/*
     This file is part of GNUnet.
     (C) 2006, 2010, 2011 Christian Grothoff (and other contributing authors)

     GNUnet 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.

     GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/

/**
 * @file src/lib/os_installation.c
 * @brief get paths used by the program; this code is almost the
 *        same as src/util/os_installation.c in libgnunetutil; however,
 *        it contains sublte changes to detect the installation path
 *        of gnunet-gtk (which may be different from the path for
 *        GNUnet itself) and also needs to be replicated anyway since
 *        some of the methods try to find the location of the binary
 *        of the test-code itself, which would never yield the
 *        correct result for gnunet-gtk if the code lives in libgnunetutil.
 * @author Milan
 * @author Christian Grothoff
 */
#include "gnunet_gtk.h"
#if DARWIN
#include <mach-o/ldsyms.h>
#include <mach-o/dyld.h>
#endif

#if LINUX
/**
 * Try to determine path by reading /proc/PID/exe
 *
 * @return NULL on error
 */
static char *
get_path_from_proc_maps ()
{
  char fn[64];
  char line[1024];
  char dir[1024];
  FILE *f;
  char *lgu;

  GNUNET_snprintf (fn, sizeof (fn), "/proc/%u/maps", getpid ());
  if (NULL == (f = FOPEN (fn, "r")))
    return NULL;
  while (NULL != fgets (line, sizeof (line), f))
  {
    if ((1 ==
         sscanf (line, "%*x-%*x %*c%*c%*c%*c %*x %*2u:%*2u %*u%*[ ]%s", dir)) &&
        (NULL != (lgu = strstr (dir, "libgnunetgtk.so"))))
    {
      lgu[0] = '\0';
      fclose (f);
      return GNUNET_strdup (dir);
    }
  }
  fclose (f);
  return NULL;
}


/**
 * Try to determine path by reading /proc/PID/exe
 *
 * @return NULL on error
 */
static char *
get_path_from_proc_exe ()
{
  char fn[64];
  char lnk[1024];
  ssize_t size;

  GNUNET_snprintf (fn, sizeof (fn), "/proc/%u/exe", getpid ());
  size = readlink (fn, lnk, sizeof (lnk) - 1);
  if (size <= 0)
  {
    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR, "readlink", fn);
    return NULL;
  }
  GNUNET_assert (size < sizeof (lnk));
  lnk[size] = '\0';
  while ((lnk[size] != '/') && (size > 0))
    size--;
 /* test for being in lib/gnunet/libexec/ */
  if ( (size > strlen ("/gnunet/libexec/")) &&
       (0 == strcmp ("/gnunet/libexec/",
		     &lnk[size - strlen ("/gnunet/libexec/")])) )
    size -= strlen ("gnunet/libexec/");
  if ((size < 4) || (lnk[size - 4] != '/'))
  {
    /* not installed in "/bin/" -- binary path probably useless */
    return NULL;
  }
  lnk[size] = '\0';
  return GNUNET_strdup (lnk);
}
#endif


#if WINDOWS
/**
 * Try to determine path with win32-specific function
 *
 * @return NULL on error
 */
static char *
get_path_from_module_filename ()
{
  size_t pathlen = 512;
  DWORD real_pathlen;
  wchar_t *idx;
  wchar_t *modulepath = NULL;
  char *upath;
  uint8_t *u8_string;
  size_t u8_string_length;

  /* This braindead function won't tell us how much space it needs, so
   * we start at 1024 and double the space up if it doesn't fit, until
   * it fits, or we exceed the threshold.
   */
  do
  {
    pathlen = pathlen * 2;
    modulepath = GNUNET_realloc (modulepath, pathlen * sizeof (wchar_t));
    SetLastError (0);
    real_pathlen = GetModuleFileNameW (dll_instance, modulepath, pathlen * sizeof (wchar_t));
  } while (real_pathlen >= pathlen && pathlen < 16*1024);
  if (real_pathlen >= pathlen)
    GNUNET_abort ();
  /* To be safe */
  modulepath[real_pathlen] = '\0';

  idx = modulepath + real_pathlen;
  while ((idx > modulepath) && (*idx != L'\\') && (*idx != L'/'))
    idx--;
  *idx = L'\0';

