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glibc/iconvdata/utf-7.c

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/* Conversion module for UTF-7.
Copyright (C) 2000-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
/* UTF-7 is a legacy encoding used for transmitting Unicode within the
ASCII character set, used primarily by mail agents. New programs
are encouraged to use UTF-8 instead.
UTF-7 is specified in RFC 2152 (and old RFC 1641, RFC 1642). The
original Base64 encoding is defined in RFC 2045. */
#include <dlfcn.h>
#include <gconv.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
enum variant
{
UTF7,
UTF_7_IMAP
};
/* Must be in the same order as enum variant above. */
static const char names[] =
"UTF-7//\0"
"UTF-7-IMAP//\0"
"\0";
static uint32_t
shift_character (enum variant const var)
{
if (var == UTF7)
return '+';
else if (var == UTF_7_IMAP)
return '&';
else
abort ();
}
static bool
between (uint32_t const ch,
uint32_t const lower_bound, uint32_t const upper_bound)
{
return (ch >= lower_bound && ch <= upper_bound);
}
/* The set of "direct characters":
A-Z a-z 0-9 ' ( ) , - . / : ? space tab lf cr
FOR UTF-7-IMAP
A-Z a-z 0-9 ' ( ) , - . / : ? space
! " # $ % + * ; < = > @ [ \ ] ^ _ ` { | } ~
*/
static bool
isdirect (uint32_t ch, enum variant var)
{
if (var == UTF7)
return (between (ch, 'A', 'Z')
|| between (ch, 'a', 'z')
|| between (ch, '0', '9')
|| ch == '\'' || ch == '(' || ch == ')'
|| between (ch, ',', '/')
|| ch == ':' || ch == '?'
|| ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r');
else if (var == UTF_7_IMAP)
return (ch != '&' && between (ch, ' ', '~'));
abort ();
}
/* The set of "direct and optional direct characters":
A-Z a-z 0-9 ' ( ) , - . / : ? space tab lf cr
(UTF-7 only)
! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
*/
static bool
isxdirect (uint32_t ch, enum variant var)
{
if (isdirect (ch, var))
return true;
if (var != UTF7)
return false;
return between (ch, '!', '&')
|| ch == '*'
|| between (ch, ';', '@')
|| (between (ch, '[', '`') && ch != '\\')
|| between (ch, '{', '}');
}
/* Characters which needs to trigger an explicit shift back to US-ASCII (UTF-7
only): Modified base64 + '-' (shift back character)
A-Z a-z 0-9 + / -
*/
static bool
needs_explicit_shift (uint32_t ch)
{
return (between (ch, 'A', 'Z')
|| between (ch, 'a', 'z')
|| between (ch, '/', '9') || ch == '+' || ch == '-');
}
/* Converts a value in the range 0..63 to a base64 encoded char. */
static unsigned char
base64 (unsigned int i, enum variant var)
{
if (i < 26)
return i + 'A';
else if (i < 52)
return i - 26 + 'a';
else if (i < 62)
return i - 52 + '0';
else if (i == 62)
return '+';
else if (i == 63 && var == UTF7)
return '/';
else if (i == 63 && var == UTF_7_IMAP)
return ',';
else
abort ();
}
/* Definitions used in the body of the `gconv' function. */
#define DEFINE_INIT 0
#define DEFINE_FINI 0
#define FROM_LOOP from_utf7_loop
#define TO_LOOP to_utf7_loop
#define MIN_NEEDED_FROM 1
#define MAX_NEEDED_FROM 6
