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/*-
* Copyright (c) 2014 Mark Johnston <markj@FreeBSD.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/gzio.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/zutil.h>
#define KERN_GZ_HDRLEN 10 /* gzip header length */
#define KERN_GZ_TRAILERLEN 8 /* gzip trailer length */
#define KERN_GZ_MAGIC1 0x1f /* first magic byte */
#define KERN_GZ_MAGIC2 0x8b /* second magic byte */
MALLOC_DEFINE(M_GZIO, "gzio", "zlib state");
struct gzio_stream {
uint8_t * gz_buffer; /* output buffer */
size_t gz_bufsz; /* total buffer size */
off_t gz_off; /* offset into the output stream */
enum gzio_mode gz_mode; /* stream mode */
uint32_t gz_crc; /* stream CRC32 */
gzio_cb gz_cb; /* output callback */
void * gz_arg; /* private callback arg */
z_stream gz_stream; /* zlib state */
};
static void * gz_alloc(void *, u_int, u_int);
static void gz_free(void *, void *);
static int gz_write(struct gzio_stream *, void *, u_int, int);
struct gzio_stream *
gzio_init(gzio_cb cb, enum gzio_mode mode, size_t bufsz, int level, void *arg)
{
struct gzio_stream *s;
uint8_t *hdr;
int error;
if (bufsz < KERN_GZ_HDRLEN)
return (NULL);
if (mode != GZIO_DEFLATE)
return (NULL);
s = gz_alloc(NULL, 1, sizeof(*s));
s->gz_bufsz = bufsz;
s->gz_buffer = gz_alloc(NULL, 1, s->gz_bufsz);
s->gz_mode = mode;
s->gz_crc = ~0U;
s->gz_cb = cb;
s->gz_arg = arg;
s->gz_stream.zalloc = gz_alloc;
s->gz_stream.zfree = gz_free;
s->gz_stream.opaque = NULL;
s->gz_stream.next_in = Z_NULL;
s->gz_stream.avail_in = 0;
error = deflateInit2(&s->gz_stream, level, Z_DEFLATED, -MAX_WBITS,
DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY);
if (error != 0)
goto fail;
s->gz_stream.avail_out = s->gz_bufsz;
s->gz_stream.next_out = s->gz_buffer;
/* Write the gzip header to the output buffer. */
hdr = s->gz_buffer;
memset(hdr, 0, KERN_GZ_HDRLEN);
hdr[0] = KERN_GZ_MAGIC1;
hdr[1] = KERN_GZ_MAGIC2;
hdr[2] = Z_DEFLATED;
hdr[9] = OS_CODE;
s->gz_stream.next_out += KERN_GZ_HDRLEN;
s->gz_stream.avail_out -= KERN_GZ_HDRLEN;
return (s);
fail:
gz_free(NULL, s->gz_buffer);
gz_free(NULL, s);
return (NULL);
}
int
gzio_write(struct gzio_stream *s, void *data, u_int len)
{
return (gz_write(s, data, len, Z_NO_FLUSH));
}
int
gzio_flush(struct gzio_stream *s)
{
return (gz_write(s, NULL, 0, Z_FINISH));
}
void
gzio_fini(struct gzio_stream *s)
{
(void)deflateEnd(&s->gz_stream);
gz_free(NULL, s->gz_buffer);
gz_free(NULL, s);
}
static void *
gz_alloc(void *arg __unused, u_int n, u_int sz)
{
/*
* Memory for zlib state is allocated using M_NODUMP since it may be
* used to compress a kernel dump, and we don't want zlib to attempt to
* compress its own state.
*/
return (malloc(n * sz, M_GZIO, M_WAITOK | M_ZERO | M_NODUMP));
}
static void
gz_free(void *arg __unused, void *ptr)
{
free(ptr, M_GZIO);
}
static int
gz_write(struct gzio_stream *s, void *buf, u_int len, int zflag)
{
uint8_t trailer[KERN_GZ_TRAILERLEN];
size_t room;
int error, zerror;
KASSERT(zflag == Z_FINISH || zflag == Z_NO_FLUSH,
("unexpected flag %d", zflag));
KASSERT(s->gz_mode == GZIO_DEFLATE,
("invalid stream mode %d", s->gz_mode));
if (len > 0) {
s->gz_stream.avail_in = len;
s->gz_stream.next_in = buf;
s->gz_crc = crc32_raw(buf, len, s->gz_crc);
} else
s->gz_crc ^= ~0U;
error = 0;
do {
zerror = deflate(&s->gz_stream, zflag);
if (zerror != Z_OK && zerror != Z_STREAM_END) {
error = EIO;
break;
}
if (s->gz_stream.avail_out == 0 || zerror == Z_STREAM_END) {
/*
* Our output buffer is full or there's nothing left
* to produce, so we're flushing the buffer.
*/
len = s->gz_bufsz - s->gz_stream.avail_out;
if (zerror == Z_STREAM_END) {
/*
* Try to pack as much of the trailer into the
* output buffer as we can.
*/
((uint32_t *)trailer)[0] = s->gz_crc;
((uint32_t *)trailer)[1] =
s->gz_stream.total_in;
room = MIN(KERN_GZ_TRAILERLEN,
s->gz_bufsz - len);
memcpy(s->gz_buffer + len, trailer, room);
len += room;
}
error = s->gz_cb(s->gz_buffer, len, s->gz_off,
s->gz_arg);
if (error != 0)
break;
s->gz_off += len;
s->gz_stream.next_out = s->gz_buffer;
s->gz_stream.avail_out = s->gz_bufsz;
/*
* If we couldn't pack the trailer into the output
* buffer, write it out now.
*/
if (zerror == Z_STREAM_END && room < KERN_GZ_TRAILERLEN)
error = s->gz_cb(trailer + room,
KERN_GZ_TRAILERLEN - room, s->gz_off,
s->gz_arg);
}
} while (zerror != Z_STREAM_END &&
(zflag == Z_FINISH || s->gz_stream.avail_in > 0));
return (error);
}
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