/src/zlib/gzread.c

Source (jump to first uncovered line)
/* gzread.c -- zlib functions for reading gzip files
 * Copyright (C) 2004-2017 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "gzguts.h"

/* Use read() to load a buffer -- return -1 on error, otherwise 0.  Read from
   state->fd, and update state->eof, state->err, and state->msg as appropriate.
   This function needs to loop on read(), since read() is not guaranteed to
   read the number of bytes requested, depending on the type of descriptor. */
local int gz_load(gz_statep state, unsigned char *buf, unsigned len,
                  unsigned *have) {
    int ret;
    unsigned get, max = ((unsigned)-1 >> 2) + 1;

    *have = 0;
    do {
        get = len - *have;
        if (get > max)
            get = max;
        ret = read(state->fd, buf + *have, get);
        if (ret <= 0)
            break;
        *have += (unsigned)ret;
    } while (*have < len);
    if (ret < 0) {
        gz_error(state, Z_ERRNO, zstrerror());
        return -1;
    }
    if (ret == 0)
        state->eof = 1;
    return 0;
}

/* Load up input buffer and set eof flag if last data loaded -- return -1 on
   error, 0 otherwise.  Note that the eof flag is set when the end of the input
   file is reached, even though there may be unused data in the buffer.  Once
   that data has been used, no more attempts will be made to read the file.
   If strm->avail_in != 0, then the current data is moved to the beginning of
   the input buffer, and then the remainder of the buffer is loaded with the
   available data from the input file. */
local int gz_avail(gz_statep state) {
    unsigned got;
    z_streamp strm = &(state->strm);

    if (state->err != Z_OK && state->err != Z_BUF_ERROR)
        return -1;
    if (state->eof == 0) {
        if (strm->avail_in) {       /* copy what's there to the start */
            unsigned char *p = state->in;
            unsigned const char *q = strm->next_in;
            unsigned n = strm->avail_in;
            do {
                *p++ = *q++;
            } while (--n);
        }
        if (gz_load(state, state->in + strm->avail_in,
                    state->size - strm->avail_in, &got) == -1)
            return -1;
        strm->avail_in += got;
        strm->next_in = state->in;
    }
    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) {
            free(state->out);
            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;
    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.
   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;
}

/* Fetch data and put it in the output buffer.  Assumes state->x.have is 0.
   Data is either copied from the input file or decompressed from the input
   file depending on state->how.  If state->how is LOOK, then a gzip header is
   looked for to determine whether to copy or decompress.  Returns -1 on error,
   otherwise 0.  gz_fetch() will leave state->how as COPY or GZIP unless the
   end of the input file has been reached and all data has been processed.  */
local int gz_fetch(gz_statep state) {
    z_streamp strm = &(state->strm);

    do {
        switch(state->how) {
        case LOOK:      /* -> LOOK, COPY (only if never GZIP), or GZIP */
            if (gz_look(state) == -1)
                return -1;
            if (state->how == LOOK)
                return 0;
            break;
        case COPY:      /* -> COPY */
            if (gz_load(state, state->out, state->size << 1, &(state->x.have))
                    == -1)
                return -1;
            state->x.next = state->out;
            return 0;
        case GZIP:      /* -> GZIP or LOOK (if end of gzip stream) */
            strm->avail_out = state->size << 1;
            strm->next_out = state->out;
            if (gz_decomp(state) == -1)
                return -1;
        }
    } while (state->x.have == 0 && (!state->eof || strm->avail_in));
    return 0;
}

/* Skip len uncompressed bytes of output.  Return -1 on error, 0 on success. */
local int gz_skip(gz_statep state, z_off64_t len) {
    unsigned n;

    /* skip over len bytes or reach end-of-file, whichever comes first */
    while (len)
        /* skip over whatever is in output buffer */
        if (state->x.have) {
            n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > len ?
                (unsigned)len : state->x.have;
            state->x.have -= n;
            state->x.next += n;
            state->x.pos += n;
            len -= n;
        }

        /* output buffer empty -- return if we're at the end of the input */
        else if (state->eof && state->strm.avail_in == 0)
            break;

        /* need more data to skip -- load up output buffer */
        else {
            /* get more output, looking for header if required */
            if (gz_fetch(state) == -1)
                return -1;
        }
    return 0;
}

