[Qemu-devel] [PATCH 2/2] qga: add guest-set-time command

[Lei Li]

Signed-off-by: Lei Li <address@hidden>
---
 qga/commands-posix.c |   76 ++++++++++++++++++++++++++++++++++++++++++++++++++
 qga/qapi-schema.json |   42 +++++++++++++++++++++++++++
 2 files changed, 118 insertions(+), 0 deletions(-)

diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 2fef2b6..5424c50 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -149,6 +149,82 @@ struct TimeInfo *qmp_guest_get_time(Error **errp)
     return time_info;
 }
 
+void qmp_guest_set_time(bool has_seconds, int64_t seconds,
+                        bool has_microseconds, int64_t microseconds,
+                        bool has_utc_offset, int64_t utc_offset, Error **errp)
+{
+    int ret;
+    int status;
+    pid_t pid, rpid;
+    struct timeval tv;
+    TimeInfo *time_info;
+
+    /* year-2038 will overflow in case time_t is 32bit */
+    if (sizeof(time_t) == 4) {
+        return;
+    }
+
+    if (!has_seconds) {
+        if (has_microseconds || has_utc_offset) {
+            error_setg(errp, "field 'seconds' missing");
+            return;
+        } else {
+            /* Grab time from the host if no arguments given. */
+            time_info = get_host_time(errp);
+            if (!time_info) {
+                return;
+            }
+
+            tv.tv_sec = time_info->seconds;
+            tv.tv_usec = time_info->microseconds;
+        }
+    } else {
+        if (abs(utc_offset) > (24 * 60)) {
+            error_setg(errp, "'utc_offset' shoud be less than 24 hours");
+            return;
+        }
+
+        if (microseconds > 1000000) {
+            error_setg(errp, "'microseconds' overflow");
+            return;
+        }
+
+        tv.tv_sec = (time_t) seconds + (has_utc_offset ? utc_offset * 60 : 0);
+        tv.tv_usec = has_microseconds ? (time_t) microseconds : 0;
+    }
+
+
+    ret = settimeofday(&tv, NULL);
+    if (ret < 0) {
+        error_set(errp, QERR_QGA_COMMAND_FAILED, strerror(errno));
+        return;
+    }
+
+    /* Set the Hardware Clock to the current System Time. */
+    pid = fork();
+    if (pid == 0) {
+        setsid();
+        reopen_fd_to_null(0);
+        reopen_fd_to_null(1);
+        reopen_fd_to_null(2);
+
+        execle("/sbin/hwclock", "hwclock", "-w", NULL, environ);
+        _exit(EXIT_FAILURE);
+    } else if (pid < 0) {
+        goto exit_err;
+    }
+
+    do {
+        rpid = waitpid(pid, &status, 0);
+    } while (rpid == -1 && errno == EINTR);
+    if (rpid == pid && WIFEXITED(status) && !WEXITSTATUS(status)) {
+        return;
+    }
+
+exit_err:
+    error_set(errp, QERR_UNDEFINED_ERROR);
+}
+
 typedef struct GuestFileHandle {
     uint64_t id;
     FILE *fh;
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index d067fa5..6eba625 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -121,6 +121,48 @@
   'returns': 'TimeInfo' }
 
 ##
+# @guest-set-time:
+#
+# Set guest time. If no arguments were given, will set
+# host time to guest.
+#
+# Right now, when a guest is paused or migrated to a file
+# then loaded from that file, the guest OS has no idea that
+# there was a big gap in the time. Depending on how long
+# the gap was, NTP might not be able to resynchronize the
+# guest.
+#
+# This command tries to set guest time based on the information
+# from host or an absolute value given by management app, and
+# set the Hardware Clock to the current System Time. This
+# will make it easier for a guest to resynchronize without
+# waiting for NTP.
+#
+# @seconds: #optional "seconds" time.
+#
+# @microseconds: #optional "microseconds" time.
+#
+# @utc-offset: #optional utc offset.
+#
+# Returns: Nothing on success.
+#
+# Notes: If no arguments were given, will grab time from
+#        the host.
+#
+#        @microseconds and @utc-offset must not be provided
+#        unless @seconds is present.
+#
+#        If just @seconds provided, other fields would be
+#        set to zero.
+#
+# present
+# Since: 1.4
+##
+{ 'command': 'guest-set-time',
+  'data': { '*seconds': 'int', '*microseconds': 'int',
+            '*utc-offset': 'int' } }
+
+##
 # @GuestAgentCommandInfo:
 #
 # Information about guest agent commands.
-- 
1.7.7.6