3rdparty/zlib/gzread.c

/* gzread.c -- zlib functions for reading gzip files
 * Copyright (C) 2004, 2005, 2010 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "gzguts.h"

/* Local functions */
local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
local int gz_avail OF((gz_statep));
local int gz_next4 OF((gz_statep, unsigned long *));
local int gz_head OF((gz_statep));
local int gz_decomp OF((gz_statep));
local int gz_make OF((gz_statep));
local int gz_skip OF((gz_statep, z_off64_t));

/* 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(state, buf, len, have)
    gz_statep state;
    unsigned char *buf;
    unsigned len;
    unsigned *have;
{
    int ret;

    *have = 0;
    do {
        ret = read(state->fd, buf + *have, len - *have);
        if (ret <= 0)
            break;
        *have += 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.
   gz_avail() assumes that strm->avail_in == 0. */
local int gz_avail(state)
    gz_statep state;
{
    z_streamp strm = &(state->strm);

    if (state->err != Z_OK)
        return -1;
    if (state->eof == 0) {
        if (gz_load(state, state->in, state->size, &(strm->avail_in)) == -1)
            return -1;
        strm->next_in = state->in;
    }
    return 0;
}

/* Get next byte from input, or -1 if end or error. */
#define NEXT() ((strm->avail_in == 0 && gz_avail(state) == -1) ? -1 : \
                (strm->avail_in == 0 ? -1 : \
                 (strm->avail_in--, *(strm->next_in)++)))

/* Get a four-byte little-endian integer and return 0 on success and the value
   in *ret.  Otherwise -1 is returned and *ret is not modified. */
local int gz_next4(state, ret)
    gz_statep state;
    unsigned long *ret;
{
    int ch;
    unsigned long val;
    z_streamp strm = &(state->strm);

    val = NEXT();
    val += (unsigned)NEXT() << 8;
    val += (unsigned long)NEXT() << 16;
    ch = NEXT();
    if (ch == -1)
        return -1;
    val += (unsigned long)ch << 24;
    *ret = val;
    return 0;
}

/* Look for gzip header, set up for inflate or copy.  state->have must be zero.
   If this is the first time in, allocate required memory.  state->how will be
   left unchanged if there is no more input data available, will be set to COPY
   if there is no gzip header and direct copying will be performed, or it will
   be set to GZIP for decompression, and the gzip header will be skipped so
   that the next available input data is the raw deflate stream.  If direct
   copying, then leftover input data from the input buffer will be copied to
   the output buffer.  In that case, all further file reads will be directly to
   either the output buffer or a user buffer.  If decompressing, the inflate
   state and the check value will be initialized.  gz_head() will return 0 on
   success or -1 on failure.  Failures may include read errors or gzip header
   errors.  */
local int gz_head(state)
    gz_statep state;
{
    z_streamp strm = &(state->strm);
    int flags;
    unsigned len;

    /* allocate read buffers and inflate memory */
    if (state->size == 0) {
        /* allocate buffers */
        state->in = malloc(state->want);
        state->out = malloc(state->want << 1);
        if (state->in == NULL || state->out == NULL) {
            if (state->out != NULL)
                free(state->out);
            if (state->in != NULL)
                free(state->in);
            gz_error(state, Z_MEM_ERROR, "out of memory");
            return -1;
        }
        state->size = state->want;

        /* allocate inflate memory */
        state->strm.zalloc = Z_NULL;
        state->strm.zfree = Z_NULL;
        state->strm.opaque = Z_NULL;
        state->strm.avail_in = 0;
        state->strm.next_in = Z_NULL;
        if (inflateInit2(&(state->strm), -15) != Z_OK) {    /* raw inflate */
            free(state->out);
            free(state->in);
            state->size = 0;
            gz_error(state, Z_MEM_ERROR, "out of memory");
            return -1;
        }
    }

    /* get some data in the input buffer */
    if (strm->avail_in == 0) {
        if (gz_avail(state) == -1)
            return -1;
        if (strm->avail_in == 0)
            return 0;
    }

    /* look for the gzip magic header bytes 31 and 139 */
    if (strm->next_in[0] == 31) {
        strm->avail_in--;
        strm->next_in++;
        if (strm->avail_in == 0 && gz_avail(state) == -1)
            return -1;
        if (strm->avail_in && strm->next_in[0] == 139) {
            /* we have a gzip header, woo hoo! */
            strm->avail_in--;
            strm->next_in++;

