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glib2.0/glib/gbase64.c

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/* gbase64.c - Base64 encoding/decoding
*
* Copyright (C) 2006 Alexander Larsson <alexl@redhat.com>
* Copyright (C) 2000-2003 Ximian Inc.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This 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.
*
* This 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 this library; if not, see <http://www.gnu.org/licenses/>.
*
* This is based on code in camel, written by:
* Michael Zucchi <notzed@ximian.com>
* Jeffrey Stedfast <fejj@ximian.com>
*/
#include "config.h"
#include <string.h>
#include "gbase64.h"
#include "gtestutils.h"
#include "glibintl.h"
/**
* SECTION:base64
* @title: Base64 Encoding
* @short_description: encodes and decodes data in Base64 format
*
* Base64 is an encoding that allows a sequence of arbitrary bytes to be
* encoded as a sequence of printable ASCII characters. For the definition
* of Base64, see
* [RFC 1421](http://www.ietf.org/rfc/rfc1421.txt)
* or
* [RFC 2045](http://www.ietf.org/rfc/rfc2045.txt).
* Base64 is most commonly used as a MIME transfer encoding
* for email.
*
* GLib supports incremental encoding using g_base64_encode_step() and
* g_base64_encode_close(). Incremental decoding can be done with
* g_base64_decode_step(). To encode or decode data in one go, use
* g_base64_encode() or g_base64_decode(). To avoid memory allocation when
* decoding, you can use g_base64_decode_inplace().
*
* Support for Base64 encoding has been added in GLib 2.12.
*/
static const char base64_alphabet[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/**
* g_base64_encode_step:
* @in: (array length=len) (element-type guint8): the binary data to encode
* @len: the length of @in
* @break_lines: whether to break long lines
* @out: (out) (array) (element-type guint8): pointer to destination buffer
* @state: (inout): Saved state between steps, initialize to 0
* @save: (inout): Saved state between steps, initialize to 0
*
* Incrementally encode a sequence of binary data into its Base-64 stringified
* representation. By calling this function multiple times you can convert
* data in chunks to avoid having to have the full encoded data in memory.
*
* When all of the data has been converted you must call
* g_base64_encode_close() to flush the saved state.
*
* The output buffer must be large enough to fit all the data that will
* be written to it. Due to the way base64 encodes you will need
* at least: (@len / 3 + 1) * 4 + 4 bytes (+ 4 may be needed in case of
* non-zero state). If you enable line-breaking you will need at least:
* ((@len / 3 + 1) * 4 + 4) / 76 + 1 bytes of extra space.
*
* @break_lines is typically used when putting base64-encoded data in emails.
* It breaks the lines at 76 columns instead of putting all of the text on
* the same line. This avoids problems with long lines in the email system.
* Note however that it breaks the lines with `LF` characters, not
* `CR LF` sequences, so the result cannot be passed directly to SMTP
* or certain other protocols.
*
* Returns: The number of bytes of output that was written
*
* Since: 2.12
*/
gsize
g_base64_encode_step (const guchar *in,
gsize len,
gboolean break_lines,
gchar *out,
gint *state,
gint *save)
{
char *outptr;
const guchar *inptr;
g_return_val_if_fail (in != NULL || len == 0, 0);
g_return_val_if_fail (out != NULL, 0);
g_return_val_if_fail (state != NULL, 0);
g_return_val_if_fail (save != NULL, 0);
if (len == 0)
return 0;
inptr = in;
outptr = out;
if (len + ((char *) save) [0] > 2)
{
const guchar *inend = in+len-2;
int c1, c2, c3;
int already;
already = *state;
switch (((char *) save) [0])
{
case 1:
c1 = ((unsigned char *) save) [1];
goto skip1;
case 2:
c1 = ((unsigned char *) save) [1];
c2 = ((unsigned char *) save) [2];
goto skip2;
}
/*
* yes, we jump into the loop, no i'm not going to change it,
* it's beautiful!
