qga/commands.c - qemu - Git at Google

 /*
  * QEMU Guest Agent common/cross-platform command implementations
  *
  * Copyright IBM Corp. 2012
  *
  * Authors:
  *  Michael Roth      <mdroth@linux.vnet.ibm.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  * See the COPYING file in the top-level directory.
  */

 #include "qemu/osdep.h"
 #include "qga/guest-agent-core.h"
 #include "qga-qmp-commands.h"
 #include "qapi/qmp/qerror.h"
 #include "qemu/base64.h"
 #include "qemu/cutils.h"
 #include "qemu/atomic.h"

 /* Maximum captured guest-exec out_data/err_data - 16MB */
 #define GUEST_EXEC_MAX_OUTPUT (16*1024*1024)
 /* Allocation and I/O buffer for reading guest-exec out_data/err_data - 4KB */
 #define GUEST_EXEC_IO_SIZE (4*1024)

 /* Note: in some situations, like with the fsfreeze, logging may be
  * temporarilly disabled. if it is necessary that a command be able
  * to log for accounting purposes, check ga_logging_enabled() beforehand,
  * and use the QERR_QGA_LOGGING_DISABLED to generate an error
  */
 void slog(const gchar *fmt, ...)
 {
     va_list ap;

     va_start(ap, fmt);
     g_logv("syslog", G_LOG_LEVEL_INFO, fmt, ap);
     va_end(ap);
 }

 int64_t qmp_guest_sync_delimited(int64_t id, Error **errp)
 {
     ga_set_response_delimited(ga_state);
     return id;
 }

 int64_t qmp_guest_sync(int64_t id, Error **errp)
 {
     return id;
 }

 void qmp_guest_ping(Error **errp)
 {
     slog("guest-ping called");
 }

 static void qmp_command_info(QmpCommand *cmd, void *opaque)
 {
     GuestAgentInfo *info = opaque;
     GuestAgentCommandInfo *cmd_info;
     GuestAgentCommandInfoList *cmd_info_list;

     cmd_info = g_new0(GuestAgentCommandInfo, 1);
     cmd_info->name = g_strdup(qmp_command_name(cmd));
     cmd_info->enabled = qmp_command_is_enabled(cmd);
     cmd_info->success_response = qmp_has_success_response(cmd);

     cmd_info_list = g_new0(GuestAgentCommandInfoList, 1);
     cmd_info_list->value = cmd_info;
     cmd_info_list->next = info->supported_commands;
     info->supported_commands = cmd_info_list;
 }

 struct GuestAgentInfo *qmp_guest_info(Error **errp)
 {
     GuestAgentInfo *info = g_new0(GuestAgentInfo, 1);

     info->version = g_strdup(QEMU_VERSION);
     qmp_for_each_command(&ga_commands, qmp_command_info, info);
     return info;
 }

 struct GuestExecIOData {
     guchar *data;
     gsize size;
     gsize length;
     bool closed;
     bool truncated;
     const char *name;
 };
 typedef struct GuestExecIOData GuestExecIOData;

 struct GuestExecInfo {
     GPid pid;
     int64_t pid_numeric;
     gint status;
     bool has_output;
     bool finished;
     GuestExecIOData in;
     GuestExecIOData out;
     GuestExecIOData err;
     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 int64_t gpid_to_int64(GPid pid)
 {
 #ifdef G_OS_WIN32
     return GetProcessId(pid);
 #else
     return (int64_t)pid;
 #endif
 }

 static GuestExecInfo *guest_exec_info_add(GPid pid)
 {
     GuestExecInfo *gei;

     gei = g_new0(GuestExecInfo, 1);
     gei->pid = pid;
     gei->pid_numeric = gpid_to_int64(pid);
     QTAILQ_INSERT_TAIL(&guest_exec_state.processes, gei, next);

     return gei;
 }

 static GuestExecInfo *guest_exec_info_find(int64_t pid_numeric)
 {
     GuestExecInfo *gei;

