Allow gzread() and related to continue after gzclearerr().
Before this fix, gzread() would lose data if a premature end of file was encountered. This prevented gzread() from being used on a file that was being written concurrently. Now gzread() returns all of the data it has available before indicating a premature end of file. This also changes the error returned on a premature end of file from Z_DATA_ERROR to Z_BUF_ERROR. This allows the user to determine if the error is recoverable, which it is if Z_BUF_ERROR is returned. If a Z_DATA_ERROR is returned, then the error is not recoverable. This patch replaces the functionality of a previous patch that fixed reading through an empty gzip stream in a concatenation of gzip streams. To implement this fix, a noticeable rewrite of gzread.c was needed. The patch has the added advantage of using inflate's gzip processing instead of replicating the functionality in gzread.c. This makes the gz code a little simpler.
This commit is contained in:
parent
a9ae24b653
commit
5ad116abda
4
gzlib.c
4
gzlib.c
@ -247,8 +247,8 @@ int ZEXPORT gzbuffer(file, size)
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return -1;
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/* check and set requested size */
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if (size == 0)
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return -1;
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if (size < 2)
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size = 2; /* need two bytes to check magic header */
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state->want = size;
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return 0;
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}
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268
gzread.c
268
gzread.c
@ -8,10 +8,9 @@
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/* Local functions */
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local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
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local int gz_avail OF((gz_statep));
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local int gz_next4 OF((gz_statep, unsigned long *));
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local int gz_head OF((gz_statep));
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local int gz_look OF((gz_statep));
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local int gz_decomp OF((gz_statep));
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local int gz_make OF((gz_statep));
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local int gz_fetch OF((gz_statep));
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local int gz_skip OF((gz_statep, z_off64_t));
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/* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from
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@ -46,67 +45,42 @@ local int gz_load(state, buf, len, have)
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error, 0 otherwise. Note that the eof flag is set when the end of the input
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file is reached, even though there may be unused data in the buffer. Once
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that data has been used, no more attempts will be made to read the file.
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gz_avail() assumes that strm->avail_in == 0. */
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If strm->avail_in != 0, then the current data is moved to the beginning of
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the input buffer, and then the remainder of the buffer is loaded with the
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available data from the input file. */
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local int gz_avail(state)
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gz_statep state;
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{
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unsigned got;
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z_streamp strm = &(state->strm);
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if (state->err != Z_OK)
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if (state->err != Z_OK && state->err != Z_BUF_ERROR)
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return -1;
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if (state->eof == 0) {
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if (gz_load(state, state->in, state->size,
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(unsigned *)&(strm->avail_in)) == -1)
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if (strm->avail_in)
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memmove(state->in, strm->next_in, strm->avail_in);
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if (gz_load(state, state->in + strm->avail_in,
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state->size - strm->avail_in, &got) == -1)
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return -1;
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strm->avail_in += got;
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strm->next_in = state->in;
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}
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return 0;
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}
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/* Get next byte from input, or -1 if end or error. */
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#define NEXT() ((strm->avail_in == 0 && gz_avail(state) == -1) ? -1 : \
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(strm->avail_in == 0 ? -1 : \
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(strm->avail_in--, *(strm->next_in)++)))
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/* Get a four-byte little-endian integer and return 0 on success and the value
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in *ret. Otherwise -1 is returned and *ret is not modified. */
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local int gz_next4(state, ret)
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gz_statep state;
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unsigned long *ret;
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{
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int ch;
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unsigned long val;
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z_streamp strm = &(state->strm);
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val = NEXT();
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val += (unsigned)NEXT() << 8;
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val += (unsigned long)NEXT() << 16;
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ch = NEXT();
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if (ch == -1)
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return -1;
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val += (unsigned long)ch << 24;
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*ret = val;
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return 0;
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}
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/* Look for gzip header, set up for inflate or copy. state->have must be zero.
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If this is the first time in, allocate required memory. state->how will be
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left unchanged if there is no more input data available, will be set to COPY
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if there is no gzip header and direct copying will be performed, or it will
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be set to GZIP for decompression, and the gzip header will be skipped so
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that the next available input data is the raw deflate stream. If direct
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copying, then leftover input data from the input buffer will be copied to
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the output buffer. In that case, all further file reads will be directly to
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either the output buffer or a user buffer. If decompressing, the inflate
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state and the check value will be initialized. gz_head() will return 0 on
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success or -1 on failure. Failures may include read errors or gzip header
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errors. */
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local int gz_head(state)
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be set to GZIP for decompression. If direct copying, then leftover input
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data from the input buffer will be copied to the output buffer. In that
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case, all further file reads will be directly to either the output buffer or
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a user buffer. If decompressing, the inflate state will be initialized.
