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/* gzread.c -- zlib functions for reading gzip files
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* Copyright (C) 2004, 2005, 2010, 2011 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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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_look OF((gz_statep));
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local int gz_decomp 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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state->fd, and update state->eof, state->err, and state->msg as appropriate.
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This function needs to loop on read(), since read() is not guaranteed to
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read the number of bytes requested, depending on the type of descriptor. */
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local int gz_load(state, buf, len, have)
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ret = read(state->fd, buf + *have, len - *have);
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} while (*have < len);
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gz_error(state, Z_ERRNO, zstrerror());
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/* Load up input buffer and set eof flag if last data loaded -- return -1 on
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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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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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z_streamp strm = &(state->strm);
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if (state->err != Z_OK && state->err != Z_BUF_ERROR)
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if (state->eof == 0) {
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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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strm->avail_in += got;
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strm->next_in = state->in;
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/* Look for gzip header, set up for inflate or copy. state->x.have must be 0.
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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. 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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z_streamp strm = &(state->strm);
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/* allocate read buffers and inflate memory */
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if (state->size == 0) {
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/* allocate buffers */
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state->in = malloc(state->want);
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state->out = malloc(state->want << 1);
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if (state->in == NULL || state->out == NULL) {
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if (state->out != NULL)
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if (state->in != NULL)
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gz_error(state, Z_MEM_ERROR, "out of memory");
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state->size = state->want;
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/* allocate inflate memory */
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state->strm.zalloc = Z_NULL;
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state->strm.zfree = Z_NULL;
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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 + 16) != Z_OK) { /* gunzip */
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gz_error(state, Z_MEM_ERROR, "out of memory");
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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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if (strm->avail_in == 0)
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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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/* no gzip header -- if we were decoding gzip before, then this is trailing
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garbage. Ignore the trailing garbage and finish. */
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if (state->direct == 0) {
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/* doing raw i/o, copy any leftover input to output -- this assumes that
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the output buffer is larger than the input buffer, which also assures
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space for gzungetc() */
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state->x.next = state->out;
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if (strm->avail_in) {
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memcpy(state->x.next, strm->next_in, strm->avail_in);
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state->x.have = strm->avail_in;
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/* Decompress from input to the provided next_out and avail_out in the state.
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On return, state->x.have and state->x.next point to the just decompressed
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data. If the gzip stream completes, state->how is reset to LOOK to look for
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the next gzip stream or raw data, once state->x.have is depleted. Returns 0
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on success, -1 on failure. */
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local int gz_decomp(state)
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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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had = strm->avail_out;
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/* get more input for inflate() */
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if (strm->avail_in == 0 && gz_avail(state) == -1)
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if (strm->avail_in == 0) {
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gz_error(state, Z_BUF_ERROR, "unexpected end of file");
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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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if (ret == Z_MEM_ERROR) {
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gz_error(state, Z_MEM_ERROR, "out of memory");
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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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} while (strm->avail_out && ret != Z_STREAM_END);
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/* update available output */
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state->x.have = had - strm->avail_out;
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state->x.next = strm->next_out - state->x.have;
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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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/* good decompression */
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/* Fetch data and put it in the output buffer. Assumes state->x.have is 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 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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z_streamp strm = &(state->strm);
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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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if (state->how == LOOK)
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case COPY: /* -> COPY */
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if (gz_load(state, state->out, state->size << 1, &(state->x.have))
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state->x.next = state->out;
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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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} while (state->x.have == 0 && (!state->eof || strm->avail_in));
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/* Skip len uncompressed bytes of output. Return -1 on error, 0 on success. */
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local int gz_skip(state, len)
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/* skip over len bytes or reach end-of-file, whichever comes first */
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/* skip over whatever is in output buffer */
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n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > len ?
