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11d0f1255b
As the command name implies, this command suspends the guest to disk.
The suspend operation is implemented by two functions: bios_supports_mode()
and guest_suspend(). Both functions are generic enough to be used by
other suspend modes (introduced by next commits).
Both functions will try to use the scripts provided by the pm-utils
package if it's available. If it's not available, a manual method,
which consists of directly writing to '/sys/power/state', will be used.
To reap terminated children, a new signal handler is installed in the
parent to catch SIGCHLD signals and a non-blocking call to waitpid()
is done to collect their exit statuses. The statuses, however, are
discarded.
The approach used to query the guest for suspend support deserves some
explanation. It's implemented by bios_supports_mode() and shown below:
qemu-ga
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create pipe
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fork()
-----------------
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| fork()
| --------------------------
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| | exec('pm-is-supported')
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| wait()
| write exit status to pipe
| exit
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read pipe
This might look complex, but the resulting code is quite simple.
The purpose of that approach is to allow qemu-ga to reap its children
(semi-)automatically from its SIGCHLD handler.
Implementing this the obvious way, that's, doing the exec() call from
the first child process, would force us to introduce a more complex way
to reap qemu-ga's children. Like registering PIDs to be reaped and
having a way to wait for them when returning their exit status to
qemu-ga is necessary. The approach explained above avoids that complexity.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
322 lines
7.1 KiB
Python
322 lines
7.1 KiB
Python
# *-*- Mode: Python -*-*
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##
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# @guest-sync:
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#
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# Echo back a unique integer value
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#
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# This is used by clients talking to the guest agent over the
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# wire to ensure the stream is in sync and doesn't contain stale
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# data from previous client. All guest agent responses should be
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# ignored until the provided unique integer value is returned,
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# and it is up to the client to handle stale whole or
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# partially-delivered JSON text in such a way that this response
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# can be obtained.
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#
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# Such clients should also precede this command
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# with a 0xFF byte to make such the guest agent flushes any
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# partially read JSON data from a previous session.
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#
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# @id: randomly generated 64-bit integer
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#
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# Returns: The unique integer id passed in by the client
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-sync'
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'data': { 'id': 'int' },
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'returns': 'int' }
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##
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# @guest-ping:
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#
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# Ping the guest agent, a non-error return implies success
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-ping' }
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##
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# @GuestAgentCommandInfo:
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#
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# Information about guest agent commands.
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#
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# @name: name of the command
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#
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# @enabled: whether command is currently enabled by guest admin
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#
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# Since 1.1.0
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##
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{ 'type': 'GuestAgentCommandInfo',
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'data': { 'name': 'str', 'enabled': 'bool' } }
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##
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# @GuestAgentInfo
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#
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# Information about guest agent.
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#
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# @version: guest agent version
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#
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# @supported_commands: Information about guest agent commands
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#
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# Since 0.15.0
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##
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{ 'type': 'GuestAgentInfo',
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'data': { 'version': 'str',
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'supported_commands': ['GuestAgentCommandInfo'] } }
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##
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# @guest-info:
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#
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# Get some information about the guest agent.
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#
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# Returns: @GuestAgentInfo
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-info',
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'returns': 'GuestAgentInfo' }
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##
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# @guest-shutdown:
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#
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# Initiate guest-activated shutdown. Note: this is an asynchronous
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# shutdown request, with no guaruntee of successful shutdown. Errors
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# will be logged to guest's syslog.
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#
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# @mode: #optional "halt", "powerdown" (default), or "reboot"
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#
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# Returns: Nothing on success
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-shutdown', 'data': { '*mode': 'str' } }
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##
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# @guest-file-open:
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#
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# Open a file in the guest and retrieve a file handle for it
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#
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# @filepath: Full path to the file in the guest to open.
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#
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# @mode: #optional open mode, as per fopen(), "r" is the default.
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#
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# Returns: Guest file handle on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-open',
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'data': { 'path': 'str', '*mode': 'str' },
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'returns': 'int' }
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##
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# @guest-file-close:
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#
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# Close an open file in the guest
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#
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# @handle: filehandle returned by guest-file-open
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#
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# Returns: Nothing on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-close',
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'data': { 'handle': 'int' } }
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##
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# @GuestFileRead
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#
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# Result of guest agent file-read operation
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#
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# @count: number of bytes read (note: count is *before*
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# base64-encoding is applied)
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#
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# @buf-b64: base64-encoded bytes read
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#
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# @eof: whether EOF was encountered during read operation.