     QTAILQ_FOREACH(gei, &guest_exec_state.processes, next) {
         if (gei->pid_numeric == pid_numeric) {
             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(pid);
     if (gei == NULL) {
         error_setg(err, QERR_INVALID_PARAMETER, "pid");
         return NULL;
     }

     ges = g_new0(GuestExecStatus, 1);

     bool finished = atomic_mb_read(&gei->finished);

     /* need to wait till output channels are closed
      * to be sure we captured all output at this point */
     if (gei->has_output) {
         finished = finished && atomic_mb_read(&gei->out.closed);
         finished = finished && atomic_mb_read(&gei->err.closed);
     }

     ges->exited = finished;
     if (finished) {
         /* Glib has no portable way to parse exit status.
          * On UNIX, we can get either exit code from normal termination
          * or signal number.
          * On Windows, it is either the same exit code or the exception
          * value for an unhandled exception that caused the process
          * to terminate.
          * See MSDN for GetExitCodeProcess() and ntstatus.h for possible
          * well-known codes, e.g. C0000005 ACCESS_DENIED - analog of SIGSEGV
          * References:
          *   https://msdn.microsoft.com/en-us/library/windows/desktop/ms683189(v=vs.85).aspx
          *   https://msdn.microsoft.com/en-us/library/aa260331(v=vs.60).aspx
          */
 #ifdef G_OS_WIN32
         /* Additionally WIN32 does not provide any additional information
          * on whether the child exited or terminated via signal.
          * We use this simple range check to distinguish application exit code
          * (usually value less then 256) and unhandled exception code with
          * ntstatus (always value greater then 0xC0000005). */
         if ((uint32_t)gei->status < 0xC0000000U) {
             ges->has_exitcode = true;
             ges->exitcode = gei->status;
         } else {
             ges->has_signal = true;
             ges->signal = gei->status;
         }
 #else
         if (WIFEXITED(gei->status)) {
             ges->has_exitcode = true;
             ges->exitcode = WEXITSTATUS(gei->status);
         } else if (WIFSIGNALED(gei->status)) {
             ges->has_signal = true;
             ges->signal = WTERMSIG(gei->status);
         }
 #endif
         if (gei->out.length > 0) {
             ges->has_out_data = true;
             ges->out_data = g_base64_encode(gei->out.data, gei->out.length);
             g_free(gei->out.data);
             ges->has_out_truncated = gei->out.truncated;
         }

         if (gei->err.length > 0) {
             ges->has_err_data = true;
             ges->err_data = g_base64_encode(gei->err.data, gei->err.length);
             g_free(gei->err.data);
             ges->has_err_truncated = gei->err.truncated;
         }

         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: %d, status: %u",
             (int32_t)gpid_to_int64(pid), (uint32_t)status);

     gei->status = status;
     atomic_mb_set(&gei->finished, true);

     g_spawn_close_pid(pid);
 }

 /** Reset ignored signals back to default. */
 static void guest_exec_task_setup(gpointer data)
 {
 #if !defined(G_OS_WIN32)
     struct sigaction sigact;

     memset(&sigact, 0, sizeof(struct sigaction));
     sigact.sa_handler = SIG_DFL;

     if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
         slog("sigaction() failed to reset child process's SIGPIPE: %s",
              strerror(errno));
     }
 #endif
 }

 static gboolean guest_exec_input_watch(GIOChannel *ch,
         GIOCondition cond, gpointer p_)
 {
     GuestExecIOData *p = (GuestExecIOData *)p_;
     gsize bytes_written = 0;
     GIOStatus status;
     GError *gerr = NULL;

     /* nothing left to write */
     if (p->size == p->length) {
         goto done;
     }

     status = g_io_channel_write_chars(ch, (gchar *)p->data + p->length,
             p->size - p->length, &bytes_written, &gerr);

     /* can be not 0 even if not G_IO_STATUS_NORMAL */
     if (bytes_written != 0) {
         p->length += bytes_written;
     }

