Re: [Qemu-devel] [PATCH v3 0/6] qemu: guest agent: implement guest-exec command

["Denis V. Lunev" <den@odin.com>]

On 08/06/15 09:42, Denis V. Lunev wrote:
> On 21/05/15 08:49, Denis V. Lunev wrote:
>> These patches for guest-agent add the functionality to execute 
>> commands on
>> a guest UNIX machine.
>>
>> These patches add the following interfaces:
>>
>> guest-pipe-open
>> guest-exec
>> guest-exec-status
>>
>> With these interfaces it's possible to:
>>
>> * Open an anonymous pipe and work with it as with a file using already
>> implemented interfaces guest-file-{read,write,flush,close}.
>>
>> * Execute a binary or a script on a guest machine.
>> We can pass arbitrary arguments and environment to a new child process.
>>
>> * Pass redirected IO from/to stdin, stdout, stderr from a child 
>> process to a
>> local file or an anonymous pipe.
>>
>> * Check the status of a child process, get its exit status if it 
>> exited or get
>> signal number if it was killed.
>>
>> We plan to add support for Windows in the near future using the same 
>> interfaces
>> we introduce here.
>>
>> Example of usage:
>>
>> {"execute": "guest-pipe-open", "arguments":{"mode": "r"}}
>> {'return': 1000}
>>
>> {"execute":"guest-exec", "arguments":{ "path": "id", "params": ["user"],
>>      "env": ["MYENV=myvalue"], "handle_stdout": 1000 }}'
>> {"return": 2636}
>>
>> {"execute": "guest-exec-status", "arguments": {"pid": 2636}}
>> {"return":{"exit":0,"handle_stderr":-1,"handle_stdin":-1,"handle_stdout":1000,"signal":-1}} 
>>
>>
>> {"execute": "guest-file-read", "arguments": {"handle": 1000, 
>> "count":128}}
>> {"return":{"count":58,"buf-b64":"dWlk...","eof":true}}
>>
>> {"execute": "guest-file-close", "arguments": {"handle": 1000}}
>> {"return":{}}
>>
>>
>> These patches are based on the patches proposed by Michael Roth in 2011:
>> http://lists.gnu.org/archive/html/qemu-devel/2011-12/msg00722.html
>>
>> We made several modifications to the interfaces proposed by Michael 
>> to simplify
>> their usage and we also added several new functions:
>>
>> * Arguments to an executable file are passed as an array of strings.
>>
>>      Before that we had to pass parameters like this:
>>      'params': [ {'param': '-b'}, {'param': '-n1'} ]
>>
>>      Now we may pass them just as an array of strings:
>>      'params': [ '-b', '-n1' ]
>>
>> * Environment can be passed to a child process.
>>
>>      "env": ["MYENV=myvalue"]
>>
>> * Removed "detach" argument from "guest-exec" - it never waits for a 
>> child
>> process to signal.  With this change it's possible to return just PID 
>> from
>> "guest-exec", a user must call "guest-exec-status" to get the status 
>> of a child.
>>
>> * Removed "wait" argument from "guest-exec-status" - waiting for a 
>> child process
>> to signal is dangerous, because it may block the whole qemu-ga. 
>> Instead, the
>> command polls just once a status of a child.
>>
>> * "guest-exec-status" returns exit status of a child process or a 
>> signal number,
>> in case a process was killed.
>>
>> * Simplified the command "guest-pipe-open" - the way how it stores 
>> the pipe
>> fd's.  No additional logic is needed about which end of pipe should 
>> be closed
>> with "guest-file-close".  This way we avoid modifying the interface 
>> of the
>> existing "guest-file-close".
>>
>> In the conversation about the original patches there was a suggestion 
>> to merge
>> "path" and "params" into one single list.  But we didn't do so, 
>> because having
>> separate "path" is similar to exec*() family functions in UNIX. That 
>> way it
>> looks more consistent.
>>
>> Changes from v2:
>> - return code of commands changed to dictionary
>> - ported to current HEAD
>> - new way for moving pipe to non-blocking state (universal)
>>
>> Changes from v1:
>> - Windows version of the patchset is added
>> - SIGPIPE processing is added for Unix version of the patchset
>> - added guest_exec_file_busy() to prevent GuestFileHandle* object 
>> from being
>>    deleted in case it's used in guest-exec command.
>>
>> Signed-off-by: Olga Krishtal <okrishtal@parallels.com>
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>>
>> P.S. Michael, this is a working version and could we consider it for 
>> merging
>>       into 2.4? If you still want to use universal GLIB code, we could
>>       re-write this later using standard refactoring way.
>>
> PING, 1 week till soft freeze.
>
> Eric, Michael, can you pls consider these patches? We have
> really small amount of time left.
>
> Regards,
>     Den
_PING_