'use strict'; // (C) 1995-2013 Jean-loup Gailly and Mark Adler // (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin // // This software is provided 'as-is', without any express or implied // warranty. In no event will the authors be held liable for any damages // arising from the use of this software. // // Permission is granted to anyone to use this software for any purpose, // including commercial applications, and to alter it and redistribute it // freely, subject to the following restrictions: // // 1. The origin of this software must not be misrepresented; you must not // claim that you wrote the original software. If you use this software // in a product, an acknowledgment in the product documentation would be // appreciated but is not required. // 2. Altered source versions must be plainly marked as such, and must not be // misrepresented as being the original software. // 3. This notice may not be removed or altered from any source distribution. const { _tr_init, _tr_stored_block, _tr_flush_block, _tr_tally, _tr_align } = require('./trees'); const adler32 = require('./adler32'); const crc32 = require('./crc32'); const msg = require('./messages'); /* Public constants ==========================================================*/ /* ===========================================================================*/ const { Z_NO_FLUSH, Z_PARTIAL_FLUSH, Z_FULL_FLUSH, Z_FINISH, Z_BLOCK, Z_OK, Z_STREAM_END, Z_STREAM_ERROR, Z_DATA_ERROR, Z_BUF_ERROR, Z_DEFAULT_COMPRESSION, Z_FILTERED, Z_HUFFMAN_ONLY, Z_RLE, Z_FIXED, Z_DEFAULT_STRATEGY, Z_UNKNOWN, Z_DEFLATED } = require('./constants'); /*============================================================================*/ const MAX_MEM_LEVEL = 9; /* Maximum value for memLevel in deflateInit2 */ const MAX_WBITS = 15; /* 32K LZ77 window */ const DEF_MEM_LEVEL = 8; const LENGTH_CODES = 29; /* number of length codes, not counting the special END_BLOCK code */ const LITERALS = 256; /* number of literal bytes 0..255 */ const L_CODES = LITERALS + 1 + LENGTH_CODES; /* number of Literal or Length codes, including the END_BLOCK code */ const D_CODES = 30; /* number of distance codes */ const BL_CODES = 19; /* number of codes used to transfer the bit lengths */ const HEAP_SIZE = 2 * L_CODES + 1; /* maximum heap size */ const MAX_BITS = 15; /* All codes must not exceed MAX_BITS bits */ const MIN_MATCH = 3; const MAX_MATCH = 258; const MIN_LOOKAHEAD = (MAX_MATCH + MIN_MATCH + 1); const PRESET_DICT = 0x20; const INIT_STATE = 42; /* zlib header -> BUSY_STATE */ //#ifdef GZIP const GZIP_STATE = 57; /* gzip header -> BUSY_STATE | EXTRA_STATE */ //#endif const EXTRA_STATE = 69; /* gzip extra block -> NAME_STATE */ const NAME_STATE = 73; /* gzip file name -> COMMENT_STATE */ const COMMENT_STATE = 91; /* gzip comment -> HCRC_STATE */ const HCRC_STATE = 103; /* gzip header CRC -> BUSY_STATE */ const BUSY_STATE = 113; /* deflate -> FINISH_STATE */ const FINISH_STATE = 666; /* stream complete */ const BS_NEED_MORE = 1; /* block not completed, need more input or more output */ const BS_BLOCK_DONE = 2; /* block flush performed */ const BS_FINISH_STARTED = 3; /* finish started, need only more output at next deflate */ const BS_FINISH_DONE = 4; /* finish done, accept no more input or output */ const OS_CODE = 0x03; // Unix :) . Don't detect, use this default. const err = (strm, errorCode) => { strm.msg = msg[errorCode]; return errorCode; }; const rank = (f) => { return ((f) * 2) - ((f) > 4 ? 9 : 0); }; const zero = (buf) => { let len = buf.length; while (--len >= 0) { buf[len] = 0; } }; /* =========================================================================== * Slide the hash table when sliding the window down (could be avoided with 32 * bit values at the expense of memory usage). We slide even when level == 0 to * keep the hash table consistent if we switch back to level > 0 later. */ const slide_hash = (s) => { let n, m; let p; let wsize = s.w_size; n = s.hash_size; p = n; do { m = s.head[--p]; s.head[p] = (m >= wsize ? m - wsize : 0); } while (--n); n = wsize; //#ifndef FASTEST p = n; do { m = s.prev[--p]; s.prev[p] = (m >= wsize ? m - wsize : 0); /* If n is not on any hash chain, prev[n] is garbage but * its value will never be used. */ } while (--n); //#endif }; /* eslint-disable new-cap */ let HASH_ZLIB = (s, prev, data) => ((prev << s.hash_shift) ^ data) & s.hash_mask; // This hash causes less collisions, https://github.com/nodeca/pako/issues/135 // But breaks binary compatibility //let HASH_FAST = (s, prev, data) => ((prev << 8) + (prev >> 8) + (data << 4)) & s.hash_mask; let HASH = HASH_ZLIB; /* ========================================================================= * Flush as much pending output as possible. All deflate() output, except for * some deflate_stored() output, goes through this function so some * applications may wish to modify it to avoid allocating a large * strm->next_out buffer and copying into it. (See also read_buf()). */ const flush_pending = (strm) => { const s = strm.state; //_tr_flush_bits(s); let len = s.pending; if (len > strm.avail_out) { len = strm.avail_out; } if (len === 0) { return; } strm.output.set(s.pending_buf.subarray(s.pending_out, s.pending_out + len), strm.next_out); strm.next_out += len; s.pending_out += len; strm.total_out += len; strm.avail_out -= len; s.pending -= len; if (s.pending === 0) { s.pending_out = 0; } }; const flush_block_only = (s, last) => { _tr_flush_block(s, (s.block_start >= 0 ? s.block_start : -1), s.strstart - s.block_start, last); s.block_start = s.strstart; flush_pending(s.strm); }; const put_byte = (s, b) => { s.pending_buf[s.pending++] = b; }; /* ========================================================================= * Put a short in the pending buffer. The 16-bit value is put in MSB order. * IN assertion: the stream state is correct and there is enough room in * pending_buf. */ const putShortMSB = (s, b) => { // put_byte(s, (Byte)(b >> 8)); // put_byte(s, (Byte)(b & 0xff)); s.pending_buf[s.pending++] = (b >>> 8) & 0xff; s.pending_buf[s.pending++] = b & 0xff; }; /* =========================================================================== * Read a new buffer from the current input stream, update the adler32 * and total number of bytes read. All deflate() input goes through * this function so some applications may wish to modify it to avoid * allocating a large strm->input buffer and copying from it. * (See also flush_pending()). */ const read_buf = (strm, buf, start, size) => { let len = strm.avail_in; if (len > size) { len = size; } if (len === 0) { return 0; } strm.avail_in -= len; // zmemcpy(buf, strm->next_in, len); buf.set(strm.input.subarray(strm.next_in, strm.next_in + len), start); if (strm.state.wrap === 1) { strm.adler = adler32(strm.adler, buf, len, start); } else if (strm.state.wrap === 2) { strm.adler = crc32(strm.adler, buf, len, start); } strm.next_in += len; strm.total_in += len; return len; }; /* =========================================================================== * Set match_start to the longest match starting at the given string and * return its length. Matches shorter or equal to prev_length are discarded, * in which case the result is equal to prev_length and match_start is * garbage. * IN assertions: cur_match is the head of the hash chain for the current * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 * OUT assertion: the match length is not greater than s->lookahead. */ const longest_match = (s, cur_match) => { let chain_length = s.max_chain_length; /* max hash chain length */ let scan = s.strstart; /* current string */ let match; /* matched string */ let len; /* length of current match */ let best_len = s.prev_length; /* best match length so far */ let nice_match = s.nice_match; /* stop if match long enough */ const limit = (s.strstart > (s.w_size - MIN_LOOKAHEAD)) ? s.strstart - (s.w_size - MIN_LOOKAHEAD) : 0/*NIL*/; const _win = s.window; // shortcut const wmask = s.w_mask; const prev = s.prev; /* Stop when cur_match becomes <= limit. To simplify the code, * we prevent matches with the string of window index 0. */ const strend = s.strstart + MAX_MATCH; let scan_end1 = _win[scan + best_len - 1]; let scan_end = _win[scan + best_len]; /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. * It is easy to get rid of this optimization if necessary. */ // Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); /* Do not waste too much time if we already have a good match: */ if (s.prev_length >= s.good_match) { chain_length >>= 2; } /* Do not look for matches beyond the end of the input. This is necessary * to make deflate deterministic. */ if (nice_match > s.lookahead) { nice_match = s.lookahead; } // Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); do { // Assert(cur_match < s->strstart, "no future"); match = cur_match; /* Skip to next match if the match length cannot increase * or if the match length is less than 2. Note that the checks below * for insufficient lookahead only occur occasionally for performance * reasons. Therefore uninitialized memory will be accessed, and * conditional jumps will be made that depend on those values. * However the length of the match is limited to the lookahead, so * the output of deflate is not affected by the uninitialized values. */ if (_win[match + best_len] !== scan_end || _win[match + best_len - 1] !== scan_end1 || _win[match] !== _win[scan] || _win[++match] !== _win[scan + 1]) { continue; } /* The check at best_len-1 can be removed because it will be made * again later. (This heuristic is not always a win.) * It is not necessary to compare scan[2] and match[2] since they * are always equal when the other bytes match, given that * the hash keys are equal and that HASH_BITS >= 8. */ scan += 2; match++; // Assert(*scan == *match, "match[2]?"); /* We check for insufficient lookahead only every 8th comparison; * the 256th check will be made at strstart+258. */ do { /*jshint noempty:false*/ } while (_win[++scan] === _win[++match] && _win[++scan] === _win[++match] && _win[++scan] === _win[++match] && _win[++scan] === _win[++match] && _win[++scan] === _win[++match] && _win[++scan] === _win[++match] && _win[++scan] === _win[++match] && _win[++scan] === _win[++match] && scan < strend); // Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); len = MAX_MATCH - (strend - scan); scan = strend - MAX_MATCH; if (len > best_len) { s.match_start = cur_match; best_len = len; if (len >= nice_match) { break; } scan_end1 = _win[scan + best_len - 1]; scan_end = _win[scan + best_len]; } } while ((cur_match = prev[cur_match & wmask]) > limit && --chain_length !== 0); if (best_len <= s.lookahead) { return best_len; } return s.lookahead; }; /* =========================================================================== * Fill the window when the lookahead becomes insufficient. * Updates strstart and lookahead. * * IN assertion: lookahead < MIN_LOOKAHEAD * OUT assertions: strstart <= window_size-MIN_LOOKAHEAD * At least one byte has been read, or avail_in == 0; reads are * performed for at least two bytes (required for the zip translate_eol * option -- not supported here). */ const fill_window = (s) => { const _w_size = s.w_size; let n, more, str; //Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); do { more = s.window_size - s.lookahead - s.strstart; // JS ints have 32 bit, block below not needed /* Deal with !@#$% 64K limit: */ //if (sizeof(int) <= 2) { // if (more == 0 && s->strstart == 0 && s->lookahead == 0) { // more = wsize; // // } else if (more == (unsigned)(-1)) { // /* Very unlikely, but possible on 16 bit machine if // * strstart == 0 && lookahead == 1 (input done a byte at time) // */ // more--; // } //} /* If the window is almost full and there is insufficient lookahead, * move the upper half to the lower one to make room in the upper half. */ if (s.strstart >= _w_size + (_w_size - MIN_LOOKAHEAD)) { s.window.set(s.window.subarray(_w_size, _w_size + _w_size - more), 0); s.match_start -= _w_size; s.strstart -= _w_size; /* we now have strstart >= MAX_DIST */ s.block_start -= _w_size; if (s.insert > s.strstart) { s.insert = s.strstart; } slide_hash(s); more += _w_size; } if (s.strm.avail_in === 0) { break; } /* If there was no sliding: * strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && * more == window_size - lookahead - strstart * => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) * => more >= window_size - 2*WSIZE + 2 * In the BIG_MEM or MMAP case (not yet supported), * window_size == input_size + MIN_LOOKAHEAD && * strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. * Otherwise, window_size == 2*WSIZE so more >= 2. * If there was sliding, more >= WSIZE. So in all cases, more >= 2. */ //Assert(more >= 2, "more < 2"); n = read_buf(s.strm, s.window, s.strstart + s.lookahead, more); s.lookahead += n; /* Initialize the hash value now that we have some input: */ if (s.lookahead + s.insert >= MIN_MATCH) { str = s.strstart - s.insert; s.ins_h = s.window[str]; /* UPDATE_HASH(s, s->ins_h, s->window[str + 1]); */ s.ins_h = HASH(s, s.ins_h, s.window[str + 1]); //#if MIN_MATCH != 3 // Call update_hash() MIN_MATCH-3 more times //#endif while (s.insert) { /* UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); */ s.ins_h = HASH(s, s.ins_h, s.window[str + MIN_MATCH - 1]); s.prev[str & s.w_mask] = s.head[s.ins_h]; s.head[s.ins_h] = str; str++; s.insert--; if (s.lookahead + s.insert < MIN_MATCH) { break; } } } /* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, * but this is not important since only literal bytes will be emitted. */ } while (s.lookahead < MIN_LOOKAHEAD && s.strm.avail_in !== 0); /* If the WIN_INIT bytes after the end of the current data have never been * written, then zero those bytes in order to avoid memory check reports of * the use of uninitialized (or uninitialised as Julian writes) bytes by * the longest match routines. Update the high water mark for the next * time through here. WIN_INIT is set to MAX_MATCH since the longest match * routines allow scanning to strstart + MAX_MATCH, ignoring lookahead. */ // if (s.high_water < s.window_size) { // const curr = s.strstart + s.lookahead; // let init = 0; // // if (s.high_water < curr) { // /* Previous high water mark below current data -- zero WIN_INIT // * bytes or up to end of window, whichever is less. // */ // init = s.window_size - curr; // if (init > WIN_INIT) // init = WIN_INIT; // zmemzero(s->window + curr, (unsigned)init); // s->high_water = curr + init; // } // else if (s->high_water < (ulg)curr + WIN_INIT) { // /* High water mark at or above current data, but below current data // * plus WIN_INIT -- zero out to current data plus WIN_INIT, or up // * to end of window, whichever is less. // */ // init = (ulg)curr + WIN_INIT - s->high_water; // if (init > s->window_size - s->high_water) // init = s->window_size - s->high_water; // zmemzero(s->window + s->high_water, (unsigned)init); // s->high_water += init; // } // } // // Assert((ulg)s->strstart <= s->window_size - MIN_LOOKAHEAD, // "not enough room for search"); }; /* =========================================================================== * Copy without compression as much as possible from the input stream, return * the current block state. * * In case deflateParams() is used to later switch to a non-zero compression * level, s->matches (otherwise unused when storing) keeps track of the number * of hash table slides to perform. If s->matches is 1, then one hash table * slide will be done when switching. If s->matches is 2, the maximum value * allowed here, then the hash table will be cleared, since two or more slides * is the same as a clear. * * deflate_stored() is written to minimize the number of times an input byte is * copied. It is most efficient with large input and output buffers, which * maximizes the opportunites to have a single copy from next_in to next_out. */ const deflate_stored = (s, flush) => { /* Smallest worthy block size when not flushing or finishing. By default * this is 32K. This can be as small as 507 bytes for memLevel == 1. For * large input and output buffers, the stored block size will be larger. */ let min_block = s.pending_buf_size - 5 > s.w_size ? s.w_size : s.pending_buf_size - 5; /* Copy as many min_block or larger stored blocks directly to next_out as * possible. If flushing, copy the remaining available input to next_out as * stored blocks, if there is enough space. */ let len, left, have, last = 0; let used = s.strm.avail_in; do { /* Set len to the maximum size block that we can copy directly with the * available input data and output space. Set left to how much of that * would be copied from what's left in the window. */ len = 65535/* MAX_STORED */; /* maximum deflate stored block length */ have = (s.bi_valid + 42) >> 3; /* number of header bytes */ if (s.strm.avail_out < have) { /* need room for header */ break; } /* maximum stored block length that will fit in avail_out: */ have = s.strm.avail_out - have; left = s.strstart - s.block_start; /* bytes left in window */ if (len > left + s.strm.avail_in) { len = left + s.strm.avail_in; /* limit len to the input */ } if (len > have) { len = have; /* limit len to the output */ } /* If the stored block would be less than min_block in length, or if * unable to copy all of the available input when flushing, then try * copying to the window and the pending buffer instead. Also don't * write an empty block when flushing -- deflate() does that. */ if (len < min_block && ((len === 0 && flush !== Z_FINISH) || flush === Z_NO_FLUSH || len !== left + s.strm.avail_in)) { break; } /* Make a dummy stored block in pending to get the header bytes, * including any pending bits. This also updates the debugging counts. */ last = flush === Z_FINISH && len === left + s.strm.avail_in ? 1 : 0; _tr_stored_block(s, 0, 0, last); /* Replace the lengths in the dummy stored block with len. */ s.pending_buf[s.pending - 4] = len; s.pending_buf[s.pending - 3] = len >> 8; s.pending_buf[s.pending - 2] = ~len; s.pending_buf[s.pending - 1] = ~len >> 8; /* Write the stored block header bytes. */ flush_pending(s.strm); //#ifdef ZLIB_DEBUG // /* Update debugging counts for the data about to be copied. */ // s->compressed_len += len << 3; // s->bits_sent += len << 3; //#endif /* Copy uncompressed bytes from the window to next_out. */ if (left) { if (left > len) { left = len; } //zmemcpy(s->strm->next_out, s->window + s->block_start, left); s.strm.output.set(s.window.subarray(s.block_start, s.block_start + left), s.strm.next_out); s.strm.next_out += left; s.strm.avail_out -= left; s.strm.total_out += left; s.block_start += left; len -= left; } /* Copy uncompressed bytes directly from next_in to next_out, updating * the check value. */ if (len) { read_buf(s.strm, s.strm.output, s.strm.next_out, len); s.strm.next_out += len; s.strm.avail_out -= len; s.strm.total_out += len; } } while (last === 0); /* Update the sliding window with the last s->w_size bytes of the copied * data, or append all of the copied data to the existing window if less * than s->w_size bytes were copied. Also update the number of bytes to * insert in the hash tables, in the event that deflateParams() switches to * a non-zero compression level. */ used -= s.strm.avail_in; /* number of input bytes directly copied */ if (used) { /* If any input was used, then no unused input remains in the window, * therefore s->block_start == s->strstart. */ if (used >= s.w_size) { /* supplant the previous history */ s.matches = 2; /* clear hash */ //zmemcpy(s->window, s->strm->next_in - s->w_size, s->w_size); s.window.set(s.strm.input.subarray(s.strm.next_in - s.w_size, s.strm.next_in), 0); s.strstart = s.w_size; s.insert = s.strstart; } else { if (s.window_size - s.strstart <= used) { /* Slide the window down. */ s.strstart -= s.w_size; //zmemcpy(s->window, s->window + s->w_size, s->strstart); s.window.set(s.window.subarray(s.w_size, s.w_size + s.strstart), 0); if (s.matches < 2) { s.matches++; /* add a pending slide_hash() */ } if (s.insert > s.strstart) { s.insert = s.strstart; } } //zmemcpy(s->window + s->strstart, s->strm->next_in - used, used); s.window.set(s.strm.input.subarray(s.strm.next_in - used, s.strm.next_in), s.strstart); s.strstart += used; s.insert += used > s.w_size - s.insert ? s.w_size - s.insert : used; } s.block_start = s.strstart; } if (s.high_water < s.strstart) { s.high_water = s.strstart; } /* If the last block was written to next_out, then done. */ if (last) { return BS_FINISH_DONE; } /* If flushing and all input has been consumed, then done. */ if (flush !== Z_NO_FLUSH && flush !== Z_FINISH && s.strm.avail_in === 0 && s.strstart === s.block_start) { return BS_BLOCK_DONE; } /* Fill the window with any remaining input. */ have = s.window_size - s.strstart; if (s.strm.avail_in > have && s.block_start >= s.w_size) { /* Slide the window down. */ s.block_start -= s.w_size; s.strstart -= s.w_size; //zmemcpy(s->window, s->window + s->w_size, s->strstart); s.window.set(s.window.subarray(s.w_size, s.w_size + s.strstart), 0); if (s.matches < 2) { s.matches++; /* add a pending slide_hash() */ } have += s.w_size; /* more space now */ if (s.insert > s.strstart) { s.insert = s.strstart; } } if (have > s.strm.avail_in) { have = s.strm.avail_in; } if (have) { read_buf(s.strm, s.window, s.strstart, have); s.strstart += have; s.insert += have > s.w_size - s.insert ? s.w_size - s.insert : have; } if (s.high_water < s.strstart) { s.high_water = s.strstart; } /* There was not enough avail_out to write a complete worthy or flushed * stored block to next_out. Write a stored block to pending instead, if we * have enough input for a worthy block, or if flushing and there is enough * room for the remaining input as a stored block in the pending buffer. */ have = (s.bi_valid + 42) >> 3; /* number of header bytes */ /* maximum stored block length that will fit in pending: */ have = s.pending_buf_size - have > 65535/* MAX_STORED */ ? 65535/* MAX_STORED */ : s.pending_buf_size - have; min_block = have > s.w_size ? s.w_size : have; left = s.strstart - s.block_start; if (left >= min_block || ((left || flush === Z_FINISH) && flush !== Z_NO_FLUSH && s.strm.avail_in === 0 && left <= have)) { len = left > have ? have : left; last = flush === Z_FINISH && s.strm.avail_in === 0 && len === left ? 