D-Bus  1.16.2
dbus-marshal-byteswap.c
1 /* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
2 /* dbus-marshal-byteswap.c Swap a block of marshaled data
3  *
4  * Copyright (C) 2005 Red Hat, Inc.
5  *
6  * SPDX-License-Identifier: AFL-2.1 OR GPL-2.0-or-later
7  *
8  * Licensed under the Academic Free License version 2.1
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18  * GNU General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  *
24  */
25 
26 #include <config.h>
27 #include "dbus-marshal-byteswap.h"
28 #include "dbus-marshal-basic.h"
29 #include "dbus-signature.h"
30 
36 static void
37 byteswap_body_helper (DBusTypeReader *reader,
38  dbus_bool_t walk_reader_to_end,
39  int old_byte_order,
40  int new_byte_order,
41  unsigned char *p,
42  unsigned char **new_p)
43 {
44  int current_type;
45 
46  while ((current_type = _dbus_type_reader_get_current_type (reader)) != DBUS_TYPE_INVALID)
47  {
48  switch (current_type)
49  {
50  case DBUS_TYPE_BYTE:
51  ++p;
52  break;
53 
54  case DBUS_TYPE_INT16:
55  case DBUS_TYPE_UINT16:
56  {
57  p = _DBUS_ALIGN_ADDRESS (p, 2);
58  *((dbus_uint16_t *) (void *) p) =
59  DBUS_UINT16_SWAP_LE_BE (*((dbus_uint16_t *) (void *) p));
60  p += 2;
61  }
62  break;
63 
64  case DBUS_TYPE_BOOLEAN:
65  case DBUS_TYPE_INT32:
66  case DBUS_TYPE_UINT32:
67  case DBUS_TYPE_UNIX_FD:
68  {
69  p = _DBUS_ALIGN_ADDRESS (p, 4);
70  *((dbus_uint32_t *) (void *) p) =
71  DBUS_UINT32_SWAP_LE_BE (*((dbus_uint32_t *) (void *) p));
72  p += 4;
73  }
74  break;
75 
76  case DBUS_TYPE_INT64:
77  case DBUS_TYPE_UINT64:
78  case DBUS_TYPE_DOUBLE:
79  {
80  p = _DBUS_ALIGN_ADDRESS (p, 8);
81  *((dbus_uint64_t *) (void *) p) =
82  DBUS_UINT64_SWAP_LE_BE (*((dbus_uint64_t *) (void *) p));
83  p += 8;
84  }
85  break;
86 
87  case DBUS_TYPE_ARRAY:
88  case DBUS_TYPE_STRING:
90  {
91  dbus_uint32_t array_len;
92 
93  p = _DBUS_ALIGN_ADDRESS (p, 4);
94 
95  array_len = _dbus_unpack_uint32 (old_byte_order, p);
96 
97  *((dbus_uint32_t *) (void *) p) =
98  DBUS_UINT32_SWAP_LE_BE (*((dbus_uint32_t *) (void *) p));
99  p += 4;
100 
101  if (current_type == DBUS_TYPE_ARRAY)
102  {
103  int elem_type;
104  int alignment;
105 
106  elem_type = _dbus_type_reader_get_element_type (reader);
107  alignment = _dbus_type_get_alignment (elem_type);
108 
109  _dbus_assert ((array_len / alignment) < DBUS_MAXIMUM_ARRAY_LENGTH);
110 
111  p = _DBUS_ALIGN_ADDRESS (p, alignment);
112 
113  if (dbus_type_is_fixed (elem_type))
114  {
115  if (alignment > 1)
116  _dbus_swap_array (p, array_len / alignment, alignment);
117  p += array_len;
118  }
119  else
120  {
121  DBusTypeReader sub;
122  const unsigned char *array_end;
123 
124  array_end = p + array_len;
125 
126  _dbus_type_reader_recurse (reader, &sub);
127 
128  while (p < array_end)
129  {
130  byteswap_body_helper (&sub,
131  FALSE,
132  old_byte_order,
133  new_byte_order,
134  p, &p);
135  }
136  }
137  }
138  else
139  {
140  _dbus_assert (current_type == DBUS_TYPE_STRING ||
141  current_type == DBUS_TYPE_OBJECT_PATH);
142 
143  p += (array_len + 1); /* + 1 for nul */
144  }
145  }
146  break;
147 
148  case DBUS_TYPE_SIGNATURE:
149  {
150  dbus_uint32_t sig_len;
151 
152  sig_len = *p;
153 
154  p += (sig_len + 2); /* +2 for len and nul */
155  }
156  break;
157 
158  case DBUS_TYPE_VARIANT:
159  {
160  /* 1 byte sig len, sig typecodes, align to
161  * contained-type-boundary, values.