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(unsigned)len : state->x.have;
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/* output buffer empty -- return if we're at the end of the input */
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else if (state->eof && state->strm.avail_in == 0)
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/* need more data to skip -- load up output buffer */
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/* get more output, looking for header if required */
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if (gz_fetch(state) == -1)
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/* -- see zlib.h -- */
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int ZEXPORT gzread(file, buf, len)
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/* get internal structure */
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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 (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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/* since an int is returned, make sure len fits in one, otherwise return
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with an error (this avoids the flaw in the interface) */
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gz_error(state, Z_DATA_ERROR, "requested length does not fit in int");
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/* if len is zero, avoid unnecessary operations */
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/* process a skip request */
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if (gz_skip(state, state->skip) == -1)
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/* get len bytes to buf, or less than len if at the end */
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/* first just try copying data from the output buffer */
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n = state->x.have > len ? len : state->x.have;
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memcpy(buf, state->x.next, n);
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/* output buffer empty -- return if we're at the end of the input */
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else if (state->eof && strm->avail_in == 0) {
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state->past = 1; /* tried to read past end */
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/* need output data -- for small len or new stream load up our output
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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_fetch(state) == -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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output buffer, allowing at least one gzungetc() to succeed */
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/* large len -- read directly into user buffer */
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else if (state->how == COPY) { /* read directly */
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if (gz_load(state, buf, len, &n) == -1)
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/* large len -- decompress directly into user buffer */
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else { /* state->how == GZIP */
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strm->avail_out = len;
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strm->next_out = buf;
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if (gz_decomp(state) == -1)
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/* update progress */
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buf = (char *)buf + n;
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/* return number of bytes read into user buffer (will fit in int) */
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/* -- see zlib.h -- */
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int ZEXPORT gzgetc_(file)
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unsigned char buf[1];
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/* get internal structure */
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state = (gz_statep)file;
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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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/* try output buffer (no need to check for skip request) */
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return *(state->x.next)++;
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/* nothing there -- try gzread() */
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ret = gzread(file, buf, 1);
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return ret < 1 ? -1 : buf[0];
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int ZEXPORT gzgetc(file)
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return gzgetc_(file);
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/* -- see zlib.h -- */
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int ZEXPORT gzungetc(c, file)
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/* get internal structure */
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state = (gz_statep)file;
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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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/* process a skip request */
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if (gz_skip(state, state->skip) == -1)
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/* if output buffer empty, put byte at end (allows more pushing) */
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if (state->x.have == 0) {
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state->x.next = state->out + (state->size << 1) - 1;
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state->x.next[0] = c;
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/* if no room, give up (must have already done a gzungetc()) */
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if (state->x.have == (state->size << 1)) {
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gz_error(state, Z_DATA_ERROR, "out of room to push characters");
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/* slide output data if needed and insert byte before existing data */
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if (state->x.next == state->out) {
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unsigned char *src = state->out + state->x.have;
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unsigned char *dest = state->out + (state->size << 1);
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while (src > state->out)
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state->x.next = dest;
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state->x.next[0] = c;
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/* -- see zlib.h -- */
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char * ZEXPORT gzgets(file, buf, len)
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/* check parameters and get internal structure */
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if (file == NULL || buf == NULL || len < 1)
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state = (gz_statep)file;
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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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/* process a skip request */
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if (gz_skip(state, state->skip) == -1)
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/* copy output bytes up to new line or len - 1, whichever comes first --
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append a terminating zero to the string (we don't check for a zero in
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the contents, let the user worry about that) */
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left = (unsigned)len - 1;
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/* assure that something is in the output buffer */
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if (state->x.have == 0 && gz_fetch(state) == -1)
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return NULL; /* error */
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if (state->x.have == 0) { /* end of file */
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state->past = 1; /* read past end */
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break; /* return what we have */
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/* look for end-of-line in current output buffer */
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n = state->x.have > left ? left : state->x.have;
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eol = memchr(state->x.next, '\n', n);
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n = (unsigned)(eol - state->x.next) + 1;
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/* copy through end-of-line, or remainder if not found */
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memcpy(buf, state->x.next, n);
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} while (left && eol == NULL);
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/* return terminated string, or if nothing, end of file */
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/* -- see zlib.h -- */
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int ZEXPORT gzdirect(file)
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/* get internal structure */
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state = (gz_statep)file;
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/* if the state is not known, but we can find out, then do so (this is
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mainly for right after a gzopen() or gzdopen()) */
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if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
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(void)gz_look(state);
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/* return 1 if transparent, 0 if processing a gzip stream */
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return state->direct;
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/* -- see zlib.h -- */
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int ZEXPORT gzclose_r(file)
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/* get internal structure */
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return Z_STREAM_ERROR;
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state = (gz_statep)file;
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/* check that we're reading */
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if (state->mode != GZ_READ)
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return Z_STREAM_ERROR;
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/* free memory and close file */
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inflateEnd(&(state->strm));
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err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
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gz_error(state, Z_OK, NULL);
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ret = close(state->fd);
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return ret ? Z_ERRNO : err;
added
removed
zlib-1.2.6/gzread.c
