/* Decompress from input to the provided next_out and avail_out in the state.
On return, state->x.have and state->x.next point to the just decompressed
data. If the gzip stream completes, state->how is reset to LOOK to look for
the next gzip stream or raw data, once state->x.have is depleted. Returns 0
on success, -1 on failure. */
local int
gz_decomp (gz_statep state)
{
int ret = Z_OK;
unsigned had;
z_streamp strm = &(state->strm);
/* fill output buffer up to end of deflate stream */
had = strm->avail_out;
do
{
/* get more input for inflate() */
if (strm->avail_in == 0 && gz_avail (state) == -1)
return -1;
if (strm->avail_in == 0)
{
gz_error (state, Z_BUF_ERROR, "unexpected end of file");
break;
}
/* decompress and handle errors */
ret = inflate (strm, Z_NO_FLUSH);
if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT)
{
gz_error (state, Z_STREAM_ERROR,
"internal error: inflate stream corrupt");
return -1;
}
if (ret == Z_MEM_ERROR)
{
gz_error (state, Z_MEM_ERROR, "out of memory");
return -1;
}
if (ret == Z_DATA_ERROR)
{ /* deflate stream invalid */
gz_error (state, Z_DATA_ERROR,
strm->msg == NULL ? "compressed data error" : strm->msg);
return -1;
}
}
while (strm->avail_out && ret != Z_STREAM_END);
/* update available output */
state->x.have = had - strm->avail_out;
state->x.next = strm->next_out - state->x.have;
/* if the gzip stream completed successfully, look for another */
if (ret == Z_STREAM_END)
state->how = LOOK;
/* good decompression */
return 0;
}
/* Look for gzip header, set up for inflate or copy. state->x.have must be 0.
If this is the first time in, allocate required memory. state->how will be
left unchanged if there is no more input data available, will be set to COPY
if there is no gzip header and direct copying will be performed, or it will
be set to GZIP for decompression. If direct copying, then leftover input
data from the input buffer will be copied to the output buffer. In that
case, all further file reads will be directly to either the output buffer or
a user buffer. If decompressing, the inflate state will be initialized.
gz_look() will return 0 on success or -1 on failure. */
local int
gz_look (gz_statep state)
{
z_streamp strm = &(state->strm);
/* allocate read buffers and inflate memory */
if (state->size == 0)
{
/* allocate buffers */
state->in = (unsigned char *) malloc (state->want);
state->out = (unsigned char *) malloc (state->want << 1);
if (state->in == NULL || state->out == NULL)
{
if (state->out != NULL)
free (state->out);
if (state->in != NULL)
free (state->in);
gz_error (state, Z_MEM_ERROR, "out of memory");
return -1;
}
state->size = state->want;
/* allocate inflate memory */
state->strm.zalloc = Z_NULL;
state->strm.zfree = Z_NULL;
state->strm.opaque = Z_NULL;
state->strm.avail_in = 0;
state->strm.next_in = Z_NULL;
if (inflateInit2 (&(state->strm), 15 + 16) != Z_OK)
{ /* gunzip */
free (state->out);
free (state->in);
state->size = 0;
gz_error (state, Z_MEM_ERROR, "out of memory");
return -1;
}
}
/* get at least the magic bytes in the input buffer */
if (strm->avail_in < 2)
{
if (gz_avail (state) == -1)
return -1;
if (strm->avail_in == 0)
return 0;
}
/* 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;
}
/* no gzip header -- if we were decoding gzip before, then this is trailing
garbage. Ignore the trailing garbage and finish. */
if (state->direct == 0)
{
strm->avail_in = 0;
state->eof = 1;
state->x.have = 0;
return 0;
}
/* doing raw i/o, copy any leftover input to output -- this assumes that
the output buffer is larger than the input buffer, which also assures
space for gzungetc() */
state->x.next = state->out;
if (strm->avail_in)
{
memcpy (state->x.next, strm->next_in, strm->avail_in);
state->x.have = strm->avail_in;
strm->avail_in = 0;
}
state->how = COPY;
state->direct = 1;
return 0;
}
/* Decompress from input to the provided next_out and avail_out in the state.
