forked from osmocom/wireshark
![Alexis La Goutte](/assets/img/avatar_default.png)
Change-Id: I69589a90077a9b009f2e1a45531059ebd61a0450 Reviewed-on: https://code.wireshark.org/review/8242 Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com> Reviewed-by: Pascal Quantin <pascal.quantin@gmail.com> Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
228 lines
7.1 KiB
C
228 lines
7.1 KiB
C
/*
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* nghttp2 - HTTP/2 C Library
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*
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* Copyright (c) 2013 Tatsuhiro Tsujikawa
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "nghttp2_hd_huffman.h"
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#include <string.h>
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#include <assert.h>
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#include <stdio.h>
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#include "nghttp2_hd.h"
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extern const nghttp2_huff_sym huff_sym_table[];
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extern const nghttp2_huff_decode huff_decode_table[][16];
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/*
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* Encodes huffman code |sym| into |*dest_ptr|, whose least |rembits|
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* bits are not filled yet. The |rembits| must be in range [1, 8],
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* inclusive. At the end of the process, the |*dest_ptr| is updated
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* and points where next output should be placed. The number of
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* unfilled bits in the pointed location is returned.
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*/
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static ssize_t huff_encode_sym(nghttp2_bufs *bufs, size_t *avail_ptr,
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size_t rembits, const nghttp2_huff_sym *sym) {
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int rv;
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size_t nbits = sym->nbits;
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uint32_t code = sym->code;
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/* We assume that sym->nbits <= 32 */
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if (rembits > nbits) {
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nghttp2_bufs_fast_orb_hold(bufs, code << (rembits - nbits));
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return (ssize_t)(rembits - nbits);
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}
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if (rembits == nbits) {
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nghttp2_bufs_fast_orb(bufs, code);
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--*avail_ptr;
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return 8;
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}
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nghttp2_bufs_fast_orb(bufs, code >> (nbits - rembits));
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--*avail_ptr;
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nbits -= rembits;
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if (nbits & 0x7) {
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/* align code to MSB byte boundary */
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code <<= 8 - (nbits & 0x7);
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}
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/* we lose at most 3 bytes, but it is not critical in practice */
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if (*avail_ptr < (nbits + 7) / 8) {
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rv = nghttp2_bufs_advance(bufs);
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if (rv != 0) {
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return rv;
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}
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*avail_ptr = nghttp2_bufs_cur_avail(bufs);
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/* we assume that we at least 3 buffer space available */
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assert(*avail_ptr >= 3);
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}
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/* fast path, since most code is less than 8 */
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if (nbits < 8) {
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nghttp2_bufs_fast_addb_hold(bufs, code);
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*avail_ptr = nghttp2_bufs_cur_avail(bufs);
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return (ssize_t)(8 - nbits);
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}
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/* handle longer code path */
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if (nbits > 24) {
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nghttp2_bufs_fast_addb(bufs, code >> 24);
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nbits -= 8;
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}
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if (nbits > 16) {
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nghttp2_bufs_fast_addb(bufs, code >> 16);
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nbits -= 8;
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}
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if (nbits > 8) {
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nghttp2_bufs_fast_addb(bufs, code >> 8);
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nbits -= 8;
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}
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if (nbits == 8) {
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nghttp2_bufs_fast_addb(bufs, code);
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*avail_ptr = nghttp2_bufs_cur_avail(bufs);
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return 8;
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}
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nghttp2_bufs_fast_addb_hold(bufs, code);
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*avail_ptr = nghttp2_bufs_cur_avail(bufs);
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return (ssize_t)(8 - nbits);
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}
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size_t nghttp2_hd_huff_encode_count(const uint8_t *src, size_t len) {
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size_t i;
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size_t nbits = 0;
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for (i = 0; i < len; ++i) {
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nbits += huff_sym_table[src[i]].nbits;
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}
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/* pad the prefix of EOS (256) */
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return (nbits + 7) / 8;
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}
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int nghttp2_hd_huff_encode(nghttp2_bufs *bufs, const uint8_t *src,
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size_t srclen) {
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int rv;
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ssize_t rembits = 8;
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size_t i;
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size_t avail;
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avail = nghttp2_bufs_cur_avail(bufs);
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for (i = 0; i < srclen; ++i) {
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const nghttp2_huff_sym *sym = &huff_sym_table[src[i]];
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if (rembits == 8) {
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if (avail) {
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nghttp2_bufs_fast_addb_hold(bufs, 0);
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} else {
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rv = nghttp2_bufs_addb_hold(bufs, 0);
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if (rv != 0) {
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return rv;
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}
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avail = nghttp2_bufs_cur_avail(bufs);
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}
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}
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rembits = huff_encode_sym(bufs, &avail, rembits, sym);
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if (rembits < 0) {
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return (int)rembits;
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}
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}
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/* 256 is special terminal symbol, pad with its prefix */
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if (rembits < 8) {
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/* if rembits < 8, we should have at least 1 buffer space
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available */
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const nghttp2_huff_sym *sym = &huff_sym_table[256];
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assert(avail);
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/* Caution we no longer adjust avail here */
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nghttp2_bufs_fast_orb(bufs, sym->code >> (sym->nbits - rembits));
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}
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return 0;
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}
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void nghttp2_hd_huff_decode_context_init(nghttp2_hd_huff_decode_context *ctx) {
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ctx->state = 0;
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ctx->accept = 1;
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}
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/* Use macro to make the code simpler..., but error case is tricky.
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We spent most of the CPU in decoding, so we are doing this
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thing. */
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#define hd_huff_decode_sym_emit(bufs, sym, avail) \
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do { \
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if ((avail)) { \
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nghttp2_bufs_fast_addb((bufs), (sym)); \
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--(avail); \
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} else { \
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rv = nghttp2_bufs_addb((bufs), (sym)); \
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if (rv != 0) { \
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return rv; \
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} \
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(avail) = nghttp2_bufs_cur_avail((bufs)); \
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} \
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} while (0)
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ssize_t nghttp2_hd_huff_decode(nghttp2_hd_huff_decode_context *ctx,
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nghttp2_bufs *bufs, const uint8_t *src,
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size_t srclen, int final) {
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size_t i;
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int rv;
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size_t avail;
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avail = nghttp2_bufs_cur_avail(bufs);
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/* We use the decoding algorithm described in
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http://graphics.ics.uci.edu/pub/Prefix.pdf */
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for (i = 0; i < srclen; ++i) {
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const nghttp2_huff_decode *t;
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t = &huff_decode_table[ctx->state][src[i] >> 4];
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if (t->flags & NGHTTP2_HUFF_FAIL) {
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return NGHTTP2_ERR_HEADER_COMP;
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}
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if (t->flags & NGHTTP2_HUFF_SYM) {
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/* this is macro, and may return from this function on error */
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hd_huff_decode_sym_emit(bufs, t->sym, avail);
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}
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t = &huff_decode_table[t->state][src[i] & 0xf];
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if (t->flags & NGHTTP2_HUFF_FAIL) {
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return NGHTTP2_ERR_HEADER_COMP;
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}
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if (t->flags & NGHTTP2_HUFF_SYM) {
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/* this is macro, and may return from this function on error */
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hd_huff_decode_sym_emit(bufs, t->sym, avail);
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}
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ctx->state = t->state;
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ctx->accept = (t->flags & NGHTTP2_HUFF_ACCEPTED) != 0;
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}
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if (final && !ctx->accept) {
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return NGHTTP2_ERR_HEADER_COMP;
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}
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return (ssize_t)i;
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}
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