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Re: [Qemu-devel] [PATCH v6 3/4] guest agent: add guest agent commands sc


From: Michael Roth
Subject: Re: [Qemu-devel] [PATCH v6 3/4] guest agent: add guest agent commands schema file
Date: Fri, 08 Jul 2011 16:42:08 -0500
User-agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:5.0) Gecko/20110624 Thunderbird/5.0

On 07/08/2011 10:08 AM, Luiz Capitulino wrote:
On Tue,  5 Jul 2011 08:21:39 -0500
Michael Roth<address@hidden>  wrote:


Signed-off-by: Michael Roth<address@hidden>
---
  qapi-schema-guest.json |  204 ++++++++++++++++++++++++++++++++++++++++++++++++
  1 files changed, 204 insertions(+), 0 deletions(-)
  create mode 100644 qapi-schema-guest.json

I think this should be folded in the next patch.

More comments below.


diff --git a/qapi-schema-guest.json b/qapi-schema-guest.json
new file mode 100644
index 0000000..367b42d
--- /dev/null
+++ b/qapi-schema-guest.json
@@ -0,0 +1,204 @@
+# *-*- Mode: Python -*-*
+
+##
+# @guest-sync:
+#
+# Echo back a unique integer value
+#
+# This is used by clients talking to the guest agent over the
+# wire to ensure the stream is in sync and doesn't contain stale
+# data from previous client. All guest agent responses should be
+# ignored until the provided unique integer value is returned,
+# and it is up to the client to handle stale whole or
+# partially-delivered JSON text in such a way that this response
+# can be obtained.
+#
+# Such clients should also preceed this command
+# with a 0xFF byte to make such the guest agent flushes any
+# partially read JSON data from a previous session.
+#
+# @id: randomly generated 64-bit integer
+#
+# Returns: The unique integer id passed in by the client
+#
+# Since: 0.15.0
+##
+{ 'command': 'guest-sync'
+  'data':    { 'id': 'int' },
+  'returns': 'int' }
+
+##
+# @guest-ping:
+#
+# Ping the guest agent, a non-error return implies success
+#
+# Since: 0.15.0
+##
+{ 'command': 'guest-ping' }
+
+##
+# @guest-info:
+#
+# Get some information about the guest agent.
+#
+# Since: 0.15.0
+##
+{ 'type': 'GuestAgentInfo', 'data': {'version': 'str'} }
+{ 'command': 'guest-info',
+  'returns': 'GuestAgentInfo' }
+
+##
+# @guest-shutdown:
+#
+# Initiate guest-activated shutdown. Note: this is an asynchronous
+# shutdown request, with no guaruntee of successful shutdown. Errors
+# will be logged to guest's syslog.
+#
+# @mode: "halt", "powerdown", or "reboot"
+#
+# Returns: Nothing on success
+#
+# Since: 0.15.0
+##
+{ 'command': 'guest-shutdown', 'data': { 'mode': 'str' } }

Shouldn't 'mode' be optional?

+
+##
+# @guest-file-open:
+#
+# Open a file in the guest and retrieve a file handle for it
+#
+# @filepath: Full path to the file in the guest to open.
+#
+# @mode: #optional open mode, as per fopen(), "r" is the default.
+#
+# Returns: Guest file handle on success.
+#          If @filepath cannot be opened, OpenFileFailed
+#
+# Since: 0.15.0
+##
+{ 'command': 'guest-file-open',
+  'data':    { 'filepath': 'str', '*mode': 'str' },
+  'returns': 'int' }

You can use 'file-path'. Actually, I'd use just 'path'.

+
+##
+# @guest-file-read:
+#
+# Read from an open file in the guest
+#
+# @filehandle: filehandle returned by guest-file-open
+#
+# @count: maximum number of bytes to read
+#
+# Returns: GuestFileRead on success.
+#          If @filehandle is not open, OpenFileFailed
+#
+# Since: 0.15.0
+##
+{ 'type': 'GuestFileRead',
+  'data': { 'count': 'int', 'buf': 'str', 'eof': 'bool' } }
+
+{ 'command': 'guest-file-read',
+  'data':    { 'filehandle': 'int', 'count': 'int' },
+  'returns': 'GuestFileRead' }

file-handle. Also, we have to say that the returned data is base64-encoded.

