[Qemu-devel] [PATCH 3/5] qga: guest exec functionality

["Denis V. Lunev" <den@openvz.org>]

From: Yuri Pudgorodskiy <yur@virtuozzo.com>

Guest-exec rewriten in platform-independant style with glib spawn.

Child process is spawn asynchroneously and exit status can later
be picked up by guest-exec-status command.

stdin/stdout/stderr of the child now is redirected to /dev/null
Later we will add ability to specify stdin in guest-exec command
and to get collected stdout/stderr with guest-exec-status.

Signed-off-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Michael Roth <mdroth@linux.vnet.ibm.com>
---
 qga/commands.c       | 168 +++++++++++++++++++++++++++++++++++++++++++++++++++
 qga/qapi-schema.json |  57 +++++++++++++++++
 2 files changed, 225 insertions(+)

diff --git a/qga/commands.c b/qga/commands.c
index 7834967..6efd6aa 100644
--- a/qga/commands.c
+++ b/qga/commands.c
@@ -70,3 +70,171 @@ struct GuestAgentInfo *qmp_guest_info(Error **errp)
     qmp_for_each_command(qmp_command_info, info);
     return info;
 }
+
+struct GuestExecInfo {
+    GPid pid;
+    gint status;
+    bool finished;
+    QTAILQ_ENTRY(GuestExecInfo) next;
+};
+typedef struct GuestExecInfo GuestExecInfo;
+
+static struct {
+    QTAILQ_HEAD(, GuestExecInfo) processes;
+} guest_exec_state = {
+    .processes = QTAILQ_HEAD_INITIALIZER(guest_exec_state.processes),
+};
+
+static GuestExecInfo *guest_exec_info_add(GPid pid)
+{
+    GuestExecInfo *gei;
+
+    gei = g_malloc0(sizeof(*gei));
+    gei->pid = pid;
+    QTAILQ_INSERT_TAIL(&guest_exec_state.processes, gei, next);
+
+    return gei;
+}
+
+static GuestExecInfo *guest_exec_info_find(GPid pid)
+{
+    GuestExecInfo *gei;
+
+    QTAILQ_FOREACH(gei, &guest_exec_state.processes, next) {
+        if (gei->pid == pid) {
+            return gei;
+        }
+    }
+
+    return NULL;
+}
+
+GuestExecStatus *qmp_guest_exec_status(int64_t pid, Error **err)
+{
+    GuestExecInfo *gei;
+    GuestExecStatus *ges;
+
+    slog("guest-exec-status called, pid: %u", (uint32_t)pid);
+
+    gei = guest_exec_info_find((GPid)pid);
+    if (gei == NULL) {
+        error_setg(err, QERR_INVALID_PARAMETER, "pid");
+        return NULL;
+    }
+
+    ges = g_malloc0(sizeof(GuestExecStatus));
+    ges->exit = ges->signal = -1;
+
+    if (gei->finished) {
+        /* glib has no platform independent way to parse exit status */
+#ifdef G_OS_WIN32
+        if ((uint32_t)gei->status < 0xC0000000U) {
+            ges->exit = gei->status;
+        } else {
+            ges->signal = gei->status;
+        }
+#else
+        if (WIFEXITED(gei->status)) {
+            ges->exit = WEXITSTATUS(gei->status);
+        } else if (WIFSIGNALED(gei->status)) {
+            ges->signal = WTERMSIG(gei->status);
+        }
+#endif
+        QTAILQ_REMOVE(&guest_exec_state.processes, gei, next);
+        g_free(gei);
+    }
+
+    return ges;
+}
+
+/* Get environment variables or arguments array for execve(). */
+static char **guest_exec_get_args(const strList *entry, bool log)
+{
+    const strList *it;
+    int count = 1, i = 0;  /* reserve for NULL terminator */
+    char **args;
+    char *str; /* for logging array of arguments */
+    size_t str_size = 1;
+
+    for (it = entry; it != NULL; it = it->next) {
+        count++;
+        str_size += 1 + strlen(it->value);
+    }
+
+    str = g_malloc(str_size);
+    *str = 0;
+    args = g_malloc(count * sizeof(char *));
+    for (it = entry; it != NULL; it = it->next) {
+        args[i++] = it->value;
+        pstrcat(str, str_size, it->value);
+        if (it->next) {
+            pstrcat(str, str_size, " ");
+        }
+    }
+    args[i] = NULL;
+
+    if (log) {
+        slog("guest-exec called: \"%s\"", str);
+    }
+    g_free(str);
+