1 : 0; _tr_stored_block(s, s.block_start, len, last); s.block_start += len; flush_pending(s.strm); } /* We've done all we can with the available input and output. */ return last ? BS_FINISH_STARTED : BS_NEED_MORE; }; /* =========================================================================== * Compress as much as possible from the input stream, return the current * block state. * This function does not perform lazy evaluation of matches and inserts * new strings in the dictionary only for unmatched strings or for short * matches. It is used only for the fast compression options. */ const deflate_fast = (s, flush) => { let hash_head; /* head of the hash chain */ let bflush; /* set if current block must be flushed */ for (;;) { /* Make sure that we always have enough lookahead, except * at the end of the input file. We need MAX_MATCH bytes * for the next match, plus MIN_MATCH bytes to insert the * string following the next match. */ if (s.lookahead < MIN_LOOKAHEAD) { fill_window(s); if (s.lookahead < MIN_LOOKAHEAD && flush === Z_NO_FLUSH) { return BS_NEED_MORE; } if (s.lookahead === 0) { break; /* flush the current block */ } } /* Insert the string window[strstart .. strstart+2] in the * dictionary, and set hash_head to the head of the hash chain: */ hash_head = 0/*NIL*/; if (s.lookahead >= MIN_MATCH) { /*** INSERT_STRING(s, s.strstart, hash_head); ***/ s.ins_h = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1]); hash_head = s.prev[s.strstart & s.w_mask] = s.head[s.ins_h]; s.head[s.ins_h] = s.strstart; /***/ } /* Find the longest match, discarding those <= prev_length. * At this point we have always match_length < MIN_MATCH */ if (hash_head !== 0/*NIL*/ && ((s.strstart - hash_head) <= (s.w_size - MIN_LOOKAHEAD))) { /* To simplify the code, we prevent matches with the string * of window index 0 (in particular we have to avoid a match * of the string with itself at the start of the input file). */ s.match_length = longest_match(s, hash_head); /* longest_match() sets match_start */ } if (s.match_length >= MIN_MATCH) { // check_match(s, s.strstart, s.match_start, s.match_length); // for debug only /*** _tr_tally_dist(s, s.strstart - s.match_start, s.match_length - MIN_MATCH, bflush); ***/ bflush = _tr_tally(s, s.strstart - s.match_start, s.match_length - MIN_MATCH); s.lookahead -= s.match_length; /* Insert new strings in the hash table only if the match length * is not too large. This saves time but degrades compression. */ if (s.match_length <= s.max_lazy_match/*max_insert_length*/ && s.lookahead >= MIN_MATCH) { s.match_length--; /* string at strstart already in table */ do { s.strstart++; /*** INSERT_STRING(s, s.strstart, hash_head); ***/ s.ins_h = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1]); hash_head = s.prev[s.strstart & s.w_mask] = s.head[s.ins_h]; s.head[s.ins_h] = s.strstart; /***/ /* strstart never exceeds WSIZE-MAX_MATCH, so there are * always MIN_MATCH bytes ahead. */ } while (--s.match_length !== 0); s.strstart++; } else { s.strstart += s.match_length; s.match_length = 0; s.ins_h = s.window[s.strstart]; /* UPDATE_HASH(s, s.ins_h, s.window[s.strstart+1]); */ s.ins_h = HASH(s, s.ins_h, s.window[s.strstart + 1]); //#if MIN_MATCH != 3 // Call UPDATE_HASH() MIN_MATCH-3 more times //#endif /* If lookahead < MIN_MATCH, ins_h is garbage, but it does not * matter since it will be recomputed at next deflate call. */ } } else { /* No match, output a literal byte */ //Tracevv((stderr,"%c", s.window[s.strstart])); /*** _tr_tally_lit(s, s.window[s.strstart], bflush); ***/ bflush = _tr_tally(s, 0, s.window[s.strstart]); s.lookahead--; s.strstart++; } if (bflush) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } } s.insert = ((s.strstart < (MIN_MATCH - 1)) ? s.strstart : MIN_MATCH - 1); if (flush === Z_FINISH) { /*** FLUSH_BLOCK(s, 1); ***/ flush_block_only(s, true); if (s.strm.avail_out === 0) { return BS_FINISH_STARTED; } /***/ return BS_FINISH_DONE; } if (s.sym_next) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } return BS_BLOCK_DONE; }; /* =========================================================================== * Same as above, but achieves better compression. We use a lazy * evaluation for matches: a match is finally adopted only if there is * no better match at the next window position. */ const deflate_slow = (s, flush) => { let hash_head; /* head of hash chain */ let bflush; /* set if current block must be flushed */ let max_insert; /* Process the input block. */ for (;;) { /* Make sure that we always have enough lookahead, except * at the end of the input file. We need MAX_MATCH bytes * for the next match, plus MIN_MATCH bytes to insert the * string following the next match. */ if (s.lookahead < MIN_LOOKAHEAD) { fill_window(s); if (s.lookahead < MIN_LOOKAHEAD && flush === Z_NO_FLUSH) { return BS_NEED_MORE; } if (s.lookahead === 0) { break; } /* flush the current block */ } /* Insert the string window[strstart .. strstart+2] in the * dictionary, and set hash_head to the head of the hash chain: */ hash_head = 0/*NIL*/; if (s.lookahead >= MIN_MATCH) { /*** INSERT_STRING(s, s.strstart, hash_head); ***/ s.ins_h = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1]); hash_head = s.prev[s.strstart & s.w_mask] = s.head[s.ins_h]; s.head[s.ins_h] = s.strstart; /***/ } /* Find the longest match, discarding those <= prev_length. */ s.prev_length = s.match_length; s.prev_match = s.match_start; s.match_length = MIN_MATCH - 1; if (hash_head !== 0/*NIL*/ && s.prev_length < s.max_lazy_match && s.strstart - hash_head <= (s.w_size - MIN_LOOKAHEAD)/*MAX_DIST(s)*/) { /* To simplify the code, we prevent matches with the string * of window index 0 (in particular we have to avoid a match * of the string with itself at the start of the input file). */ s.match_length = longest_match(s, hash_head); /* longest_match() sets match_start */ if (s.match_length <= 5 && (s.strategy === Z_FILTERED || (s.match_length === MIN_MATCH && s.strstart - s.match_start > 4096/*TOO_FAR*/))) { /* If prev_match is also MIN_MATCH, match_start is garbage * but we will ignore the current match anyway. */ s.match_length = MIN_MATCH - 1; } } /* If there was a match at the previous step and the current * match is not better, output the previous match: */ if (s.prev_length >= MIN_MATCH && s.match_length <= s.prev_length) { max_insert = s.strstart + s.lookahead - MIN_MATCH; /* Do not insert strings in hash table beyond this. */ //check_match(s, s.strstart-1, s.prev_match, s.prev_length); /***_tr_tally_dist(s, s.strstart - 1 - s.prev_match, s.prev_length - MIN_MATCH, bflush);***/ bflush = _tr_tally(s, s.strstart - 1 - s.prev_match, s.prev_length - MIN_MATCH); /* Insert in hash table all strings up to the end of the match. * strstart-1 and strstart are already inserted. If there is not * enough lookahead, the last two strings are not inserted in * the hash table. */ s.lookahead -= s.prev_length - 1; s.prev_length -= 2; do { if (++s.strstart <= max_insert) { /*** INSERT_STRING(s, s.strstart, hash_head); ***/ s.ins_h = HASH(s, s.ins_h, s.window[s.strstart + MIN_MATCH - 1]); hash_head = s.prev[s.strstart & s.w_mask] = s.head[s.ins_h]; s.head[s.ins_h] = s.strstart; /***/ } } while (--s.prev_length !