  /* Now modulepath holds full path to the directory where libgnunetutil is.
   * This directory should look like <GNUNET_PREFIX>/bin or <GNUNET_PREFIX>.
   */
  if (wcschr (modulepath, L'/') || wcschr (modulepath, L'\\'))
  {
    /* At least one directory component (i.e. we're not in a root directory) */
    wchar_t *dirname = idx;
    while ((dirname > modulepath) && (*dirname != L'\\') && (*dirname != L'/'))
      dirname--;
    *dirname = L'\0';
    if (dirname > modulepath)
    {
      dirname++;
      /* Now modulepath holds full path to the parent directory of the directory
       * where libgnunetutil is.
       * dirname holds the name of the directory where libgnunetutil is.
       */
      if (wcsicmp (dirname, L"bin") == 0)
      {
        /* pass */
      }
      else
      {
        /* Roll back our changes to modulepath */
        dirname--;
        *dirname = L'/';
      }
    }
  }

  /* modulepath is GNUNET_PREFIX */
  u8_string = u16_to_u8 (modulepath, wcslen (modulepath), NULL, &u8_string_length);
  if (NULL == u8_string)
    GNUNET_abort ();

  upath = GNUNET_malloc (u8_string_length + 1);
  memcpy (upath, u8_string, u8_string_length);
  upath[u8_string_length] = '\0';

  free (u8_string);
  GNUNET_free (modulepath);

  return upath;
}
#endif

#if DARWIN

/**
 * Signature of the '_NSGetExecutablePath" function.
 *
 * @param buf where to write the path
 * @param number of bytes available in 'buf'
 * @return 0 on success, otherwise desired number of bytes is stored in 'bufsize'
 */
typedef int (*MyNSGetExecutablePathProto) (char *buf, size_t * bufsize);


/**
 * Try to obtain the path of our executable using '_NSGetExecutablePath'.
 *
 * @return NULL on error
 */
static char *
get_path_from_NSGetExecutablePath ()
{
  static char zero = '\0';
  char *path;
  size_t len;
  MyNSGetExecutablePathProto func;
  int ret;

  path = NULL;
  if (NULL == (func =
	       (MyNSGetExecutablePathProto) dlsym (RTLD_DEFAULT, "_NSGetExecutablePath")))
    return NULL;
  path = &zero;
  len = 0;
  /* get the path len, including the trailing \0 */
  func (path, &len);
  if (len == 0)
    return NULL;
  path = GNUNET_malloc (len);
  ret = func (path, &len);
  if (ret != 0)
  {
    GNUNET_free (path);
    return NULL;
  }
  len = strlen (path);
  while ((path[len] != '/') && (len > 0))
    len--;
  path[len] = '\0';
  return path;
}


/**
 * Try to obtain the path of our executable using '_dyld_image' API.
 *
 * @return NULL on error
 */
static char *
get_path_from_dyld_image ()
{
  const char *path;
  char *p;
  char *s;
  unsigned int i;
  int c;

  c = _dyld_image_count ();
  for (i = 0; i < c; i++)
  {
    if (_dyld_get_image_header (i) != &_mh_dylib_header)
      continue;
    path = _dyld_get_image_name (i);
    if ( (NULL == path) || (0 == strlen (path)) )
      continue;
    p = GNUNET_strdup (path);
    s = p + strlen (p);
    while ((s > p) && ('/' != *s))
      s--;
    s++;
    *s = '\0';
    return p;
  }
  return NULL;
}
#endif


