145392f07f
* src/b64dec.c, src/mbox-util.c, src/mbox-util.h: These three files are explicitly licensed under LGPL, but their comments suggest that details about the warranty can be found in the GPL. Adjust comments to refer to the correct license. Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
252 lines
7.0 KiB
C
252 lines
7.0 KiB
C
/* b64dec.c - Simple Base64 decoder.
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* Copyright (C) 2008, 2011 Free Software Foundation, Inc.
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* Copyright (C) 2008, 2011, 2016 g10 Code GmbH
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*
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* This file is part of GnuPG.
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*
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* This file is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as
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* published by the Free Software Foundation; either version 2.1 of
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* the License, or (at your option) any later version.
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*
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* This file 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
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* GNU 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 License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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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 "gpgme.h"
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#include "util.h"
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/* The reverse base-64 list used for base-64 decoding. */
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static unsigned char const asctobin[128] =
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{
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0xff, 0xff, 0x3e, 0xff, 0xff, 0xff, 0x3f,
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0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
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0x3c, 0x3d, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
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0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
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0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
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0x17, 0x18, 0x19, 0xff, 0xff, 0xff, 0xff, 0xff,
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0xff, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
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0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
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0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
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0x31, 0x32, 0x33, 0xff, 0xff, 0xff, 0xff, 0xff
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};
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enum decoder_states
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{
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s_init, s_idle, s_lfseen, s_beginseen, s_waitheader, s_waitblank, s_begin,
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s_b64_0, s_b64_1, s_b64_2, s_b64_3,
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s_waitendtitle, s_waitend
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};
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/* Initialize the context for the base64 decoder. If TITLE is NULL a
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plain base64 decoding is done. If it is the empty string the
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decoder will skip everything until a "-----BEGIN " line has been
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seen, decoding ends at a "----END " line. */
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gpg_error_t
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_gpgme_b64dec_start (struct b64state *state, const char *title)
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{
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memset (state, 0, sizeof *state);
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if (title)
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{
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state->title = strdup (title);
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if (!state->title)
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state->lasterr = gpg_error_from_syserror ();
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else
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state->idx = s_init;
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}
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else
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state->idx = s_b64_0;
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return state->lasterr;
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}
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/* Do in-place decoding of base-64 data of LENGTH in BUFFER. Stores the
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new length of the buffer at R_NBYTES. */
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gpg_error_t
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_gpgme_b64dec_proc (struct b64state *state, void *buffer, size_t length,
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size_t *r_nbytes)
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{
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enum decoder_states ds = state->idx;
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unsigned char val = state->radbuf[0];
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int pos = state->quad_count;
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char *d, *s;
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if (state->lasterr)
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return state->lasterr;
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if (state->stop_seen)
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{
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*r_nbytes = 0;
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state->lasterr = gpg_error (GPG_ERR_EOF);
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free (state->title);
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state->title = NULL;
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return state->lasterr;
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}
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for (s=d=buffer; length && !state->stop_seen; length--, s++)
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{
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again:
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switch (ds)
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{
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case s_idle:
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if (*s == '\n')
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{
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ds = s_lfseen;
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pos = 0;
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}
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break;
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case s_init:
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ds = s_lfseen;
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case s_lfseen:
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if (*s != "-----BEGIN "[pos])
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{
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ds = s_idle;
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goto again;
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}
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else if (pos == 10)
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{
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pos = 0;
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ds = s_beginseen;
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}
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else
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pos++;
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break;
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case s_beginseen:
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if (*s != "PGP "[pos])
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ds = s_begin; /* Not a PGP armor. */
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else if (pos == 3)
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ds = s_waitheader;
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else
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pos++;
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break;
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case s_waitheader:
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if (*s == '\n')
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ds = s_waitblank;
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break;
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case s_waitblank:
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if (*s == '\n')
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ds = s_b64_0; /* blank line found. */
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else if (*s == ' ' || *s == '\r' || *s == '\t')
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; /* Ignore spaces. */
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else
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{
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/* Armor header line. Note that we don't care that our
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* FSM accepts a header prefixed with spaces. */
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ds = s_waitheader; /* Wait for next header. */
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}
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break;
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case s_begin:
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if (*s == '\n')
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ds = s_b64_0;
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break;
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case s_b64_0:
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case s_b64_1:
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case s_b64_2:
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case s_b64_3:
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{
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int c;
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if (*s == '-' && state->title)
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{
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/* Not a valid Base64 character: assume end
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header. */
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ds = s_waitend;
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}
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else if (*s == '=')
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{
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/* Pad character: stop */
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if (ds == s_b64_1)
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*d++ = val;
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ds = state->title? s_waitendtitle : s_waitend;
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}
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else if (*s == '\n' || *s == ' ' || *s == '\r' || *s == '\t')
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; /* Skip white spaces. */
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else if ( (*s & 0x80)
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|| (c = asctobin[*(unsigned char *)s]) == 255)
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{
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/* Skip invalid encodings. */
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state->invalid_encoding = 1;
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}
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else if (ds == s_b64_0)
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{
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val = c << 2;
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ds = s_b64_1;
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}
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else if (ds == s_b64_1)
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{
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val |= (c>>4)&3;
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*d++ = val;
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val = (c<<4)&0xf0;
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ds = s_b64_2;
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}
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else if (ds == s_b64_2)
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{
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val |= (c>>2)&15;
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*d++ = val;
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val = (c<<6)&0xc0;
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ds = s_b64_3;
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}
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else
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{
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val |= c&0x3f;
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*d++ = val;
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ds = s_b64_0;
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}
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}
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break;
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case s_waitendtitle:
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if (*s == '-')
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ds = s_waitend;
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break;
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case s_waitend:
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if ( *s == '\n')
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state->stop_seen = 1;
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break;
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default:
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assert (!"invalid state");
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}
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}
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state->idx = ds;
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state->radbuf[0] = val;
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state->quad_count = pos;
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*r_nbytes = (d -(char*) buffer);
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return 0;
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}
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/* This function needs to be called before releasing the decoder
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state. It may return an error code in case an encoding error has
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been found during decoding. */
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gpg_error_t
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_gpgme_b64dec_finish (struct b64state *state)
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{
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if (state->lasterr)
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return state->lasterr;
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free (state->title);
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state->title = NULL;
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return state->invalid_encoding? gpg_error(GPG_ERR_BAD_DATA): 0;
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}
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