            /* skip rest of header */
            if (NEXT() != 8) {      /* compression method */
                gz_error(state, Z_DATA_ERROR, "unknown compression method");
                return -1;
            }
            flags = NEXT();
            if (flags & 0xe0) {     /* reserved flag bits */
                gz_error(state, Z_DATA_ERROR, "unknown header flags set");
                return -1;
            }
            NEXT();                 /* modification time */
            NEXT();
            NEXT();
            NEXT();
            NEXT();                 /* extra flags */
            NEXT();                 /* operating system */
            if (flags & 4) {        /* extra field */
                len = (unsigned)NEXT();
                len += (unsigned)NEXT() << 8;
                while (len--)
                    if (NEXT() < 0)
                        break;
            }
            if (flags & 8)          /* file name */
                while (NEXT() > 0)
                    ;
            if (flags & 16)         /* comment */
                while (NEXT() > 0)
                    ;
            if (flags & 2) {        /* header crc */
                NEXT();
                NEXT();
            }
            /* an unexpected end of file is not checked for here -- it will be
               noticed on the first request for uncompressed data */

            /* set up for decompression */
            inflateReset(strm);
            strm->adler = crc32(0L, Z_NULL, 0);
            state->how = GZIP;
            state->direct = 0;
            return 0;
        }
        else {
            /* not a gzip file -- save first byte (31) and fall to raw i/o */
            state->out[0] = 31;
            state->have = 1;
        }
    }

    /* doing raw i/o, save start of raw data for seeking, copy any leftover
       input to output -- this assumes that the output buffer is larger than
       the input buffer, which also assures space for gzungetc() */
    state->raw = state->pos;
    state->next = state->out;
    if (strm->avail_in) {
        memcpy(state->next + state->have, strm->next_in, strm->avail_in);
        state->have += strm->avail_in;
        strm->avail_in = 0;
    }
    state->how = COPY;
    state->direct = 1;
    return 0;
}

/* Decompress from input to the provided next_out and avail_out in the state.
   If the end of the compressed data is reached, then verify the gzip trailer
   check value and length (modulo 2^32).  state->have and state->next are set
   to point to the just decompressed data, and the crc is updated.  If the
   trailer is verified, state->how is reset to LOOK to look for the next gzip
   stream or raw data, once state->have is depleted.  Returns 0 on success, -1
   on failure.  Failures may include invalid compressed data or a failed gzip
   trailer verification. */
local int gz_decomp(state)
    gz_statep state;
{
    int ret;
    unsigned had;
    unsigned long crc, len;
    z_streamp strm = &(state->strm);

    /* fill output buffer up to end of deflate stream */
    had = strm->avail_out;
    do {
        /* get more input for inflate() */
        if (strm->avail_in == 0 && gz_avail(state) == -1)
            return -1;
        if (strm->avail_in == 0) {
            gz_error(state, Z_DATA_ERROR, "unexpected end of file");
            return -1;
        }

        /* decompress and handle errors */
        ret = inflate(strm, Z_NO_FLUSH);
        if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
            gz_error(state, Z_STREAM_ERROR,
                      "internal error: inflate stream corrupt");
            return -1;
        }
        if (ret == Z_MEM_ERROR) {
            gz_error(state, Z_MEM_ERROR, "out of memory");
            return -1;
        }
        if (ret == Z_DATA_ERROR) {              /* deflate stream invalid */
            gz_error(state, Z_DATA_ERROR,
                      strm->msg == NULL ? "compressed data error" : strm->msg);
            return -1;
        }
    } while (strm->avail_out && ret != Z_STREAM_END);

    /* update available output and crc check value */
    state->have = had - strm->avail_out;
    state->next = strm->next_out - state->have;
    strm->adler = crc32(strm->adler, state->next, state->have);

    /* check gzip trailer if at end of deflate stream */
    if (ret == Z_STREAM_END) {
        if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) {
            gz_error(state, Z_DATA_ERROR, "unexpected end of file");
            return -1;
        }
        if (crc != strm->adler) {
            gz_error(state, Z_DATA_ERROR, "incorrect data check");
            return -1;
        }
        if (len != (strm->total_out & 0xffffffffL)) {
            gz_error(state, Z_DATA_ERROR, "incorrect length check");
            return -1;
        }
        state->how = LOOK;      /* ready for next stream, once have is 0 (leave
                                   state->direct unchanged to remember how) */
    }