#define MIN_NEEDED_TO 4
#define MAX_NEEDED_TO 4
#define ONE_DIRECTION 0
#define FROM_DIRECTION (dir == from_utf7)
#define PREPARE_LOOP \
mbstate_t saved_state; \
mbstate_t *statep = data->__statep; \
enum direction dir = ((struct utf7_data *) step->__data)->dir; \
enum variant var = ((struct utf7_data *) step->__data)->var;
#define EXTRA_LOOP_ARGS , statep, var
enum direction
{
illegal_dir,
from_utf7,
to_utf7
};
struct utf7_data
{
enum direction dir;
enum variant var;
};
/* Since we might have to reset input pointer we must be able to save
and restore the state. */
#define SAVE_RESET_STATE(Save) \
if (Save) \
saved_state = *statep; \
else \
*statep = saved_state
int
gconv_init (struct __gconv_step *step)
{
/* Determine which direction. */
struct utf7_data *new_data;
enum direction dir = illegal_dir;
enum variant var = 0;
for (const char *name = names; *name != '\0';
name = strchr (name, '\0') + 1)
{
if (__strcasecmp (step->__from_name, name) == 0)
{
dir = from_utf7;
break;
}
else if (__strcasecmp (step->__to_name, name) == 0)
{
dir = to_utf7;
break;
}
++var;
}
if (__glibc_likely (dir != illegal_dir))
{
new_data = malloc (sizeof (*new_data));
if (new_data == NULL)
return __GCONV_NOMEM;
new_data->dir = dir;
new_data->var = var;
step->__data = new_data;
if (dir == from_utf7)
{
step->__min_needed_from = MIN_NEEDED_FROM;
step->__max_needed_from = MAX_NEEDED_FROM;
step->__min_needed_to = MIN_NEEDED_TO;
step->__max_needed_to = MAX_NEEDED_TO;
}
else
{
step->__min_needed_from = MIN_NEEDED_TO;
step->__max_needed_from = MAX_NEEDED_TO;
step->__min_needed_to = MIN_NEEDED_FROM;
step->__max_needed_to = MAX_NEEDED_FROM;
}
}
else
return __GCONV_NOCONV;
step->__stateful = 1;
return __GCONV_OK;
}
void
gconv_end (struct __gconv_step *data)
{
free (data->__data);
}
/* First define the conversion function from UTF-7 to UCS4.
The state is structured as follows:
__count bit 2..0: zero
__count bit 8..3: shift
__wch: data
Precise meaning:
shift data
0 -- not inside base64 encoding
1..32 XX..XX00..00 inside base64, (32 - shift) bits pending
This state layout is simpler than relying on STORE_REST/UNPACK_BYTES.
When shift = 0, __wch needs to store at most one lookahead byte (see
__GCONV_INCOMPLETE_INPUT below).
*/
#define MIN_NEEDED_INPUT MIN_NEEDED_FROM
#define MAX_NEEDED_INPUT MAX_NEEDED_FROM
#define MIN_NEEDED_OUTPUT MIN_NEEDED_TO
#define MAX_NEEDED_OUTPUT MAX_NEEDED_TO
#define LOOPFCT FROM_LOOP
#define BODY \
{ \
uint_fast8_t ch = *inptr; \
\
if ((statep->__count >> 3) == 0) \
{ \
/* base64 encoding inactive. */ \
if (isxdirect (ch, var)) \
{ \
inptr++; \
put32 (outptr, ch); \
outptr += 4; \
} \
else if (__glibc_likely (ch == shift_character (var))) \
{ \
if (__glibc_unlikely (inptr + 2 > inend)) \
{ \
/* Not enough input available. */ \
result = __GCONV_INCOMPLETE_INPUT; \
break; \
} \
if (inptr[1] == '-') \
{ \
inptr += 2; \
put32 (outptr, ch); \
outptr += 4; \
} \
else \
{ \
/* Switch into base64 mode. */ \
inptr++; \
statep->__count = (32 << 3); \
