- /* look for the gzip magic header bytes 31 and 139 */
- if (strm->next_in[0] == 31) {
- strm->avail_in--;
- strm->next_in++;
- if (strm->avail_in == 0 && gz_avail(state) == -1)
- return -1;
- if (strm->avail_in && strm->next_in[0] == 139) {
- /* we have a gzip header, woo hoo! */
- strm->avail_in--;
- strm->next_in++;
-
- /* skip rest of header */
- if (NEXT() != 8) { /* compression method */
- gz_error(state, Z_DATA_ERROR, "unknown compression method");
- return -1;
- }
- flags = NEXT();
- if (flags & 0xe0) { /* reserved flag bits */
- gz_error(state, Z_DATA_ERROR, "unknown header flags set");
- return -1;
- }
- NEXT(); /* modification time */
- NEXT();
- NEXT();
- NEXT();
- NEXT(); /* extra flags */
- NEXT(); /* operating system */
- if (flags & 4) { /* extra field */
- len = (unsigned)NEXT();
- len += (unsigned)NEXT() << 8;
- while (len--)
- if (NEXT() < 0)
- break;
- }
- if (flags & 8) /* file name */
- while (NEXT() > 0)
- ;
- if (flags & 16) /* comment */
- while (NEXT() > 0)
- ;
- if (flags & 2) { /* header crc */
- NEXT();
- NEXT();
- }
- /* an unexpected end of file is not checked for here -- it will be
- noticed on the first request for uncompressed data */
-
- /* set up for decompression */
- inflateReset(strm);
- strm->adler = crc32(0L, Z_NULL, 0);
- state->how = GZIP;
- state->direct = 0;
- return 0;
- }
- else {
- /* not a gzip file -- save first byte (31) and fall to raw i/o */
- state->out[0] = 31;
- state->have = 1;
- }
+ /* look for gzip magic bytes -- if there, do gzip decoding (note: there is
+ a logical dilemma here when considering the case of a partially written
+ gzip file, to wit, if a single 31 byte is written, then we cannot tell
+ whether this is a single-byte file, or just a partially written gzip
+ file -- for here we assume that if a gzip file is being written, then
+ the header will be written in a single operation, so that reading a
+ single byte is sufficient indication that it is not a gzip file) */
+ if (strm->avail_in > 1 &&
+ strm->next_in[0] == 31 && strm->next_in[1] == 139) {
+ inflateReset(strm);
+ state->how = GZIP;
+ state->direct = 0;
+ return 0;