    /* good decompression */
    return 0;
}

/* Make data and put in the output buffer.  Assumes that state->have == 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 (and skipped if found) to determine wither to copy or decompress.
   Returns -1 on error, otherwise 0.  gz_make() will leave state->have as COPY
   or GZIP unless the end of the input file has been reached and all data has
   been processed.  */
local int gz_make(state)
    gz_statep state;
{
    z_streamp strm = &(state->strm);

    if (state->how == LOOK) {           /* look for gzip header */
        if (gz_head(state) == -1)
            return -1;
        if (state->have)                /* got some data from gz_head() */
            return 0;
    }
    if (state->how == COPY) {           /* straight copy */
        if (gz_load(state, state->out, state->size << 1, &(state->have)) == -1)
            return -1;
        state->next = state->out;
    }
    else if (state->how == GZIP) {      /* decompress */
        strm->avail_out = state->size << 1;
        strm->next_out = state->out;
        if (gz_decomp(state) == -1)
            return -1;
    }
    return 0;
}

/* Skip len uncompressed bytes of output.  Return -1 on error, 0 on success. */
local int gz_skip(state, len)
    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->have) {
            n = GT_OFF(state->have) || (z_off64_t)state->have > len ?
                (unsigned)len : state->have;
            state->have -= n;
            state->next += n;
            state->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_make(state) == -1)
                return -1;
        }
    return 0;
}

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

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

    /* check that we're reading and that there's no error */
    if (state->mode != GZ_READ || state->err != Z_OK)
        return -1;

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

    /* 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 -1;
    }

    /* get len bytes to buf, or less than len if at the end */
    got = 0;
    do {
        /* first just try copying data from the output buffer */
        if (state->have) {
            n = state->have > len ? len : state->have;
            memcpy(buf, state->next, n);
            state->next += n;
            state->have -= n;
        }

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

        /* need output data -- for small len or new stream load up our output
           buffer */
        else if (state->how == LOOK || len < (state->size << 1)) {
            /* get more output, looking for header if required */
            if (gz_make(state) == -1)
                return -1;
            continue;       /* no progress yet -- go back to memcpy() 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, buf, len, &n) == -1)
                return -1;
        }

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

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

    /* return number of bytes read into user buffer (will fit in int) */
    return (int)got;
}

/* -- see zlib.h -- */
int ZEXPORT gzgetc(file)
    gzFile file;
{
    int ret;
    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 error */
    if (state->mode != GZ_READ || state->err != Z_OK)
        return -1;

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

    /* nothing there -- try gzread() */
    ret = gzread(file, buf, 1);
    return ret < 1 ? -1 : buf[0];
}

/* -- see zlib.h -- */
int ZEXPORT gzungetc(c, file)
    int c;
    gzFile file;
{
    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 error */
    if (state->mode != GZ_READ || state->err != Z_OK)
        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->have == 0) {
        state->have = 1;
        state->next = state->out + (state->size << 1) - 1;
        state->next[0] = c;
        state->pos--;
        return c;
    }

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

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

/* -- see zlib.h -- */
char * ZEXPORT gzgets(file, buf, len)
    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 error */
    if (state->mode != GZ_READ || state->err != Z_OK)
        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->have == 0) {
            if (gz_make(state) == -1)
                return NULL;            /* error */
            if (state->have == 0) {     /* end of file */
                if (buf == str)         /* got bupkus */
                    return NULL;
                break;                  /* got something -- return it */
            }
        }

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

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

    /* found end-of-line or out of space -- terminate string and return it */
    buf[0] = 0;
    return str;
}

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

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

    /* check that we're reading */
    if (state->mode != GZ_READ)
        return 0;

    /* 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);