/* Read len bytes into buf from file, or less than len up to the end of the
   input.  Return the number of bytes read.  If zero is returned, either the
   end of file was reached, or there was an error.  state->err must be
   consulted in that case to determine which. */
local z_size_t gz_read(gz_statep state, voidp buf, z_size_t len) {
    z_size_t got;
    unsigned n;

    /* if len is zero, avoid unnecessary operations */
    if (len == 0)
        return 0;

    /* process a skip request */
    if (state->seek) {
        state->seek = 0;
        if (gz_skip(state, state->skip) == -1)
            return 0;
    }

    /* get len bytes to buf, or less than len if at the end */
    got = 0;
    do {
        /* set n to the maximum amount of len that fits in an unsigned int */
        n = (unsigned)-1;
        if (n > len)
            n = (unsigned)len;

        /* first just try copying data from the output buffer */
        if (state->x.have) {
            if (state->x.have < n)
                n = state->x.have;
            memcpy(buf, state->x.next, n);
            state->x.next += n;
            state->x.have -= n;
        }

        /* output buffer empty -- return if we're at the end of the input */
        else if (state->eof && state->strm.avail_in == 0) {
            state->past = 1;        /* tried to read past end */
            break;
        }

        /* need output data -- for small len or new stream load up our output
           buffer */
        else if (state->how == LOOK || n < (state->size << 1)) {
            /* get more output, looking for header if required */
            if (gz_fetch(state) == -1)
                return 0;
            continue;       /* no progress yet -- go back to copy above */
            /* the copy above assures that we will leave with space in the
               output buffer, allowing at least one gzungetc() to succeed */
        }

        /* large len -- read directly into user buffer */
        else if (state->how == COPY) {      /* read directly */
            if (gz_load(state, (unsigned char *)buf, n, &n) == -1)
                return 0;
        }

        /* large len -- decompress directly into user buffer */
        else {  /* state->how == GZIP */
            state->strm.avail_out = n;
            state->strm.next_out = (unsigned char *)buf;
            if (gz_decomp(state) == -1)
                return 0;
            n = state->x.have;
            state->x.have = 0;
        }

        /* update progress */
        len -= n;
        buf = (char *)buf + n;
        got += n;
        state->x.pos += n;
    } while (len);

    /* return number of bytes read into user buffer */
    return got;
}

/* -- see zlib.h -- */
int ZEXPORT gzread(gzFile file, voidp buf, unsigned len) {
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return -1;
    state = (gz_statep)file;

    /* 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 -1;

    /* since an int is returned, make sure len fits in one, otherwise return
       with an error (this avoids a flaw in the interface) */
    if ((int)len < 0) {
        gz_error(state, Z_STREAM_ERROR, "request does not fit in an int");
        return -1;
    }

    /* read len or fewer bytes to buf */
    len = (unsigned)gz_read(state, buf, len);

    /* check for an error */
    if (len == 0 && state->err != Z_OK && state->err != Z_BUF_ERROR)
        return -1;

    /* return the number of bytes read (this is assured to fit in an int) */
    return (int)len;
}

/* -- see zlib.h -- */
z_size_t ZEXPORT gzfread(voidp buf, z_size_t size, z_size_t nitems,
                         gzFile file) {
    z_size_t len;
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return 0;
    state = (gz_statep)file;

    /* 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 0;

    /* compute bytes to read -- error on overflow */
    len = nitems * size;
    if (size && len / size != nitems) {
        gz_error(state, Z_STREAM_ERROR, "request does not fit in a size_t");
        return 0;
    }

    /* read len or fewer bytes to buf, return the number of full items read */
    return len ? gz_read(state, buf, len) / size : 0;
}

/* -- see zlib.h -- */
#ifdef Z_PREFIX_SET
#  undef z_gzgetc
#else
#  undef gzgetc
#endif
int ZEXPORT gzgetc(gzFile file) {
    unsigned char buf[1];
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return -1;
    state = (gz_statep)file;

    /* 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 -1;

    /* try output buffer (no need to check for skip request) */
    if (state->x.have) {
        state->x.have--;
        state->x.pos++;
        return *(state->x.next)++;
    }

    /* nothing there -- try gz_read() */
    return gz_read(state, buf, 1) < 1 ? -1 : buf[0];
}

int ZEXPORT gzgetc_(gzFile file) {
    return gzgetc(file);
}

/* -- see zlib.h -- */
int ZEXPORT gzungetc(int c, gzFile file) {
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return -1;
    state = (gz_statep)file;

