char *guess_gzip_options(const char *f) {
char orig[SAMPLE];
{ /* Read sample of the header of the compressed file */
FILE *s = fopen(f, "r");
if (!s) {
perror("open");
return NULL;
}
if (!read_sample_and_close(s, SAMPLE, orig))
return NULL;
}
{
int i;
const char *o;
char *enc_f = encode_filename(f);
int has_mtime_fname;
{
int has_mtime = zhead_has_mtime(orig);
int has_fname = zhead_has_fname(orig);
if (has_mtime && !has_fname) {
fprintf(stderr, "can't recompress, stream has mtime but no fname\n");
return NULL;
}
else if (has_fname && !has_mtime) {
fprintf(stderr, "can't recompress, stream has fname but no mtime\n");
return NULL;
}
else {
has_mtime_fname = has_fname; /* which = has_mtime */
}
}
/* For each likely set of options, try recompressing the content with
* those options */
for (i = 0; (o = try_opts[i]) != NULL; i++) {
FILE *p;
{ /* Compose command line */
char cmd[1024];
snprintf(cmd, sizeof(cmd), "zcat %s | gzip -n %s 2> /dev/null",
enc_f, o);
/* And run it */
if (verbose)
fprintf(stderr, "running %s to determine gzip options\n",
cmd);
p = popen(cmd, "r");
if (!p) {
perror(cmd);
}
}
if (p) { /* Read the recompressed content */
char samp[SAMPLE];
if (!read_sample_and_close(p, SAMPLE, samp)) {
; /* Read error - just fail this one and let the loop
* try another */
}
else {
/* We have the compressed version with these options.
* Compare with the original */
const char *a = skip_zhead(orig);
const char *b = skip_zhead(samp);
if (!memcmp(a, b, 900))
break;
}
}
}
free(enc_f);
if (!o) {
return NULL;
}
else if (has_mtime_fname) {
return strdup(o);
}
else { /* Add --no-name to options to return */
static const char noname[] = { "--no-name" };
char* opts = malloc(strlen(o)+strlen(noname)+2);
if (o[0]) {
strcpy(opts, o);
strcat(opts, " ");
}
else { opts[0] = 0; }
strcat(opts, noname);
return opts;
}
}
}
/* zsync_recompress(self)
* Called when we have a complete local copy of the uncompressed data, to
* perform compression requested in the .zsync.
*
* Shells out to the standard system gzip(1). Replaces the gzip file header
* with the one supplied in the .zsync; this means we should get an identical
* compressed file output to the original compressed file on the source system
* (to allow the user to verify a checksum on the compressed file, or just
* because the user is picky and wants their compressed file to match the
* original).
*
* Returns 0 on success, -1 on error (which is reported on stderr). */
static int zsync_recompress(struct zsync_state *zs) {
/* Recompression. This is a fugly mess, calling gzip on the temporary file with options
* read out of the .zsync, reading its output and replacing the gzip header. Ugh. */
FILE *g;
FILE *zout;
int rc = 0;
char cmd[1024];
snprintf(cmd, sizeof(cmd), "gzip -n %s < ", zs->gzopts);
{ /* Add input filename, shell-escaped, to the command line */
int i = 0;
size_t j = strlen(cmd);
char c;
while ((c = zs->cur_filename[i++]) != 0 && j < (int)sizeof(cmd) - 2) {
if (!isalnum(c))
cmd[j++] = '\\';
cmd[j++] = c;
}
cmd[j] = 0;
}
/* Read gzipped version of the data via pipe from gzip; write it to our new
* output file, except that we replace the gzip header with our own from
* the .zsync file. */
g = popen(cmd, "r");
if (g) {
char zoname[1024];
snprintf(zoname, sizeof(zoname), "%s.gz", zs->cur_filename);
zout = fopen(zoname, "w");
if (zout) {
char *p = zs->gzhead;
int skip = 1;
while (p[0] && p[1]) {
if (fputc((hexdigit(p[0]) << 4) + hexdigit(p[1]), zout) == EOF) {
perror("putc");
rc = -1;
}
p += 2;
}
while (!feof(g)) {
char buf[1024];
int r;
const char *p = buf;
if ((r = fread(buf, 1, sizeof(buf), g)) < 0) {
perror("fread");
rc = -1;
goto leave_it;
}
if (skip) {
p = skip_zhead(buf);
skip = 0;
}
if ((int)fwrite(p, 1, r - (p - buf), zout) != r - (p - buf)) {
perror("fwrite");
rc = -1;
goto leave_it;
}
}
leave_it:
if (fclose(zout) != 0) {
perror("close");
rc = -1;
}
}
if (fclose(g) != 0) {
perror("close");
rc = -1;
}
/* Free our old filename and replace with the new one */
unlink(zs->cur_filename);
free(zs->cur_filename);
zs->cur_filename = strdup(zoname);
}
else {
fprintf(stderr, "problem with gzip, unable to compress.\n");
}
return rc;
}
/* do_zstream(data_stream, zsync_stream, buffer, buffer_len)
* Constructs the zmap for a compressed data stream, in a temporary file.
* The compressed data is from data_stream, except that some bytes have already
* been read from it - those are supplied in buffer (buffer_len of them).
* The zsync block checksums are written to zsync_stream, and the zmap is
* written to a temp file and the handle returned in the global var zmap.