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

/* -- see zlib.h -- */
int ZEXPORT gzclose_r(file)
    gzFile file;
{
    int ret;
    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);
    }
    gz_error(state, Z_OK, NULL);
    free(state->path);
    ret = close(state->fd);
    free(state);
    return ret ? Z_ERRNO : Z_OK;
}
1	/* gzread.c -- zlib functions for reading gzip files
2	* Copyright (C) 2004, 2005, 2010 Mark Adler
3	* For conditions of distribution and use, see copyright notice in zlib.h
4	*/
5
6	#include "gzguts.h"
7
8	/* Local functions */
9	local int gz_load OF((gz_statep, unsigned char , unsigned, unsigned ));
10	local int gz_avail OF((gz_statep));
11	local int gz_next4 OF((gz_statep, unsigned long *));
12	local int gz_head OF((gz_statep));
13	local int gz_decomp OF((gz_statep));
14	local int gz_make OF((gz_statep));
15	local int gz_skip OF((gz_statep, z_off64_t));
16
17	/* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from
18	state->fd, and update state->eof, state->err, and state->msg as appropriate.
19	This function needs to loop on read(), since read() is not guaranteed to
20	read the number of bytes requested, depending on the type of descriptor. */
21	local int gz_load(state, buf, len, have)
22	gz_statep state;
23	unsigned char *buf;
24	unsigned len;
25	unsigned *have;
26	{
27	int ret;
28
29	*have = 0;
30	do {
31	ret = read(state->fd, buf + have, len - have);
32	if (ret <= 0)
33	break;
34	*have += ret;
35	} while (*have < len);
36	if (ret < 0) {
37	gz_error(state, Z_ERRNO, zstrerror());
38	return -1;
39	}
40	if (ret == 0)
41	state->eof = 1;
42	return 0;
43	}
44
45	/* Load up input buffer and set eof flag if last data loaded -- return -1 on
46	error, 0 otherwise. Note that the eof flag is set when the end of the input
47	file is reached, even though there may be unused data in the buffer. Once
48	that data has been used, no more attempts will be made to read the file.
49	gz_avail() assumes that strm->avail_in == 0. */
50	local int gz_avail(state)
51	gz_statep state;
52	{
53	z_streamp strm = &(state->strm);
54
55	if (state->err != Z_OK)
56	return -1;
57	if (state->eof == 0) {
58	if (gz_load(state, state->in, state->size, &(strm->avail_in)) == -1)
59	return -1;
60	strm->next_in = state->in;
61	}
62	return 0;
63	}
64
65	/* Get next byte from input, or -1 if end or error. */
66	#define NEXT() ((strm->avail_in == 0 && gz_avail(state) == -1) ? -1 : \
67	(strm->avail_in == 0 ? -1 : \
68	(strm->avail_in--, *(strm->next_in)++)))
69
70	/* Get a four-byte little-endian integer and return 0 on success and the value
71	in ret. Otherwise -1 is returned and ret is not modified. */
72	local int gz_next4(state, ret)
73	gz_statep state;
74	unsigned long *ret;
75	{
76	int ch;
77	unsigned long val;
78	z_streamp strm = &(state->strm);
79
80	val = NEXT();
81	val += (unsigned)NEXT() << 8;
82	val += (unsigned long)NEXT() << 16;
83	ch = NEXT();
84	if (ch == -1)
85	return -1;
86	val += (unsigned long)ch << 24;
87	*ret = val;
88	return 0;
89	}
90
91	/* Look for gzip header, set up for inflate or copy. state->have must be zero.
92	If this is the first time in, allocate required memory. state->how will be
93	left unchanged if there is no more input data available, will be set to COPY
94	if there is no gzip header and direct copying will be performed, or it will
95	be set to GZIP for decompression, and the gzip header will be skipped so
96	that the next available input data is the raw deflate stream. If direct
97	copying, then leftover input data from the input buffer will be copied to
98	the output buffer. In that case, all further file reads will be directly to
99	either the output buffer or a user buffer. If decompressing, the inflate
100	state and the check value will be initialized. gz_head() will return 0 on
101	success or -1 on failure. Failures may include read errors or gzip header
