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Re: [Libvir] [PATCH] increase storage domains of a definition file



On Fri, Apr 20, 2007 at 02:43:31PM +0900, S.Sakamoto wrote:
> Hi,
> 
> When I install by virt-intall with long command
> (e.g."# /usr/sbin/virt-install --name testvm --ram 350 --vcpus 2 --file /root/test.img --file-size 1 --file /root/tmp02.img --
> file-size 1 --file /root/tmp03.img --file-size 1 --file /root/tmp04.img --file-size 1 --file /root/tmp05.img --file-size 
> 1 --file /root/tmp06.img --file-size 1 --file /root/tmp07.img --file-size 1 --file /root/tmp08.img --file-size 1 --file 
> /root/tmp09.img --file-size 1 --file /root/tmp10.img --file-size 1 --file /root/tmp11.img --file-size 1 --file 
> /root/tmp12.img --file-size 1 --file /root/tmp13.img --file-size 1 --file /root/tmp14.img --file-size 1 --file 
> /root/tmp15.img --file-size 1 --file /root/tmp16.img --file-size 1 --vnc --paravirt --location ftp://xx.xx.xx.xx/rhel5ga_x86 --noautoconsole --
> debug"),
> put out "abort".
> Because a definition file is long, it overflows from buffer.
> 
> So, this patch increase buffer size.
> 
> 
> Thanks,
> Shigeki Sakamoto.
> 
> 
> Index: src/internal.h
> ===================================================================
> RCS file: /data/cvs/libvirt/src/internal.h,v
> retrieving revision 1.37
> diff -u -p -r1.37 internal.h
> --- src/internal.h	4 Apr 2007 14:19:49 -0000	1.37
> +++ src/internal.h	19 Apr 2007 11:01:12 -0000
> @@ -106,6 +106,11 @@ extern "C" {
>  #define VIR_CONNECT_RO 1
>  
>  /**
> + * buffer size for definition file
> + */
> +#define VIR_XML_STRING_BUFLEN (1024 + PATH_MAX * 16 + FILENAME_MAX * 16)

Considering we were only rarely overflowing the 1024 byte buffer,
I think increasing the default buffer size to 132096 - is little bit
of overkill. I'd rather see all buffers dynamically allocated and
then this constant wouldn't be needed.

> +
> +/**
>   * _virConnect:
>   *
>   * Internal structure associated to a connection
> Index: src/xend_internal.c
> ===================================================================
> RCS file: /data/cvs/libvirt/src/xend_internal.c,v
> retrieving revision 1.109
> diff -u -p -r1.109 xend_internal.c
> --- src/xend_internal.c	13 Apr 2007 14:08:38 -0000	1.109
> +++ src/xend_internal.c	19 Apr 2007 11:01:16 -0000
> @@ -587,7 +587,7 @@ static int
>  xend_op_ext2(virConnectPtr xend, const char *path, char *error,
>               size_t n_error, const char *key, va_list ap)
>  {
> -    char ops[1024];
> +    char ops[VIR_XML_STRING_BUFLEN];

This gives a 130 KB static string. I can't help thinking this method 
would be better off using the dyn allocated virBuffer* routines instead
of a static string & snprintf.

NB, this patch doesn't modify the proxy code at all which has a 4096 
byte field defined for this, on the wire.

Regards,
Dan.
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