Re: [Qemu-devel] [PATCH] qemu-ga: add guest-get-osinfo command

[Vinzenz Feenstra]

> On Mar 21, 2017, at 2:39 PM, Eric Blake <address@hidden> wrote:
> 
> On 03/16/2017 05:23 AM, Vinzenz 'evilissimo' Feenstra wrote:
>> From: Vinzenz Feenstra <address@hidden>
>> 
>> Add a new 'guest-get-osinfo' command for reporting basic information of
>> the guest operating system (hereafter just 'OS'). This information
>> includes the type of the OS, the version, and the architecture.
>> Additionally reported would be a name, distribution type and kernel
>> version where applicable.
>> 
>> Here an example for a Fedora 25 VM:
>> 
>> $ virsh -c qemu:////system qemu-agent-command F25 \
>>    '{ "execute": "guest-get-osinfo" }'
>>  {"return":{"arch":"x86_64","codename":"Server Edition","version":"25",
>>   "kernel":"4.8.6-300.fc25.x86_64","type":"linux","distribution":"Fedora"}}
>> 
>> And an example for a Windows 2012 R2 VM:
>> 
>> $ virsh -c qemu:////system qemu-agent-command Win2k12R2 \
>>    '{ "execute": "guest-get-osinfo" }'
>>  {"return":{"arch":"x86_64","codename":"Win 2012 R2",
>>   "version":"6.3","kernel":"","type":"windows","distribution":""}}
>> 
>> Signed-off-by: Vinzenz Feenstra <address@hidden>
>> ---
> 
> 
>> +static void ga_get_linux_distribution_info(GuestOSInfo *info)
>> +{
>> +    FILE *fp = NULL;
>> +    fp = fopen("/etc/os-release", "r");
> 
> Rather than read random files, I'm thinking that the uname() syscall is
> a better approach.  It is portable to more guests (since uname is a
> POSIX interface), even if it is somewhat more limited on the information
> it provides.

How about using it as a fallback option only but still use the information 
available
on the other places. I think it’s useful information what can be found there.

> 
>> +++ b/qga/commands-win32.c
>> @@ -1536,3 +1536,108 @@ void ga_command_state_init(GAState *s, 
>> GACommandState *cs)
>>         ga_command_state_add(cs, NULL, guest_fsfreeze_cleanup);
>>     }
>> }
> 
>> +static char *ga_get_win_ver(void)
>> +{
>> +    OSVERSIONINFOEXW os_version;
>> +    ga_get_version(&os_version);
>> +    char buf[64] = {};
>> +    int major = (int)os_version.dwMajorVersion;
>> +    int minor = (int)os_version.dwMinorVersion;
>> +    sprintf(buf, "%d.%d", major, minor);
>> +    return strdup(buf);
> 
> Instead of using strdup() (which uses malloc()), you should be using
> g_strdup_printf() (which uses g_malloc().  In general, we prefer
> g_malloc/g_free over raw malloc.  And once you use g_strdup_printf, you
> no longer have to worry about whether buf is allocated large enough to
> avoid overflow with sprintf.
Will do with the next version. Thanks for that hint with sprintf I didn’t know 
about that.

> 
> 
>> +++ b/qga/qapi-schema.json
>> @@ -1042,3 +1042,43 @@
>>   'data':    { 'path': 'str', '*arg': ['str'], '*env': ['str'],
>>                '*input-data': 'str', '*capture-output': 'bool' },
>>   'returns': 'GuestExec' }
>> +
>> +##
>> +# @GuestOSType:
>> +#
>> +# @linux:    Indicator for linux distributions
>> +# @windows:  Indicator for windows versions
>> +# @other:    Indicator for any other operating system that is not yet
>> +#            explicitly supported
>> +#
>> +# Since: 2.8
> 
> You've missed 2.8 by a long shot. In fact, you've missed hard freeze for
> 2.9, so this needs to be 2.10.

I don’t even know where I was looking for finding that number.

> 
>> +##
>> +{ 'enum': 'GuestOSType', 'data': ['linux', 'windows', 'other'] }
>> +
>> +##
>> +# @GuestOSInfo:
>> +#
>> +# @version:      OS version, e.g. 25 for FC25 etc.
>> +# @distribution: Fedora, Ubuntu, Debian, CentOS...
>> +# @codename:     Code name of the OS. e.g. Ubuntu has Xenial Xerus etc.
>> +# @arch:         Architecture of the OS e.g. x86, x86_64, ppc64, aarch64...
>> +# @type:         Specifies the type of the OS.
>> +# @kernel:       Linux kernel version (Might be used by other OS types too).
>> +#                May be empty.
> 
> Rather than printing an empty string, would it be better to make the
> fields optional, and omit them when there is nothing useful to supply?

I tried to keep it as stable as possible, but optional would work for me too, 
if it is preferred.

> 
> -- 
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org <http://libvirt.org/>