102	errors. */
103	local int gz_head(state)
104	gz_statep state;
105	{
106	z_streamp strm = &(state->strm);
107	int flags;
108	unsigned len;
109
110	/* allocate read buffers and inflate memory */
111	if (state->size == 0) {
112	/* allocate buffers */
113	state->in = malloc(state->want);
114	state->out = malloc(state->want << 1);
115	if (state->in == NULL \|\| state->out == NULL) {
116	if (state->out != NULL)
117	free(state->out);
118	if (state->in != NULL)
119	free(state->in);
120	gz_error(state, Z_MEM_ERROR, "out of memory");
121	return -1;
122	}
123	state->size = state->want;
124
125	/* allocate inflate memory */
126	state->strm.zalloc = Z_NULL;
127	state->strm.zfree = Z_NULL;
128	state->strm.opaque = Z_NULL;
129	state->strm.avail_in = 0;
130	state->strm.next_in = Z_NULL;
131	if (inflateInit2(&(state->strm), -15) != Z_OK) { /* raw inflate */
132	free(state->out);
133	free(state->in);
134	state->size = 0;
135	gz_error(state, Z_MEM_ERROR, "out of memory");
136	return -1;
137	}
138	}
139
140	/* get some data in the input buffer */
141	if (strm->avail_in == 0) {
142	if (gz_avail(state) == -1)
143	return -1;
144	if (strm->avail_in == 0)
145	return 0;
146	}
147
148	/* look for the gzip magic header bytes 31 and 139 */
149	if (strm->next_in[0] == 31) {
150	strm->avail_in--;
151	strm->next_in++;
152	if (strm->avail_in == 0 && gz_avail(state) == -1)
153	return -1;
154	if (strm->avail_in && strm->next_in[0] == 139) {
155	/* we have a gzip header, woo hoo! */
156	strm->avail_in--;
157	strm->next_in++;
158
159	/* skip rest of header */
160	if (NEXT() != 8) { /* compression method */
161	gz_error(state, Z_DATA_ERROR, "unknown compression method");
162	return -1;
163	}
164	flags = NEXT();
165	if (flags & 0xe0) { /* reserved flag bits */
166	gz_error(state, Z_DATA_ERROR, "unknown header flags set");
167	return -1;
168	}
169	NEXT(); /* modification time */
170	NEXT();
171	NEXT();
172	NEXT();
173	NEXT(); /* extra flags */
174	NEXT(); /* operating system */
175	if (flags & 4) { /* extra field */
176	len = (unsigned)NEXT();
177	len += (unsigned)NEXT() << 8;
178	while (len--)
179	if (NEXT() < 0)
180	break;
181	}
182	if (flags & 8) /* file name */
183	while (NEXT() > 0)
184	;
185	if (flags & 16) /* comment */
186	while (NEXT() > 0)
187	;
188	if (flags & 2) { /* header crc */
189	NEXT();
190	NEXT();
191	}
192	/* an unexpected end of file is not checked for here -- it will be
193	noticed on the first request for uncompressed data */
194
195	/* set up for decompression */
196	inflateReset(strm);
197	strm->adler = crc32(0L, Z_NULL, 0);
198	state->how = GZIP;
199	state->direct = 0;
200	return 0;
201	}
202	else {
203	/* not a gzip file -- save first byte (31) and fall to raw i/o */
204	state->out[0] = 31;
205	state->have = 1;
206	}
207	}
208
209	/* doing raw i/o, save start of raw data for seeking, copy any leftover
210	input to output -- this assumes that the output buffer is larger than
211	the input buffer, which also assures space for gzungetc() */
212	state->raw = state->pos;
213	state->next = state->out;
214	if (strm->avail_in) {
215	memcpy(state->next + state->have, strm->next_in, strm->avail_in);
216	state->have += strm->avail_in;
217	strm->avail_in = 0;
218	}
219	state->how = COPY;
220	state->direct = 1;
221	return 0;
222	}
223
224	/* Decompress from input to the provided next_out and avail_out in the state.
225	If the end of the compressed data is reached, then verify the gzip trailer
226	check value and length (modulo 2^32). state->have and state->next are set
227	to point to the just decompressed data, and the crc is updated. If the
228	trailer is verified, state->how is reset to LOOK to look for the next gzip
229	stream or raw data, once state->have is depleted. Returns 0 on success, -1
230	on failure. Failures may include invalid compressed data or a failed gzip