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gz_look() will return 0 on success or -1 on failure. */
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local int gz_look(state)
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gz_statep state;
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{
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z_streamp strm = &(state->strm);
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int flags;
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unsigned len;
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/* allocate read buffers and inflate memory */
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if (state->size == 0) {
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@ -129,7 +103,7 @@ local int gz_head(state)
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state->strm.opaque = Z_NULL;
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state->strm.avail_in = 0;
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state->strm.next_in = Z_NULL;
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if (inflateInit2(&(state->strm), -15) != Z_OK) { /* raw inflate */
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if (inflateInit2(&(state->strm), 15 + 16) != Z_OK) { /* gunzip */
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free(state->out);
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free(state->in);
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state->size = 0;
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@ -138,73 +112,27 @@ local int gz_head(state)
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}
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}
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/* get some data in the input buffer */
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if (strm->avail_in == 0) {
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/* get at least the magic bytes in the input buffer */
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if (strm->avail_in < 2) {
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if (gz_avail(state) == -1)
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return -1;
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if (strm->avail_in == 0)
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return 0;
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}
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/* look for the gzip magic header bytes 31 and 139 */
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if (strm->next_in[0] == 31) {
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strm->avail_in--;
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strm->next_in++;
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if (strm->avail_in == 0 && gz_avail(state) == -1)
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return -1;
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if (strm->avail_in && strm->next_in[0] == 139) {
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/* we have a gzip header, woo hoo! */
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strm->avail_in--;
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strm->next_in++;
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/* skip rest of header */
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if (NEXT() != 8) { /* compression method */
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gz_error(state, Z_DATA_ERROR, "unknown compression method");
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return -1;
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}
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flags = NEXT();
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if (flags & 0xe0) { /* reserved flag bits */
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gz_error(state, Z_DATA_ERROR, "unknown header flags set");
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return -1;
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}
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NEXT(); /* modification time */
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NEXT();
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NEXT();
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NEXT();
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NEXT(); /* extra flags */
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NEXT(); /* operating system */
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if (flags & 4) { /* extra field */
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len = (unsigned)NEXT();
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len += (unsigned)NEXT() << 8;
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while (len--)
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if (NEXT() < 0)
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break;
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}
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if (flags & 8) /* file name */
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while (NEXT() > 0)
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;
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if (flags & 16) /* comment */
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while (NEXT() > 0)
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;
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if (flags & 2) { /* header crc */
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NEXT();
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NEXT();
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}
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/* an unexpected end of file is not checked for here -- it will be
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noticed on the first request for uncompressed data */
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/* set up for decompression */
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inflateReset(strm);
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strm->adler = crc32(0L, Z_NULL, 0);
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state->how = GZIP;
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state->direct = 0;
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return 0;
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}
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else {
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/* not a gzip file -- save first byte (31) and fall to raw i/o */
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state->out[0] = 31;
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state->have = 1;
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}
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/* look for gzip magic bytes -- if there, do gzip decoding (note: there is
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a logical dilemma here when considering the case of a partially written
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gzip file, to wit, if a single 31 byte is written, then we cannot tell
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whether this is a single-byte file, or just a partially written gzip
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file -- for here we assume that if a gzip file is being written, then
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the header will be written in a single operation, so that reading a
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single byte is sufficient indication that it is not a gzip file) */
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if (strm->avail_in > 1 &&
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strm->next_in[0] == 31 && strm->next_in[1] == 139) {
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inflateReset(strm);
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state->how = GZIP;
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state->direct = 0;
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return 0;
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}
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/* no gzip header -- if we were decoding gzip before, then this is trailing
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@ -222,8 +150,8 @@ local int gz_head(state)
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state->raw = state->pos;
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state->next = state->out;
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if (strm->avail_in) {
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memcpy(state->next + state->have, strm->next_in, strm->avail_in);
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state->have += strm->avail_in;
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memcpy(state->next, strm->next_in, strm->avail_in);
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state->have = strm->avail_in;
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strm->avail_in = 0;
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}
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state->how = COPY;
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@ -232,19 +160,15 @@ local int gz_head(state)
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}
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/* Decompress from input to the provided next_out and avail_out in the state.