*/
while (inptr < inend)
{
c1 = *inptr++;
skip1:
c2 = *inptr++;
skip2:
c3 = *inptr++;
*outptr++ = base64_alphabet [ c1 >> 2 ];
*outptr++ = base64_alphabet [ c2 >> 4 |
((c1&0x3) << 4) ];
*outptr++ = base64_alphabet [ ((c2 &0x0f) << 2) |
(c3 >> 6) ];
*outptr++ = base64_alphabet [ c3 & 0x3f ];
/* this is a bit ugly ... */
if (break_lines && (++already) >= 19)
{
*outptr++ = '\n';
already = 0;
}
}
((char *)save)[0] = 0;
len = 2 - (inptr - inend);
*state = already;
}
g_assert (len == 0 || len == 1 || len == 2);
{
char *saveout;
/* points to the slot for the next char to save */
saveout = & (((char *)save)[1]) + ((char *)save)[0];
/* len can only be 0 1 or 2 */
switch(len)
{
case 2:
*saveout++ = *inptr++;
G_GNUC_FALLTHROUGH;
case 1:
*saveout++ = *inptr++;
}
((char *)save)[0] += len;
}
return outptr - out;
}
/**
* g_base64_encode_close:
* @break_lines: whether to break long lines
* @out: (out) (array) (element-type guint8): pointer to destination buffer
* @state: (inout): Saved state from g_base64_encode_step()
* @save: (inout): Saved state from g_base64_encode_step()
*
* Flush the status from a sequence of calls to g_base64_encode_step().
*
* The output buffer must be large enough to fit all the data that will
* be written to it. It will need up to 4 bytes, or up to 5 bytes if
* line-breaking is enabled.
*
* The @out array will not be automatically nul-terminated.
*
* Returns: The number of bytes of output that was written
*
* Since: 2.12
*/
gsize
g_base64_encode_close (gboolean break_lines,
gchar *out,
gint *state,
gint *save)
{
int c1, c2;
char *outptr = out;
g_return_val_if_fail (out != NULL, 0);
g_return_val_if_fail (state != NULL, 0);
g_return_val_if_fail (save != NULL, 0);
c1 = ((unsigned char *) save) [1];
c2 = ((unsigned char *) save) [2];
switch (((char *) save) [0])
{
case 2:
outptr [2] = base64_alphabet[ ( (c2 &0x0f) << 2 ) ];
g_assert (outptr [2] != 0);
goto skip;
case 1:
outptr[2] = '=';
c2 = 0; /* saved state here is not relevant */
skip:
outptr [0] = base64_alphabet [ c1 >> 2 ];
outptr [1] = base64_alphabet [ c2 >> 4 | ( (c1&0x3) << 4 )];
outptr [3] = '=';
outptr += 4;
break;
}
if (break_lines)
*outptr++ = '\n';
*save = 0;
*state = 0;
return outptr - out;
}
/**
* g_base64_encode:
* @data: (array length=len) (element-type guint8) (nullable): the binary data to encode
* @len: the length of @data
*
* Encode a sequence of binary data into its Base-64 stringified
* representation.
*
* Returns: (transfer full): a newly allocated, zero-terminated Base-64
* encoded string representing @data. The returned string must
* be freed with g_free().
*
* Since: 2.12
*/
gchar *
g_base64_encode (const guchar *data,
gsize len)
{
gchar *out;
gint state = 0, outlen;
gint save = 0;
g_return_val_if_fail (data != NULL || len == 0, NULL);
/* We can use a smaller limit here, since we know the saved state is 0,
+1 is needed for trailing \0, also check for unlikely integer overflow */
g_return_val_if_fail (len < ((G_MAXSIZE - 1) / 4 - 1) * 3, NULL);
out = g_malloc ((len / 3 + 1) * 4 + 1);
outlen = g_base64_encode_step (data, len, FALSE, out, &state, &save);
outlen += g_base64_encode_close (FALSE, out + outlen, &state, &save);
out[outlen] = '\0';
return (gchar *) out;
}
static const unsigned char mime_base64_rank[256] = {
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255, 62,255,255,255, 63,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255, 0,255,255,
255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,255,255,255,255,255,
255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,
};
/**
* g_base64_decode_step: (skip)
* @in: (array length=len) (element-type guint8): binary input data
* @len: max length of @in data to decode
* @out: (out caller-allocates) (array) (element-type guint8): output buffer
* @state: (inout): Saved state between steps, initialize to 0
* @save: (inout): Saved state between steps, initialize to 0
*
* Incrementally decode a sequence of binary data from its Base-64 stringified
* representation. By calling this function multiple times you can convert
* data in chunks to avoid having to have the full encoded data in memory.