     /* continue write, our callback will be called again */
     if (status == G_IO_STATUS_NORMAL || status == G_IO_STATUS_AGAIN) {
         return true;
     }

     if (gerr) {
         g_warning("qga: i/o error writing to input_data channel: %s",
                 gerr->message);
         g_error_free(gerr);
     }

 done:
     g_io_channel_shutdown(ch, true, NULL);
     g_io_channel_unref(ch);
     atomic_mb_set(&p->closed, true);
     g_free(p->data);

     return false;
 }

 static gboolean guest_exec_output_watch(GIOChannel *ch,
         GIOCondition cond, gpointer p_)
 {
     GuestExecIOData *p = (GuestExecIOData *)p_;
     gsize bytes_read;
     GIOStatus gstatus;

     if (cond == G_IO_HUP || cond == G_IO_ERR) {
         goto close;
     }

     if (p->size == p->length) {
         gpointer t = NULL;
         if (!p->truncated && p->size < GUEST_EXEC_MAX_OUTPUT) {
             t = g_try_realloc(p->data, p->size + GUEST_EXEC_IO_SIZE);
         }
         if (t == NULL) {
             /* ignore truncated output */
             gchar buf[GUEST_EXEC_IO_SIZE];

             p->truncated = true;
             gstatus = g_io_channel_read_chars(ch, buf, sizeof(buf),
                                               &bytes_read, NULL);
             if (gstatus == G_IO_STATUS_EOF || gstatus == G_IO_STATUS_ERROR) {
                 goto close;
             }

             return true;
         }
         p->size += GUEST_EXEC_IO_SIZE;
         p->data = t;
     }

     /* Calling read API once.
      * On next available data our callback will be called again */
     gstatus = g_io_channel_read_chars(ch, (gchar *)p->data + p->length,
             p->size - p->length, &bytes_read, NULL);
     if (gstatus == G_IO_STATUS_EOF || gstatus == G_IO_STATUS_ERROR) {
         goto close;
     }

     p->length += bytes_read;

     return true;

 close:
     g_io_channel_shutdown(ch, true, NULL);
     g_io_channel_unref(ch);
     atomic_mb_set(&p->closed, true);
     return false;
 }

 GuestExec *qmp_guest_exec(const char *path,
                        bool has_arg, strList *arg,
                        bool has_env, strList *env,
                        bool has_input_data, const char *input_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;
     gint in_fd, out_fd, err_fd;
     GIOChannel *in_ch, *out_ch, *err_ch;
     GSpawnFlags flags;
     bool has_output = (has_capture_output && capture_output);
     uint8_t *input = NULL;
     size_t ninput = 0;

     arglist.value = (char *)path;
     arglist.next = has_arg ? arg : NULL;

     if (has_input_data) {
         input = qbase64_decode(input_data, -1, &ninput, err);
         if (!input) {
             return NULL;
         }
     }

     argv = guest_exec_get_args(&arglist, true);
     envp = has_env ? guest_exec_get_args(env, false) : NULL;

     flags = G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD;
 #if GLIB_CHECK_VERSION(2, 33, 2)
     flags |= G_SPAWN_SEARCH_PATH_FROM_ENVP;
 #endif
     if (!has_output) {
         flags |= G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL;
     }

     ret = g_spawn_async_with_pipes(NULL, argv, envp, flags,
             guest_exec_task_setup, NULL, &pid, has_input_data ? &in_fd : NULL,
             has_output ? &out_fd : NULL, has_output ? &err_fd : NULL, &gerr);
     if (!ret) {
         error_setg(err, QERR_QGA_COMMAND_FAILED, gerr->message);
         g_error_free(gerr);
         goto done;
     }

     ge = g_new0(GuestExec, 1);
     ge->pid = gpid_to_int64(pid);

     gei = guest_exec_info_add(pid);
     gei->has_output = has_output;
     g_child_watch_add(pid, guest_exec_child_watch, gei);

     if (has_input_data) {
         gei->in.data = input;
         gei->in.size = ninput;
 #ifdef G_OS_WIN32
         in_ch = g_io_channel_win32_new_fd(in_fd);
 #else
         in_ch = g_io_channel_unix_new(in_fd);
 #endif
         g_io_channel_set_encoding(in_ch, NULL, NULL);
         g_io_channel_set_buffered(in_ch, false);
         g_io_channel_set_flags(in_ch, G_IO_FLAG_NONBLOCK, NULL);
         g_io_channel_set_close_on_unref(in_ch, true);
         g_io_add_watch(in_ch, G_IO_OUT, guest_exec_input_watch, &gei->in);
     }