    /* in case this was just opened, set up the input buffer */
    if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
        (void)gz_look(state);

    /* 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 -1;

    /* process a skip request */
    if (state->seek) {
        state->seek = 0;
        if (gz_skip(state, state->skip) == -1)
            return -1;
    }

    /* can't push EOF */
    if (c < 0)
        return -1;

    /* if output buffer empty, put byte at end (allows more pushing) */
    if (state->x.have == 0) {
        state->x.have = 1;
        state->x.next = state->out + (state->size << 1) - 1;
        state->x.next[0] = (unsigned char)c;
        state->x.pos--;
        state->past = 0;
        return c;
    }

    /* if no room, give up (must have already done a gzungetc()) */
    if (state->x.have == (state->size << 1)) {
        gz_error(state, Z_DATA_ERROR, "out of room to push characters");
        return -1;
    }

    /* slide output data if needed and insert byte before existing data */
    if (state->x.next == state->out) {
        unsigned char *src = state->out + state->x.have;
        unsigned char *dest = state->out + (state->size << 1);
        while (src > state->out)
            *--dest = *--src;
        state->x.next = dest;
    }
    state->x.have++;
    state->x.next--;
    state->x.next[0] = (unsigned char)c;
    state->x.pos--;
    state->past = 0;
    return c;
}

/* -- see zlib.h -- */
char * ZEXPORT gzgets(gzFile file, char *buf, int len) {
    unsigned left, n;
    char *str;
    unsigned char *eol;
    gz_statep state;

    /* check parameters and get internal structure */
    if (file == NULL || buf == NULL || len < 1)
        return NULL;
    state = (gz_statep)file;

    /* 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 */
    if (state->seek) {
        state->seek = 0;
        if (gz_skip(state, state->skip) == -1)
            return NULL;
    }

    /* copy output bytes up to new line or len - 1, whichever comes first --
       append a terminating zero to the string (we don't check for a zero in
       the contents, let the user worry about that) */
    str = buf;
    left = (unsigned)len - 1;
    if (left) do {
        /* assure that something is in the output buffer */
        if (state->x.have == 0 && gz_fetch(state) == -1)
            return NULL;                /* error */
        if (state->x.have == 0) {       /* end of file */
            state->past = 1;            /* read past end */
            break;                      /* return what we have */
        }

        /* look for end-of-line in current output buffer */
        n = state->x.have > left ? left : state->x.have;
        eol = (unsigned char *)memchr(state->x.next, '\n', n);
        if (eol != NULL)
            n = (unsigned)(eol - state->x.next) + 1;

        /* copy through end-of-line, or remainder if not found */
        memcpy(buf, state->x.next, n);
        state->x.have -= n;
        state->x.next += n;
        state->x.pos += n;
        left -= n;
        buf += n;
    } while (left && eol == NULL);

    /* return terminated string, or if nothing, end of file */
    if (buf == str)
        return NULL;
    buf[0] = 0;
    return str;
}

/* -- see zlib.h -- */
int ZEXPORT gzdirect(gzFile file) {
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return 0;
    state = (gz_statep)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->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
        (void)gz_look(state);

    /* return 1 if transparent, 0 if processing a gzip stream */
    return state->direct;
}

/* -- see zlib.h -- */
int ZEXPORT gzclose_r(gzFile file) {
    int ret, err;
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return Z_STREAM_ERROR;
    state = (gz_statep)file;

    /* check that we're reading */
    if (state->mode != GZ_READ)
        return Z_STREAM_ERROR;

    /* free memory and close file */
    if (state->size) {
        inflateEnd(&(state->strm));
        free(state->out);
        free(state->in);
    }
    err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
    gz_error(state, Z_OK, NULL);
    free(state->path);
    ret = close(state->fd);
    free(state);
    return ret ? Z_ERRNO : err;
}