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If the end of the compressed data is reached, then verify the gzip trailer
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check value and length (modulo 2^32). state->have and state->next are set
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to point to the just decompressed data, and the crc is updated. If the
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trailer is verified, state->how is reset to LOOK to look for the next gzip
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stream or raw data, once state->have is depleted. Returns 0 on success, -1
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on failure. Failures may include invalid compressed data or a failed gzip
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trailer verification. */
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state->have and state->next are set to point to the just decompressed data,
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If the gzip stream completes, state->how is reset to LOOK to look for the
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next gzip stream or raw data, once state->have is depleted. Returns 0 on
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success, -1 on failure. */
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local int gz_decomp(state)
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gz_statep state;
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{
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int ret;
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int ret = Z_OK;
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unsigned had;
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unsigned long crc, len;
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z_streamp strm = &(state->strm);
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/* fill output buffer up to end of deflate stream */
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@ -254,15 +178,15 @@ local int gz_decomp(state)
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if (strm->avail_in == 0 && gz_avail(state) == -1)
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return -1;
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if (strm->avail_in == 0) {
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gz_error(state, Z_DATA_ERROR, "unexpected end of file");
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return -1;
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gz_error(state, Z_BUF_ERROR, "unexpected end of file");
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break;
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}
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/* decompress and handle errors */
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ret = inflate(strm, Z_NO_FLUSH);
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if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
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gz_error(state, Z_STREAM_ERROR,
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"internal error: inflate stream corrupt");
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"internal error: inflate stream corrupt");
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return -1;
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}
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if (ret == Z_MEM_ERROR) {
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@ -271,67 +195,55 @@ local int gz_decomp(state)
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}
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if (ret == Z_DATA_ERROR) { /* deflate stream invalid */
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gz_error(state, Z_DATA_ERROR,
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strm->msg == NULL ? "compressed data error" : strm->msg);
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strm->msg == NULL ? "compressed data error" : strm->msg);
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return -1;
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}
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} while (strm->avail_out && ret != Z_STREAM_END);
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/* update available output and crc check value */
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/* update available output */
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state->have = had - strm->avail_out;
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state->next = strm->next_out - state->have;
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strm->adler = crc32(strm->adler, state->next, state->have);
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/* check gzip trailer if at end of deflate stream */
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if (ret == Z_STREAM_END) {
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if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) {
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gz_error(state, Z_DATA_ERROR, "unexpected end of file");
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return -1;
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}
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if (crc != strm->adler) {
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gz_error(state, Z_DATA_ERROR, "incorrect data check");
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return -1;
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}
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if (len != (strm->total_out & 0xffffffffL)) {
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gz_error(state, Z_DATA_ERROR, "incorrect length check");
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return -1;
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}
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state->how = LOOK; /* ready for next stream, once have is 0 (leave
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state->direct unchanged to remember how) */
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}
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/* if the gzip stream completed successfully, look for another */
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if (ret == Z_STREAM_END)
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state->how = LOOK;
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/* good decompression */
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return 0;
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}
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/* Make data and put in the output buffer. Assumes that state->have == 0.
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/* Fetch data and put it in the output buffer. Assumes that state->have == 0.
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Data is either copied from the input file or decompressed from the input
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file depending on state->how. If state->how is LOOK, then a gzip header is
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looked for (and skipped if found) to discern whether to copy or decompress.