162  */
163  dbus_uint32_t sig_len;
164  DBusString sig;
165  DBusTypeReader sub;
166  int contained_alignment;
167 
168  sig_len = *p;
169  ++p;
170 
171  _dbus_string_init_const_len (&sig, (const char *) p, sig_len);
172 
173  p += (sig_len + 1); /* 1 for nul */
174 
175  contained_alignment = _dbus_type_get_alignment (_dbus_first_type_in_signature (&sig, 0));
176 
177  p = _DBUS_ALIGN_ADDRESS (p, contained_alignment);
178 
179  _dbus_type_reader_init_types_only (&sub, &sig, 0);
180 
181  byteswap_body_helper (&sub, FALSE, old_byte_order, new_byte_order, p, &p);
182  }
183  break;
184 
185  case DBUS_TYPE_STRUCT:
187  {
188  DBusTypeReader sub;
189 
190  p = _DBUS_ALIGN_ADDRESS (p, 8);
191 
192  _dbus_type_reader_recurse (reader, &sub);
193 
194  byteswap_body_helper (&sub, TRUE, old_byte_order, new_byte_order, p, &p);
195  }
196  break;
197 
198  default:
199  _dbus_assert_not_reached ("invalid typecode in supposedly-validated signature");
200  break;
201  }
202 
203  if (walk_reader_to_end)
204  _dbus_type_reader_next (reader);
205  else
206  break;
207  }
208 
209  if (new_p)
210  *new_p = p;
211 }
212 
223 void
225  int signature_start,
226  int old_byte_order,
227  int new_byte_order,
228  DBusString *value_str,
229  int value_pos)
230 {
231  DBusTypeReader reader;
232 
233  _dbus_assert (value_pos >= 0);
234  _dbus_assert (value_pos <= _dbus_string_get_length (value_str));
235 
236  if (old_byte_order == new_byte_order)
237  return;
238 
240  signature, signature_start);
241 
242  byteswap_body_helper (&reader, TRUE,
243  old_byte_order, new_byte_order,
244  _dbus_string_get_udata_len (value_str, value_pos, 0),
245  NULL);
246 }
247 
250 /* Tests in dbus-marshal-byteswap-util.c */
dbus_bool_t dbus_type_is_fixed(int typecode)
Tells you whether values of this type can change length if you set them to some other value...
unsigned int dbus_uint32_t
A 32-bit unsigned integer on all platforms.
#define DBUS_TYPE_UINT16
Type code marking a 16-bit unsigned integer.
Definition: dbus-protocol.h:80
#define NULL
A null pointer, defined appropriately for C or C++.
int _dbus_first_type_in_signature(const DBusString *str, int pos)
Get the first type in the signature.
void _dbus_type_reader_recurse(DBusTypeReader *reader, DBusTypeReader *sub)
Initialize a new reader pointing to the first type and corresponding value that's a child of the curr...
#define DBUS_TYPE_STRUCT
STRUCT and DICT_ENTRY are sort of special since their codes can't appear in a type string...