== 0); s.match_available = 0; s.match_length = MIN_MATCH - 1; s.strstart++; if (bflush) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } } else if (s.match_available) { /* If there was no match at the previous position, output a * single literal. If there was a match but the current match * is longer, truncate the previous match to a single literal. */ //Tracevv((stderr,"%c", s->window[s->strstart-1])); /*** _tr_tally_lit(s, s.window[s.strstart-1], bflush); ***/ bflush = _tr_tally(s, 0, s.window[s.strstart - 1]); if (bflush) { /*** FLUSH_BLOCK_ONLY(s, 0) ***/ flush_block_only(s, false); /***/ } s.strstart++; s.lookahead--; if (s.strm.avail_out === 0) { return BS_NEED_MORE; } } else { /* There is no previous match to compare with, wait for * the next step to decide. */ s.match_available = 1; s.strstart++; s.lookahead--; } } //Assert (flush != Z_NO_FLUSH, "no flush?"); if (s.match_available) { //Tracevv((stderr,"%c", s->window[s->strstart-1])); /*** _tr_tally_lit(s, s.window[s.strstart-1], bflush); ***/ bflush = _tr_tally(s, 0, s.window[s.strstart - 1]); s.match_available = 0; } s.insert = s.strstart < MIN_MATCH - 1 ? s.strstart : MIN_MATCH - 1; if (flush === Z_FINISH) { /*** FLUSH_BLOCK(s, 1); ***/ flush_block_only(s, true); if (s.strm.avail_out === 0) { return BS_FINISH_STARTED; } /***/ return BS_FINISH_DONE; } if (s.sym_next) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } return BS_BLOCK_DONE; }; /* =========================================================================== * For Z_RLE, simply look for runs of bytes, generate matches only of distance * one. Do not maintain a hash table. (It will be regenerated if this run of * deflate switches away from Z_RLE.) */ const deflate_rle = (s, flush) => { let bflush; /* set if current block must be flushed */ let prev; /* byte at distance one to match */ let scan, strend; /* scan goes up to strend for length of run */ const _win = s.window; for (;;) { /* Make sure that we always have enough lookahead, except * at the end of the input file. We need MAX_MATCH bytes * for the longest run, plus one for the unrolled loop. */ if (s.lookahead <= MAX_MATCH) { fill_window(s); if (s.lookahead <= MAX_MATCH && flush === Z_NO_FLUSH) { return BS_NEED_MORE; } if (s.lookahead === 0) { break; } /* flush the current block */ } /* See how many times the previous byte repeats */ s.match_length = 0; if (s.lookahead >= MIN_MATCH && s.strstart > 0) { scan = s.strstart - 1; prev = _win[scan]; if (prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan]) { strend = s.strstart + MAX_MATCH; do { /*jshint noempty:false*/ } while (prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan] && prev === _win[++scan] && scan < strend); s.match_length = MAX_MATCH - (strend - scan); if (s.match_length > s.lookahead) { s.match_length = s.lookahead; } } //Assert(scan <= s->window+(uInt)(s->window_size-1), "wild scan"); } /* Emit match if have run of MIN_MATCH or longer, else emit literal */ if (s.match_length >= MIN_MATCH) { //check_match(s, s.strstart, s.strstart - 1, s.match_length); /*** _tr_tally_dist(s, 1, s.match_length - MIN_MATCH, bflush); ***/ bflush = _tr_tally(s, 1, s.match_length - MIN_MATCH); s.lookahead -= s.match_length; s.strstart += s.match_length; s.match_length = 0; } else { /* No match, output a literal byte */ //Tracevv((stderr,"%c", s->window[s->strstart])); /*** _tr_tally_lit(s, s.window[s.strstart], bflush); ***/ bflush = _tr_tally(s, 0, s.window[s.strstart]); s.lookahead--; s.strstart++; } if (bflush) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } } s.insert = 0; if (flush === Z_FINISH) { /*** FLUSH_BLOCK(s, 1); ***/ flush_block_only(s, true); if (s.strm.avail_out === 0) { return BS_FINISH_STARTED; } /***/ return BS_FINISH_DONE; } if (s.sym_next) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } return BS_BLOCK_DONE; }; /* =========================================================================== * For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table. * (It will be regenerated if this run of deflate switches away from Huffman.) */ const deflate_huff = (s, flush) => { let bflush; /* set if current block must be flushed */ for (;;) { /* Make sure that we have a literal to write. */ if (s.lookahead === 0) { fill_window(s); if (s.lookahead === 0) { if (flush === Z_NO_FLUSH) { return BS_NEED_MORE; } break; /* flush the current block */ } } /* Output a literal byte */ s.match_length = 0; //Tracevv((stderr,"%c", s->window[s->strstart])); /*** _tr_tally_lit(s, s.window[s.strstart], bflush); ***/ bflush = _tr_tally(s, 0, s.window[s.strstart]); s.lookahead--; s.strstart++; if (bflush) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } } s.insert = 0; if (flush === Z_FINISH) { /*** FLUSH_BLOCK(s, 1); ***/ flush_block_only(s, true); if (s.strm.avail_out === 0) { return BS_FINISH_STARTED; } /***/ return BS_FINISH_DONE; } if (s.sym_next) { /*** FLUSH_BLOCK(s, 0); ***/ flush_block_only(s, false); if (s.strm.avail_out === 0) { return BS_NEED_MORE; } /***/ } return BS_BLOCK_DONE; }; /* Values for max_lazy_match, good_match and max_chain_length, depending on * the desired pack level (0..9). The values given below have been tuned to * exclude worst case performance for pathological files. Better values may be * found for specific files. */ function Config(good_length, max_lazy, nice_length, max_chain, func) { this.good_length = good_length; this.max_lazy = max_lazy; this.nice_length = nice_length; this.max_chain = max_chain; this.func = func; } const configuration_table = [ /* good lazy nice chain */ new Config(0, 0, 0, 0, deflate_stored), /* 0 store only */ new Config(4, 4, 8, 4, deflate_fast), /* 1 max speed, no lazy matches */ new Config(4, 5, 16, 8, deflate_fast), /* 2 */ new Config(4, 6, 32, 32, deflate_fast), /* 3 */ new Config(4, 4, 16, 16, deflate_slow), /* 4 lazy matches */ new Config(8, 16, 32, 32, deflate_slow), /* 5 */ new Config(8, 16, 128, 128, deflate_slow), /* 6 */ new Config(8, 32, 128, 256, deflate_slow), /* 7 */ new Config(32, 128, 258, 1024, deflate_slow), /* 8 */ new Config(32, 258, 258, 4096, deflate_slow) /* 9 max compression */ ]; /* =========================================================================== * Initialize the "longest match" routines for a new zlib stream */ const lm_init = (s) => { s.window_size = 2 * s.w_size; /*** CLEAR_HASH(s); ***/ zero(s.head); // Fill with NIL (= 0); /* Set the default configuration parameters: */ s.max_lazy_match = configuration_table[s.level].max_lazy; s.good_match = configuration_table[s.level].good_length; s.nice_match = configuration_table[s.level].nice_length; s.max_chain_length = configuration_table[s.level].max_chain; s.strstart = 0; s.block_start = 0; s.lookahead = 0; s.insert = 0; s.match_length = s.prev_length = MIN_MATCH - 1; s.match_available = 0; s.ins_h = 0; }; function DeflateState() { this.strm = null; /* pointer back to this zlib stream */ this.status = 0; /* as the name implies */ this.pending_buf = null; /* output still pending */ this.pending_buf_size = 0; /* size of pending_buf */ this.pending_out = 0; /* next pending byte to output to the stream */ this.pending = 0; /* nb of bytes in the pending buffer */ this.wrap = 0; /* bit 0 true for zlib, bit 1 true for gzip */ this.gzhead = null; /* gzip header information to write */ this.gzindex = 0; /* where in extra, name, or comment */ this.method = Z_DEFLATED; /* can only be DEFLATED */ this.last_flush = -1; /* value of flush param for previous deflate call */ this.w_size = 0; /* LZ77 window size (32K by default) */ this.w_bits = 0; /* log2(w_size) (8..16) */ this.w_mask = 0; /* w_size - 1 */ this.window = null; /* Sliding window. Input bytes are read into the second half of the window, * and move to the first half later to keep a dictionary of at least wSize * bytes. With this organization, matches are limited to a distance of * wSize-MAX_MATCH bytes, but this ensures that IO is always * performed with a length multiple of the block size. */ this.window_size = 0; /* Actual size of window: 2*wSize, except when the user input buffer * is directly used as sliding window. */ this.prev = null; /* Link to older string with same hash index. To limit the size of this * array to 64K, this link is maintained only for the last 32K strings. * An index in this array is thus a window index modulo 32K. */ this.head = null; /* Heads of the hash chains or NIL. */ this.ins_h = 0; /* hash index of string to be inserted */ this.hash_size = 0; /* number of elements in hash table */ this.hash_bits = 0; /* log2(hash_size) */ this.hash_mask = 0; /* hash_size-1 */ this.hash_shift = 0; /* Number of bits by which ins_h must be shifted at each input * step. It must be such that after MIN_MATCH steps, the oldest * byte no longer takes part in the hash key, that is: * hash_shift * MIN_MATCH >= hash_bits */ this.block_start = 0; /* Window position at the beginning of the current output block. Gets * negative when the window is moved backwards. */ this.match_length = 0; /* length of best match */ this.prev_match = 0; /* previous match */ this.match_available = 0; /* set if previous match exists */ this.strstart = 0; /* start of string to insert */ this.match_start = 0; /* start of matching string */ this.lookahead = 0; /* number of valid bytes ahead in window */ this.prev_length = 0; /* Length of the best match at previous step. Matches not greater than this * are discarded. This is used in the lazy match evaluation. */ this.max_chain_length = 0; /* To speed up deflation, hash chains are never searched beyond this * length. A higher limit improves compression ratio but degrades the * speed. */ this.max_lazy_match = 0; /* Attempt to find a better match only when the current match is strictly * smaller than this value. This mechanism is used only for compression * levels >= 4. */ // That's alias to max_lazy_match, don't use directly //this.max_insert_length = 0; /* Insert new strings in the hash table only if the match length is not * greater than this length. This saves time but degrades compression. * max_insert_length is used only for compression levels <= 3. */ this.level = 0; /* compression level (1..9) */ this.strategy = 0; /* favor or force Huffman coding*/ this.good_match = 0; /* Use a faster search when the previous match is longer than this */ this.nice_match = 0; /* Stop searching when current match exceeds this */ /* used by trees.c: */ /* Didn't use ct_data typedef below to suppress compiler warning */ // struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ // struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ // struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ // Use flat array of DOUBLE size, with interleaved fata, // because JS does not support effective this.dyn_ltree = new Uint16Array(HEAP_SIZE * 2); this.dyn_dtree = new Uint16Array((2 * D_CODES + 1) * 2); this.bl_tree = new Uint16Array((2 * BL_CODES + 1) * 2); zero(this.dyn_ltree); zero(this.dyn_dtree); zero(this.bl_tree); this.l_desc = null; /* desc. for literal tree */ this.d_desc = null; /* desc. for distance tree */ this.bl_desc = null; /* desc. for bit length tree */ //ush bl_count[MAX_BITS+1]; this.bl_count = new Uint16Array(MAX_BITS + 1); /* number of codes at each bit length for an optimal tree */ //int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ this.heap = new Uint16Array(2 * L_CODES + 1); /* heap used to build the Huffman trees */ zero(this.heap); this.heap_len = 0; /* number of elements in the heap */ this.heap_max = 0; /* element of largest frequency */ /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. * The same heap array is used to build all trees. */ this.depth = new Uint16Array(2 * L_CODES + 1); //uch depth[2*L_CODES+1]; zero(this.depth); /* Depth of each subtree used as tie breaker for trees of equal frequency */ this.sym_buf = 0; /* buffer for distances and literals/lengths */ this.lit_bufsize = 0; /* Size of match buffer for literals/lengths. There are 4 reasons for * limiting lit_bufsize to 64K: * - frequencies can be kept in 16 bit counters * - if compression is not successful for the first block, all input * data is still in the window so we can still emit a stored block even * when input comes from standard input. (This can also be done for * all blocks if lit_bufsize is not greater than 32K.) * - if compression is not successful for a file smaller than 64K, we can * even emit a stored file instead of a stored block (saving 5 bytes). * This is applicable only for zip (not gzip or zlib). * - creating new Huffman trees less frequently may not provide fast * adaptation to changes in the input data statistics. (Take for * example a binary file with poorly compressible code followed by * a highly compressible string table.) Smaller buffer sizes give * fast adaptation but have of course the overhead of transmitting * trees more frequently. * - I can't count above 4 */ this.sym_next = 0; /* running index in sym_buf */ this.sym_end = 0; /* symbol table full when sym_next reaches this */ this.opt_len = 0; /* bit length of current block with optimal trees */ this.static_len = 0; /* bit length of current block with static trees */ this.matches = 0; /* number of string matches in current block */ this.insert = 0; /* bytes at end of window left to insert */ this.bi_buf = 0; /* Output buffer. bits are inserted starting at the bottom (least * significant bits). */ this.bi_valid = 0; /* Number of valid bits in bi_buf. All bits above the last valid bit * are always zero. */ // Used for window memory init. We safely ignore it for JS. That makes // sense only for pointers and memory check tools. //this.high_water = 0; /* High water mark offset in window for initialized bytes -- bytes above * this are set to zero in order to avoid memory check warnings when * longest match routines access bytes past the input. This is then * updated to the new high water mark. */ } /* ========================================================================= * Check for a valid deflate stream state. Return 0 if ok, 1 if not. */ const deflateStateCheck = (strm) => { if (!strm) { return 1; } const s = strm.state; if (!s || s.strm !== strm || (s.status !== INIT_STATE && //#ifdef GZIP s.status !== GZIP_STATE && //#endif s.status !== EXTRA_STATE && s.status !== NAME_STATE && s.status !== COMMENT_STATE && s.status !== HCRC_STATE && s.status !== BUSY_STATE && s.status !== FINISH_STATE)) { return 1; } return 0; }; const deflateResetKeep = (strm) => { if (deflateStateCheck(strm)) { return err(strm, Z_STREAM_ERROR); } strm.total_in = strm.total_out = 0; strm.data_type = Z_UNKNOWN; const s = strm.state; s.pending = 0; s.pending_out = 0; if (s.wrap < 0) { s.wrap = -s.wrap; /* was made negative by deflate(..., Z_FINISH); */ } s.status = //#ifdef GZIP s.wrap === 2 ? GZIP_STATE : //#endif s.wrap ? INIT_STATE : BUSY_STATE; strm.adler = (s.wrap === 2) ? 0 // crc32(0, Z_NULL, 0) : 1; // adler32(0, Z_NULL, 0) s.last_flush = -2; _tr_init(s); return Z_OK; }; const deflateReset = (strm) => { const ret = deflateResetKeep(strm); if (ret === Z_OK) { lm_init(strm.state); } return ret; }; const deflateSetHeader = (strm, head) => { if (deflateStateCheck(strm) || strm.state.wrap !== 2) { return Z_STREAM_ERROR; } strm.state.gzhead = head; return Z_OK; }; const deflateInit2 = (strm, level, method, windowBits, memLevel, strategy) => { if (!strm) { // === Z_NULL return Z_STREAM_ERROR; } let wrap = 1; if (level === Z_DEFAULT_COMPRESSION) { level = 6; } if (windowBits < 0) { /* suppress zlib wrapper */ wrap = 0; windowBits = -windowBits; } else if (windowBits > 15) { wrap = 2; /* write gzip wrapper instead */ windowBits -= 16; } if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method !== Z_DEFLATED || windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED || (windowBits === 8 && wrap !