Coverage Report

Created: 2025-07-23 08:18

Line	Count	Source (jump to first uncovered line)
1		/* gzread.c -- zlib functions for reading gzip files
2		* Copyright (C) 2004-2017 Mark Adler
3		* For conditions of distribution and use, see copyright notice in zlib.h
4		*/
5
6		#include "gzguts.h"
7
8		/* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from
9		state->fd, and update state->eof, state->err, and state->msg as appropriate.
10		This function needs to loop on read(), since read() is not guaranteed to
11		read the number of bytes requested, depending on the type of descriptor. */
12		local int gz_load(gz_statep state, unsigned char *buf, unsigned len,
13	0	unsigned *have) {
14	0	int ret;
15	0	unsigned get, max = ((unsigned)-1 >> 2) + 1;
16
17	0	*have = 0;
18	0	do {
19	0	get = len - *have;
20	0	if (get > max)
21	0	get = max;
22	0	ret = read(state->fd, buf + *have, get);
23	0	if (ret <= 0)
24	0	break;
25	0	*have += (unsigned)ret;
26	0	} while (*have < len);
27	0	if (ret < 0) {
28	0	gz_error(state, Z_ERRNO, zstrerror());
29	0	return -1;
30	0	}
31	0	if (ret == 0)
32	0	state->eof = 1;
33	0	return 0;
34	0	}
35
36		/* Load up input buffer and set eof flag if last data loaded -- return -1 on
37		error, 0 otherwise. Note that the eof flag is set when the end of the input
38		file is reached, even though there may be unused data in the buffer. Once
39		that data has been used, no more attempts will be made to read the file.
40		If strm->avail_in != 0, then the current data is moved to the beginning of
41		the input buffer, and then the remainder of the buffer is loaded with the
42		available data from the input file. */
43	0	local int gz_avail(gz_statep state) {
44	0	unsigned got;
45	0	z_streamp strm = &(state->strm);
46
47	0	if (state->err != Z_OK && state->err != Z_BUF_ERROR)
48	0	return -1;
49	0	if (state->eof == 0) {
50	0	if (strm->avail_in) { /* copy what's there to the start */
51	0	unsigned char *p = state->in;
52	0	unsigned const char *q = strm->next_in;
53	0	unsigned n = strm->avail_in;
54	0	do {
55	0	p++ = q++;
56	0	} while (--n);
57	0	}
58	0	if (gz_load(state, state->in + strm->avail_in,
59	0	state->size - strm->avail_in, &got) == -1)
60	0	return -1;
61	0	strm->avail_in += got;
62	0	strm->next_in = state->in;
63	0	}
64	0	return 0;
65	0	}
66
67		/* Look for gzip header, set up for inflate or copy. state->x.have must be 0.
68		If this is the first time in, allocate required memory. state->how will be
69		left unchanged if there is no more input data available, will be set to COPY
70		if there is no gzip header and direct copying will be performed, or it will
71		be set to GZIP for decompression. If direct copying, then leftover input
72		data from the input buffer will be copied to the output buffer. In that
73		case, all further file reads will be directly to either the output buffer or
74		a user buffer. If decompressing, the inflate state will be initialized.
75		gz_look() will return 0 on success or -1 on failure. */
76	0	local int gz_look(gz_statep state) {
77	0	z_streamp strm = &(state->strm);
78
79		/* allocate read buffers and inflate memory */
80	0	if (state->size == 0) {
81		/* allocate buffers */
82	0	state->in = (unsigned char *)malloc(state->want);
83	0	state->out = (unsigned char *)malloc(state->want << 1);
84	0	if (state->in == NULL \|\| state->out == NULL) {
85	0	free(state->out);
86	0	free(state->in);
87	0	gz_error(state, Z_MEM_ERROR, "out of memory");
88	0	return -1;
89	0	}
90	0	state->size = state->want;
91
92		/* allocate inflate memory */
93	0	state->strm.zalloc = Z_NULL;
94	0	state->strm.zfree = Z_NULL;
95	0	state->strm.opaque = Z_NULL;
96	0	state->strm.avail_in = 0;
97	0	state->strm.next_in = Z_NULL;
98	0	if (inflateInit2(&(state->strm), 15 + 16) != Z_OK) { /* gunzip */
99	0	free(state->out);
100	0	free(state->in);
101	0	state->size = 0;
102	0	gz_error(state, Z_MEM_ERROR, "out of memory");
103	0	return -1;
104	0	}
105	0	}
106
