/* fhandler_procsys.cc: fhandler for native NT namespace.

   Copyright 2010 Red Hat, Inc.

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#include "winsup.h"
#include <stdlib.h>
#include "cygerrno.h"
#include "security.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "cygheap.h"
#include <winioctl.h>
#include "ntdll.h"
#include "tls_pbuf.h"

#include <dirent.h>

/* Path of the /proc/sys filesystem */
const char procsys[] = "/proc/sys";
const size_t procsys_len = sizeof (procsys) - 1;

#define mk_unicode_path(p) \
	WCHAR namebuf[strlen (get_name ()) + 1]; \
	{ \
	  const char *from; \
	  PWCHAR to; \
	  for (to = namebuf, from = get_name () + procsys_len; *from; \
	       to++, from++) \
	    /* The NT device namespace is ASCII only. */ \
	    *to = (*from == '/') ? L'\\' : (WCHAR) *from; \
	  if (to == namebuf) \
	    *to++ = L'\\'; \
	  *to = L'\0'; \
	  RtlInitUnicodeString ((p), namebuf); \
	}

/* Returns 0 if path doesn't exist, >0 if path is a directory,
   -1 if path is a file, -2 if it's a symlink.  */
virtual_ftype_t
fhandler_procsys::exists (struct __stat64 *buf)
{
  UNICODE_STRING path; \
  OBJECT_ATTRIBUTES attr;
  IO_STATUS_BLOCK io;
  NTSTATUS status;
  HANDLE h;
  FILE_BASIC_INFORMATION fbi;
  virtual_ftype_t file_type = virt_chr;

  if (strlen (get_name ()) == procsys_len)
    return virt_rootdir;
  mk_unicode_path (&path);
  /* First try to open as file/device to get more info. */
  InitializeObjectAttributes (&attr, &path, OBJ_CASE_INSENSITIVE, NULL, NULL);
  status = NtOpenFile (&h, READ_CONTROL | FILE_READ_ATTRIBUTES, &attr, &io,
		       FILE_SHARE_VALID_FLAGS, FILE_OPEN_FOR_BACKUP_INTENT);
  if (status == STATUS_OBJECT_PATH_NOT_FOUND)
    return virt_none;
  /* If the name isn't found, or we get this dreaded sharing violation, let
     the caller try again as normal file. */
  if (status == STATUS_OBJECT_NAME_NOT_FOUND
      || status == STATUS_NO_MEDIA_IN_DEVICE
      || status == STATUS_SHARING_VIOLATION)
    return virt_fsfile;	/* Just try again as normal file. */
  /* Check for pipe errors, which make a good hint... */
  if (status >= STATUS_PIPE_NOT_AVAILABLE && status <= STATUS_PIPE_BUSY)
    file_type = virt_pipe;
  else if (status == STATUS_ACCESS_DENIED)
    {
      /* Check if this is just some file or dir on a real FS to circumvent
         most permission problems. */
      status = NtQueryAttributesFile (&attr, &fbi);
      if (NT_SUCCESS (status))
	return (fbi.FileAttributes & FILE_ATTRIBUTE_DIRECTORY)
	       ? virt_fsdir : virt_fsfile;
    }
  else if (NT_SUCCESS (status))
    {
      NTSTATUS dev_stat;
      FILE_FS_DEVICE_INFORMATION ffdi;