== 1)) { return err(strm, Z_STREAM_ERROR); } if (windowBits === 8) { windowBits = 9; } /* until 256-byte window bug fixed */ const s = new DeflateState(); strm.state = s; s.strm = strm; s.status = INIT_STATE; /* to pass state test in deflateReset() */ s.wrap = wrap; s.gzhead = null; s.w_bits = windowBits; s.w_size = 1 << s.w_bits; s.w_mask = s.w_size - 1; s.hash_bits = memLevel + 7; s.hash_size = 1 << s.hash_bits; s.hash_mask = s.hash_size - 1; s.hash_shift = ~~((s.hash_bits + MIN_MATCH - 1) / MIN_MATCH); s.window = new Uint8Array(s.w_size * 2); s.head = new Uint16Array(s.hash_size); s.prev = new Uint16Array(s.w_size); // Don't need mem init magic for JS. //s.high_water = 0; /* nothing written to s->window yet */ s.lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ /* We overlay pending_buf and sym_buf. This works since the average size * for length/distance pairs over any compressed block is assured to be 31 * bits or less. * * Analysis: The longest fixed codes are a length code of 8 bits plus 5 * extra bits, for lengths 131 to 257. The longest fixed distance codes are * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest * possible fixed-codes length/distance pair is then 31 bits total. * * sym_buf starts one-fourth of the way into pending_buf. So there are * three bytes in sym_buf for every four bytes in pending_buf. Each symbol * in sym_buf is three bytes -- two for the distance and one for the * literal/length. As each symbol is consumed, the pointer to the next * sym_buf value to read moves forward three bytes. From that symbol, up to * 31 bits are written to pending_buf. The closest the written pending_buf * bits gets to the next sym_buf symbol to read is just before the last * code is written. At that time, 31*(n-2) bits have been written, just * after 24*(n-2) bits have been consumed from sym_buf. sym_buf starts at * 8*n bits into pending_buf. (Note that the symbol buffer fills when n-1 * symbols are written.) The closest the writing gets to what is unread is * then n+14 bits. Here n is lit_bufsize, which is 16384 by default, and * can range from 128 to 32768. * * Therefore, at a minimum, there are 142 bits of space between what is * written and what is read in the overlain buffers, so the symbols cannot * be overwritten by the compressed data. That space is actually 139 bits, * due to the three-bit fixed-code block header. * * That covers the case where either Z_FIXED is specified, forcing fixed * codes, or when the use of fixed codes is chosen, because that choice * results in a smaller compressed block than dynamic codes. That latter * condition then assures that the above analysis also covers all dynamic * blocks. A dynamic-code block will only be chosen to be emitted if it has * fewer bits than a fixed-code block would for the same set of symbols. * Therefore its average symbol length is assured to be less than 31. So * the compressed data for a dynamic block also cannot overwrite the * symbols from which it is being constructed. */ s.pending_buf_size = s.lit_bufsize * 4; s.pending_buf = new Uint8Array(s.pending_buf_size); // It is offset from `s.pending_buf` (size is `s.lit_bufsize * 2`) //s->sym_buf = s->pending_buf + s->lit_bufsize; s.sym_buf = s.lit_bufsize; //s->sym_end = (s->lit_bufsize - 1) * 3; s.sym_end = (s.lit_bufsize - 1) * 3; /* We avoid equality with lit_bufsize*3 because of wraparound at 64K * on 16 bit machines and because stored blocks are restricted to * 64K-1 bytes. */ s.level = level; s.strategy = strategy; s.method = method; return deflateReset(strm); }; const deflateInit = (strm, level) => { return deflateInit2(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY); }; /* ========================================================================= */ const deflate = (strm, flush) => { if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { return strm ? err(strm, Z_STREAM_ERROR) : Z_STREAM_ERROR; } const s = strm.state; if (!strm.output || (strm.avail_in !== 0 && !strm.input) || (s.status === FINISH_STATE && flush !== Z_FINISH)) { return err(strm, (strm.avail_out === 0) ? Z_BUF_ERROR : Z_STREAM_ERROR); } const old_flush = s.last_flush; s.last_flush = flush; /* Flush as much pending output as possible */ if (s.pending !== 0) { flush_pending(strm); if (strm.avail_out === 0) { /* Since avail_out is 0, deflate will be called again with * more output space, but possibly with both pending and * avail_in equal to zero. There won't be anything to do, * but this is not an error situation so make sure we * return OK instead of BUF_ERROR at next call of deflate: */ s.last_flush = -1; return Z_OK; } /* Make sure there is something to do and avoid duplicate consecutive * flushes. For repeated and useless calls with Z_FINISH, we keep * returning Z_STREAM_END instead of Z_BUF_ERROR. */ } else if (strm.avail_in === 0 && rank(flush) <= rank(old_flush) && flush !== Z_FINISH) { return err(strm, Z_BUF_ERROR); } /* User must not provide more input after the first FINISH: */ if (s.status === FINISH_STATE && strm.avail_in !== 0) { return err(strm, Z_BUF_ERROR); } /* Write the header */ if (s.status === INIT_STATE && s.wrap === 0) { s.status = BUSY_STATE; } if (s.status === INIT_STATE) { /* zlib header */ let header = (Z_DEFLATED + ((s.w_bits - 8) << 4)) << 8; let level_flags = -1; if (s.strategy >= Z_HUFFMAN_ONLY || s.level < 2) { level_flags = 0; } else if (s.level < 6) { level_flags = 1; } else if (s.level === 6) { level_flags = 2; } else { level_flags = 3; } header |= (level_flags << 6); if (s.strstart !== 0) { header |= PRESET_DICT; } header += 31 - (header % 31); putShortMSB(s, header); /* Save the adler32 of the preset dictionary: */ if (s.strstart !== 0) { putShortMSB(s, strm.adler >>> 16); putShortMSB(s, strm.adler & 0xffff); } strm.adler = 1; // adler32(0L, Z_NULL, 0); s.status = BUSY_STATE; /* Compression must start with an empty pending buffer */ flush_pending(strm); if (s.pending !== 0) { s.last_flush = -1; return Z_OK; } } //#ifdef GZIP if (s.status === GZIP_STATE) { /* gzip header */ strm.adler = 0; //crc32(0L, Z_NULL, 0); put_byte(s, 31); put_byte(s, 139); put_byte(s, 8); if (!s.gzhead) { // s->gzhead == Z_NULL put_byte(s, 0); put_byte(s, 0); put_byte(s, 0); put_byte(s, 0); put_byte(s, 0); put_byte(s, s.level === 9 ? 2 : (s.strategy >= Z_HUFFMAN_ONLY || s.level < 2 ? 4 : 0)); put_byte(s, OS_CODE); s.status = BUSY_STATE; /* Compression must start with an empty pending buffer */ flush_pending(strm); if (s.pending !== 0) { s.last_flush = -1; return Z_OK; } } else { put_byte(s, (s.gzhead.text ? 1 : 0) + (s.gzhead.hcrc ? 2 : 0) + (!s.gzhead.extra ? 0 : 4) + (!s.gzhead.name ? 0 : 8) + (!s.gzhead.comment ? 0 : 16) ); put_byte(s, s.gzhead.time & 0xff); put_byte(s, (s.gzhead.time >> 8) & 0xff); put_byte(s, (s.gzhead.time >> 16) & 0xff); put_byte(s, (s.gzhead.time >> 24) & 0xff); put_byte(s, s.level === 9 ? 2 : (s.strategy >= Z_HUFFMAN_ONLY || s.level < 2 ? 4 : 0)); put_byte(s, s.gzhead.os & 0xff); if (s.gzhead.extra && s.gzhead.extra.length) { put_byte(s, s.gzhead.extra.length & 0xff); put_byte(s, (s.gzhead.extra.length >> 8) & 0xff); } if (s.gzhead.hcrc) { strm.adler = crc32(strm.adler, s.pending_buf, s.pending, 0); } s.gzindex = 0; s.status = EXTRA_STATE; } } if (s.status === EXTRA_STATE) { if (s.gzhead.extra/* != Z_NULL*/) { let beg = s.pending; /* start of bytes to update crc */ let left = (s.gzhead.extra.length & 0xffff) - s.gzindex; while (s.pending + left > s.pending_buf_size) { let copy = s.pending_buf_size - s.pending; // zmemcpy(s.pending_buf + s.pending, // s.gzhead.extra + s.gzindex, copy); s.pending_buf.set(s.gzhead.extra.subarray(s.gzindex, s.gzindex + copy), s.pending); s.pending = s.pending_buf_size; //--- HCRC_UPDATE(beg) ---// if (s.gzhead.hcrc && s.pending > beg) { strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg); } //---// s.gzindex += copy; flush_pending(strm); if (s.pending !