     if (has_output) {
 #ifdef G_OS_WIN32
         out_ch = g_io_channel_win32_new_fd(out_fd);
         err_ch = g_io_channel_win32_new_fd(err_fd);
 #else
         out_ch = g_io_channel_unix_new(out_fd);
         err_ch = g_io_channel_unix_new(err_fd);
 #endif
         g_io_channel_set_encoding(out_ch, NULL, NULL);
         g_io_channel_set_encoding(err_ch, NULL, NULL);
         g_io_channel_set_buffered(out_ch, false);
         g_io_channel_set_buffered(err_ch, false);
         g_io_channel_set_close_on_unref(out_ch, true);
         g_io_channel_set_close_on_unref(err_ch, true);
         g_io_add_watch(out_ch, G_IO_IN | G_IO_HUP,
                 guest_exec_output_watch, &gei->out);
         g_io_add_watch(err_ch, G_IO_IN | G_IO_HUP,
                 guest_exec_output_watch, &gei->err);
     }

 done:
     g_free(argv);
     g_free(envp);

     return ge;
 }

 /* Convert GuestFileWhence (either a raw integer or an enum value) into
  * the guest's SEEK_ constants.  */
 int ga_parse_whence(GuestFileWhence *whence, Error **errp)
 {
     /* Exploit the fact that we picked values to match QGA_SEEK_*. */
     if (whence->type == QTYPE_QSTRING) {
         whence->type = QTYPE_QINT;
         whence->u.value = whence->u.name;
     }
     switch (whence->u.value) {
     case QGA_SEEK_SET:
         return SEEK_SET;
     case QGA_SEEK_CUR:
         return SEEK_CUR;
     case QGA_SEEK_END:
         return SEEK_END;
     }
     error_setg(errp, "invalid whence code %"PRId64, whence->u.value);
     return -1;
 }
	/*
	* QEMU Guest Agent common/cross-platform command implementations
	*
	* Copyright IBM Corp. 2012
	*
	* Authors:
	* Michael Roth <mdroth@linux.vnet.ibm.com>
	*
	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	* See the COPYING file in the top-level directory.
	*/

	#include "qemu/osdep.h"
	#include "qga/guest-agent-core.h"
	#include "qga-qmp-commands.h"
	#include "qapi/qmp/qerror.h"
	#include "qemu/base64.h"
	#include "qemu/cutils.h"
	#include "qemu/atomic.h"

	/* Maximum captured guest-exec out_data/err_data - 16MB */
	#define GUEST_EXEC_MAX_OUTPUT (1610241024)
	/* Allocation and I/O buffer for reading guest-exec out_data/err_data - 4KB */
	#define GUEST_EXEC_IO_SIZE (4*1024)

	/* Note: in some situations, like with the fsfreeze, logging may be
	* temporarilly disabled. if it is necessary that a command be able
	* to log for accounting purposes, check ga_logging_enabled() beforehand,
	* and use the QERR_QGA_LOGGING_DISABLED to generate an error
	*/
	void slog(const gchar *fmt, ...)
	{
	va_list ap;

	va_start(ap, fmt);
	g_logv("syslog", G_LOG_LEVEL_INFO, fmt, ap);
	va_end(ap);
	}

	int64_t qmp_guest_sync_delimited(int64_t id, Error **errp)
	{
	ga_set_response_delimited(ga_state);
	return id;
	}

	int64_t qmp_guest_sync(int64_t id, Error **errp)
	{
	return id;
	}

	void qmp_guest_ping(Error **errp)
	{
	slog("guest-ping called");
	}

	static void qmp_command_info(QmpCommand cmd, void opaque)
	{
	GuestAgentInfo *info = opaque;
	GuestAgentCommandInfo *cmd_info;
	GuestAgentCommandInfoList *cmd_info_list;

