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https://gitlab.com/qemu-project/qemu
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3cf0bed836
guest-sync leaves it as an exercise to the user as to how to reliably obtain the response to guest-sync if the client had previously read in a partial response (due qemu-ga previously being restarted mid-"sentence" due to reboot, forced restart, etc). qemu-ga handles this situation on its end by having a client precede their guest-sync request with a 0xFF byte (invalid UTF-8), which qemu-ga/QEMU JSON parsers will treat as a flush event. Thus we can reliably flush the qemu-ga parser state in preparation for receiving the guest-sync request. guest-sync-delimited provides the same functionality for a client: when a guest-sync-delimited is issued, qemu-ga will precede it's response with a 0xFF byte that the client can use as an indicator to flush its buffer/parser state in preparation for reliably receiving the guest-sync-delimited response. It is also useful as an optimization for clients, since, after issuing a guest-sync-delimited, clients can safely discard all stale data read from the channel until the 0xFF is found. More information available on the wiki: http://wiki.qemu.org/Features/QAPI/GuestAgent#QEMU_Guest_Agent_Protocol Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
79 lines
2 KiB
C
79 lines
2 KiB
C
/*
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* QEMU Guest Agent common/cross-platform command implementations
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*
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* Copyright IBM Corp. 2012
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*
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* Authors:
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* Michael Roth <mdroth@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include <glib.h>
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#include "qga/guest-agent-core.h"
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#include "qga-qmp-commands.h"
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#include "qerror.h"
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/* Note: in some situations, like with the fsfreeze, logging may be
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* temporarilly disabled. if it is necessary that a command be able
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* to log for accounting purposes, check ga_logging_enabled() beforehand,
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* and use the QERR_QGA_LOGGING_DISABLED to generate an error
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*/
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void slog(const gchar *fmt, ...)
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{
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va_list ap;
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va_start(ap, fmt);
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g_logv("syslog", G_LOG_LEVEL_INFO, fmt, ap);
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va_end(ap);
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}
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int64_t qmp_guest_sync_delimited(int64_t id, Error **errp)
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{
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ga_set_response_delimited(ga_state);
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return id;
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}
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int64_t qmp_guest_sync(int64_t id, Error **errp)
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{
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return id;
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}
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void qmp_guest_ping(Error **err)
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{
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slog("guest-ping called");
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}
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struct GuestAgentInfo *qmp_guest_info(Error **err)
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{
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GuestAgentInfo *info = g_malloc0(sizeof(GuestAgentInfo));
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GuestAgentCommandInfo *cmd_info;
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GuestAgentCommandInfoList *cmd_info_list;
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char **cmd_list_head, **cmd_list;
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info->version = g_strdup(QGA_VERSION);
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cmd_list_head = cmd_list = qmp_get_command_list();
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if (*cmd_list_head == NULL) {
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goto out;
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}
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while (*cmd_list) {
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cmd_info = g_malloc0(sizeof(GuestAgentCommandInfo));
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cmd_info->name = strdup(*cmd_list);
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cmd_info->enabled = qmp_command_is_enabled(cmd_info->name);
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cmd_info_list = g_malloc0(sizeof(GuestAgentCommandInfoList));
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cmd_info_list->value = cmd_info;
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cmd_info_list->next = info->supported_commands;
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info->supported_commands = cmd_info_list;
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g_free(*cmd_list);
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cmd_list++;
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}
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out:
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g_free(cmd_list_head);
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return info;
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}
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