statep->__value.__wch = 0; \
} \
} \
else \
{ \
/* The input is invalid. */ \
STANDARD_FROM_LOOP_ERR_HANDLER (1); \
} \
} \
else \
{ \
/* base64 encoding active. */ \
uint32_t i; \
int shift; \
\
if (ch >= 'A' && ch <= 'Z') \
i = ch - 'A'; \
else if (ch >= 'a' && ch <= 'z') \
i = ch - 'a' + 26; \
else if (ch >= '0' && ch <= '9') \
i = ch - '0' + 52; \
else if (ch == '+') \
i = 62; \
else if ((var == UTF7 && ch == '/') \
|| (var == UTF_7_IMAP && ch == ',')) \
i = 63; \
else \
{ \
/* Terminate base64 encoding. */ \
\
/* If accumulated data is nonzero, the input is invalid. */ \
/* Also, partial UTF-16 characters are invalid. */ \
/* In IMAP variant, must be terminated by '-'. */ \
if (__glibc_unlikely (statep->__value.__wch != 0) \
|| __glibc_unlikely ((statep->__count >> 3) <= 26) \
|| __glibc_unlikely (var == UTF_7_IMAP && ch != '-')) \
{ \
STANDARD_FROM_LOOP_ERR_HANDLER ((statep->__count = 0, 1)); \
} \
\
if (ch == '-') \
inptr++; \
\
statep->__count = 0; \
continue; \
} \
\
/* Concatenate the base64 integer i to the accumulator. */ \
shift = (statep->__count >> 3); \
if (shift > 6) \
{ \
uint32_t wch; \
\
shift -= 6; \
wch = statep->__value.__wch | (i << shift); \
\
if (shift <= 16 && shift > 10) \
{ \
/* An UTF-16 character has just been completed. */ \
uint32_t wc1 = wch >> 16; \
\
/* UTF-16: When we see a High Surrogate, we must also decode \
the following Low Surrogate. */ \
if (!(wc1 >= 0xd800 && wc1 < 0xdc00)) \
{ \
wch = wch << 16; \
shift += 16; \
put32 (outptr, wc1); \
outptr += 4; \
} \
} \
else if (shift <= 10 && shift > 4) \
{ \
/* After a High Surrogate, verify that the next 16 bit \
indeed form a Low Surrogate. */ \
uint32_t wc2 = wch & 0xffff; \
\
if (! __glibc_likely (wc2 >= 0xdc00 && wc2 < 0xe000)) \
{ \
STANDARD_FROM_LOOP_ERR_HANDLER ((statep->__count = 0, 1));\
} \
} \
\
statep->__value.__wch = wch; \
} \
else \
{ \
/* An UTF-16 surrogate pair has just been completed. */ \
uint32_t wc1 = (uint32_t) statep->__value.__wch >> 16; \
uint32_t wc2 = ((uint32_t) statep->__value.__wch & 0xffff) \
| (i >> (6 - shift)); \
\
statep->__value.__wch = (i << shift) << 26; \
shift += 26; \
\
assert (wc1 >= 0xd800 && wc1 < 0xdc00); \
assert (wc2 >= 0xdc00 && wc2 < 0xe000); \
put32 (outptr, \
0x10000 + ((wc1 - 0xd800) << 10) + (wc2 - 0xdc00)); \
outptr += 4; \
} \
\
statep->__count = shift << 3; \
\
/* Now that we digested the input increment the input pointer. */ \
inptr++; \
} \
}
#define LOOP_NEED_FLAGS
#define EXTRA_LOOP_DECLS , mbstate_t *statep, enum variant var
#include <iconv/loop.c>
/* Next, define the conversion from UCS4 to UTF-7.
The state is structured as follows:
__count bit 2..0: zero
__count bit 4..3: shift
__count bit 8..5: data
Precise meaning:
shift data
0 0 not inside base64 encoding
1 0 inside base64, no pending bits
2 XX00 inside base64, 2 bits known for next byte
3 XXXX inside base64, 4 bits known for next byte
__count bit 2..0 and __wch are always zero, because this direction
never returns __GCONV_INCOMPLETE_INPUT.