	cmd_info = g_new0(GuestAgentCommandInfo, 1);
	cmd_info->name = g_strdup(qmp_command_name(cmd));
	cmd_info->enabled = qmp_command_is_enabled(cmd);
	cmd_info->success_response = qmp_has_success_response(cmd);

	cmd_info_list = g_new0(GuestAgentCommandInfoList, 1);
	cmd_info_list->value = cmd_info;
	cmd_info_list->next = info->supported_commands;
	info->supported_commands = cmd_info_list;
	}

	struct GuestAgentInfo qmp_guest_info(Error *errp)
	{
	GuestAgentInfo *info = g_new0(GuestAgentInfo, 1);

	info->version = g_strdup(QEMU_VERSION);
	qmp_for_each_command(&ga_commands, qmp_command_info, info);
	return info;
	}

	struct GuestExecIOData {
	guchar *data;
	gsize size;
	gsize length;
	bool closed;
	bool truncated;
	const char *name;
	};
	typedef struct GuestExecIOData GuestExecIOData;

	struct GuestExecInfo {
	GPid pid;
	int64_t pid_numeric;
	gint status;
	bool has_output;
	bool finished;
	GuestExecIOData in;
	GuestExecIOData out;
	GuestExecIOData err;
	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 int64_t gpid_to_int64(GPid pid)
	{
	#ifdef G_OS_WIN32
	return GetProcessId(pid);
	#else
	return (int64_t)pid;
	#endif
	}

	static GuestExecInfo *guest_exec_info_add(GPid pid)
	{
	GuestExecInfo *gei;

	gei = g_new0(GuestExecInfo, 1);
	gei->pid = pid;
	gei->pid_numeric = gpid_to_int64(pid);
	QTAILQ_INSERT_TAIL(&guest_exec_state.processes, gei, next);

	return gei;
	}

	static GuestExecInfo *guest_exec_info_find(int64_t pid_numeric)
	{
	GuestExecInfo *gei;

	QTAILQ_FOREACH(gei, &guest_exec_state.processes, next) {
	if (gei->pid_numeric == pid_numeric) {
	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(pid);
	if (gei == NULL) {
	error_setg(err, QERR_INVALID_PARAMETER, "pid");
	return NULL;
	}

	ges = g_new0(GuestExecStatus, 1);

	bool finished = atomic_mb_read(&gei->finished);

	/* need to wait till output channels are closed
	* to be sure we captured all output at this point */
	if (gei->has_output) {
	finished = finished && atomic_mb_read(&gei->out.closed);
	finished = finished && atomic_mb_read(&gei->err.closed);
	}

	ges->exited = finished;
	if (finished) {
	/* Glib has no portable way to parse exit status.
	* On UNIX, we can get either exit code from normal termination
	* or signal number.
	* On Windows, it is either the same exit code or the exception
	* value for an unhandled exception that caused the process
	* to terminate.
	* See MSDN for GetExitCodeProcess() and ntstatus.h for possible
	* well-known codes, e.g. C0000005 ACCESS_DENIED - analog of SIGSEGV
	* References:
	* https://msdn.microsoft.com/en-us/library/windows/desktop/ms683189(v=vs.85).aspx
	* https://msdn.microsoft.com/en-us/library/aa260331(v=vs.60).aspx
	*/
	#ifdef G_OS_WIN32
	/* Additionally WIN32 does not provide any additional information
	* on whether the child exited or terminated via signal.
	* We use this simple range check to distinguish application exit code
	* (usually value less then 256) and unhandled exception code with
	* ntstatus (always value greater then 0xC0000005). */
	if ((uint32_t)gei->status < 0xC0000000U) {
	ges->has_exitcode = true;
	ges->exitcode = gei->status;
	} else {
	ges->has_signal = true;
	ges->signal = gei->status;
	}
	#else
	if (WIFEXITED(gei->status)) {
	ges->has_exitcode = true;
	ges->exitcode = WEXITSTATUS(gei->status);
	} else if (WIFSIGNALED(gei->status)) {
	ges->has_signal = true;
	ges->signal = WTERMSIG(gei->status);
	}
	#endif
	if (gei->out.length > 0) {
	ges->has_out_data = true;
	ges->out_data = g_base64_encode(gei->out.data, gei->out.length);
	g_free(gei->out.data);
	ges->has_out_truncated = gei->out.truncated;
	}

	if (gei->err.length > 0) {
	ges->has_err_data = true;
	ges->err_data = g_base64_encode(gei->err.data, gei->err.length);
	g_free(gei->err.data);
	ges->has_err_truncated = gei->err.truncated;
	}