*
* The output buffer must be large enough to fit all the data that will
* be written to it. Since base64 encodes 3 bytes in 4 chars you need
* at least: (@len / 4) * 3 + 3 bytes (+ 3 may be needed in case of non-zero
* state).
*
* Returns: The number of bytes of output that was written
*
* Since: 2.12
**/
gsize
g_base64_decode_step (const gchar *in,
gsize len,
guchar *out,
gint *state,
guint *save)
{
const guchar *inptr;
guchar *outptr;
const guchar *inend;
guchar c, rank;
guchar last[2];
unsigned int v;
int i;
g_return_val_if_fail (in != NULL || len == 0, 0);
g_return_val_if_fail (out != NULL, 0);
g_return_val_if_fail (state != NULL, 0);
g_return_val_if_fail (save != NULL, 0);
if (len == 0)
return 0;
inend = (const guchar *)in+len;
outptr = out;
/* convert 4 base64 bytes to 3 normal bytes */
v=*save;
i=*state;
last[0] = last[1] = 0;
/* we use the sign in the state to determine if we got a padding character
in the previous sequence */
if (i < 0)
{
i = -i;
last[0] = '=';
}
inptr = (const guchar *)in;
while (inptr < inend)
{
c = *inptr++;
rank = mime_base64_rank [c];
if (rank != 0xff)
{
last[1] = last[0];
last[0] = c;
v = (v<<6) | rank;
i++;
if (i==4)
{
*outptr++ = v>>16;
if (last[1] != '=')
*outptr++ = v>>8;
if (last[0] != '=')
*outptr++ = v;
i=0;
}
}
}
*save = v;
*state = last[0] == '=' ? -i : i;
return outptr - out;
}
/**
* g_base64_decode:
* @text: (not nullable): zero-terminated string with base64 text to decode
* @out_len: (out): The length of the decoded data is written here
*
* Decode a sequence of Base-64 encoded text into binary data. Note
* that the returned binary data is not necessarily zero-terminated,
* so it should not be used as a character string.
*
* Returns: (transfer full) (array length=out_len) (element-type guint8):
* newly allocated buffer containing the binary data
* that @text represents. The returned buffer must
* be freed with g_free().
*
* Since: 2.12
*/
guchar *
g_base64_decode (const gchar *text,
gsize *out_len)
{
guchar *ret;
gsize input_length;
gint state = 0;
guint save = 0;
g_return_val_if_fail (text != NULL, NULL);
g_return_val_if_fail (out_len != NULL, NULL);
input_length = strlen (text);
/* We can use a smaller limit here, since we know the saved state is 0,
+1 used to avoid calling g_malloc0(0), and hence returning NULL */
ret = g_malloc0 ((input_length / 4) * 3 + 1);
*out_len = g_base64_decode_step (text, input_length, ret, &state, &save);
return ret;
}
/**
* g_base64_decode_inplace:
* @text: (inout) (array length=out_len) (element-type guint8): zero-terminated
* string with base64 text to decode
* @out_len: (inout): The length of the decoded data is written here
*
* Decode a sequence of Base-64 encoded text into binary data
* by overwriting the input data.
*
* Returns: (transfer none): The binary data that @text responds. This pointer
* is the same as the input @text.
*
* Since: 2.20
*/
guchar *
g_base64_decode_inplace (gchar *text,
gsize *out_len)
{
gint input_length, state = 0;
guint save = 0;
g_return_val_if_fail (text != NULL, NULL);
g_return_val_if_fail (out_len != NULL, NULL);
input_length = strlen (text);
g_return_val_if_fail (input_length > 1, NULL);
*out_len = g_base64_decode_step (text, input_length, (guchar *) text, &state, &save);
return (guchar *) text;
}
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