decompress_unzip.c

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		if (i != 0) {
			abort_unzip(PASS_STATE_ONLY); //return i;	/* incomplete code set */
		}

		/* read in literal and distance code lengths */
		n = nl + nd;
		m = mask_bits[bl];
		i = l = 0;
		while ((unsigned) i < n) {
			b_dynamic = fill_bitbuffer(PASS_STATE b_dynamic, &k_dynamic, (unsigned)bl);
			td = inflate_codes_tl + ((unsigned) b_dynamic & m);
			j = td->b;
			b_dynamic >>= j;
			k_dynamic -= j;
			j = td->v.n;
			if (j < 16) {	/* length of code in bits (0..15) */
				ll[i++] = l = j;	/* save last length in l */
			} else if (j == 16) {	/* repeat last length 3 to 6 times */
				b_dynamic = fill_bitbuffer(PASS_STATE b_dynamic, &k_dynamic, 2);
				j = 3 + ((unsigned) b_dynamic & 3);
				b_dynamic >>= 2;
				k_dynamic -= 2;
				if ((unsigned) i + j > n) {
					abort_unzip(PASS_STATE_ONLY); //return 1;
				}
				while (j--) {
					ll[i++] = l;
				}
			} else if (j == 17) {	/* 3 to 10 zero length codes */
				b_dynamic = fill_bitbuffer(PASS_STATE b_dynamic, &k_dynamic, 3);
				j = 3 + ((unsigned) b_dynamic & 7);
				b_dynamic >>= 3;
				k_dynamic -= 3;
				if ((unsigned) i + j > n) {
					abort_unzip(PASS_STATE_ONLY); //return 1;
				}
				while (j--) {
					ll[i++] = 0;
				}
				l = 0;
			} else {	/* j == 18: 11 to 138 zero length codes */
				b_dynamic = fill_bitbuffer(PASS_STATE b_dynamic, &k_dynamic, 7);
				j = 11 + ((unsigned) b_dynamic & 0x7f);
				b_dynamic >>= 7;
				k_dynamic -= 7;
				if ((unsigned) i + j > n) {
					abort_unzip(PASS_STATE_ONLY); //return 1;
				}
				while (j--) {
					ll[i++] = 0;
				}
				l = 0;
			}
		}

		/* free decoding table for trees */
		huft_free(inflate_codes_tl);

		/* restore the global bit buffer */
		gunzip_bb = b_dynamic;
		gunzip_bk = k_dynamic;

		/* build the decoding tables for literal/length and distance codes */
		bl = lbits;

		i = huft_build(ll, nl, 257, cplens, cplext, &inflate_codes_tl, &bl);
		if (i != 0)
			abort_unzip(PASS_STATE_ONLY);
		bd = dbits;
		i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &inflate_codes_td, &bd);
		if (i != 0)
			abort_unzip(PASS_STATE_ONLY);

		/* set up data for inflate_codes() */
		inflate_codes_setup(PASS_STATE bl, bd);

		/* huft_free code moved into inflate_codes */

		return -2;
	}
	default:
		abort_unzip(PASS_STATE_ONLY);
	}
}

/* Two callsites, both in inflate_get_next_window */
static void calculate_gunzip_crc(STATE_PARAM_ONLY)
{
	unsigned n;
	for (n = 0; n < gunzip_outbuf_count; n++) {
		gunzip_crc = gunzip_crc_table[((int) gunzip_crc ^ (gunzip_window[n])) & 0xff] ^ (gunzip_crc >> 8);
	}
	gunzip_bytes_out += gunzip_outbuf_count;
}

/* One callsite in inflate_unzip_internal */
static int inflate_get_next_window(STATE_PARAM_ONLY)
{
	gunzip_outbuf_count = 0;

	while (1) {
		int ret;

		if (need_another_block) {
			if (end_reached) {
				calculate_gunzip_crc(PASS_STATE_ONLY);
				end_reached = 0;
				/* NB: need_another_block is still set */
				return 0; /* Last block */
			}
			method = inflate_block(PASS_STATE &end_reached);
			need_another_block = 0;
		}

		switch (method) {
		case -1:
			ret = inflate_stored(PASS_STATE_ONLY);
			break;
		case -2:
			ret = inflate_codes(PASS_STATE_ONLY);
			break;
		default: /* cannot happen */
			abort_unzip(PASS_STATE_ONLY);
		}

		if (ret == 1) {
			calculate_gunzip_crc(PASS_STATE_ONLY);
			return 1; /* more data left */
		}
		need_another_block = 1; /* end of that block */
	}
	/* Doesnt get here */
}