	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: %d, status: %u",
	(int32_t)gpid_to_int64(pid), (uint32_t)status);

	gei->status = status;
	atomic_mb_set(&gei->finished, true);

	g_spawn_close_pid(pid);
	}

	/** Reset ignored signals back to default. */
	static void guest_exec_task_setup(gpointer data)
	{
	#if !defined(G_OS_WIN32)
	struct sigaction sigact;

	memset(&sigact, 0, sizeof(struct sigaction));
	sigact.sa_handler = SIG_DFL;

	if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
	slog("sigaction() failed to reset child process's SIGPIPE: %s",
	strerror(errno));
	}
	#endif
	}

	static gboolean guest_exec_input_watch(GIOChannel *ch,
	GIOCondition cond, gpointer p_)
	{
	GuestExecIOData p = (GuestExecIOData )p_;
	gsize bytes_written = 0;
	GIOStatus status;
	GError *gerr = NULL;

	/* nothing left to write */
	if (p->size == p->length) {
	goto done;
	}

	status = g_io_channel_write_chars(ch, (gchar *)p->data + p->length,
	p->size - p->length, &bytes_written, &gerr);

	/* can be not 0 even if not G_IO_STATUS_NORMAL */
	if (bytes_written != 0) {
	p->length += bytes_written;
	}

	/* continue write, our callback will be called again */
	if (status == G_IO_STATUS_NORMAL \|\| status == G_IO_STATUS_AGAIN) {
	return true;
	}

	if (gerr) {
	g_warning("qga: i/o error writing to input_data channel: %s",
	gerr->message);
	g_error_free(gerr);
	}

	done:
	g_io_channel_shutdown(ch, true, NULL);
	g_io_channel_unref(ch);
	atomic_mb_set(&p->closed, true);
	g_free(p->data);

	return false;
	}

	static gboolean guest_exec_output_watch(GIOChannel *ch,
	GIOCondition cond, gpointer p_)
	{
	GuestExecIOData p = (GuestExecIOData )p_;
	gsize bytes_read;
	GIOStatus gstatus;

	if (cond == G_IO_HUP \|\| cond == G_IO_ERR) {
	goto close;
	}

	if (p->size == p->length) {
	gpointer t = NULL;
	if (!p->truncated && p->size < GUEST_EXEC_MAX_OUTPUT) {
	t = g_try_realloc(p->data, p->size + GUEST_EXEC_IO_SIZE);
	}
	if (t == NULL) {
	/* ignore truncated output */
	gchar buf[GUEST_EXEC_IO_SIZE];

	p->truncated = true;
	gstatus = g_io_channel_read_chars(ch, buf, sizeof(buf),
	&bytes_read, NULL);
	if (gstatus == G_IO_STATUS_EOF \|\| gstatus == G_IO_STATUS_ERROR) {
	goto close;
	}

	return true;
	}
	p->size += GUEST_EXEC_IO_SIZE;
	p->data = t;
	}

	/* Calling read API once.
	* On next available data our callback will be called again */
	gstatus = g_io_channel_read_chars(ch, (gchar *)p->data + p->length,
	p->size - p->length, &bytes_read, NULL);
	if (gstatus == G_IO_STATUS_EOF \|\| gstatus == G_IO_STATUS_ERROR) {
	goto close;
	}

	p->length += bytes_read;

	return true;

	close:
	g_io_channel_shutdown(ch, true, NULL);
	g_io_channel_unref(ch);
	atomic_mb_set(&p->closed, true);
	return false;
	}

