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458 lines
13 KiB
C
458 lines
13 KiB
C
/* ***** BEGIN LICENSE BLOCK *****
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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* This code is based on nssb64e.c from Mozilla.org, which allows
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* the code to be licensed under MPL/GPL/or LGPL. We will license it
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* under LGPL --mwang 8/22/07
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "genutil_base64.h"
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/*
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* The following implementation of base64 decoding was based on code
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* found in libmime (specifically, in mimeenc.c). It has been adapted to
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* use PR types and naming as well as to provide other necessary semantics
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* (like buffer-in/buffer-out in addition to "streaming" without undue
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* performance hit of extra copying if you made the buffer versions
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* use the output_fn). It also incorporates some aspects of the current
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* NSPR base64 decoding code. As such, you may find similarities to
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* both of those implementations. I tried to use names that reflected
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* the original code when possible. For this reason you may find some
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* inconsistencies -- libmime used lots of "in" and "out" whereas the
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* NSPR version uses "src" and "dest"; sometimes I changed one to the other
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* and sometimes I left them when I thought the subroutines were at least
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* self-consistent.
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*/
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/*
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* Opaque object used by the decoder to store state.
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*/
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typedef struct PLBase64DecoderStr {
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/* Current token (or portion, if token_size < 4) being decoded. */
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unsigned char token[4];
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SINT32 token_size;
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/*
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* Where the decoded output goes -- this will
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* be the entire buffered result for users of the buffer version.
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*/
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unsigned char *output_buffer;
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UINT32 output_buflen; /* the total length of allocated buffer */
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UINT32 output_length; /* the length that is currently populated */
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} PLBase64Decoder;
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/*
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* Table to convert an ascii "code" to its corresponding binary value.
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* For ease of use, the binary values in the table are the actual values
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* PLUS ONE. This is so that the special value of zero can denote an
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* invalid mapping; that was much easier than trying to fill in the other
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* values with some value other than zero, and to check for it.
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* Just remember to SUBTRACT ONE when using the value retrieved.
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*/
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static unsigned char base64_codetovaluep1[256] = {
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/* 0: */ 0, 0, 0, 0, 0, 0, 0, 0,
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/* 8: */ 0, 0, 0, 0, 0, 0, 0, 0,
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/* 16: */ 0, 0, 0, 0, 0, 0, 0, 0,
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/* 24: */ 0, 0, 0, 0, 0, 0, 0, 0,
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/* 32: */ 0, 0, 0, 0, 0, 0, 0, 0,
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/* 40: */ 0, 0, 0, 63, 0, 0, 0, 64,
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/* 48: */ 53, 54, 55, 56, 57, 58, 59, 60,
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/* 56: */ 61, 62, 0, 0, 0, 0, 0, 0,
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/* 64: */ 0, 1, 2, 3, 4, 5, 6, 7,
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/* 72: */ 8, 9, 10, 11, 12, 13, 14, 15,
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/* 80: */ 16, 17, 18, 19, 20, 21, 22, 23,
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/* 88: */ 24, 25, 26, 0, 0, 0, 0, 0,
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/* 96: */ 0, 27, 28, 29, 30, 31, 32, 33,
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/* 104: */ 34, 35, 36, 37, 38, 39, 40, 41,
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/* 112: */ 42, 43, 44, 45, 46, 47, 48, 49,
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/* 120: */ 50, 51, 52, 0, 0, 0, 0, 0,
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/* 128: */ 0, 0, 0, 0, 0, 0, 0, 0
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/* and rest are all zero as well */
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};
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#define B64_PAD '='
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/*
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* Reads 4; writes 3 (known, or expected, to have no trailing padding).
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* Returns bytes written; -1 on error (unexpected character).
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*/
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static int
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pl_base64_decode_4to3 (const unsigned char *in, unsigned char *out)
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{
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int j;
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SINT32 num = 0;
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unsigned char bits;
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for (j = 0; j < 4; j++) {
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bits = base64_codetovaluep1[in[j]];
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if (bits == 0)
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return -1;
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num = (num << 6) | (bits - 1);
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}
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out[0] = (unsigned char) (num >> 16);
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out[1] = (unsigned char) ((num >> 8) & 0xFF);
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out[2] = (unsigned char) (num & 0xFF);
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return 3;
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}
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/*
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* Reads 3; writes 2 (caller already confirmed EOF or trailing padding).
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* Returns bytes written; -1 on error (unexpected character).