231	trailer verification. */
232	local int gz_decomp(state)
233	gz_statep state;
234	{
235	int ret;
236	unsigned had;
237	unsigned long crc, len;
238	z_streamp strm = &(state->strm);
239
240	/* fill output buffer up to end of deflate stream */
241	had = strm->avail_out;
242	do {
243	/* get more input for inflate() */
244	if (strm->avail_in == 0 && gz_avail(state) == -1)
245	return -1;
246	if (strm->avail_in == 0) {
247	gz_error(state, Z_DATA_ERROR, "unexpected end of file");
248	return -1;
249	}
250
251	/* decompress and handle errors */
252	ret = inflate(strm, Z_NO_FLUSH);
253	if (ret == Z_STREAM_ERROR \|\| ret == Z_NEED_DICT) {
254	gz_error(state, Z_STREAM_ERROR,
255	"internal error: inflate stream corrupt");
256	return -1;
257	}
258	if (ret == Z_MEM_ERROR) {
259	gz_error(state, Z_MEM_ERROR, "out of memory");
260	return -1;
261	}
262	if (ret == Z_DATA_ERROR) { /* deflate stream invalid */
263	gz_error(state, Z_DATA_ERROR,
264	strm->msg == NULL ? "compressed data error" : strm->msg);
265	return -1;
266	}
267	} while (strm->avail_out && ret != Z_STREAM_END);
268
269	/* update available output and crc check value */
270	state->have = had - strm->avail_out;
271	state->next = strm->next_out - state->have;
272	strm->adler = crc32(strm->adler, state->next, state->have);
273
274	/* check gzip trailer if at end of deflate stream */
275	if (ret == Z_STREAM_END) {
276	if (gz_next4(state, &crc) == -1 \|\| gz_next4(state, &len) == -1) {
277	gz_error(state, Z_DATA_ERROR, "unexpected end of file");
278	return -1;
279	}
280	if (crc != strm->adler) {
281	gz_error(state, Z_DATA_ERROR, "incorrect data check");
282	return -1;
283	}
284	if (len != (strm->total_out & 0xffffffffL)) {
285	gz_error(state, Z_DATA_ERROR, "incorrect length check");
286	return -1;
287	}
288	state->how = LOOK; /* ready for next stream, once have is 0 (leave
289	state->direct unchanged to remember how) */
290	}
291
292	/* good decompression */
293	return 0;
294	}
295
296	/* Make data and put in the output buffer. Assumes that state->have == 0.
297	Data is either copied from the input file or decompressed from the input
298	file depending on state->how. If state->how is LOOK, then a gzip header is
299	looked for (and skipped if found) to determine wither to copy or decompress.
300	Returns -1 on error, otherwise 0. gz_make() will leave state->have as COPY
301	or GZIP unless the end of the input file has been reached and all data has
302	been processed. */
303	local int gz_make(state)
304	gz_statep state;
305	{
306	z_streamp strm = &(state->strm);
307
308	if (state->how == LOOK) { /* look for gzip header */
309	if (gz_head(state) == -1)
310	return -1;
311	if (state->have) /* got some data from gz_head() */
312	return 0;
313	}
314	if (state->how == COPY) { /* straight copy */
315	if (gz_load(state, state->out, state->size << 1, &(state->have)) == -1)
316	return -1;
317	state->next = state->out;
318	}
319	else if (state->how == GZIP) { /* decompress */
320	strm->avail_out = state->size << 1;
321	strm->next_out = state->out;
322	if (gz_decomp(state) == -1)
323	return -1;
324	}
325	return 0;
326	}
327
328	/* Skip len uncompressed bytes of output. Return -1 on error, 0 on success. */
329	local int gz_skip(state, len)
330	gz_statep state;
331	z_off64_t len;
332	{
333	unsigned n;
334
335	/* skip over len bytes or reach end-of-file, whichever comes first */
336	while (len)
337	/* skip over whatever is in output buffer */
338	if (state->have) {
339	n = GT_OFF(state->have) \|\| (z_off64_t)state->have > len ?
340	(unsigned)len : state->have;
341	state->have -= n;
342	state->next += n;
343	state->pos += n;
344	len -= n;
345	}
346
347	/* output buffer empty -- return if we're at the end of the input */
348	else if (state->eof && state->strm.avail_in == 0)
349	break;
350
351	/* need more data to skip -- load up output buffer */
352	else {