107		/* get at least the magic bytes in the input buffer */
108	0	if (strm->avail_in < 2) {
109	0	if (gz_avail(state) == -1)
110	0	return -1;
111	0	if (strm->avail_in == 0)
112	0	return 0;
113	0	}
114
115		/* look for gzip magic bytes -- if there, do gzip decoding (note: there is
116		a logical dilemma here when considering the case of a partially written
117		gzip file, to wit, if a single 31 byte is written, then we cannot tell
118		whether this is a single-byte file, or just a partially written gzip
119		file -- for here we assume that if a gzip file is being written, then
120		the header will be written in a single operation, so that reading a
121		single byte is sufficient indication that it is not a gzip file) */
122	0	if (strm->avail_in > 1 &&
123	0	strm->next_in[0] == 31 && strm->next_in[1] == 139) {
124	0	inflateReset(strm);
125	0	state->how = GZIP;
126	0	state->direct = 0;
127	0	return 0;
128	0	}
129
130		/* no gzip header -- if we were decoding gzip before, then this is trailing
131		garbage. Ignore the trailing garbage and finish. */
132	0	if (state->direct == 0) {
133	0	strm->avail_in = 0;
134	0	state->eof = 1;
135	0	state->x.have = 0;
136	0	return 0;
137	0	}
138
139		/* doing raw i/o, copy any leftover input to output -- this assumes that
140		the output buffer is larger than the input buffer, which also assures
141		space for gzungetc() */
142	0	state->x.next = state->out;
143	0	memcpy(state->x.next, strm->next_in, strm->avail_in);
144	0	state->x.have = strm->avail_in;
145	0	strm->avail_in = 0;
146	0	state->how = COPY;
147	0	state->direct = 1;
148	0	return 0;
149	0	}
150
151		/* Decompress from input to the provided next_out and avail_out in the state.
152		On return, state->x.have and state->x.next point to the just decompressed
153		data. If the gzip stream completes, state->how is reset to LOOK to look for
154		the next gzip stream or raw data, once state->x.have is depleted. Returns 0
155		on success, -1 on failure. */
156	0	local int gz_decomp(gz_statep state) {
157	0	int ret = Z_OK;
158	0	unsigned had;
159	0	z_streamp strm = &(state->strm);
160
161		/* fill output buffer up to end of deflate stream */
162	0	had = strm->avail_out;
163	0	do {
164		/* get more input for inflate() */
165	0	if (strm->avail_in == 0 && gz_avail(state) == -1)
166	0	return -1;
167	0	if (strm->avail_in == 0) {
168	0	gz_error(state, Z_BUF_ERROR, "unexpected end of file");
169	0	break;
170	0	}
171
172		/* decompress and handle errors */
173	0	ret = inflate(strm, Z_NO_FLUSH);
174	0	if (ret == Z_STREAM_ERROR \|\| ret == Z_NEED_DICT) {
175	0	gz_error(state, Z_STREAM_ERROR,
176	0	"internal error: inflate stream corrupt");
177	0	return -1;
178	0	}
179	0	if (ret == Z_MEM_ERROR) {
180	0	gz_error(state, Z_MEM_ERROR, "out of memory");
181	0	return -1;
182	0	}
183	0	if (ret == Z_DATA_ERROR) { /* deflate stream invalid */
184	0	gz_error(state, Z_DATA_ERROR,
185	0	strm->msg == NULL ? "compressed data error" : strm->msg);
186	0	return -1;
187	0	}
188	0	} while (strm->avail_out && ret != Z_STREAM_END);
189
190		/* update available output */
191	0	state->x.have = had - strm->avail_out;
192	0	state->x.next = strm->next_out - state->x.have;
193
194		/* if the gzip stream completed successfully, look for another */
195	0	if (ret == Z_STREAM_END)
196	0	state->how = LOOK;
197
198		/* good decompression */
199	0	return 0;
200	0	}
201
202		/* Fetch data and put it in the output buffer. Assumes state->x.have is 0.
203		Data is either copied from the input file or decompressed from the input
204		file depending on state->how. If state->how is LOOK, then a gzip header is
205		looked for to determine whether to copy or decompress. Returns -1 on error,
206		otherwise 0. gz_fetch() will leave state->how as COPY or GZIP unless the
207		end of the input file has been reached and all data has been processed. */
208	0	local int gz_fetch(gz_statep state) {
209	0	z_streamp strm = &(state->strm);
210
211	0	do {
