binutils-gdb/gdb/common/pathstuff.c

/* Path manipulation routines for GDB and gdbserver.

   Copyright (C) 1986-2018 Free Software Foundation, Inc.

   This file is part of GDB.

   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 of the License, 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, see <http://www.gnu.org/licenses/>.  */

#include "common-defs.h"
#include "pathstuff.h"
#include "host-defs.h"
#include "filenames.h"
#include "gdb_tilde_expand.h"

#ifdef USE_WIN32API
#include <windows.h>
#endif

/* See common/pathstuff.h.  */

gdb::unique_xmalloc_ptr<char>
gdb_realpath (const char *filename)
{
/* On most hosts, we rely on canonicalize_file_name to compute
   the FILENAME's realpath.

   But the situation is slightly more complex on Windows, due to some
   versions of GCC which were reported to generate paths where
   backlashes (the directory separator) were doubled.  For instance:
      c:\\some\\double\\slashes\\dir
   ... instead of ...
      c:\some\double\slashes\dir
   Those double-slashes were getting in the way when comparing paths,
   for instance when trying to insert a breakpoint as follow:
      (gdb) b c:/some/double/slashes/dir/foo.c:4
      No source file named c:/some/double/slashes/dir/foo.c:4.
      (gdb) b c:\some\double\slashes\dir\foo.c:4
      No source file named c:\some\double\slashes\dir\foo.c:4.
   To prevent this from happening, we need this function to always
   strip those extra backslashes.  While canonicalize_file_name does
   perform this simplification, it only works when the path is valid.
   Since the simplification would be useful even if the path is not
   valid (one can always set a breakpoint on a file, even if the file
   does not exist locally), we rely instead on GetFullPathName to
   perform the canonicalization.  */

#if defined (_WIN32)
  {
    char buf[MAX_PATH];
    DWORD len = GetFullPathName (filename, MAX_PATH, buf, NULL);

    /* The file system is case-insensitive but case-preserving.
       So it is important we do not lowercase the path.  Otherwise,
       we might not be able to display the original casing in a given
       path.  */
    if (len > 0 && len < MAX_PATH)
      return gdb::unique_xmalloc_ptr<char> (xstrdup (buf));
  }
#else
  {
    char *rp = canonicalize_file_name (filename);

    if (rp != NULL)
      return gdb::unique_xmalloc_ptr<char> (rp);
  }
#endif

  /* This system is a lost cause, just dup the buffer.  */
  return gdb::unique_xmalloc_ptr<char> (xstrdup (filename));
}

/* See common/pathstuff.h.  */

gdb::unique_xmalloc_ptr<char>
gdb_realpath_keepfile (const char *filename)
{
  const char *base_name = lbasename (filename);
  char *dir_name;
  char *result;

  /* Extract the basename of filename, and return immediately
     a copy of filename if it does not contain any directory prefix.  */
  if (base_name == filename)
    return gdb::unique_xmalloc_ptr<char> (xstrdup (filename));

  dir_name = (char *) alloca ((size_t) (base_name - filename + 2));
  /* Allocate enough space to store the dir_name + plus one extra
     character sometimes needed under Windows (see below), and
     then the closing \000 character.  */
  strncpy (dir_name, filename, base_name - filename);
  dir_name[base_name - filename] = '\000';

#ifdef HAVE_DOS_BASED_FILE_SYSTEM
  /* We need to be careful when filename is of the form 'd:foo', which
     is equivalent of d:./foo, which is totally different from d:/foo.  */
  if (strlen (dir_name) == 2 && isalpha (dir_name[0]) && dir_name[1] == ':')
    {
      dir_name[2] = '.';
      dir_name[3] = '\000';
    }
#endif

  /* Canonicalize the directory prefix, and build the resulting
     filename.  If the dirname realpath already contains an ending
     directory separator, avoid doubling it.  */
  gdb::unique_xmalloc_ptr<char> path_storage = gdb_realpath (dir_name);
  const char *real_path = path_storage.get ();
  if (IS_DIR_SEPARATOR (real_path[strlen (real_path) - 1]))
    result = concat (real_path, base_name, (char *) NULL);
  else
    result = concat (real_path, SLASH_STRING, base_name, (char *) NULL);

  return gdb::unique_xmalloc_ptr<char> (result);
}

/* See common/pathstuff.h.  */

gdb::unique_xmalloc_ptr<char>
gdb_abspath (const char *path)
{
  gdb_assert (path != NULL && path[0] != '\0');

  if (path[0] == '~')
    return gdb_tilde_expand_up (path);

  if (IS_ABSOLUTE_PATH (path))
    return gdb::unique_xmalloc_ptr<char> (xstrdup (path));

  /* Beware the // my son, the Emacs barfs, the botch that catch...  */
  return gdb::unique_xmalloc_ptr<char>
    (concat (current_directory,
	     IS_DIR_SEPARATOR (current_directory[strlen (current_directory) - 1])
	     ? "" : SLASH_STRING,
	     path, (char *) NULL));
}

/* See common/pathstuff.h.  */

bool
contains_dir_separator (const char *path)
{
  for (; *path != '\0'; path++)
    {
      if (IS_DIR_SEPARATOR (*path))
	return true;
    }

  return false;
}

/* See common/pathstuff.h.  */

std::string
get_standard_cache_dir ()
{
  char *xdg_cache_home = getenv ("XDG_CACHE_HOME");
  if (xdg_cache_home != NULL)
    {
      /* Make sure the path is absolute and tilde-expanded.  */
      gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (xdg_cache_home));
      return string_printf ("%s/gdb", abs.get ());
    }

  char *home = getenv ("HOME");
  if (home != NULL)
    {
      /* Make sure the path is absolute and tilde-expanded.  */
      gdb::unique_xmalloc_ptr<char> abs (gdb_abspath (home));
      return string_printf ("%s/.cache/gdb", abs.get ());
    }

  return {};
}