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*/
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static int
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pl_base64_decode_3to2 (const unsigned char *in, unsigned char *out)
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{
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SINT32 num = 0;
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unsigned char bits1, bits2, bits3;
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bits1 = base64_codetovaluep1[in[0]];
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bits2 = base64_codetovaluep1[in[1]];
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bits3 = base64_codetovaluep1[in[2]];
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if ((bits1 == 0) || (bits2 == 0) || (bits3 == 0))
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return -1;
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num = ((UINT32)(bits1 - 1)) << 10;
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num |= ((UINT32)(bits2 - 1)) << 4;
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num |= ((UINT32)(bits3 - 1)) >> 2;
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out[0] = (unsigned char) (num >> 8);
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out[1] = (unsigned char) (num & 0xFF);
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return 2;
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}
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/*
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* Reads 2; writes 1 (caller already confirmed EOF or trailing padding).
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* Returns bytes written; -1 on error (unexpected character).
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*/
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static int
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pl_base64_decode_2to1 (const unsigned char *in, unsigned char *out)
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{
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SINT32 num = 0;
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unsigned char bits1, bits2;
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bits1 = base64_codetovaluep1[in[0]];
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bits2 = base64_codetovaluep1[in[1]];
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if ((bits1 == 0) || (bits2 == 0))
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return -1;
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num = ((UINT32)(bits1 - 1)) << 2;
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num |= ((UINT32)(bits2 - 1)) >> 4;
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out[0] = (unsigned char) num;
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return 1;
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}
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/*
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* Reads 4; writes 0-3. Returns bytes written or -1 on error.
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* (Writes less than 3 only at (presumed) EOF.)
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*/
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static int
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pl_base64_decode_token (const unsigned char *in, unsigned char *out)
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{
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if (in[3] != B64_PAD)
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return pl_base64_decode_4to3 (in, out);
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if (in[2] == B64_PAD)
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return pl_base64_decode_2to1 (in, out);
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return pl_base64_decode_3to2 (in, out);
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}
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static SINT32
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pl_base64_decode_buffer (PLBase64Decoder *data, const unsigned char *in, UINT32 length)
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{
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unsigned char *out = data->output_buffer;
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unsigned char *token = data->token;
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int i, n = 0;
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i = data->token_size;
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data->token_size = 0;
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while (length > 0)
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{
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while (i < 4 && length > 0)
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{
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/*
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* XXX Note that the following simply ignores any unexpected
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* characters. This is exactly what the original code in
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* libmime did, and I am leaving it. We certainly want to skip
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* over whitespace (we must); this does much more than that.
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* I am not confident changing it, and I don't want to slow
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* the processing down doing more complicated checking, but
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* someone else might have different ideas in the future.
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*/
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if (base64_codetovaluep1[*in] > 0 || *in == B64_PAD)
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{
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token[i++] = *in;
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}
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in++;
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length--;
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}
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if (i < 4)
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{
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/* Didn't get enough for a complete token. */
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data->token_size = i;
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break;
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}
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i = 0;
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assert((out - data->output_buffer + 3) <= (SINT32) data->output_buflen);
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/*
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* Assume we are not at the end; the following function only works
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* for an internal token (no trailing padding characters) but is
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* faster that way. If it hits an invalid character (padding) it
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* will return an error; we break out of the loop and try again
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* calling the routine that will handle a final token.
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* Note that we intentionally do it this way rather than explicitly
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* add a check for padding here (because that would just slow down
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* the normal case) nor do we rely on checking whether we have more
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* input to process (because that would also slow it down but also
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* because we want to allow trailing garbage, especially white space
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* and cannot tell that without read-ahead, also a slow proposition).
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* Whew. Understand?
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*/
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n = pl_base64_decode_4to3 (token, out);
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if (n < 0)
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{
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break;
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}
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/* Advance "out" by the number of bytes just written to it. */
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out += n;
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n = 0;
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}
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/*
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* See big comment above, before call to pl_base64_decode_4to3.
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* Here we check if we error'd out of loop, and allow for the case
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* that we are processing the last interesting token. If the routine
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* which should handle padding characters also fails, then we just
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* have bad input and give up.
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*/
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if (n < 0)
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{
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n = pl_base64_decode_token (token, out);
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if (n < 0)
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{
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return B64RET_INTERNAL_ERROR;
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}
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out += n;
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}
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/*
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* As explained above, we can get here with more input remaining, but
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* it should be all characters we do not care about (i.e. would be
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* ignored when transferring from "in" to "token" in loop above,
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* except here we choose to ignore extraneous pad characters, too).
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* Swallow it, performing that check. If we find more characters that
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* we would expect to decode, something is wrong.
