/* pathchk -- check whether file names are valid or portable
   Copyright (C) 1991-2006 Free Software Foundation, Inc.

   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,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>
#if HAVE_WCHAR_H
# include <wchar.h>
#endif

#include "system.h"
#include "error.h"
#include "euidaccess.h"
#include "quote.h"
#include "quotearg.h"

#if ! (HAVE_MBRLEN && HAVE_MBSTATE_T)
# define mbrlen(s, n, ps) 1
# define mbstate_t int
#endif

/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "pathchk"

#define AUTHORS "Paul Eggert", "David MacKenzie", "Jim Meyering"

#ifndef _POSIX_PATH_MAX
# define _POSIX_PATH_MAX 256
#endif
#ifndef _POSIX_NAME_MAX
# define _POSIX_NAME_MAX 14
#endif

#ifdef _XOPEN_NAME_MAX
# define NAME_MAX_MINIMUM _XOPEN_NAME_MAX
#else
# define NAME_MAX_MINIMUM _POSIX_NAME_MAX
#endif
#ifdef _XOPEN_PATH_MAX
# define PATH_MAX_MINIMUM _XOPEN_PATH_MAX
#else
# define PATH_MAX_MINIMUM _POSIX_PATH_MAX
#endif

#if ! (HAVE_PATHCONF && defined _PC_NAME_MAX && defined _PC_PATH_MAX)
# ifndef _PC_NAME_MAX
#  define _PC_NAME_MAX 0
#  define _PC_PATH_MAX 1
# endif
# ifndef pathconf
#  define pathconf(file, flag) \
     (flag == _PC_NAME_MAX ? NAME_MAX_MINIMUM : PATH_MAX_MINIMUM)
# endif
#endif

static bool validate_file_name (char *, bool, bool);

/* The name this program was run with. */
char *program_name;

/* For long options that have no equivalent short option, use a
   non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
enum
{
  PORTABILITY_OPTION = CHAR_MAX + 1
};

static struct option const longopts[] =
{
  {"portability", no_argument, NULL, PORTABILITY_OPTION},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {NULL, 0, NULL, 0}
};

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
	     program_name);
  else
    {
      printf (_("Usage: %s [OPTION]... NAME...\n"), program_name);
      fputs (_("\
Diagnose unportable constructs in NAME.\n\
\n\
  -p                  check for most POSIX systems\n\
  -P                  check for empty names and leading \"-\"\n\
      --portability   check for all POSIX systems (equivalent to -p -P)\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    }
  exit (status);
}

int
main (int argc, char **argv)
{
  bool ok = true;
  bool check_basic_portability = false;
  bool check_extra_portability = false;
  int optc;

  initialize_main (&argc, &argv);
  program_name = argv[0];
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  while ((optc = getopt_long (argc, argv, "+pP", longopts, NULL)) != -1)
    {
      switch (optc)
	{
	case PORTABILITY_OPTION:
	  check_basic_portability = true;
	  check_extra_portability = true;
	  break;

	case 'p':
	  check_basic_portability = true;
	  break;

	case 'P':
	  check_extra_portability = true;
	  break;

	case_GETOPT_HELP_CHAR;

	case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);

	default:
	  usage (EXIT_FAILURE);
	}
    }

  if (optind == argc)
    {
      error (0, 0, _("missing operand"));
      usage (EXIT_FAILURE);
    }

  for (; optind < argc; ++optind)
    ok &= validate_file_name (argv[optind],
			      check_basic_portability, check_extra_portability);

  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
}

/* If FILE contains a component with a leading "-", report an error
   and return false; otherwise, return true.  */

static bool
no_leading_hyphen (char const *file)
{
  char const *p;

  for (p = file;  (p = strchr (p, '-'));  p++)
    if (p == file || p[-1] == '/')
      {
	error (0, 0, _("leading `-' in a component of file name %s"),
	       quote (file));
	return false;
      }

  return true;
}

/* If FILE (of length FILELEN) contains only portable characters,
   return true, else report an error and return false.  */

static bool
portable_chars_only (char const *file, size_t filelen)
{
  size_t validlen = strspn (file,
			    ("/"
			     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
			     "abcdefghijklmnopqrstuvwxyz"
			     "0123456789._-"));
  char const *invalid = file + validlen;

  if (*invalid)
    {
      mbstate_t mbstate = { 0, };
      size_t charlen = mbrlen (invalid, filelen - validlen, &mbstate);
      error (0, 0,
	     _("nonportable character %s in file name %s"),
	     quotearg_n_style_mem (1, locale_quoting_style, invalid,
				   (charlen <= MB_LEN_MAX ? charlen : 1)),
	     quote_n (0, file));
      return false;
    }

  return true;
}

/* Return the address of the start of the next file name component in F.  */

static char *
component_start (char *f)
{
  while (*f == '/')
    f++;
  return f;
}

/* Return the size of the file name component F.  F must be nonempty.  */

static size_t
component_len (char const *f)
{
  size_t len;
  for (len = 1; f[len] != '/' && f[len]; len++)
    continue;
  return len;
}

/* Make sure that
   strlen (FILE) <= PATH_MAX
   && strlen (each-existing-directory-in-FILE) <= NAME_MAX

   If CHECK_BASIC_PORTABILITY is true, compare against _POSIX_PATH_MAX and
   _POSIX_NAME_MAX instead, and make sure that FILE contains no
   characters not in the POSIX portable filename character set, which
   consists of A-Z, a-z, 0-9, ., _, - (plus / for separators).