      /* If requested, check permissions. */
      if (buf)
      	get_object_attribute (h, &buf->st_uid, &buf->st_gid, &buf->st_mode);
      /* Check for the device type. */
      dev_stat = NtQueryVolumeInformationFile (h, &io, &ffdi, sizeof ffdi,
					       FileFsDeviceInformation);
      /* And check for file attributes.  If we get them, we peeked into
	 a real FS through /proc/sys. */
      status = NtQueryInformationFile (h, &io, &fbi, sizeof fbi,
				       FileBasicInformation);
      NtClose (h);
      if (NT_SUCCESS (dev_stat))
	{
	  if (ffdi.DeviceType == FILE_DEVICE_NAMED_PIPE)
	    file_type = NT_SUCCESS (status) ? virt_pipe : virt_blk;
	  else if (NT_SUCCESS (status))
	    file_type = (fbi.FileAttributes & FILE_ATTRIBUTE_DIRECTORY)
			? virt_fsdir : virt_fsfile;
	  else if (ffdi.DeviceType == FILE_DEVICE_DISK
		   || ffdi.DeviceType == FILE_DEVICE_CD_ROM
		   || ffdi.DeviceType == FILE_DEVICE_DFS
		   || ffdi.DeviceType == FILE_DEVICE_VIRTUAL_DISK)
	    file_type = virt_blk;
	}
    }
  /* Then check if it's a symlink. */
  status = NtOpenSymbolicLinkObject (&h, READ_CONTROL | SYMBOLIC_LINK_QUERY,
				     &attr);
  if (NT_SUCCESS (status))
    {
      /* If requested, check permissions. */
      if (buf)
      	get_object_attribute (h, &buf->st_uid, &buf->st_gid, &buf->st_mode);
      NtClose (h);
      return virt_symlink;
    }
  /* Eventually, test if it's an object directory. */
  status = NtOpenDirectoryObject (&h, READ_CONTROL | DIRECTORY_QUERY, &attr);
  if (NT_SUCCESS (status))
    {
      /* If requested, check permissions. */
      if (buf)
      	get_object_attribute (h, &buf->st_uid, &buf->st_gid, &buf->st_mode);
      NtClose (h);
      return virt_directory;
    }
  else if (status == STATUS_ACCESS_DENIED)
    return virt_directory;
  /* Give up.  Just treat as character device. */
  return file_type;
}

virtual_ftype_t
fhandler_procsys::exists ()
{
  return exists (NULL);
}

fhandler_procsys::fhandler_procsys ():
  fhandler_virtual ()
{
}

bool
fhandler_procsys::fill_filebuf ()
{
  /* The NT device namespace is ASCII only. */
  char *fnamep;
  UNICODE_STRING path, target;
  OBJECT_ATTRIBUTES attr;
  NTSTATUS status;
  HANDLE h;
  tmp_pathbuf tp;

  mk_unicode_path (&path);
  if (path.Buffer[path.Length / sizeof (WCHAR) - 1] == L'\\')
    path.Length -= sizeof (WCHAR);
  InitializeObjectAttributes (&attr, &path, OBJ_CASE_INSENSITIVE, NULL, NULL);
  status = NtOpenSymbolicLinkObject (&h, SYMBOLIC_LINK_QUERY, &attr);
  if (!NT_SUCCESS (status))
    return false;
  RtlInitEmptyUnicodeString (&target, tp.w_get (),
			     (NT_MAX_PATH - 1) * sizeof (WCHAR));
  status = NtQuerySymbolicLinkObject (h, &target, NULL);
  NtClose (h);
  if (!NT_SUCCESS (status))
    return false;
  size_t len = sys_wcstombs (NULL, 0, target.Buffer,
			     target.Length / sizeof (WCHAR));
  filebuf = (char *) crealloc_abort (filebuf, procsys_len + len + 1);
  sys_wcstombs (fnamep = stpcpy (filebuf, procsys), len + 1, target.Buffer,
		target.Length / sizeof (WCHAR));
  while ((fnamep = strchr (fnamep, '\\')))
    *fnamep = '/';
  return true;
}

int
fhandler_procsys::fstat (struct __stat64 *buf)
{
  const char *path = get_name ();
  debug_printf ("fstat (%s)", path);

  fhandler_base::fstat (buf);
  /* Best bet. */
  buf->st_mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;
  buf->st_uid = 544;
  buf->st_gid = 18;
  buf->st_dev = buf->st_rdev = dev ().devn;
  buf->st_ino = get_ino ();
  switch (exists (buf))
    {
    case virt_directory:
    case virt_rootdir:
    case virt_fsdir:
      buf->st_mode |= S_IFDIR;
      if (buf->st_mode & S_IRUSR)
	buf->st_mode |= S_IXUSR;
      if (buf->st_mode & S_IRGRP)
	buf->st_mode |= S_IXGRP;
      if (buf->st_mode & S_IROTH)
	buf->st_mode |= S_IXOTH;
      break;
    case virt_file:
    case virt_fsfile:
      buf->st_mode |= S_IFREG;
      break;
    case virt_symlink:
      buf->st_mode |= S_IFLNK;
      break;
    case virt_pipe:
      buf->st_mode |= S_IFIFO;
      break;
    case virt_socket:
      buf->st_mode |= S_IFSOCK;
      break;
    case virt_chr:
      buf->st_mode |= S_IFCHR;
      break;
    case virt_blk:
      buf->st_mode |= S_IFBLK;
      break;
    default:
      set_errno (ENOENT);
      return -1;
    }
  return 0;
}