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*/
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while (length > 0)
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{
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if (base64_codetovaluep1[*in] > 0)
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{
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return B64RET_INTERNAL_ERROR;
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}
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in++;
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length--;
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}
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/* Record the length of decoded data we have left in output_buffer. */
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data->output_length = (UINT32) (out - data->output_buffer);
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return B64RET_SUCCESS;
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}
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/*
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* Flush any remaining buffered characters. Given well-formed input,
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* this will have nothing to do. If the input was missing the padding
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* characters at the end, though, there could be 1-3 characters left
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* behind -- we will tolerate that by adding the padding for them.
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*/
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static SINT32 pl_base64_decode_flush (PLBase64Decoder *data)
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{
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int count;
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/*
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* If no remaining characters, or all are padding (also not well-formed
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* input, but again, be tolerant), then nothing more to do. (And, that
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* is considered successful.)
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*/
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if (data->token_size == 0 || data->token[0] == B64_PAD)
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{
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return B64RET_SUCCESS;
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}
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/*
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* Assume we have all the interesting input except for some expected
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* padding characters. Add them and decode the resulting token.
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*/
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while (data->token_size < 4)
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{
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data->token[data->token_size++] = B64_PAD;
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}
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data->token_size = 0; /* so a subsequent flush call is a no-op */
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count = pl_base64_decode_token (data->token,
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data->output_buffer + data->output_length);
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if (count < 0)
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{
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return B64RET_INTERNAL_ERROR;
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}
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data->output_length += count;
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return B64RET_SUCCESS;
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}
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/*
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* The maximum space needed to hold the output of the decoder given
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* input data of length "size".
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*/
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UINT32 genUtl_b64DecodedBufferLength(UINT32 size)
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{
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return ((size * 3) / 4);
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}
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/*
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* A distinct internal creation function for the buffer version to use.
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* (It does not want to specify an output_fn, and we want the normal
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* Create function to require that.) If more common initialization
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* of the decoding context needs to be done, it should be done *here*.
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*/
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static PLBase64Decoder *
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pl_base64_create_decoder (void)
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{
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return ((PLBase64Decoder *) calloc(1, sizeof(PLBase64Decoder)));
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}
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/*
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* When you're done decoding, call this to free the data.
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*/
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static void PL_DestroyBase64Decoder (PLBase64Decoder *data)
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{
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/* don't free output_buffer. That is the user's buffer.
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* just free the context buffer. */
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free(data);
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return;
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}
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SINT32 genUtl_b64DecodeMalloc(const char *b64Str,
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UINT8 **binaryBuf, UINT32 *binaryBufLen)
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{
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UINT32 b64StrLen;
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SINT32 ret;
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if (b64Str == NULL || b64Str[0] == '\0' ||
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binaryBuf == NULL || binaryBufLen == NULL)
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{
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return B64RET_INVALID_ARGUMENTS;
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}
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b64StrLen = strlen(b64Str);
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*binaryBufLen = genUtl_b64DecodedBufferLength(b64StrLen);
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*binaryBuf = calloc(1, *binaryBufLen);
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if (*binaryBuf == NULL)
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{
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return B64RET_RESOURCE_EXCEEDED;
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}
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ret = genUtl_b64Decode(b64Str, *binaryBuf, binaryBufLen);
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if (ret != B64RET_SUCCESS)
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{
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free(*binaryBuf);
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*binaryBuf = NULL;
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*binaryBufLen = 0;
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}
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return ret;
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}
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SINT32 genUtl_b64Decode(const char *b64Str,
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UINT8 *binaryBuf, UINT32 *binaryBufLen)
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{
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PLBase64Decoder *data = NULL;
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UINT32 b64StrLen;
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SINT32 ret;
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if (b64Str == NULL || b64Str[0] == '\0')
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{
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return B64RET_INVALID_ARGUMENTS;
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}
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b64StrLen = strlen(b64Str);
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/*
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* Allocate the decoding structure.
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*/
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if ((data = pl_base64_create_decoder()) == NULL)
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{
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return B64RET_INTERNAL_ERROR;
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}
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data->output_buflen = *binaryBufLen;
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data->output_buffer = binaryBuf;
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ret = pl_base64_decode_buffer(data, (const unsigned char *) b64Str, b64StrLen);
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/*
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* We do not wait for Destroy to flush, because Destroy will also
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* get rid of our decoder context, which we need to look at first!
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*/
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if (ret == B64RET_SUCCESS)
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{
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ret = pl_base64_decode_flush(data);
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}
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if (ret == B64RET_SUCCESS)
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{
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assert(data->output_length <= *binaryBufLen);
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*binaryBufLen = data->output_length;
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}
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PL_DestroyBase64Decoder(data);
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return ret;
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}
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