If the end of the compressed data is reached, then verify the gzip trailer
check value and length (modulo 2^32). state->have and state->next are set
to point to the just decompressed data, and the crc is updated. If the
trailer is verified, state->how is reset to LOOK to look for the next gzip
stream or raw data, once state->have is depleted. Returns 0 on success, -1
on failure. Failures may include invalid compressed data or a failed gzip
trailer verification. */
local int gz_decomp(gz_statep state)
{
int ret;
unsigned had;
unsigned long crc, len;
z_streamp strm = &(state->strm);
/* fill output buffer up to end of deflate stream */
had = strm->avail_out;
do {
/* get more input for inflate() */
if (strm->avail_in == 0 && gz_avail(state) == -1)
return -1;
if (strm->avail_in == 0) {
gz_error(state, Z_DATA_ERROR, "unexpected end of file");
return -1;
}
/* decompress and handle errors */
ret = inflate(strm, Z_NO_FLUSH);
if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
gz_error(state, Z_STREAM_ERROR,
"internal error: inflate stream corrupt");
return -1;
}
if (ret == Z_MEM_ERROR) {
gz_error(state, Z_MEM_ERROR, "out of memory");
return -1;
}
if (ret == Z_DATA_ERROR) { /* deflate stream invalid */
gz_error(state, Z_DATA_ERROR,
strm->msg == NULL ? "compressed data error" : strm->msg);
return -1;
}
} while (strm->avail_out && ret != Z_STREAM_END);
/* update available output and crc check value */
state->have = had - strm->avail_out;
state->next = strm->next_out - state->have;
strm->adler = crc32(strm->adler, state->next, state->have);
/* check gzip trailer if at end of deflate stream */
if (ret == Z_STREAM_END) {
if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) {
gz_error(state, Z_DATA_ERROR, "unexpected end of file");
return -1;
}
if (crc != strm->adler) {
gz_error(state, Z_DATA_ERROR, "incorrect data check");
return -1;
}
if (len != (strm->total_out & 0xffffffffL)) {
gz_error(state, Z_DATA_ERROR, "incorrect length check");
return -1;
}
state->how = LOOK; /* ready for next stream, once have is 0 (leave
state->direct unchanged to remember how) */
}
/* good decompression */
return 0;
}
/* Look for gzip header, set up for inflate or copy. state->have must be zero.
If this is the first time in, allocate required memory. state->how will be
left unchanged if there is no more input data available, will be set to COPY
if there is no gzip header and direct copying will be performed, or it will
be set to GZIP for decompression, and the gzip header will be skipped so
that the next available input data is the raw deflate stream. If direct
copying, then leftover input data from the input buffer will be copied to
the output buffer. In that case, all further file reads will be directly to
either the output buffer or a user buffer. If decompressing, the inflate
state and the check value will be initialized. gz_head() will return 0 on
success or -1 on failure. Failures may include read errors or gzip header
errors. */
local int gz_head(gz_statep state)
{
z_streamp strm = &(state->strm);
int flags;
unsigned len;
/* allocate read buffers and inflate memory */
if (state->size == 0) {
/* allocate buffers */
state->in = (unsigned char *)malloc(state->want);
state->out = (unsigned char *)malloc(state->want << 1);
if (state->in == NULL || state->out == NULL) {
if (state->out != NULL)
free(state->out);
if (state->in != NULL)
free(state->in);
gz_error(state, Z_MEM_ERROR, "out of memory");
return -1;
}
state->size = state->want;
/* allocate inflate memory */
state->strm.zalloc = Z_NULL;
state->strm.zfree = Z_NULL;
state->strm.opaque = Z_NULL;
state->strm.avail_in = 0;
state->strm.next_in = Z_NULL;
if (inflateInit2(&(state->strm), -15) != Z_OK) { /* raw inflate */
free(state->out);
free(state->in);
state->size = 0;
gz_error(state, Z_MEM_ERROR, "out of memory");
return -1;
}
}
/* get some data in the input buffer */
if (strm->avail_in == 0) {
if (gz_avail(state) == -1)
return -1;
if (strm->avail_in == 0)
return 0;
}
/* 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;
}
}
/* doing raw i/o, save start of raw data for seeking, copy any leftover
input to output -- this assumes that the output buffer is larger than
the input buffer, which also assures space for gzungetc() */
state->raw = state->pos;
state->next = state->out;
if (strm->avail_in) {
memcpy(state->next + state->have, strm->next_in, strm->avail_in);
state->have += strm->avail_in;
strm->avail_in = 0;
}
state->how = COPY;
state->direct = 1;
return 0;
}