/* Called from unpack_gz_stream() and inflate_unzip() */
static USE_DESKTOP(long long) int
inflate_unzip_internal(STATE_PARAM int in, int out)
{
	USE_DESKTOP(long long) int n = 0;
	ssize_t nwrote;

	/* Allocate all global buffers (for DYN_ALLOC option) */
	gunzip_window = xmalloc(GUNZIP_WSIZE);
	gunzip_outbuf_count = 0;
	gunzip_bytes_out = 0;
	gunzip_src_fd = in;

	/* (re) initialize state */
	method = -1;
	need_another_block = 1;
	resume_copy = 0;
	gunzip_bk = 0;
	gunzip_bb = 0;

	/* Create the crc table */
	gunzip_crc_table = crc32_filltable(NULL, 0);
	gunzip_crc = ~0;

	error_msg = "corrupted data";
	if (setjmp(error_jmp)) {
		/* Error from deep inside zip machinery */
		n = -1;
		goto ret;
	}

	while (1) {
		int r = inflate_get_next_window(PASS_STATE_ONLY);
		nwrote = full_write(out, gunzip_window, gunzip_outbuf_count);
		if (nwrote != (ssize_t)gunzip_outbuf_count) {
			bb_perror_msg("write");
			n = -1;
			goto ret;
		}
		USE_DESKTOP(n += nwrote;)
		if (r == 0) break;
	}

	/* Store unused bytes in a global buffer so calling applets can access it */
	if (gunzip_bk >= 8) {
		/* Undo too much lookahead. The next read will be byte aligned
		 * so we can discard unused bits in the last meaningful byte. */
		bytebuffer_offset--;
		bytebuffer[bytebuffer_offset] = gunzip_bb & 0xff;
		gunzip_bb >>= 8;
		gunzip_bk -= 8;
	}
 ret:
	/* Cleanup */
	free(gunzip_window);
	free(gunzip_crc_table);
	return n;
}


/* External entry points */

/* For unzip */

USE_DESKTOP(long long) int FAST_FUNC
inflate_unzip(inflate_unzip_result *res, off_t compr_size, int in, int out)
{
	USE_DESKTOP(long long) int n;
	DECLARE_STATE;

	ALLOC_STATE;

	to_read = compr_size;
//	bytebuffer_max = 0x8000;
	bytebuffer_offset = 4;
	bytebuffer = xmalloc(bytebuffer_max);
	n = inflate_unzip_internal(PASS_STATE in, out);
	free(bytebuffer);

	res->crc = gunzip_crc;
	res->bytes_out = gunzip_bytes_out;
	DEALLOC_STATE;
	return n;
}


/* For gunzip */

/* helpers first */

/* Top up the input buffer with at least n bytes. */
static int top_up(STATE_PARAM unsigned n)
{
	int count = bytebuffer_size - bytebuffer_offset;

	if (count < (int)n) {
		memmove(bytebuffer, &bytebuffer[bytebuffer_offset], count);
		bytebuffer_offset = 0;
		bytebuffer_size = full_read(gunzip_src_fd, &bytebuffer[count], bytebuffer_max - count);
		if ((int)bytebuffer_size < 0) {
			bb_error_msg("read error");
			return 0;
		}
		bytebuffer_size += count;
		if (bytebuffer_size < n)
			return 0;
	}
	return 1;
}

static uint16_t buffer_read_le_u16(STATE_PARAM_ONLY)
{
	uint16_t res;
#if BB_LITTLE_ENDIAN
	/* gcc 4.2.1 is very clever */
	memcpy(&res, &bytebuffer[bytebuffer_offset], 2);
#else
	res = bytebuffer[bytebuffer_offset];
	res |= bytebuffer[bytebuffer_offset + 1] << 8;
#endif
	bytebuffer_offset += 2;
	return res;
}

static uint32_t buffer_read_le_u32(STATE_PARAM_ONLY)
{
	uint32_t res;
#if BB_LITTLE_ENDIAN
	memcpy(&res, &bytebuffer[bytebuffer_offset], 4);
#else
	res = bytebuffer[bytebuffer_offset];
	res |= bytebuffer[bytebuffer_offset + 1] << 8;
	res |= bytebuffer[bytebuffer_offset + 2] << 16;
	res |= bytebuffer[bytebuffer_offset + 3] << 24;
#endif
	bytebuffer_offset += 4;
	return res;
}

static int check_header_gzip(STATE_PARAM unpack_info_t *info)
{
	union {
		unsigned char raw[8];
		struct {
			uint8_t gz_method;
			uint8_t flags;
			uint32_t mtime;
			uint8_t xtra_flags_UNUSED;
			uint8_t os_flags_UNUSED;
		} __attribute__((packed)) formatted;
	} header;
	struct BUG_header {
		char BUG_header[sizeof(header) == 8 ? 1 : -1];
	};

