Zlib Interface

Simplified implementation of zlib functions. More...

Files
file	zlib.c
	Simplified implementation of zlib functions.

Data Structures
struct	zobj
	Zlib buffer used for compression and decompression. More...

Functions
struct zobj *	zcompress (uint8_t *buff, uint16_t len, uint8_t level)
	Allocate a buffer and return it with compressed data. More...
void	zuncompress (struct zobj *buff, uint8_t *obuff)
	Uncompress zobj buffer to buffer. More...
int	is_gzip (uint8_t *buf, int buf_size)
	check a buffer if it contains gzip magic More...
uint8_t *	gzinflatebuf (uint8_t *buf_in, int buf_size, uint32_t *len)
	Ungzip a buffer. More...

Detailed Description

Simplified implementation of zlib functions.

Function Documentation

uint8_t* gzinflatebuf	(	uint8_t *	buf_in,
		int	buf_size,
		uint32_t *	len
	)

Ungzip a buffer.

Parameters

buf_in	Buffer to inflate.
buf_size	Size of buf_in buffer.
len	Pointer that will contain the uncompressed data length.

Returns

Uncompressed data in a buffer or NULL on error.

Definition at line 101 of file zlib.c.

Referenced by curl_ungzip().

                                                                           {
    z_stream zdat;
    uint8_t *buf = NULL, *tmp;
    int res;

    zdat.opaque = NULL;
    zdat.zalloc = NULL;
    zdat.zfree = NULL;

    zdat.next_in = buf_in;
    zdat.avail_in = buf_size;
    zdat.next_out = buf;
    zdat.avail_out = 0;
    zdat.total_out = 0;

    if (inflateInit2(&zdat, 31)) {
        return NULL;
    }

    do {
        if (!(tmp = realloc(buf,zdat.total_out + (zdat.avail_in * 5) + 1))) {
            res = Z_MEM_ERROR;
            break;
        } else {
            buf = tmp;
        }
        buf[zdat.total_out] = '\0';
        zdat.next_out = &buf[zdat.total_out];
        zdat.avail_out += zdat.avail_in * 5;
    } while ((res = inflate(&zdat, Z_NO_FLUSH)) == Z_OK);

    if (res == Z_STREAM_END) {
        buf = realloc(buf, zdat.total_out);
        *len = zdat.total_out;
    } else {
        free(buf);
        *len = 0;
        buf = NULL;
    }
    inflateEnd(&zdat);

    return buf;
}

int is_gzip	(	uint8_t *	buf,
		int	buf_size
	)

check a buffer if it contains gzip magic

Parameters

buf	buffer to check.
buf_size	buffer len it must be more than 4.

Returns

non zero value if the buffer contains gzip data

Definition at line 85 of file zlib.c.

Referenced by curl_ungzip().

                                               {
    if (buf_size < 4) {
        return 0;
    }
    if (memcmp(buf, gzipMagicBytes, 4)) {
        return 0;
    }
    return 1;
}

struct zobj* zcompress	(	uint8_t *	buff,
		uint16_t	len,
		uint8_t	level
	)

Allocate a buffer and return it with compressed data.

Parameters

buff	Buffer to compress.
len	Length of the buffer.
level	Compression level.

Returns

reference to zobj data structure containing compressed data or NULL on error.

Definition at line 47 of file zlib.c.

References zobj::buff, objalloc(), zobj::olen, and zobj::zlen.

                                                                          {
    struct zobj *ret;

    if (!(ret = objalloc(sizeof(*ret), zobj_free))) {
        return (NULL);
    }

    ret->zlen = compressBound(len);
    ret->olen = len;

    if (!(ret->buff = malloc(ret->zlen))) {
        return (NULL);
    }
    compress2(ret->buff, (uLongf *)&ret->zlen, buff, len, level);

    return (ret);
}

void zuncompress	(	struct zobj *	buff,
		uint8_t *	obuff
	)

Uncompress zobj buffer to buffer.

Parameters

buff	Compressed buffer to uncompress.
obuff	Buffer to uncompress too.

Warning

obuff needs to be large enough to contain the data.

Todo:

Implement this without needing original buff len using inflate

Definition at line 71 of file zlib.c.

References zobj::buff, zobj::olen, and zobj::zlen.

                                                           {
    uLongf olen = buff->olen;

    if (!obuff) {
        return;
    }

    uncompress(obuff, &olen, buff->buff, buff->zlen);
}