212	0	switch(state->how) {
213	0	case LOOK: /* -> LOOK, COPY (only if never GZIP), or GZIP */
214	0	if (gz_look(state) == -1)
215	0	return -1;
216	0	if (state->how == LOOK)
217	0	return 0;
218	0	break;
219	0	case COPY: /* -> COPY */
220	0	if (gz_load(state, state->out, state->size << 1, &(state->x.have))
221	0	== -1)
222	0	return -1;
223	0	state->x.next = state->out;
224	0	return 0;
225	0	case GZIP: /* -> GZIP or LOOK (if end of gzip stream) */
226	0	strm->avail_out = state->size << 1;
227	0	strm->next_out = state->out;
228	0	if (gz_decomp(state) == -1)
229	0	return -1;
230	0	}
231	0	} while (state->x.have == 0 && (!state->eof \|\| strm->avail_in));
232	0	return 0;
233	0	}
234
235		/* Skip len uncompressed bytes of output. Return -1 on error, 0 on success. */
236	0	local int gz_skip(gz_statep state, z_off64_t len) {
237	0	unsigned n;
238
239		/* skip over len bytes or reach end-of-file, whichever comes first */
240	0	while (len)
241		/* skip over whatever is in output buffer */
242	0	if (state->x.have) {
243	0	n = GT_OFF(state->x.have) \|\| (z_off64_t)state->x.have > len ?
244	0	(unsigned)len : state->x.have;
245	0	state->x.have -= n;
246	0	state->x.next += n;
247	0	state->x.pos += n;
248	0	len -= n;
249	0	}
250
251		/* output buffer empty -- return if we're at the end of the input */
252	0	else if (state->eof && state->strm.avail_in == 0)
253	0	break;
254
255		/* need more data to skip -- load up output buffer */
256	0	else {
257		/* get more output, looking for header if required */
258	0	if (gz_fetch(state) == -1)
259	0	return -1;
260	0	}
261	0	return 0;
262	0	}
263
264		/* Read len bytes into buf from file, or less than len up to the end of the
265		input. Return the number of bytes read. If zero is returned, either the
266		end of file was reached, or there was an error. state->err must be
267		consulted in that case to determine which. */
268	0	local z_size_t gz_read(gz_statep state, voidp buf, z_size_t len) {
269	0	z_size_t got;
270	0	unsigned n;
271
272		/* if len is zero, avoid unnecessary operations */
273	0	if (len == 0)
274	0	return 0;
275
276		/* process a skip request */
277	0	if (state->seek) {
278	0	state->seek = 0;
279	0	if (gz_skip(state, state->skip) == -1)
280	0	return 0;
281	0	}
282
283		/* get len bytes to buf, or less than len if at the end */
284	0	got = 0;
285	0	do {
286		/* set n to the maximum amount of len that fits in an unsigned int */
287	0	n = (unsigned)-1;
288	0	if (n > len)
289	0	n = (unsigned)len;
290
291		/* first just try copying data from the output buffer */
292	0	if (state->x.have) {
293	0	if (state->x.have < n)
294	0	n = state->x.have;
295	0	memcpy(buf, state->x.next, n);
296	0	state->x.next += n;
297	0	state->x.have -= n;
298	0	}
299
300		/* output buffer empty -- return if we're at the end of the input */
301	0	else if (state->eof && state->strm.avail_in == 0) {
302	0	state->past = 1; /* tried to read past end */
303	0	break;
304	0	}
305
306		/* need output data -- for small len or new stream load up our output
307		buffer */
308	0	else if (state->how == LOOK \|\| n < (state->size << 1)) {
309		/* get more output, looking for header if required */
310	0	if (gz_fetch(state) == -1)
311	0	return 0;
312	0	continue; /* no progress yet -- go back to copy above */
313		/* the copy above assures that we will leave with space in the
314		output buffer, allowing at least one gzungetc() to succeed */
315	0	}
316
317		/* large len -- read directly into user buffer */
318	0	else if (state->how == COPY) { /* read directly */
319	0	if (gz_load(state, (unsigned char *)buf, n, &n) == -1)
320	0	return 0;
321	0	}
322
323		/* large len -- decompress directly into user buffer */
324	0	else { /* state->how == GZIP */
325	0	state->strm.avail_out = n;
326	0	state->strm.next_out = (unsigned char *)buf;
327	0	if (gz_decomp(state) == -1)
328	0	return 0;
329	0	n = state->x.have;
330	0	state->x.have = 0;
331	0	}
332
333		/* update progress */