/**
 * Return the actual path to a file found in the current
 * PATH environment variable.
 *
 * @param binary the name of the file to find
 * @return path to binary, NULL if not found
 */
static char *
get_path_from_PATH ()
{
  char *path;
  char *pos;
  char *end;
  char *buf;
  const char *p;

  p = getenv ("PATH");
  if (p == NULL)
    return NULL;
  path = GNUNET_strdup (p);     /* because we write on it */
  buf = GNUNET_malloc (strlen (path) + 20);
  pos = path;

  while (NULL != (end = strchr (pos, ':')))
  {
    *end = '\0';
    sprintf (buf, "%s/%s", pos, "gnunet-fs-gtk");
    if (GNUNET_DISK_file_test (buf) == GNUNET_YES)
    {
      pos = GNUNET_strdup (pos);
      GNUNET_free (buf);
      GNUNET_free (path);
      return pos;
    }
    pos = end + 1;
  }
  sprintf (buf, "%s/%s", pos, "gnunet-fs-gtk");
  if (GNUNET_DISK_file_test (buf) == GNUNET_YES)
  {
    pos = GNUNET_strdup (pos);
    GNUNET_free (buf);
    GNUNET_free (path);
    return pos;
  }
  GNUNET_free (buf);
  GNUNET_free (path);
  return NULL;
}


/**
 * Try to obtain the installation path using the "GNUNET_PREFIX" environment
 * variable.
 *
 * @return NULL on error (environment variable not set)
 */
static char *
get_path_from_GNUNET_PREFIX ()
{
  const char *p;

  p = getenv ("GNUNET_GTK_PREFIX");
  if (p != NULL)
    return GNUNET_strdup (p);
  return NULL;
}


/*
 * @brief get the path to GNUnet bin/ or lib/, prefering the lib/ path
 * @author Milan
 *
 * @return a pointer to the executable path, or NULL on error
 */
static char *
os_get_gnunet_path ()
{
  char *ret;

  ret = get_path_from_GNUNET_PREFIX ();
  if (ret != NULL)
    return ret;
#if LINUX
  ret = get_path_from_proc_maps ();
  if (ret != NULL)
    return ret;
  ret = get_path_from_proc_exe ();
  if (ret != NULL)
    return ret;
#endif
#if WINDOWS
  ret = get_path_from_module_filename ();
  if (ret != NULL)
    return ret;
#endif
#if DARWIN
  ret = get_path_from_dyld_image ();
  if (ret != NULL)
    return ret;
  ret = get_path_from_NSGetExecutablePath ();
  if (ret != NULL)
    return ret;
#endif
  ret = get_path_from_PATH ();
  if (ret != NULL)
    return ret;
  /* other attempts here */
  GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
              _
              ("Could not determine installation path for %s.  Set `%s' environment variable.\n"),
              "gnunet-gtk", "GNUNET_GTK_PREFIX");
  return NULL;
}

/*
 * @brief get the path to current app's bin/
 * @author Milan
 *
 * @return a pointer to the executable path, or NULL on error
 */
static char *
os_get_exec_path ()
{
  char *ret;

  ret = NULL;
#if LINUX
  ret = get_path_from_proc_exe ();
  if (ret != NULL)
    return ret;
#endif
#if WINDOWS
  ret = get_path_from_module_filename ();
  if (ret != NULL)
    return ret;
#endif
#if DARWIN
  ret = get_path_from_NSGetExecutablePath ();
  if (ret != NULL)
    return ret;
#endif
  /* other attempts here */
  return ret;
}



/**
 * @brief get the path to a specific GNUnet installation directory or,
 * with GNUNET_IPK_SELF_PREFIX, the current running apps installation directory
 * @author Milan
 * @return a pointer to the dir path (to be freed by the caller)
 */
char *
GNUNET_GTK_installation_get_path (enum GNUNET_OS_InstallationPathKind dirkind)
{
  size_t n;
  const char *dirname;
  char *execpath = NULL;
  char *tmp;
  int isbasedir;