#define DBUS_TYPE_DICT_ENTRY
Type code used to represent a dict entry; however, this type code does not appear in type signatures...
#define DBUS_TYPE_STRING
Type code marking a UTF-8 encoded, nul-terminated Unicode string.
#define DBUS_TYPE_BYTE
Type code marking an 8-bit unsigned integer.
Definition: dbus-protocol.h:68
void _dbus_swap_array(unsigned char *data, int n_elements, int alignment)
Swaps the elements of an array to the opposite byte order.
void _dbus_type_reader_init_types_only(DBusTypeReader *reader, const DBusString *type_str, int type_pos)
Like _dbus_type_reader_init() but the iteration is over the signature, not over values.
#define DBUS_TYPE_DOUBLE
Type code marking an 8-byte double in IEEE 754 format.
#define DBUS_TYPE_ARRAY
Type code marking a D-Bus array type.
#define DBUS_TYPE_INT64
Type code marking a 64-bit signed integer.
Definition: dbus-protocol.h:92
dbus_uint32_t _dbus_unpack_uint32(int byte_order, const unsigned char *data)
Unpacks a 32 bit unsigned integer from a data pointer.
dbus_uint32_t dbus_bool_t
A boolean, valid values are TRUE and FALSE.
Definition: dbus-types.h:37
_DBUS_GNUC_EXTENSION typedef unsigned long dbus_uint64_t
A 64-bit unsigned integer.
#define DBUS_TYPE_INT32
Type code marking a 32-bit signed integer.
Definition: dbus-protocol.h:84
dbus_bool_t _dbus_type_reader_next(DBusTypeReader *reader)
Skip to the next value on this "level".
#define DBUS_TYPE_SIGNATURE
Type code marking a D-Bus type signature.
#define DBUS_TYPE_UINT64
Type code marking a 64-bit unsigned integer.
Definition: dbus-protocol.h:96
#define DBUS_TYPE_VARIANT
Type code marking a D-Bus variant type.
#define DBUS_TYPE_UINT32
Type code marking a 32-bit unsigned integer.
Definition: dbus-protocol.h:88
#define _dbus_assert_not_reached(explanation)
Aborts with an error message if called.
The type reader is an iterator for reading values from a block of values.
#define TRUE
Expands to "1".
#define _dbus_assert(condition)
Aborts with an error message if the condition is false.
#define DBUS_TYPE_OBJECT_PATH
Type code marking a D-Bus object path.
#define DBUS_TYPE_UNIX_FD
Type code marking a unix file descriptor.
#define DBUS_TYPE_INVALID
Type code that is never equal to a legitimate type code.
Definition: dbus-protocol.h:62
#define DBUS_MAXIMUM_ARRAY_LENGTH
Max length of a marshaled array in bytes (64M, 2^26) We use signed int for lengths so must be INT_MAX...
#define DBUS_TYPE_INT16
Type code marking a 16-bit signed integer.
Definition: dbus-protocol.h:76
#define DBUS_TYPE_BOOLEAN
Type code marking a boolean.
Definition: dbus-protocol.h:72
int _dbus_type_reader_get_element_type(const DBusTypeReader *reader)
Gets the type of an element of the array the reader is currently pointing to.
int _dbus_type_reader_get_current_type(const DBusTypeReader *reader)
Gets the type of the value the reader is currently pointing to; or for a types-only reader gets the t...
#define FALSE
Expands to "0".
int _dbus_type_get_alignment(int typecode)
Gets the alignment requirement for the given type; will be 1, 2, 4, or 8.
void _dbus_string_init_const_len(DBusString *str, const char *value, int len)
Initializes a constant string with a length.
Definition: dbus-string.c:217
unsigned short dbus_uint16_t
A 16-bit unsigned integer on all platforms.
void _dbus_marshal_byteswap(const DBusString *signature, int signature_start, int old_byte_order, int new_byte_order, DBusString *value_str, int value_pos)
Byteswaps the marshaled data in the given value_str.