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Date: Mon, 04 Jul 2011 12:38:54 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v7 03/12] VMDK: probe for monolithicFlat
	images
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To: Fam Zheng <famcool@gmail.com>
Cc: stefanha@gmail.com, qemu-devel@nongnu.org, hch@lst.de

Am 03.07.2011 17:06, schrieb Fam Zheng:
> Probe as the same behavior as VMware does.
> Recognize image as monolithicFlat descriptor file when the file is text
> and the first effective line (not '#' leaded comment or space line) is
> either 'version=1' or 'version=2'. No space or upper case charactors
> accepted.
> 
> Signed-off-by: Fam Zheng <famcool@gmail.com>
> ---
>  block/vmdk.c |   44 ++++++++++++++++++++++++++++++++++++++++++--
>  1 files changed, 42 insertions(+), 2 deletions(-)
> 
> diff --git a/block/vmdk.c b/block/vmdk.c
> index 03a4619..05a58db 100644
> --- a/block/vmdk.c
> +++ b/block/vmdk.c
> @@ -103,10 +103,50 @@ static int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename)
>          return 0;
>      magic = be32_to_cpu(*(uint32_t *)buf);
>      if (magic == VMDK3_MAGIC ||
> -        magic == VMDK4_MAGIC)
> +        magic == VMDK4_MAGIC) {
>          return 100;
> -    else
> +    } else {
> +        const char *p = (const char *)buf;
> +        const char *end = p + buf_size;
> +        while (p < end) {
> +            if (*p == '#') {
> +                /* skip comment line */
> +                while (p < end && *p != '\n') {
> +                    p++;
> +                }
> +                p++;
> +                continue;
> +            }
> +            if (*p == ' ') {
> +                while (p < end && *p == ' ') {
> +                    p++;
> +                }
> +                /* skip '\r' if windows line endings used. */
> +                if (p < end && *p == '\r') {
> +                    p++;
> +                }
> +                /* only accept blank lines before 'version=' line */
> +                if (p == end || *p != '\n') {
> +                    return 0;
> +                }
> +                p++;
> +                continue;
> +            }
> +            if (end - p >= strlen("version=X\n")) {
> +                if (strncmp("version=1\n", p, strlen("version=1\n")) == 0 ||
> +                    strncmp("version=2\n", p, strlen("version=2\n")) == 0) {
> +                    return 100;
> +                }
> +            }
> +            if (end - p >= strlen("version=X\r\n")) {
> +                if (strncmp("version=1\r\n", p, strlen("version=1\r\n")) == 0 ||
> +                    strncmp("version=2\r\n", p, strlen("version=2\r\n")) == 0) {
> +                    return 100;
> +                }
> +            }

I think you may want to insert something right here. :-)

This code (actually v6, but it doesn't seem to have changed) gives my an
endless loop in vmdk_probe when trying to open a qcow2 image. So
"something" might be p++ or probably just return 0;

Kevin

> +        }
>          return 0;
> +    }
>  }
>  
>  #define CHECK_CID 1