*/
void do_zstream(FILE * fin, FILE * fout, const char *bufsofar, size_t got) {
z_stream zs;
Bytef *inbuf = malloc(blocksize);
const size_t inbufsz = blocksize;
Bytef *outbuf = malloc(blocksize);
int eoz = 0;
int header_bits;
long long prev_in = 0;
long long prev_out = 0;
long long midblock_in = 0;
long long midblock_out = 0;
int want_zdelta = 0;
if (!inbuf || !outbuf) {
fprintf(stderr, "memory allocation failure\n");
exit(1);
}
/* Initialize decompressor */
zs.zalloc = Z_NULL;
zs.zfree = Z_NULL;
zs.opaque = NULL;
zs.next_in = inbuf;
zs.avail_in = 0;
zs.total_in = 0;
zs.next_out = outbuf;
zs.avail_out = 0;
if (inflateInit2(&zs, -MAX_WBITS) != Z_OK)
exit(-1);
{ /* Skip gzip header and do initial buffer fill */
const char *p = skip_zhead(bufsofar);
{ /* Store hex version of gzip header in zhead */
int header_bytes = p - bufsofar;
int i;
header_bits = 8 * header_bytes;
got -= header_bytes;
zhead = malloc(1 + 2 * header_bytes);
for (i = 0; i < header_bytes; i++)
sprintf(zhead + 2 * i, "%02x", (unsigned char)bufsofar[i]);
}
if (got > inbufsz) {
fprintf(stderr,
"internal failure, " SIZE_T_PF " > " SIZE_T_PF
" input buffer available\n", got, inbufsz);
exit(2);
}
/* Copy any remaining already-read data from the buffer to the
* decompressor input buffer */
memcpy(inbuf, p, got);
zs.avail_in = got;
/* Fill the buffer up to offset inbufsz of the input file - we want to
* try and keep the input blocks aligned with block boundaries in the
* underlying filesystem and physical storage */
if (inbufsz > got + (header_bits / 8))
zs.avail_in +=
fread(inbuf + got, 1, inbufsz - got - (header_bits / 8), fin);
}
/* Start the zmap. We write into a temp file, which the caller then copies into the zsync file later. */
zmap = tmpfile();
if (!zmap) {
perror("tmpfile");
exit(2);
}
/* We are past the header, so we are now at the start of the first block */
write_zmap_delta(&prev_in, &prev_out, header_bits, zs.total_out, 1);
zs.avail_out = blocksize;
/* keep going until the end of the compressed stream */
while (!eoz) {
/* refill input buffer if empty */
if (zs.avail_in == 0) {
int rc = fread(inbuf, 1, inbufsz, fin);
if (rc < 0) {
perror("read");
exit(2);
}
/* Still expecting data (!eoz and avail_in == 0) but none there. */
if (rc == 0) {
fprintf(stderr, "Premature end of compressed data.\n");
exit(1);
}
zs.next_in = inbuf;
zs.avail_in = rc;
}
{
int rc;
/* Okay, decompress more data from inbuf to outbuf.
* Z_BLOCK means that decompression will halt if we reach the end of a
* compressed block in the input file.
* And decompression will also stop if outbuf is filled (at which point
* we have a whole block of uncompressed data and so should write its
* checksums)
*
* Terminology note:
* Compressed block = zlib block (stream of bytes compressed with
* common huffman table)
* Uncompressed block = Block of blocksize bytes (starting at an
* offset that is a whole number of blocksize
* bytes blocks from the start of the
* (uncompressed) data. I.e. a zsync block.
*/
rc = inflate(&zs, Z_BLOCK);
switch (rc) {
case Z_STREAM_END:
eoz = 1;
case Z_BUF_ERROR: /* Not really an error, just means we provided stingy buffers */
case Z_OK:
break;
default:
fprintf(stderr, "zlib error %s\n", zs.msg);
exit(1);
}
/* If the output buffer is filled, i.e. we've now got a whole block of uncompressed data. */
if (zs.avail_out == 0 || rc == Z_STREAM_END) {
/* Add to the running SHA1 of the entire file. */
SHA1Update(&shactx, outbuf, blocksize - zs.avail_out);
/* Completed a block; write out its checksums */
write_block_sums(outbuf, blocksize - zs.avail_out, fout);
/* Clear the decompressed data buffer, ready for the next block of uncompressed data. */
zs.next_out = outbuf;
zs.avail_out = blocksize;
/* Having passed a block boundary in the uncompressed data */
want_zdelta = 1;
}
/* If we have reached a block boundary in the compressed data */
if (zs.data_type & 128 || rc == Z_STREAM_END) {
/* write out info on this block */
write_zmap_delta(&prev_in, &prev_out,
header_bits + in_position(&zs), zs.total_out,
1);
midblock_in = midblock_out = 0;
want_zdelta = 0;
}
/* If we passed a block boundary in the uncompressed data, record the
* next available point at which we could stop or start decompression.
* Write a zmap delta with the 1st when we see the 2nd, etc */
if (want_zdelta && inflateSafePoint(&zs)) {
long long cur_in = header_bits + in_position(&zs);
if (midblock_in) {
write_zmap_delta(&prev_in, &prev_out, midblock_in,
midblock_out, 0);
}
midblock_in = cur_in;
midblock_out = zs.total_out;
want_zdelta = 0;
}
}
}
/* Record uncompressed length */
len += zs.total_out;
fputc('\n', fout);
/* Move back to the start of the zmap constructed, ready for the caller to read it back in */
rewind(zmap);
/* Clean up */
inflateEnd(&zs);
free(inbuf);
free(outbuf);
}
