 sometimes yield a result with no separator when one was coded
	 and intended by the user, causing two path components to run
	 together.  */

      old_name = name;
      name = concat (prefix, &name[keylen + 1], NULL);
      free (old_name);
    }

  return name;
}

/* In a NUL-terminated STRING, replace character C1 with C2 in-place.  */
static void
tr (char *string, int c1, int c2)
{
  do
    {
      if (*string == c1)
	*string = c2;
    }
  while (*string++);
}

/* Update PATH using KEY if PATH starts with PREFIX as a directory.
   The returned string is always malloc-ed, and the caller is
   responsible for freeing it.  */

char *
update_path (const char *path, const char *key)
{
  char *result, *p;
  const int len = strlen (std_prefix);

  if (! filename_ncmp (path, std_prefix, len)
      && (IS_DIR_SEPARATOR (path[len])
          || path[len] == '\0')
      && key != 0)
    {
      bool free_key = false;

      if (key[0] != '$')
	{
	  key = concat ("@", key, NULL);
	  free_key = true;
	}

      result = concat (key, &path[len], NULL);
      if (free_key)
	free (CONST_CAST (char *, key));
      result = translate_name (result);
    }
  else
    result = xstrdup (path);

  p = result;
  while (1)
    {
      char *src, *dest;

      p = strchr (p, '.');
      if (p == NULL)
	break;
      /* Look for `/../'  */
      if (p[1] == '.'
	  && IS_DIR_SEPARATOR (p[2])
	  && (p != result && IS_DIR_SEPARATOR (p[-1])))
	{
	  *p = 0;
	  if (!targetm_common.always_strip_dotdot
	      && access (result, X_OK) == 0)
	    {
	      *p = '.';
	      break;
	    }
	  else
	    {
	      /* We can't access the dir, so we won't be able to
		 access dir/.. either.  Strip out `dir/../'.  If `dir'
		 turns out to be `.', strip one more path component.  */
	      dest = p;
	      do
		{
		  --dest;
		  while (dest != result && IS_DIR_SEPARATOR (*dest))
		    --dest;
		  while (dest != result && !IS_DIR_SEPARATOR (dest[-1]))
		    --dest;
		}
	      while (dest != result && *dest == '.');
	      /* If we have something like `./..' or `/..', don't
		 strip anything more.  */
	      if (*dest == '.' || IS_DIR_SEPARATOR (*dest))
		{
		  *p = '.';
		  break;
		}
	      src = p + 3;
	      while (IS_DIR_SEPARATOR (*src))
		++src;
	      p = dest;
	      while ((*dest++ = *src++) != 0)
		;
	    }
	}
      else
	++p;
    }

#ifdef UPDATE_PATH_HOST_CANONICALIZE
  /* Perform host dependent canonicalization when needed.  */
  UPDATE_PATH_HOST_CANONICALIZE (result);
#endif

#ifdef DIR_SEPARATOR_2
  /* Convert DIR_SEPARATOR_2 to DIR_SEPARATOR.  */
  if (DIR_SEPARATOR_2 != DIR_SEPARATOR)
    tr (result, DIR_SEPARATOR_2, DIR_SEPARATOR);
#endif

#if defined (DIR_SEPARATOR) && !defined (DIR_SEPARATOR_2)
  if (DIR_SEPARATOR != '/')
    tr (result, '/', DIR_SEPARATOR);
#endif

  return result;
}

/* Reset the standard prefix.  */
void
set_std_prefix (const char *prefix, int len)
{
  std_prefix = save_string (prefix, len);
}