334	0	len -= n;
335	0	buf = (char *)buf + n;
336	0	got += n;
337	0	state->x.pos += n;
338	0	} while (len);
339
340		/* return number of bytes read into user buffer */
341	0	return got;
342	0	}
343
344		/* -- see zlib.h -- */
345	0	int ZEXPORT gzread(gzFile file, voidp buf, unsigned len) {
346	0	gz_statep state;
347
348		/* get internal structure */
349	0	if (file == NULL)
350	0	return -1;
351	0	state = (gz_statep)file;
352
353		/* check that we're reading and that there's no (serious) error */
354	0	if (state->mode != GZ_READ \|\|
355	0	(state->err != Z_OK && state->err != Z_BUF_ERROR))
356	0	return -1;
357
358		/* since an int is returned, make sure len fits in one, otherwise return
359		with an error (this avoids a flaw in the interface) */
360	0	if ((int)len < 0) {
361	0	gz_error(state, Z_STREAM_ERROR, "request does not fit in an int");
362	0	return -1;
363	0	}
364
365		/* read len or fewer bytes to buf */
366	0	len = (unsigned)gz_read(state, buf, len);
367
368		/* check for an error */
369	0	if (len == 0 && state->err != Z_OK && state->err != Z_BUF_ERROR)
370	0	return -1;
371
372		/* return the number of bytes read (this is assured to fit in an int) */
373	0	return (int)len;
374	0	}
375
376		/* -- see zlib.h -- */
377		z_size_t ZEXPORT gzfread(voidp buf, z_size_t size, z_size_t nitems,
378	0	gzFile file) {
379	0	z_size_t len;
380	0	gz_statep state;
381
382		/* get internal structure */
383	0	if (file == NULL)
384	0	return 0;
385	0	state = (gz_statep)file;
386
387		/* check that we're reading and that there's no (serious) error */
388	0	if (state->mode != GZ_READ \|\|
389	0	(state->err != Z_OK && state->err != Z_BUF_ERROR))
390	0	return 0;
391
392		/* compute bytes to read -- error on overflow */
393	0	len = nitems * size;
394	0	if (size && len / size != nitems) {
395	0	gz_error(state, Z_STREAM_ERROR, "request does not fit in a size_t");
396	0	return 0;
397	0	}
398
399		/* read len or fewer bytes to buf, return the number of full items read */
400	0	return len ? gz_read(state, buf, len) / size : 0;
401	0	}
402
403		/* -- see zlib.h -- */
404		#ifdef Z_PREFIX_SET
405		# undef z_gzgetc
406		#else
407		# undef gzgetc
408		#endif
409	0	int ZEXPORT gzgetc(gzFile file) {
410	0	unsigned char buf[1];
411	0	gz_statep state;
412
413		/* get internal structure */
414	0	if (file == NULL)
415	0	return -1;
416	0	state = (gz_statep)file;
417
418		/* check that we're reading and that there's no (serious) error */
419	0	if (state->mode != GZ_READ \|\|
420	0	(state->err != Z_OK && state->err != Z_BUF_ERROR))
421	0	return -1;
422
423		/* try output buffer (no need to check for skip request) */
424	0	if (state->x.have) {
425	0	state->x.have--;
426	0	state->x.pos++;
427	0	return *(state->x.next)++;
428	0	}
429
430		/* nothing there -- try gz_read() */
431	0	return gz_read(state, buf, 1) < 1 ? -1 : buf[0];
432	0	}
433
434	0	int ZEXPORT gzgetc_(gzFile file) {
435	0	return gzgetc(file);
436	0	}
437
438		/* -- see zlib.h -- */
439	0	int ZEXPORT gzungetc(int c, gzFile file) {
440	0	gz_statep state;
441
442		/* get internal structure */
443	0	if (file == NULL)
444	0	return -1;
445	0	state = (gz_statep)file;
446
447		/* in case this was just opened, set up the input buffer */
448	0	if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
449	0	(void)gz_look(state);
450
451		/* check that we're reading and that there's no (serious) error */
452	0	if (state->mode != GZ_READ \|\|
453	0	(state->err != Z_OK && state->err != Z_BUF_ERROR))
454	0	return -1;
455
456		/* process a skip request */
457	0	if (state->seek) {
458	0	state->seek = 0;
459	0	if (gz_skip(state, state->skip) == -1)
460	0	return -1;
461	0	}
462
463		/* can't push EOF */
464	0	if (c < 0)
465	0	return -1;
466
467		/* if output buffer empty, put byte at end (allows more pushing) */
468	0	if (state->x.have == 0) {
469	0	state->x.have = 1;
470	0	state->x.next = state->out + (state->size << 1) - 1;
471	0	state->x.next[0] = (unsigned char)c;