*/
#define MIN_NEEDED_INPUT MIN_NEEDED_TO
#define MAX_NEEDED_INPUT MAX_NEEDED_TO
#define MIN_NEEDED_OUTPUT MIN_NEEDED_FROM
#define MAX_NEEDED_OUTPUT MAX_NEEDED_FROM
#define LOOPFCT TO_LOOP
#define BODY \
{ \
uint32_t ch = get32 (inptr); \
\
if ((statep->__count & 0x18) == 0) \
{ \
/* base64 encoding inactive */ \
if (isdirect (ch, var)) \
{ \
*outptr++ = (unsigned char) ch; \
} \
else \
{ \
size_t count; \
\
if (ch == shift_character (var)) \
count = 2; \
else if (ch < 0x10000) \
count = 3; \
else if (ch < 0x110000) \
count = 6; \
else \
STANDARD_TO_LOOP_ERR_HANDLER (4); \
\
if (__glibc_unlikely (outptr + count > outend)) \
{ \
result = __GCONV_FULL_OUTPUT; \
break; \
} \
\
*outptr++ = shift_character (var); \
if (ch == shift_character (var)) \
*outptr++ = '-'; \
else if (ch < 0x10000) \
{ \
*outptr++ = base64 (ch >> 10, var); \
*outptr++ = base64 ((ch >> 4) & 0x3f, var); \
statep->__count = ((ch & 15) << 5) | (3 << 3); \
} \
else if (ch < 0x110000) \
{ \
uint32_t ch1 = 0xd800 + ((ch - 0x10000) >> 10); \
uint32_t ch2 = 0xdc00 + ((ch - 0x10000) & 0x3ff); \
\
ch = (ch1 << 16) | ch2; \
*outptr++ = base64 (ch >> 26, var); \
*outptr++ = base64 ((ch >> 20) & 0x3f, var); \
*outptr++ = base64 ((ch >> 14) & 0x3f, var); \
*outptr++ = base64 ((ch >> 8) & 0x3f, var); \
*outptr++ = base64 ((ch >> 2) & 0x3f, var); \
statep->__count = ((ch & 3) << 7) | (2 << 3); \
} \
else \
abort (); \
} \
} \
else \
{ \
/* base64 encoding active */ \
if ((var == UTF_7_IMAP && ch == '&') || isdirect (ch, var)) \
{ \
/* deactivate base64 encoding */ \
size_t count; \
\
count = ((statep->__count & 0x18) >= 0x10) \
+ (var == UTF_7_IMAP || needs_explicit_shift (ch)) \
+ (var == UTF_7_IMAP && ch == '&') \
+ 1; \
if (__glibc_unlikely (outptr + count > outend)) \
{ \
result = __GCONV_FULL_OUTPUT; \
break; \
} \
\
if ((statep->__count & 0x18) >= 0x10) \
*outptr++ = base64 ((statep->__count >> 3) & ~3, var); \
if (var == UTF_7_IMAP || needs_explicit_shift (ch)) \
*outptr++ = '-'; \
*outptr++ = (unsigned char) ch; \
if (var == UTF_7_IMAP && ch == '&') \
*outptr++ = '-'; \
statep->__count = 0; \
} \
else \
{ \
size_t count; \
\
if (ch < 0x10000) \
count = ((statep->__count & 0x18) >= 0x10 ? 3 : 2); \
else if (ch < 0x110000) \
count = ((statep->__count & 0x18) >= 0x18 ? 6 : 5); \
else \
STANDARD_TO_LOOP_ERR_HANDLER (4); \
\
if (__glibc_unlikely (outptr + count > outend)) \
{ \
result = __GCONV_FULL_OUTPUT; \
break; \
} \
\
if (ch < 0x10000) \
{ \
switch ((statep->__count >> 3) & 3) \
{ \
case 1: \
*outptr++ = base64 (ch >> 10, var); \
*outptr++ = base64 ((ch >> 4) & 0x3f, var); \
statep->__count = ((ch & 15) << 5) | (3 << 3); \
break; \
case 2: \
*outptr++ = \
base64 (((statep->__count >> 3) & ~3) | (ch >> 12), \
var); \
*outptr++ = base64 ((ch >> 6) & 0x3f, var); \
*outptr++ = base64 (ch & 0x3f, var); \
statep->__count = (1 << 3); \