353	/* get more output, looking for header if required */
354	if (gz_make(state) == -1)
355	return -1;
356	}
357	return 0;
358	}
359
360	/* -- see zlib.h -- */
361	int ZEXPORT gzread(file, buf, len)
362	gzFile file;
363	voidp buf;
364	unsigned len;
365	{
366	unsigned got, n;
367	gz_statep state;
368	z_streamp strm;
369
370	/* get internal structure */
371	if (file == NULL)
372	return -1;
373	state = (gz_statep)file;
374	strm = &(state->strm);
375
376	/* check that we're reading and that there's no error */
377	if (state->mode != GZ_READ \|\| state->err != Z_OK)
378	return -1;
379
380	/* since an int is returned, make sure len fits in one, otherwise return
381	with an error (this avoids the flaw in the interface) */
382	if ((int)len < 0) {
383	gz_error(state, Z_BUF_ERROR, "requested length does not fit in int");
384	return -1;
385	}
386
387	/* if len is zero, avoid unnecessary operations */
388	if (len == 0)
389	return 0;
390
391	/* process a skip request */
392	if (state->seek) {
393	state->seek = 0;
394	if (gz_skip(state, state->skip) == -1)
395	return -1;
396	}
397
398	/* get len bytes to buf, or less than len if at the end */
399	got = 0;
400	do {
401	/* first just try copying data from the output buffer */
402	if (state->have) {
403	n = state->have > len ? len : state->have;
404	memcpy(buf, state->next, n);
405	state->next += n;
406	state->have -= n;
407	}
408
409	/* output buffer empty -- return if we're at the end of the input */
410	else if (state->eof && strm->avail_in == 0)
411	break;
412
413	/* need output data -- for small len or new stream load up our output
414	buffer */
415	else if (state->how == LOOK \|\| len < (state->size << 1)) {
416	/* get more output, looking for header if required */
417	if (gz_make(state) == -1)
418	return -1;
419	continue; /* no progress yet -- go back to memcpy() above */
420	/* the copy above assures that we will leave with space in the
421	output buffer, allowing at least one gzungetc() to succeed */
422	}
423
424	/* large len -- read directly into user buffer */
425	else if (state->how == COPY) { /* read directly */
426	if (gz_load(state, buf, len, &n) == -1)
427	return -1;
428	}
429
430	/* large len -- decompress directly into user buffer */
431	else { /* state->how == GZIP */
432	strm->avail_out = len;
433	strm->next_out = buf;
434	if (gz_decomp(state) == -1)
435	return -1;
436	n = state->have;
437	state->have = 0;
438	}
439
440	/* update progress */
441	len -= n;
442	buf = (char *)buf + n;
443	got += n;
444	state->pos += n;
445	} while (len);
446
447	/* return number of bytes read into user buffer (will fit in int) */
448	return (int)got;
449	}
450
451	/* -- see zlib.h -- */
452	int ZEXPORT gzgetc(file)
453	gzFile file;
454	{
455	int ret;
456	unsigned char buf[1];
457	gz_statep state;
458
459	/* get internal structure */
460	if (file == NULL)
461	return -1;
462	state = (gz_statep)file;
463
464	/* check that we're reading and that there's no error */
465	if (state->mode != GZ_READ \|\| state->err != Z_OK)
466	return -1;
467
468	/* try output buffer (no need to check for skip request) */
469	if (state->have) {
470	state->have--;
471	state->pos++;
472	return *(state->next)++;
473	}
474
475	/* nothing there -- try gzread() */
476	ret = gzread(file, buf, 1);
477	return ret < 1 ? -1 : buf[0];
478	}
479
480	/* -- see zlib.h -- */
481	int ZEXPORT gzungetc(c, file)
482	int c;
483	gzFile file;
484	{
485	gz_statep state;
486
487	/* get internal structure */
488	if (file == NULL)
489	return -1;
490	state = (gz_statep)file;
491
492	/* check that we're reading and that there's no error */
493	if (state->mode != GZ_READ \|\| state->err != Z_OK)
494	return -1;
495
496	/* process a skip request */
497	if (state->seek) {
498	state->seek = 0;
499	if (gz_skip(state, state->skip) == -1)
500	return -1;
501	}
502
503	/* can't push EOF */
504	if (c < 0)
505	return -1;
506