DIR *
fhandler_procsys::opendir (int fd)
{
  UNICODE_STRING path;
  OBJECT_ATTRIBUTES attr;
  NTSTATUS status;
  HANDLE h;
  DIR *dir = fhandler_virtual::opendir (fd);

  mk_unicode_path (&path);
  InitializeObjectAttributes (&attr, &path, OBJ_CASE_INSENSITIVE, NULL, NULL);
  status = NtOpenDirectoryObject (&h, DIRECTORY_QUERY, &attr);
  if (!NT_SUCCESS (status))
    {
      free (dir);
      __seterrno_from_nt_status (status);
      return NULL;
    }
  dir->__handle = h;
  return dir;
}

int
fhandler_procsys::readdir (DIR *dir, dirent *de)
{
  NTSTATUS status;
  struct fdbi
  {
    DIRECTORY_BASIC_INFORMATION dbi;
    WCHAR buf[2][NAME_MAX + 1];
  } f;
  int res = EBADF;

  if (dir->__handle != INVALID_HANDLE_VALUE)
    {
      BOOLEAN restart = dir->__d_position ? FALSE : TRUE;
      status = NtQueryDirectoryObject (dir->__handle, &f, sizeof f, TRUE,
				       restart, (PULONG) &dir->__d_position,
				       NULL);
      if (!NT_SUCCESS (status))
	res = ENMFILE;
      else
	{
	  sys_wcstombs (de->d_name, NAME_MAX + 1, f.dbi.ObjectName.Buffer,
			f.dbi.ObjectName.Length / sizeof (WCHAR));
	  de->d_ino = hash_path_name (get_ino (), de->d_name);
	  de->d_type = 0;
	  res = 0;
	}
    }
  syscall_printf ("%d = readdir (%p, %p)", res, dir, de);
  return res;
}

long
fhandler_procsys::telldir (DIR *dir)
{
  return dir->__d_position;
}

void
fhandler_procsys::seekdir (DIR *dir, long pos)
{
  dir->__d_position = pos;
}

int
fhandler_procsys::closedir (DIR *dir)
{
  if (dir->__handle != INVALID_HANDLE_VALUE)
    {
      NtClose (dir->__handle);
      dir->__handle = INVALID_HANDLE_VALUE;
    }
  return fhandler_virtual::closedir (dir);
}

void __stdcall
fhandler_procsys::read (void *ptr, size_t& len)
{
  NTSTATUS status;
  IO_STATUS_BLOCK io;
  LARGE_INTEGER off = { QuadPart:0LL };

  status = NtReadFile (get_handle (), NULL, NULL, NULL, &io, ptr, len,
		       &off, NULL);
  if (!NT_SUCCESS (status))
    {
      __seterrno_from_nt_status (status);
      len = -1;
    }
  else
    len = io.Information;
}

ssize_t __stdcall
fhandler_procsys::write (const void *ptr, size_t len)
{
  return fhandler_base::raw_write (ptr, len);
}

int
fhandler_procsys::open (int flags, mode_t mode)
{
  int res = 0;

  if ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
    set_errno (EINVAL);
  else
    {
      switch (exists ())
	{
	case virt_directory:
	case virt_rootdir:
	  if ((flags & O_ACCMODE) != O_RDONLY)
	    set_errno (EISDIR);
	  else
	    {
	      nohandle (true);
	      res = 1;
	    }
	  break;
	case virt_none:
	  set_errno (ENOENT);
	  break;
	default:
	  res = fhandler_base::open (flags, mode);
	  break;
	}
    }
  syscall_printf ("%d = fhandler_procsys::open (%p, %d)", res, flags, mode);
  return res;
}

int
fhandler_procsys::close ()
{
  if (!nohandle ())
    NtClose (get_handle ());
  return fhandler_virtual::close ();
}
#if 0
int
fhandler_procsys::ioctl (unsigned int cmd, void *)
{
}
#endif