zlib/examples/gzappend.c

266     file gz;
269     gz.name = name;
270     gz.fd = open(name, O_RDWR, 0);
271     if (gz.fd == -1) bye("cannot open ", name);
272     gz.buf = malloc(CHUNK);
273     if (gz.buf == NULL) bye("out of memory", "");
274     gz.size = LGCHUNK;
275     gz.left = 0;
278     gzheader(&gz);
291     lastoff = lseek(gz.fd, 0L, SEEK_CUR) - gz.left;
293     strm->avail_in = gz.left;
294     strm->next_in = gz.next;
300             readmore(&gz);
301             strm->avail_in = gz.left;
302             strm->next_in = gz.next;
331                 lastoff = lseek(gz.fd, 0L, SEEK_CUR) - strm->avail_in;
336     gz.left = strm->avail_in;
337     gz.next = strm->next_in;
340     end = lseek(gz.fd, 0L, SEEK_CUR) - gz.left;
343     if (crc != read4(&gz))
346     if ((tot & 0xffffffffUL) != read4(&gz))
350     if (gz.left || readin(&gz))
355     lseek(gz.fd, lastoff - (lastbit != 0), SEEK_SET);
356     if (read(gz.fd, gz.buf, 1) != 1) bye("reading after seek on ", name);
357     *gz.buf = (unsigned char)(*gz.buf ^ (1 << ((8 - lastbit) & 7)));
358     lseek(gz.fd, -1L, SEEK_CUR);
359     if (write(gz.fd, gz.buf, 1) != 1) bye("writing after seek to ", name);
374         lseek(gz.fd, --end, SEEK_SET);
375         if (read(gz.fd, gz.buf, 1) != 1) bye("reading after seek on ", name);
376         deflatePrime(strm, 8 - left, *gz.buf);
378     lseek(gz.fd, end, SEEK_SET);
382     free(gz.buf);
383     return gz.fd;
480             "usage: gzappend [-level] file.gz [ addthis [ andthis ... ]]\n");