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Returns -1 on error, otherwise 0. gz_make() will leave state->how as COPY
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or GZIP unless the end of the input file has been reached and all data has
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been processed. */
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local int gz_make(state)
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looked for to determine whether to copy or decompress. Returns -1 on error,
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otherwise 0. gz_fetch() will leave state->how as COPY or GZIP unless the
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end of the input file has been reached and all data has been processed. */
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local int gz_fetch(state)
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gz_statep state;
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{
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z_streamp strm = &(state->strm);
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if (state->how == LOOK) { /* look for gzip header */
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if (gz_head(state) == -1)
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return -1;
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if (state->have) /* got some data from gz_head() */
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do {
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switch(state->how) {
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case LOOK: /* -> LOOK, COPY (only if never GZIP), or GZIP */
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if (gz_look(state) == -1)
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return -1;
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if (state->how == LOOK)
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return 0;
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break;
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case COPY: /* -> COPY */
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if (gz_load(state, state->out, state->size << 1, &(state->have))
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== -1)
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return -1;
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state->next = state->out;
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return 0;
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}
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if (state->how == COPY) { /* straight copy */
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if (gz_load(state, state->out, state->size << 1, &(state->have)) == -1)
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return -1;
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state->next = state->out;
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}
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else if (state->how == GZIP) { /* decompress */
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strm->avail_out = state->size << 1;
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strm->next_out = state->out;
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if (gz_decomp(state) == -1)
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return -1;
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}
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case GZIP: /* -> GZIP or LOOK (if end of gzip stream) */
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strm->avail_out = state->size << 1;
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strm->next_out = state->out;
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if (gz_decomp(state) == -1)
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return -1;
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}
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} while (state->have == 0);
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return 0;
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}
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@ -361,7 +273,7 @@ local int gz_skip(state, len)
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/* need more data to skip -- load up output buffer */
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else {
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/* get more output, looking for header if required */
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if (gz_make(state) == -1)
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if (gz_fetch(state) == -1)
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return -1;
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}
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return 0;
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@ -383,8 +295,9 @@ int ZEXPORT gzread(file, buf, len)
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state = (gz_statep)file;
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strm = &(state->strm);
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/* check that we're reading and that there's no error */
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if (state->mode != GZ_READ || state->err != Z_OK)
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/* check that we're reading and that there's no (serious) error */
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if (state->mode != GZ_READ ||
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(state->err != Z_OK && state->err != Z_BUF_ERROR))
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return -1;
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/* since an int is returned, make sure len fits in one, otherwise return
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@ -424,7 +337,7 @@ int ZEXPORT gzread(file, buf, len)
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buffer */
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else if (state->how == LOOK || len < (state->size << 1)) {
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/* get more output, looking for header if required */
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if (gz_make(state) == -1)
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if (gz_fetch(state) == -1)
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return -1;
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continue; /* no progress yet -- go back to memcpy() above */
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/* the copy above assures that we will leave with space in the
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@ -471,8 +384,9 @@ int ZEXPORT gzgetc(file)
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return -1;
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state = (gz_statep)file;
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/* check that we're reading and that there's no error */
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if (state->mode != GZ_READ || state->err != Z_OK)
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/* check that we're reading and that there's no (serious) error */
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if (state->mode != GZ_READ ||
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(state->err != Z_OK && state->err != Z_BUF_ERROR))
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return -1;
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/* try output buffer (no need to check for skip request) */
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@ -499,8 +413,9 @@ int ZEXPORT gzungetc(c, file)
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return -1;
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state = (gz_statep)file;
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/* check that we're reading and that there's no error */
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if (state->mode != GZ_READ || state->err != Z_OK)
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/* check that we're reading and that there's no (serious) error */
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if (state->mode != GZ_READ ||
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(state->err != Z_OK && state->err != Z_BUF_ERROR))
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return -1;
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/* process a skip request */
|
||||
@ -560,8 +475,9 @@ char * ZEXPORT gzgets(file, buf, len)
|
||||
return NULL;
|
||||
state = (gz_statep)file;
|
||||
|
||||
/* check that we're reading and that there's no error */
|
||||
if (state->mode != GZ_READ || state->err != Z_OK)
|
||||
/* check that we're reading and that there's no (serious) error */
|
||||
if (state->mode != GZ_READ ||
|
||||
(state->err != Z_OK && state->err != Z_BUF_ERROR))
|
||||
return NULL;
|
||||
|
||||
/* process a skip request */
|
||||
@ -578,10 +494,8 @@ char * ZEXPORT gzgets(file, buf, len)
|
||||
left = (unsigned)len - 1;
|
||||
if (left) do {
|
||||
/* assure that something is in the output buffer */
|
||||
while (state->have == 0 && (state->strm.avail_in || !state->eof)) {
|
||||
if (gz_make(state) == -1)
|
||||
return NULL; /* error */
|
||||
}
|
||||
if (state->have == 0 && gz_fetch(state) == -1)
|
||||
return NULL; /* error */
|
||||
if (state->have == 0) { /* end of file */
|
||||
if (buf == str) /* got bupkus */
|
||||
return NULL;
|
||||
@ -626,7 +540,7 @@ int ZEXPORT gzdirect(file)
|
||||
/* if the state is not known, but we can find out, then do so (this is
|
||||
mainly for right after a gzopen() or gzdopen()) */
|
||||
if (state->how == LOOK && state->have == 0)
|
||||
(void)gz_head(state);
|
||||
(void)gz_look(state);
|
||||
|
||||
/* return 1 if reading direct, 0 if decompressing a gzip stream */
|
||||
return state->direct;
|
||||
|
Loading…
x
Reference in New Issue
Block a user