Am 29.06.2017 um 12:57 hat Peter Lieven geschrieben:
> we now read the extension on open and write it on update, but
> do not yet use it.
>
> Signed-off-by: Peter Lieven <p...@kamp.de>
> ---
> block/qcow2.c | 100
> ++++++++++++++++++++++++++++++++++++++++++++++++++--------
> block/qcow2.h | 23 +++++++++++---
> 2 files changed, 104 insertions(+), 19 deletions(-)
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 308121a..39a8afc 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -63,6 +63,7 @@ typedef struct {
> #define QCOW2_EXT_MAGIC_END 0
> #define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
> #define QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857
> +#define QCOW2_EXT_MAGIC_COMPRESS_FORMAT 0xC03183A3
>
> static int qcow2_probe(const uint8_t *buf, int buf_size, const char
> *filename)
> {
> @@ -76,6 +77,26 @@ static int qcow2_probe(const uint8_t *buf, int buf_size,
> const char *filename)
> return 0;
> }
>
> +static int qcow2_compress_format_from_name(char *fmt)
> +{
> + if (!fmt || !fmt[0]) {
> + return QCOW2_COMPRESS_ZLIB_COMPAT;
> + } else if (g_str_equal(fmt, "zlib")) {
> + return QCOW2_COMPRESS_ZLIB;
> + } else {
> + return -EINVAL;
> + }
> +}
It might make sense to allow specifying the old compression format in
the compression header. But I'm not so sure about using the empty string
rather than a proper name for it, and even less about not documenting
it.
Kevin