+    return args;
+}
+
+static void guest_exec_child_watch(GPid pid, gint status, gpointer data)
+{
+    GuestExecInfo *gei = (GuestExecInfo *)data;
+
+    g_debug("guest_exec_child_watch called, pid: %u, status: %u",
+            (uint32_t)pid, (uint32_t)status);
+
+    gei->status = status;
+    gei->finished = true;
+
+    g_spawn_close_pid(pid);
+}
+
+GuestExec *qmp_guest_exec(const char *path,
+                       bool has_arg, strList *arg,
+                       bool has_env, strList *env,
+                       bool has_inp_data, const char *inp_data,
+                       bool has_capture_output, bool capture_output,
+                       Error **err)
+{
+    GPid pid;
+    GuestExec *ge = NULL;
+    GuestExecInfo *gei;
+    char **argv, **envp;
+    strList arglist;
+    gboolean ret;
+    GError *gerr = NULL;
+
+    arglist.value = (char *)path;
+    arglist.next = has_arg ? arg : NULL;
+
+    argv = guest_exec_get_args(&arglist, true);
+    envp = guest_exec_get_args(has_env ? env : NULL, false);
+
+    ret = g_spawn_async_with_pipes(NULL, argv, envp,
+            G_SPAWN_SEARCH_PATH |
+            G_SPAWN_DO_NOT_REAP_CHILD |
+            G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL,
+            NULL, NULL, &pid, NULL, NULL, NULL, &gerr);
+    if (!ret) {
+        error_setg(err, QERR_QGA_COMMAND_FAILED, gerr->message);
+        g_error_free(gerr);
+        goto done;
+    }
+
+    ge = g_malloc(sizeof(*ge));
+    ge->pid = (int64_t)pid;
+
+    gei = guest_exec_info_add(pid);
+    g_child_watch_add(pid, guest_exec_child_watch, gei);
+
+done:
+    g_free(argv);
+    g_free(envp);
+
+    return ge;
+}
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index 82894c6..ca9a633 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -930,3 +930,60 @@
 ##
 { 'command': 'guest-get-memory-block-info',
   'returns': 'GuestMemoryBlockInfo' }
+
+##
+# @guest-exec-status
+#
+# Check status of process associated with PID retrieved via guest-exec.
+# Reap the process and associated metadata if it has exited.
+#
+# @pid: pid returned from guest-exec
+#
+# Returns: GuestExecStatus on success.  If a child process exited, "exit" is set
+#          to the exit code.  If a child process was killed by a signal,
+#          "signal" is set to the signal number. For Windows guest, "signal" is
+#          actually an unhandled exception code. If a child process is still
+#          running, both "exit" and "signal" are set to -1. If a guest cannot
+#          reliably detect exit signals, "signal" will be -1.
+#          'out-data' and 'err-data' contains captured data when guest-exec was
+#          called with 'capture-output' flag.
+#
+# Since: 2.5
+##
+{ 'struct': 'GuestExecStatus',
+  'data': { 'exit': 'int', 'signal': 'int',
+            '*out-data': 'str', '*err-data': 'str' }}
+
+{ 'command': 'guest-exec-status',
+  'data':    { 'pid': 'int' },
+  'returns': 'GuestExecStatus' }
+
+##
+# @GuestExec:
+# @pid: pid of child process in guest OS
+#
+#Since: 2.5
+##
+{ 'struct': 'GuestExec',
+  'data': { 'pid': 'int'} }
+
+##
+# @guest-exec:
+#
+# Execute a command in the guest
+#
+# @path: path or executable name to execute
+# @arg: #optional argument list to pass to executable
+# @env: #optional environment variables to pass to executable
+# @inp-data: #optional data to be passed to process stdin (base64 encoded)
+# @capture-output: #optional bool flags to enable capture of
+#                  stdout/stderr of running process
+#
+# Returns: PID on success.
+#
+# Since: 2.5
+##
+{ 'command': 'guest-exec',
+  'data':    { 'path': 'str', '*arg': ['str'], '*env': ['str'],
+               '*inp-data': 'str', '*capture-output': 'bool' },
+  'returns': 'GuestExec' }
-- 
2.1.4