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#
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# Since: 0.15.0
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##
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{ 'type': 'GuestFileRead',
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'data': { 'count': 'int', 'buf-b64': 'str', 'eof': 'bool' } }
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##
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# @guest-file-read:
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#
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# Read from an open file in the guest. Data will be base64-encoded
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#
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# @handle: filehandle returned by guest-file-open
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#
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# @count: #optional maximum number of bytes to read (default is 4KB)
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#
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# Returns: @GuestFileRead on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-read',
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'data': { 'handle': 'int', '*count': 'int' },
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'returns': 'GuestFileRead' }
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##
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# @GuestFileWrite
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#
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# Result of guest agent file-write operation
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#
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# @count: number of bytes written (note: count is actual bytes
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# written, after base64-decoding of provided buffer)
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#
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# @eof: whether EOF was encountered during write operation.
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#
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# Since: 0.15.0
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##
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{ 'type': 'GuestFileWrite',
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'data': { 'count': 'int', 'eof': 'bool' } }
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##
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# @guest-file-write:
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#
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# Write to an open file in the guest.
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#
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# @handle: filehandle returned by guest-file-open
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#
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# @buf-b64: base64-encoded string representing data to be written
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#
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# @count: #optional bytes to write (actual bytes, after base64-decode),
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# default is all content in buf-b64 buffer after base64 decoding
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#
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# Returns: @GuestFileWrite on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-write',
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'data': { 'handle': 'int', 'buf-b64': 'str', '*count': 'int' },
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'returns': 'GuestFileWrite' }
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##
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# @GuestFileSeek
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#
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# Result of guest agent file-seek operation
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#
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# @position: current file position
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#
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# @eof: whether EOF was encountered during file seek
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#
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# Since: 0.15.0
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##
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{ 'type': 'GuestFileSeek',
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'data': { 'position': 'int', 'eof': 'bool' } }
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##
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# @guest-file-seek:
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#
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# Seek to a position in the file, as with fseek(), and return the
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# current file position afterward. Also encapsulates ftell()'s
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# functionality, just Set offset=0, whence=SEEK_CUR.
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#
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# @handle: filehandle returned by guest-file-open
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#
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# @offset: bytes to skip over in the file stream
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#
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# @whence: SEEK_SET, SEEK_CUR, or SEEK_END, as with fseek()
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#
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# Returns: @GuestFileSeek on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-seek',
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'data': { 'handle': 'int', 'offset': 'int', 'whence': 'int' },
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'returns': 'GuestFileSeek' }
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##
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# @guest-file-flush:
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#
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# Write file changes bufferred in userspace to disk/kernel buffers
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#
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# @handle: filehandle returned by guest-file-open
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#
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# Returns: Nothing on success.
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-file-flush',
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'data': { 'handle': 'int' } }
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##
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# @GuestFsFreezeStatus
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#
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# An enumation of filesystem freeze states
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#
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# @thawed: filesystems thawed/unfrozen
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#
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# @frozen: all non-network guest filesystems frozen
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#
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# @error: failure to thaw 1 or more
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# previously frozen filesystems, or failure to open a previously
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# cached filesytem (filesystem unmounted/directory changes, etc).
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#
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# Since: 0.15.0
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##
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{ 'enum': 'GuestFsfreezeStatus',
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'data': [ 'thawed', 'frozen', 'error' ] }
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##
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# @guest-fsfreeze-status:
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#
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# Get guest fsfreeze state. error state indicates
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#
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# Returns: GuestFsfreezeStatus ("thawed", "frozen", etc., as defined below)
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-fsfreeze-status',
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'returns': 'GuestFsfreezeStatus' }
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##
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# @guest-fsfreeze-freeze:
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#
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# Sync and freeze all non-network guest filesystems
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#
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# Returns: Number of file systems frozen on success
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-fsfreeze-freeze',
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'returns': 'int' }
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##
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# @guest-fsfreeze-thaw:
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#
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# Unfreeze frozen guest fileystems
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#
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# Returns: Number of file systems thawed
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# If error, -1 (unknown error) or -errno
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#
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# Since: 0.15.0
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##
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{ 'command': 'guest-fsfreeze-thaw',
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'returns': 'int' }
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##
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# @guest-suspend-disk
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#
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# Suspend guest to disk.
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#
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# This command tries to execute the scripts provided by the pm-utils package.
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# If it's not available, the suspend operation will be performed by manually
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# writing to a sysfs file.
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#
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# For the best results it's strongly recommended to have the pm-utils
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# package installed in the guest.
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#
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# Returns: nothing on success
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# If suspend to disk is not supported, Unsupported
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#
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# Notes: o This is an asynchronous request. There's no guarantee a response
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# will be sent
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# o It's strongly recommended to issue the guest-sync command before
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# sending commands when the guest resumes
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#
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# Since: 1.1
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##
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{ 'command': 'guest-suspend-disk' }
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