   If CHECK_BASIC_PORTABILITY is false, make sure that all leading directories
   along FILE that exist are searchable.

   If CHECK_EXTRA_PORTABILITY is true, check that file name components do not
   begin with "-".

   If either CHECK_BASIC_PORTABILITY or CHECK_EXTRA_PORTABILITY is true,
   check that the file name is not empty.

   Return true if all of these tests are successful, false if any fail.  */

static bool
validate_file_name (char *file, bool check_basic_portability,
		    bool check_extra_portability)
{
  size_t filelen = strlen (file);

  /* Start of file name component being checked.  */
  char *start;

  /* True if component lengths need to be checked.  */
  bool check_component_lengths;

  /* True if the file is known to exist.  */
  bool file_exists = false;

  if (check_extra_portability && ! no_leading_hyphen (file))
    return false;

  if ((check_basic_portability | check_extra_portability)
      && filelen == 0)
    {
      /* Fail, since empty names are not portable.  As of
	 2005-01-06 POSIX does not address whether "pathchk -p ''"
	 should (or is allowed to) fail, so this is not a
	 conformance violation.  */
      error (0, 0, _("empty file name"));
      return false;
    }

  if (check_basic_portability)
    {
      if (! portable_chars_only (file, filelen))
	return false;
    }
  else
    {
      /* Check whether a file name component is in a directory that
	 is not searchable, or has some other serious problem.
	 POSIX does not allow "" as a file name, but some non-POSIX
	 hosts do (as an alias for "."), so allow "" if lstat does.  */

      struct stat st;
      if (lstat (file, &st) == 0)
	file_exists = true;
      else if (errno != ENOENT || filelen == 0)
	{
	  error (0, errno, "%s", file);
	  return false;
	}
    }

  if (check_basic_portability
      || (! file_exists && PATH_MAX_MINIMUM <= filelen))
    {
      size_t maxsize;

      if (check_basic_portability)
	maxsize = _POSIX_PATH_MAX;
      else
	{
	  long int size;
	  char const *dir = (*file == '/' ? "/" : ".");
	  errno = 0;
	  size = pathconf (dir, _PC_PATH_MAX);
	  if (size < 0 && errno != 0)
	    {
	      error (0, errno,
		     _("%s: unable to determine maximum file name length"),
		     dir);
	      return false;
	    }
	  maxsize = MIN (size, SIZE_MAX);
	}

      if (maxsize <= filelen)
	{
	  unsigned long int len = filelen;
	  unsigned long int maxlen = maxsize - 1;
	  error (0, 0, _("limit %lu exceeded by length %lu of file name %s"),
		 maxlen, len, quote (file));
	  return false;
	}
    }

  /* Check whether pathconf (..., _PC_NAME_MAX) can be avoided, i.e.,
     whether all file name components are so short that they are valid
     in any file system on this platform.  If CHECK_BASIC_PORTABILITY, though,
     it's more convenient to check component lengths below.  */

  check_component_lengths = check_basic_portability;
  if (! check_component_lengths && ! file_exists)
    {
      for (start = file; *(start = component_start (start)); )
	{
	  size_t length = component_len (start);

	  if (NAME_MAX_MINIMUM < length)
	    {
	      check_component_lengths = true;
	      break;
	    }

	  start += length;
	}
    }

  if (check_component_lengths)
    {
      /* The limit on file name components for the current component.
         This defaults to NAME_MAX_MINIMUM, for the sake of non-POSIX
         systems (NFS, say?) where pathconf fails on "." or "/" with
         errno == ENOENT.  */
      size_t name_max = NAME_MAX_MINIMUM;

      /* If nonzero, the known limit on file name components.  */
      size_t known_name_max = (check_basic_portability ? _POSIX_NAME_MAX : 0);

      for (start = file; *(start = component_start (start)); )
	{
	  size_t length;

	  if (known_name_max)
	    name_max = known_name_max;
	  else
	    {
	      long int len;
	      char const *dir = (start == file ? "." : file);
	      char c = *start;
	      errno = 0;
	      *start = '\0';
	      len = pathconf (dir, _PC_NAME_MAX);
	      *start = c;
	      if (0 <= len)
		name_max = MIN (len, SIZE_MAX);
	      else
		switch (errno)
		  {
		  case 0:
		    /* There is no limit.  */
		    name_max = SIZE_MAX;
		    break;

		  case ENOENT:
		    /* DIR does not exist; use its parent's maximum.  */
		    known_name_max = name_max;
		    break;

		  default:
		    *start = '\0';
		    error (0, errno, "%s", dir);
		    *start = c;
		    return false;
		  }
	    }

	  length = component_len (start);

	  if (name_max < length)
	    {
	      unsigned long int len = length;
	      unsigned long int maxlen = name_max;
	      char c = start[len];
	      start[len] = '\0';
	      error (0, 0,
		     _("limit %lu exceeded by length %lu "
		       "of file name component %s"),
		     maxlen, len, quote (start));
	      start[len] = c;
	      return false;
	    }

	  start += length;
	}
    }

  return true;
}