  /* if wanted, try to get the current app's bin/ */
  if (dirkind == GNUNET_OS_IPK_SELF_PREFIX)
    execpath = os_get_exec_path ();

  /* try to get GNUnet's bin/ or lib/, or if previous was unsuccessful some
   * guess for the current app */
  if (execpath == NULL)
    execpath = os_get_gnunet_path ();

  if (NULL == execpath)
    return NULL;

  n = strlen (execpath);
  if (n == 0)
  {
    /* should never happen, but better safe than sorry */
    GNUNET_free (execpath);
    return NULL;
  }
  /* remove filename itself */
  while ((n > 1) && (execpath[n - 1] == DIR_SEPARATOR))
    execpath[--n] = '\0';

  isbasedir = 1;
  if ((n > 5) &&
      ((0 == strcasecmp (&execpath[n - 5], "lib32")) ||
       (0 == strcasecmp (&execpath[n - 5], "lib64"))))
  {
    if ( (GNUNET_OS_IPK_LIBDIR != dirkind) &&
	 (GNUNET_OS_IPK_LIBEXECDIR != dirkind) )
    {
      /* strip '/lib32' or '/lib64' */
      execpath[n - 5] = '\0';
      n -= 5;
    }
    else
      isbasedir = 0;
  }
  else if ((n > 3) &&
           ((0 == strcasecmp (&execpath[n - 3], "bin")) ||
            (0 == strcasecmp (&execpath[n - 3], "lib"))))
  {
    /* strip '/bin' or '/lib' */
    execpath[n - 3] = '\0';
    n -= 3;
  }
  /* in case this was a directory named foo-bin, remove "foo-" */
  while ((n > 1) && (execpath[n - 1] == DIR_SEPARATOR))
    execpath[--n] = '\0';
  switch (dirkind)
  {
  case GNUNET_OS_IPK_PREFIX:
  case GNUNET_OS_IPK_SELF_PREFIX:
    dirname = DIR_SEPARATOR_STR;
    break;
  case GNUNET_OS_IPK_BINDIR:
    dirname = DIR_SEPARATOR_STR "bin" DIR_SEPARATOR_STR;
    break;
  case GNUNET_OS_IPK_LIBDIR:
    if (isbasedir)
      dirname =
          DIR_SEPARATOR_STR "lib" DIR_SEPARATOR_STR "gnunet-gtk"
          DIR_SEPARATOR_STR;
    else
      dirname = DIR_SEPARATOR_STR "gnunet-gtk" DIR_SEPARATOR_STR;
    break;
  case GNUNET_OS_IPK_DATADIR:
    dirname =
        DIR_SEPARATOR_STR "share" DIR_SEPARATOR_STR "gnunet-gtk"
        DIR_SEPARATOR_STR;
    break;
  case GNUNET_OS_IPK_ICONDIR:
    dirname =
        DIR_SEPARATOR_STR "share" DIR_SEPARATOR_STR "icons" DIR_SEPARATOR_STR;
    break;
  case GNUNET_OS_IPK_LOCALEDIR:
    dirname =
        DIR_SEPARATOR_STR "share" DIR_SEPARATOR_STR "locale" DIR_SEPARATOR_STR;
    break;
  case GNUNET_OS_IPK_LIBEXECDIR:
    if (isbasedir)
      dirname =
        DIR_SEPARATOR_STR "lib" DIR_SEPARATOR_STR "gnunet" DIR_SEPARATOR_STR \
        "libexec" DIR_SEPARATOR_STR;
    else
      dirname =
        DIR_SEPARATOR_STR "gnunet" DIR_SEPARATOR_STR \
        "libexec" DIR_SEPARATOR_STR;
    break;
  default:
    GNUNET_free (execpath);
    return NULL;
  }
  tmp = GNUNET_malloc (strlen (execpath) + strlen (dirname) + 1);
  sprintf (tmp, "%s%s", execpath, dirname);
  GNUNET_free (execpath);
  return tmp;
}

/* end of os_installation.c */