	/*
	 * Rewind bytebuffer. We use the beginning because the header has 8
	 * bytes, leaving enough for unwinding afterwards.
	 */
	bytebuffer_size -= bytebuffer_offset;
	memmove(bytebuffer, &bytebuffer[bytebuffer_offset], bytebuffer_size);
	bytebuffer_offset = 0;

	if (!top_up(PASS_STATE 8))
		return 0;
	memcpy(header.raw, &bytebuffer[bytebuffer_offset], 8);
	bytebuffer_offset += 8;

	/* Check the compression method */
	if (header.formatted.gz_method != 8) {
		return 0;
	}

	if (header.formatted.flags & 0x04) {
		/* bit 2 set: extra field present */
		unsigned extra_short;

		if (!top_up(PASS_STATE 2))
			return 0;
		extra_short = buffer_read_le_u16(PASS_STATE_ONLY);
		if (!top_up(PASS_STATE extra_short))
			return 0;
		/* Ignore extra field */
		bytebuffer_offset += extra_short;
	}

	/* Discard original name and file comment if any */
	/* bit 3 set: original file name present */
	/* bit 4 set: file comment present */
	if (header.formatted.flags & 0x18) {
		while (1) {
			do {
				if (!top_up(PASS_STATE 1))
					return 0;
			} while (bytebuffer[bytebuffer_offset++] != 0);
			if ((header.formatted.flags & 0x18) != 0x18)
				break;
			header.formatted.flags &= ~0x18;
		}
	}

	if (info)
		info->mtime = SWAP_LE32(header.formatted.mtime);

	/* Read the header checksum */
	if (header.formatted.flags & 0x02) {
		if (!top_up(PASS_STATE 2))
			return 0;
		bytebuffer_offset += 2;
	}
	return 1;
}

USE_DESKTOP(long long) int FAST_FUNC
unpack_gz_stream_with_info(int in, int out, unpack_info_t *info)
{
	uint32_t v32;
	USE_DESKTOP(long long) int n;
	DECLARE_STATE;

	n = 0;

	ALLOC_STATE;
	to_read = -1;
//	bytebuffer_max = 0x8000;
	bytebuffer = xmalloc(bytebuffer_max);
	gunzip_src_fd = in;

 again:
	if (!check_header_gzip(PASS_STATE info)) {
		bb_error_msg("corrupted data");
		n = -1;
		goto ret;
	}
	n += inflate_unzip_internal(PASS_STATE in, out);
	if (n < 0)
		goto ret;

	if (!top_up(PASS_STATE 8)) {
		bb_error_msg("corrupted data");
		n = -1;
		goto ret;
	}

	/* Validate decompression - crc */
	v32 = buffer_read_le_u32(PASS_STATE_ONLY);
	if ((~gunzip_crc) != v32) {
		bb_error_msg("crc error");
		n = -1;
		goto ret;
	}

	/* Validate decompression - size */
	v32 = buffer_read_le_u32(PASS_STATE_ONLY);
	if ((uint32_t)gunzip_bytes_out != v32) {
		bb_error_msg("incorrect length");
		n = -1;
	}

	if (!top_up(PASS_STATE 2))
		goto ret; /* EOF */

	if (bytebuffer[bytebuffer_offset] == 0x1f
	 && bytebuffer[bytebuffer_offset + 1] == 0x8b
	) {
		bytebuffer_offset += 2;
		goto again;
	}
	/* GNU gzip says: */
	/*bb_error_msg("decompression OK, trailing garbage ignored");*/

 ret:
	free(bytebuffer);
	DEALLOC_STATE;
	return n;
}

USE_DESKTOP(long long) int FAST_FUNC
unpack_gz_stream(int in, int out)
{
	return unpack_gz_stream_with_info(in, out, NULL);
}