+
+##
+# @guest-file-write:
+#
+# Write to an open file in the guest
+#
+# @filehandle: filehandle returned by guest-file-open
+#
+# @data_b64: base64-encoded string representing data to be written
+#
+# @count: bytes to write (actual bytes, after b64-decode)
+#
+# Returns: GuestFileWrite on success.
+#          If @filehandle is not opened, OpenFileFailed
+#
+# Since: 0.15.0
+##
+{ 'type': 'GuestFileWrite',
+  'data': { 'count': 'int', 'eof': 'bool' } }
+{ 'command': 'guest-file-write',
+  'data':    { 'filehandle': 'int', 'data_b64': 'str', 'count': 'int' },
+  'returns': 'GuestFileWrite' }

data-b64

+
+##
+# @guest-file-seek:
+#
+# Seek to a position in the file, as with fseek(), and return the
+# current file position afterward. Also encapsulates ftell()'s
+# functionality, just Set offset=0, whence=SEEK_CUR.
+#
+# @filehandle: filehandle returned by guest-file-open
+#
+# @offset: bytes to skip over in the file stream
+#
+# @whence: SEEK_SET, SEEK_CUR, or SEEK_END, as with fseek()
+#
+# Returns: GuestFileSeek on success.
+#          If @filehandle is not opened, OpenFileFailed
+#
+# Since: 0.15.0
+##
+{ 'type': 'GuestFileSeek',
+  'data': { 'position': 'int', 'eof': 'bool' } }
+
+{ 'command': 'guest-file-seek',
+  'data':    { 'filehandle': 'int', 'offset': 'int', 'whence': 'int' },
+  'returns': 'GuestFileSeek' }
+
+##
+# @guest-file-close:
+#
+# Close an open file in the guest
+#
+# @filehandle: filehandle returned by guest-file-open
+#
+# Returns: Nothing on success.
+#          If @filehandle is not opened, OpenFileFailed
+#
+# Since: 0.15.0
+##
+{ 'command': 'guest-file-close',
+  'data': { 'filehandle': 'int' } }
+
+##
+# @guest-fsfreeze-status:
+#
+# get guest fsfreeze state
+#
+# Returns: GuestFsfreezeStatus (enumeration starts at 1)
+#
+# Since: 0.15.0
+##
+{ 'enum': 'GuestFsfreezeStatus',
+  'data': [ 'thawed', 'inprogress', 'frozen', 'error' ] }
+{ 'command': 'guest-fsfreeze-status',
+  'returns': 'GuestFsfreezeStatus' }

hmm, I thought a qapi command implementation would return an enum (ie. int),
but the qapi would translate it to a string and return the string to the
client. However, this returns an int (as explained above).

Did I misunderstand how the qapi handles enums then?


No, I think you're right... the original code generation seemed to support this at least. With the switchover to visitor functions Anthony treated enum types as integers when handling input/output, but now that I look at it again there was a commented-out block that suggested a possible TODO here.

It could be done by generating a lookup table for each qapi-defined enum and then passing that to qmp_input_type_enum()/qapi_output_type_enum()

Sure would make the enum functionality more useful :) I'll see if I can work it into set2 without too much churn.

+
+##
+# @guest-fsfreeze-freeze:
+#
+# Sync and freeze all non-network guest filesystems
+#
+# Returns: Number of file systems frozen
+#          If error, -1 (unknown error) or -errno
+#
+# Since: 0.15.0
+##
+{ 'command': 'guest-fsfreeze-freeze',
+  'returns': 'int' }
+
+##
+# @guest-fsfreeze-thaw:
+#
+# Unfreeze frozen guest fileystems
+#
+# Returns: Number of file systems thawed
+#          If error, -1 (unknown error) or -errno
+#
+# Since: 0.15.0
+##
+{ 'command': 'guest-fsfreeze-thaw',
+  'returns': 'int' }





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