472	0	state->x.pos--;
473	0	state->past = 0;
474	0	return c;
475	0	}
476
477		/* if no room, give up (must have already done a gzungetc()) */
478	0	if (state->x.have == (state->size << 1)) {
479	0	gz_error(state, Z_DATA_ERROR, "out of room to push characters");
480	0	return -1;
481	0	}
482
483		/* slide output data if needed and insert byte before existing data */
484	0	if (state->x.next == state->out) {
485	0	unsigned char *src = state->out + state->x.have;
486	0	unsigned char *dest = state->out + (state->size << 1);
487	0	while (src > state->out)
488	0	--dest = --src;
489	0	state->x.next = dest;
490	0	}
491	0	state->x.have++;
492	0	state->x.next--;
493	0	state->x.next[0] = (unsigned char)c;
494	0	state->x.pos--;
495	0	state->past = 0;
496	0	return c;
497	0	}
498
499		/* -- see zlib.h -- */
500	0	char * ZEXPORT gzgets(gzFile file, char *buf, int len) {
501	0	unsigned left, n;
502	0	char *str;
503	0	unsigned char *eol;
504	0	gz_statep state;
505
506		/* check parameters and get internal structure */
507	0	if (file == NULL \|\| buf == NULL \|\| len < 1)
508	0	return NULL;
509	0	state = (gz_statep)file;
510
511		/* check that we're reading and that there's no (serious) error */
512	0	if (state->mode != GZ_READ \|\|
513	0	(state->err != Z_OK && state->err != Z_BUF_ERROR))
514	0	return NULL;
515
516		/* process a skip request */
517	0	if (state->seek) {
518	0	state->seek = 0;
519	0	if (gz_skip(state, state->skip) == -1)
520	0	return NULL;
521	0	}
522
523		/* copy output bytes up to new line or len - 1, whichever comes first --
524		append a terminating zero to the string (we don't check for a zero in
525		the contents, let the user worry about that) */
526	0	str = buf;
527	0	left = (unsigned)len - 1;
528	0	if (left) do {
529		/* assure that something is in the output buffer */
530	0	if (state->x.have == 0 && gz_fetch(state) == -1)
531	0	return NULL; /* error */
532	0	if (state->x.have == 0) { /* end of file */
533	0	state->past = 1; /* read past end */
534	0	break; /* return what we have */
535	0	}
536
537		/* look for end-of-line in current output buffer */
538	0	n = state->x.have > left ? left : state->x.have;
539	0	eol = (unsigned char *)memchr(state->x.next, '\n', n);
540	0	if (eol != NULL)
541	0	n = (unsigned)(eol - state->x.next) + 1;
542
543		/* copy through end-of-line, or remainder if not found */
544	0	memcpy(buf, state->x.next, n);
545	0	state->x.have -= n;
546	0	state->x.next += n;
547	0	state->x.pos += n;
548	0	left -= n;
549	0	buf += n;
550	0	} while (left && eol == NULL);
551
552		/* return terminated string, or if nothing, end of file */
553	0	if (buf == str)
554	0	return NULL;
555	0	buf[0] = 0;
556	0	return str;
557	0	}
558
559		/* -- see zlib.h -- */
560	0	int ZEXPORT gzdirect(gzFile file) {
561	0	gz_statep state;
562
563		/* get internal structure */
564	0	if (file == NULL)
565	0	return 0;
566	0	state = (gz_statep)file;
567
568		/* if the state is not known, but we can find out, then do so (this is
569		mainly for right after a gzopen() or gzdopen()) */
570	0	if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
571	0	(void)gz_look(state);
572
573		/* return 1 if transparent, 0 if processing a gzip stream */
574	0	return state->direct;
575	0	}
576
577		/* -- see zlib.h -- */
578	0	int ZEXPORT gzclose_r(gzFile file) {
579	0	int ret, err;
580	0	gz_statep state;
581
582		/* get internal structure */
583	0	if (file == NULL)
584	0	return Z_STREAM_ERROR;
585	0	state = (gz_statep)file;
586
587		/* check that we're reading */
588	0	if (state->mode != GZ_READ)
589	0	return Z_STREAM_ERROR;
590
591		/* free memory and close file */
592	0	if (state->size) {
593	0	inflateEnd(&(state->strm));
594	0	free(state->out);
595	0	free(state->in);
596	0	}
597	0	err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
598	0	gz_error(state, Z_OK, NULL);
599	0	free(state->path);
600	0	ret = close(state->fd);
601	0	free(state);
602	0	return ret ? Z_ERRNO : err;
603	0	}