[04/10] core: Add generic XZ decoding function

This adds a simple function to decode any given XZ data area.
The uncomp_len value is optional. Unfortunately we cannot calculate the
uncompressed size of the XZ region before decompressing it.
We can pass in the value if this is known, otherwise we allocate a region
10x the original size. Which may be significantly more than necessary.

Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
---
 core/Makefile.inc  |   2 +-
 core/decode-xz.c   | 112 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/platform.h |   2 +
 3 files changed, 115 insertions(+), 1 deletion(-)
 create mode 100644 core/decode-xz.c

On Fri, 2017-06-09 at 16:55 +1000, Matt Brown wrote:
> This adds a simple function to decode any given XZ data area.
> The uncomp_len value is optional. Unfortunately we cannot calculate the
> uncompressed size of the XZ region before decompressing it.
> We can pass in the value if this is known, otherwise we allocate a region
> 10x the original size. Which may be significantly more than necessary.
> 
> Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
> ---
>  core/Makefile.inc  |   2 +-
>  core/decode-xz.c   | 112 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/platform.h |   2 +
>  3 files changed, 115 insertions(+), 1 deletion(-)
>  create mode 100644 core/decode-xz.c
> 
> diff --git a/core/Makefile.inc b/core/Makefile.inc
> index b09c30c..7f376bd 100644
> --- a/core/Makefile.inc
> +++ b/core/Makefile.inc
> @@ -8,7 +8,7 @@ CORE_OBJS += pci-opal.o fast-reboot.o device.o exceptions.o trace.o affinity.o
>  CORE_OBJS += vpd.o hostservices.o platform.o nvram.o nvram-format.o hmi.o
>  CORE_OBJS += console-log.o ipmi.o time-utils.o pel.o pool.o errorlog.o
>  CORE_OBJS += timer.o i2c.o rtc.o flash.o sensor.o ipmi-opal.o
> -CORE_OBJS += flash-subpartition.o bitmap.o buddy.o pci-quirk.o
> +CORE_OBJS += flash-subpartition.o bitmap.o buddy.o pci-quirk.o decode-xz.o
>  
>  ifeq ($(SKIBOOT_GCOV),1)
>  CORE_OBJS += gcov-profiling.o
> diff --git a/core/decode-xz.c b/core/decode-xz.c
> new file mode 100644
> index 0000000..4855e9b
> --- /dev/null
> +++ b/core/decode-xz.c
> @@ -0,0 +1,112 @@
> +/* Copyright 2017 IBM Corp.
> + *
> + * Licensed under the Apache License, Version 2.0 (the "License");
> + * you may not use this file except in compliance with the License.
> + * You may obtain a copy of the License at
> + *
> + * 	http://www.apache.org/licenses/LICENSE-2.0
> + *
> + * Unless required by applicable law or agreed to in writing, software
> + * distributed under the License is distributed on an "AS IS" BASIS,
> + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
> + * implied.
> + * See the License for the specific language governing permissions and
> + * limitations under the License.
> + */
> +
> +#include <skiboot.h>
> +#include <platform.h>
> +#include <libxz/xz.h>
> +
> +
> +#define HEADER_MAGIC "\3757zXZ"
> +#define HEADER_MAGIC_SIZE 6
> +/*
> + * decode_resource_xz
> + * Decodes any xz compressed memory region.
> + *
> + * @buf : pointer to memory region pointer
> + * @len : pointer to length of compressed region
> + * @uncomp_len: pointer to uncompressed length (optional)
> + *
> + * Returns 1 - successful or 0 - failed 
> + */
> +int decode_resource_xz(void **buf, size_t *len, size_t *uncomp_len)

If decode_resource_xz is used in patch 1 ("Decode payload initrd on FSP
machines"), this patch should come before it.

> +{
> +	struct xz_dec *file;
> +	struct xz_buf bufs;
> +	char *input_header;
> +	uint64_t *out_len;
> +	enum xz_ret rc;
> +	
> +	uint8_t *r_buf = (uint8_t *)(*buf);
> +	size_t   r_len = *len;
> +
> +	/* Check if input header matched XZ encoding signature */
> +	input_header = malloc(HEADER_MAGIC_SIZE);
> +	if (!input_header)
> +		return 0;
> +
> +	memcpy(input_header, r_buf, HEADER_MAGIC_SIZE);
> +	if (strcmp(input_header, HEADER_MAGIC)){
> +		prlog(PR_PRINTF, "DECODE: resource header magic does not match\
> +				  xz format\n");
> +		free(input_header);
> +		return 0;
> +	}
> +
> +
> +	/* Set up decoder */
> +	file = xz_dec_init(XZ_SINGLE, 0x100000);
> +
> +	if (!file) {
> +		/* Allocation failed */
> +		prlog(PR_PRINTF, "DECODE: xz_dec_init allocation error\n ");
> +		free(input_header);
> +		return 0;
> +	}
> +
> +	out_len = (uint64_t *)malloc(sizeof(uint64_t));

I think you only use out_len within the function and don't pass the
pointer anywhere - would it be worth just having this instead? One less
thing to free :)

	uint64_t out_len;
	..
	out_len = uncomp_len ? *uncomp_len : (r_len * 10);

> +	if (!uncomp_len)
> +       		*out_len = (r_len) * 10;
> +	else
> +		*out_len = *uncomp_len;
> +
> +	bufs.in       = (const uint8_t *)r_buf;
> +	bufs.in_pos   = 0;
> +	bufs.in_size  = r_len;
> +	bufs.out      = (uint8_t *)local_alloc(0, *out_len, 0x10000);
> +	bufs.out_pos  = 0;
> +	bufs.out_size = *(size_t *)out_len;

I don't think you need these casts (or for eg. r_buf, could declare it as
const to begin with).

> +
> +	if (bufs.out == NULL) {
> +		/* Buffer allocation failed */
> +		prlog(PR_PRINTF, "DECODE: bufs.out allocation error\n ");
> +		free(out_len);
> +		free(input_header);
> +		return 0;
> +	}
> +
> +	rc = xz_dec_run(file, &bufs);
> +
> +	if (rc != XZ_STREAM_END) {
> +		prlog(PR_ALERT, "DECODE: XZ decompression failed rc:%d\n", rc);
> +		free(bufs.out);
> +		free(out_len);
> +		free(input_header);
> +		return 0;
> +	}
> +
> +	/* Redefine resource base and size */
> +	*buf = (void *)bufs.out;
> +	*len = (size_t)*out_len;
> +
> +	prlog(PR_PRINTF, "DECODE: decode_resource_xz base: %p, len: %llu \
> +			remote: %p\n", bufs.out, *out_len, *buf);
> +
> +	xz_dec_end(file);
> +	free(out_len);
> +	free(input_header);
> +
> +	return 1;
> +}
> diff --git a/include/platform.h b/include/platform.h
> index e8848ca..0c41c35 100644
> --- a/include/platform.h
> +++ b/include/platform.h
> @@ -234,4 +234,6 @@ extern void set_bmc_platform(const struct bmc_platform *bmc);
>  
>  extern struct cpu_job* start_async_load(struct boot_resources *r);
>  
> +/* XZ decoding*/
> +extern int decode_resource_xz(void **buf, size_t *len, size_t *uncomp_len);
>  #endif /* __PLATFORM_H */