break; \
case 3: \
*outptr++ = \
base64 (((statep->__count >> 3) & ~3) | (ch >> 14), \
var); \
*outptr++ = base64 ((ch >> 8) & 0x3f, var); \
*outptr++ = base64 ((ch >> 2) & 0x3f, var); \
statep->__count = ((ch & 3) << 7) | (2 << 3); \
break; \
default: \
abort (); \
} \
} \
else if (ch < 0x110000) \
{ \
uint32_t ch1 = 0xd800 + ((ch - 0x10000) >> 10); \
uint32_t ch2 = 0xdc00 + ((ch - 0x10000) & 0x3ff); \
\
ch = (ch1 << 16) | ch2; \
switch ((statep->__count >> 3) & 3) \
{ \
case 1: \
*outptr++ = base64 (ch >> 26, var); \
*outptr++ = base64 ((ch >> 20) & 0x3f, var); \
*outptr++ = base64 ((ch >> 14) & 0x3f, var); \
*outptr++ = base64 ((ch >> 8) & 0x3f, var); \
*outptr++ = base64 ((ch >> 2) & 0x3f, var); \
statep->__count = ((ch & 3) << 7) | (2 << 3); \
break; \
case 2: \
*outptr++ = \
base64 (((statep->__count >> 3) & ~3) | (ch >> 28), \
var); \
*outptr++ = base64 ((ch >> 22) & 0x3f, var); \
*outptr++ = base64 ((ch >> 16) & 0x3f, var); \
*outptr++ = base64 ((ch >> 10) & 0x3f, var); \
*outptr++ = base64 ((ch >> 4) & 0x3f, var); \
statep->__count = ((ch & 15) << 5) | (3 << 3); \
break; \
case 3: \
*outptr++ = \
base64 (((statep->__count >> 3) & ~3) | (ch >> 30), \
var); \
*outptr++ = base64 ((ch >> 24) & 0x3f, var); \
*outptr++ = base64 ((ch >> 18) & 0x3f, var); \
*outptr++ = base64 ((ch >> 12) & 0x3f, var); \
*outptr++ = base64 ((ch >> 6) & 0x3f, var); \
*outptr++ = base64 (ch & 0x3f, var); \
statep->__count = (1 << 3); \
break; \
default: \
abort (); \
} \
} \
else \
abort (); \
} \
} \
\
/* Now that we wrote the output increment the input pointer. */ \
inptr += 4; \
}
#define LOOP_NEED_FLAGS
#define EXTRA_LOOP_DECLS , mbstate_t *statep, enum variant var
#include <iconv/loop.c>
/* Since this is a stateful encoding we have to provide code which resets
the output state to the initial state. This has to be done during the
flushing. */
#define EMIT_SHIFT_TO_INIT \
if (FROM_DIRECTION) \
/* Nothing to emit. */ \
memset (data->__statep, '\0', sizeof (mbstate_t)); \
else \
{ \
/* The "to UTF-7" direction. Flush the remaining bits and terminate \
with a '-' byte. This will guarantee correct decoding if more \
UTF-7 encoded text is added afterwards. */ \
int state = data->__statep->__count; \
\
if (state & 0x18) \
{ \
/* Deactivate base64 encoding. */ \
size_t count = ((state & 0x18) >= 0x10) + 1; \
\
if (__glibc_unlikely (outbuf + count > outend)) \
/* We don't have enough room in the output buffer. */ \
status = __GCONV_FULL_OUTPUT; \
else \
{ \
/* Write out the shift sequence. */ \
if ((state & 0x18) >= 0x10) \
*outbuf++ = base64 ((state >> 3) & ~3, var); \
*outbuf++ = '-'; \
\
data->__statep->__count = 0; \
} \
} \
else \
data->__statep->__count = 0; \
}
/* Now define the toplevel functions. */
#include <iconv/skeleton.c>
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