507	/* if output buffer empty, put byte at end (allows more pushing) */
508	if (state->have == 0) {
509	state->have = 1;
510	state->next = state->out + (state->size << 1) - 1;
511	state->next[0] = c;
512	state->pos--;
513	return c;
514	}
515
516	/* if no room, give up (must have already done a gzungetc()) */
517	if (state->have == (state->size << 1)) {
518	gz_error(state, Z_BUF_ERROR, "out of room to push characters");
519	return -1;
520	}
521
522	/* slide output data if needed and insert byte before existing data */
523	if (state->next == state->out) {
524	unsigned char *src = state->out + state->have;
525	unsigned char *dest = state->out + (state->size << 1);
526	while (src > state->out)
527	--dest = --src;
528	state->next = dest;
529	}
530	state->have++;
531	state->next--;
532	state->next[0] = c;
533	state->pos--;
534	return c;
535	}
536
537	/* -- see zlib.h -- */
538	char * ZEXPORT gzgets(file, buf, len)
539	gzFile file;
540	char *buf;
541	int len;
542	{
543	unsigned left, n;
544	char *str;
545	unsigned char *eol;
546	gz_statep state;
547
548	/* check parameters and get internal structure */
549	if (file == NULL \|\| buf == NULL \|\| len < 1)
550	return NULL;
551	state = (gz_statep)file;
552
553	/* check that we're reading and that there's no error */
554	if (state->mode != GZ_READ \|\| state->err != Z_OK)
555	return NULL;
556
557	/* process a skip request */
558	if (state->seek) {
559	state->seek = 0;
560	if (gz_skip(state, state->skip) == -1)
561	return NULL;
562	}
563
564	/* copy output bytes up to new line or len - 1, whichever comes first --
565	append a terminating zero to the string (we don't check for a zero in
566	the contents, let the user worry about that) */
567	str = buf;
568	left = (unsigned)len - 1;
569	if (left) do {
570	/* assure that something is in the output buffer */
571	if (state->have == 0) {
572	if (gz_make(state) == -1)
573	return NULL; /* error */
574	if (state->have == 0) { /* end of file */
575	if (buf == str) /* got bupkus */
576	return NULL;
577	break; /* got something -- return it */
578	}
579	}
580
581	/* look for end-of-line in current output buffer */
582	n = state->have > left ? left : state->have;
583	eol = memchr(state->next, '\n', n);
584	if (eol != NULL)
585	n = (unsigned)(eol - state->next) + 1;
586
587	/* copy through end-of-line, or remainder if not found */
588	memcpy(buf, state->next, n);
589	state->have -= n;
590	state->next += n;
591	state->pos += n;
592	left -= n;
593	buf += n;
594	} while (left && eol == NULL);
595
596	/* found end-of-line or out of space -- terminate string and return it */
597	buf[0] = 0;
598	return str;
599	}
600
601	/* -- see zlib.h -- */
602	int ZEXPORT gzdirect(file)
603	gzFile file;
604	{
605	gz_statep state;
606
607	/* get internal structure */
608	if (file == NULL)
609	return 0;
610	state = (gz_statep)file;
611
612	/* check that we're reading */
613	if (state->mode != GZ_READ)
614	return 0;
615
616	/* if the state is not known, but we can find out, then do so (this is
617	mainly for right after a gzopen() or gzdopen()) */
618	if (state->how == LOOK && state->have == 0)
619	(void)gz_head(state);
620
621	/* return 1 if reading direct, 0 if decompressing a gzip stream */
622	return state->direct;
623	}
624
625	/* -- see zlib.h -- */
626	int ZEXPORT gzclose_r(file)
627	gzFile file;
628	{
629	int ret;
630	gz_statep state;
631
632	/* get internal structure */
633	if (file == NULL)
634	return Z_STREAM_ERROR;
635	state = (gz_statep)file;
636
637	/* check that we're reading */
638	if (state->mode != GZ_READ)
639	return Z_STREAM_ERROR;
640
641	/* free memory and close file */
642	if (state->size) {
643	inflateEnd(&(state->strm));
644	free(state->out);
645	free(state->in);
646	}
647	gz_error(state, Z_OK, NULL);
648	free(state->path);
649	ret = close(state->fd);
650	free(state);
651	return ret ? Z_ERRNO : Z_OK;
652	}