== 0) { s.last_flush = -1; return Z_OK; } beg = 0; left -= copy; } // JS specific: s.gzhead.extra may be TypedArray or Array for backward compatibility // TypedArray.slice and TypedArray.from don't exist in IE10-IE11 let gzhead_extra = new Uint8Array(s.gzhead.extra); // zmemcpy(s->pending_buf + s->pending, // s->gzhead->extra + s->gzindex, left); s.pending_buf.set(gzhead_extra.subarray(s.gzindex, s.gzindex + left), s.pending); s.pending += left; //--- HCRC_UPDATE(beg) ---// if (s.gzhead.hcrc && s.pending > beg) { strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg); } //---// s.gzindex = 0; } s.status = NAME_STATE; } if (s.status === NAME_STATE) { if (s.gzhead.name/* != Z_NULL*/) { let beg = s.pending; /* start of bytes to update crc */ let val; do { if (s.pending === s.pending_buf_size) { //--- HCRC_UPDATE(beg) ---// if (s.gzhead.hcrc && s.pending > beg) { strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg); } //---// flush_pending(strm); if (s.pending !== 0) { s.last_flush = -1; return Z_OK; } beg = 0; } // JS specific: little magic to add zero terminator to end of string if (s.gzindex < s.gzhead.name.length) { val = s.gzhead.name.charCodeAt(s.gzindex++) & 0xff; } else { val = 0; } put_byte(s, val); } while (val !== 0); //--- HCRC_UPDATE(beg) ---// if (s.gzhead.hcrc && s.pending > beg) { strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg); } //---// s.gzindex = 0; } s.status = COMMENT_STATE; } if (s.status === COMMENT_STATE) { if (s.gzhead.comment/* != Z_NULL*/) { let beg = s.pending; /* start of bytes to update crc */ let val; do { if (s.pending === s.pending_buf_size) { //--- HCRC_UPDATE(beg) ---// if (s.gzhead.hcrc && s.pending > beg) { strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg); } //---// flush_pending(strm); if (s.pending !== 0) { s.last_flush = -1; return Z_OK; } beg = 0; } // JS specific: little magic to add zero terminator to end of string if (s.gzindex < s.gzhead.comment.length) { val = s.gzhead.comment.charCodeAt(s.gzindex++) & 0xff; } else { val = 0; } put_byte(s, val); } while (val !== 0); //--- HCRC_UPDATE(beg) ---// if (s.gzhead.hcrc && s.pending > beg) { strm.adler = crc32(strm.adler, s.pending_buf, s.pending - beg, beg); } //---// } s.status = HCRC_STATE; } if (s.status === HCRC_STATE) { if (s.gzhead.hcrc) { if (s.pending + 2 > s.pending_buf_size) { flush_pending(strm); if (s.pending !== 0) { s.last_flush = -1; return Z_OK; } } put_byte(s, strm.adler & 0xff); put_byte(s, (strm.adler >> 8) & 0xff); strm.adler = 0; //crc32(0L, Z_NULL, 0); } s.status = BUSY_STATE; /* Compression must start with an empty pending buffer */ flush_pending(strm); if (s.pending !== 0) { s.last_flush = -1; return Z_OK; } } //#endif /* Start a new block or continue the current one. */ if (strm.avail_in !== 0 || s.lookahead !== 0 || (flush !== Z_NO_FLUSH && s.status !== FINISH_STATE)) { let bstate = s.level === 0 ? deflate_stored(s, flush) : s.strategy === Z_HUFFMAN_ONLY ? deflate_huff(s, flush) : s.strategy === Z_RLE ? deflate_rle(s, flush) : configuration_table[s.level].func(s, flush); if (bstate === BS_FINISH_STARTED || bstate === BS_FINISH_DONE) { s.status = FINISH_STATE; } if (bstate === BS_NEED_MORE || bstate === BS_FINISH_STARTED) { if (strm.avail_out === 0) { s.last_flush = -1; /* avoid BUF_ERROR next call, see above */ } return Z_OK; /* If flush != Z_NO_FLUSH && avail_out == 0, the next call * of deflate should use the same flush parameter to make sure * that the flush is complete. So we don't have to output an * empty block here, this will be done at next call. This also * ensures that for a very small output buffer, we emit at most * one empty block. */ } if (bstate === BS_BLOCK_DONE) { if (flush === Z_PARTIAL_FLUSH) { _tr_align(s); } else if (flush !== Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */ _tr_stored_block(s, 0, 0, false); /* For a full flush, this empty block will be recognized * as a special marker by inflate_sync(). */ if (flush === Z_FULL_FLUSH) { /*** CLEAR_HASH(s); ***/ /* forget history */ zero(s.head); // Fill with NIL (= 0); if (s.lookahead === 0) { s.strstart = 0; s.block_start = 0; s.insert = 0; } } } flush_pending(strm); if (strm.avail_out === 0) { s.last_flush = -1; /* avoid BUF_ERROR at next call, see above */ return Z_OK; } } } if (flush !== Z_FINISH) { return Z_OK; } if (s.wrap <= 0) { return Z_STREAM_END; } /* Write the trailer */ if (s.wrap === 2) { put_byte(s, strm.adler & 0xff); put_byte(s, (strm.adler >> 8) & 0xff); put_byte(s, (strm.adler >> 16) & 0xff); put_byte(s, (strm.adler >> 24) & 0xff); put_byte(s, strm.total_in & 0xff); put_byte(s, (strm.total_in >> 8) & 0xff); put_byte(s, (strm.total_in >> 16) & 0xff); put_byte(s, (strm.total_in >> 24) & 0xff); } else { putShortMSB(s, strm.adler >>> 16); putShortMSB(s, strm.adler & 0xffff); } flush_pending(strm); /* If avail_out is zero, the application will call deflate again * to flush the rest. */ if (s.wrap > 0) { s.wrap = -s.wrap; } /* write the trailer only once! */ return s.pending !== 0 ? Z_OK : Z_STREAM_END; }; const deflateEnd = (strm) => { if (deflateStateCheck(strm)) { return Z_STREAM_ERROR; } const status = strm.state.status; strm.state = null; return status === BUSY_STATE ? err(strm, Z_DATA_ERROR) : Z_OK; }; /* ========================================================================= * Initializes the compression dictionary from the given byte * sequence without producing any compressed output. */ const deflateSetDictionary = (strm, dictionary) => { let dictLength = dictionary.length; if (deflateStateCheck(strm)) { return Z_STREAM_ERROR; } const s = strm.state; const wrap = s.wrap; if (wrap === 2 || (wrap === 1 && s.status !== INIT_STATE) || s.lookahead) { return Z_STREAM_ERROR; } /* when using zlib wrappers, compute Adler-32 for provided dictionary */ if (wrap === 1) { /* adler32(strm->adler, dictionary, dictLength); */ strm.adler = adler32(strm.adler, dictionary, dictLength, 0); } s.wrap = 0; /* avoid computing Adler-32 in read_buf */ /* if dictionary would fill window, just replace the history */ if (dictLength >= s.w_size) { if (wrap === 0) { /* already empty otherwise */ /*** CLEAR_HASH(s); ***/ zero(s.head); // Fill with NIL (= 0); s.strstart = 0; s.block_start = 0; s.insert = 0; } /* use the tail */ // dictionary = dictionary.slice(dictLength - s.w_size); let tmpDict = new Uint8Array(s.w_size); tmpDict.set(dictionary.subarray(dictLength - s.w_size, dictLength), 0); dictionary = tmpDict; dictLength = s.w_size; } /* insert dictionary into window and hash */ const avail = strm.avail_in; const next = strm.next_in; const input = strm.input; strm.avail_in = dictLength; strm.next_in = 0; strm.input = dictionary; fill_window(s); while (s.lookahead >= MIN_MATCH) { let str = s.strstart; let n = s.lookahead - (MIN_MATCH - 1); do { /* UPDATE_HASH(s, s->ins_h, s->window[str + MIN_MATCH-1]); */ s.ins_h = HASH(s, s.ins_h, s.window[str + MIN_MATCH - 1]); s.prev[str & s.w_mask] = s.head[s.ins_h]; s.head[s.ins_h] = str; str++; } while (--n); s.strstart = str; s.lookahead = MIN_MATCH - 1; fill_window(s); } s.strstart += s.lookahead; s.block_start = s.strstart; s.insert = s.lookahead; s.lookahead = 0; s.match_length = s.prev_length = MIN_MATCH - 1; s.match_available = 0; strm.next_in = next; strm.input = input; strm.avail_in = avail; s.wrap = wrap; return Z_OK; }; module.exports.deflateInit = deflateInit; module.exports.deflateInit2 = deflateInit2; module.exports.deflateReset = deflateReset; module.exports.deflateResetKeep = deflateResetKeep; module.exports.deflateSetHeader = deflateSetHeader; module.exports.deflate = deflate; module.exports.deflateEnd = deflateEnd; module.exports.deflateSetDictionary = deflateSetDictionary; module.exports.deflateInfo = 'pako deflate (from Nodeca project)'; /* Not implemented module.exports.deflateBound = deflateBound; module.exports.deflateCopy = deflateCopy; module.exports.deflateGetDictionary = deflateGetDictionary; module.exports.deflateParams = deflateParams; module.exports.deflatePending = deflatePending; module.exports.deflatePrime = deflatePrime; module.exports.deflateTune = deflateTune; */