	GuestExec qmp_guest_exec(const char path,
	bool has_arg, strList *arg,
	bool has_env, strList *env,
	bool has_input_data, const char *input_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;
	gint in_fd, out_fd, err_fd;
	GIOChannel in_ch, out_ch, *err_ch;
	GSpawnFlags flags;
	bool has_output = (has_capture_output && capture_output);
	uint8_t *input = NULL;
	size_t ninput = 0;

	arglist.value = (char *)path;
	arglist.next = has_arg ? arg : NULL;

	if (has_input_data) {
	input = qbase64_decode(input_data, -1, &ninput, err);
	if (!input) {
	return NULL;
	}
	}

	argv = guest_exec_get_args(&arglist, true);
	envp = has_env ? guest_exec_get_args(env, false) : NULL;

	flags = G_SPAWN_SEARCH_PATH \| G_SPAWN_DO_NOT_REAP_CHILD;
	#if GLIB_CHECK_VERSION(2, 33, 2)
	flags \|= G_SPAWN_SEARCH_PATH_FROM_ENVP;
	#endif
	if (!has_output) {
	flags \|= G_SPAWN_STDOUT_TO_DEV_NULL \| G_SPAWN_STDERR_TO_DEV_NULL;
	}

	ret = g_spawn_async_with_pipes(NULL, argv, envp, flags,
	guest_exec_task_setup, NULL, &pid, has_input_data ? &in_fd : NULL,
	has_output ? &out_fd : NULL, has_output ? &err_fd : NULL, &gerr);
	if (!ret) {
	error_setg(err, QERR_QGA_COMMAND_FAILED, gerr->message);
	g_error_free(gerr);
	goto done;
	}

	ge = g_new0(GuestExec, 1);
	ge->pid = gpid_to_int64(pid);

	gei = guest_exec_info_add(pid);
	gei->has_output = has_output;
	g_child_watch_add(pid, guest_exec_child_watch, gei);

	if (has_input_data) {
	gei->in.data = input;
	gei->in.size = ninput;
	#ifdef G_OS_WIN32
	in_ch = g_io_channel_win32_new_fd(in_fd);
	#else
	in_ch = g_io_channel_unix_new(in_fd);
	#endif
	g_io_channel_set_encoding(in_ch, NULL, NULL);
	g_io_channel_set_buffered(in_ch, false);
	g_io_channel_set_flags(in_ch, G_IO_FLAG_NONBLOCK, NULL);
	g_io_channel_set_close_on_unref(in_ch, true);
	g_io_add_watch(in_ch, G_IO_OUT, guest_exec_input_watch, &gei->in);
	}

	if (has_output) {
	#ifdef G_OS_WIN32
	out_ch = g_io_channel_win32_new_fd(out_fd);
	err_ch = g_io_channel_win32_new_fd(err_fd);
	#else
	out_ch = g_io_channel_unix_new(out_fd);
	err_ch = g_io_channel_unix_new(err_fd);
	#endif
	g_io_channel_set_encoding(out_ch, NULL, NULL);
	g_io_channel_set_encoding(err_ch, NULL, NULL);
	g_io_channel_set_buffered(out_ch, false);
	g_io_channel_set_buffered(err_ch, false);
	g_io_channel_set_close_on_unref(out_ch, true);
	g_io_channel_set_close_on_unref(err_ch, true);
	g_io_add_watch(out_ch, G_IO_IN \| G_IO_HUP,
	guest_exec_output_watch, &gei->out);
	g_io_add_watch(err_ch, G_IO_IN \| G_IO_HUP,
	guest_exec_output_watch, &gei->err);
	}

	done:
	g_free(argv);
	g_free(envp);

	return ge;
	}

	/* Convert GuestFileWhence (either a raw integer or an enum value) into
	* the guest's SEEK_ constants. */
	int ga_parse_whence(GuestFileWhence whence, Error *errp)
	{
	/* Exploit the fact that we picked values to match QGA_SEEK_. /
	if (whence->type == QTYPE_QSTRING) {
	whence->type = QTYPE_QINT;
	whence->u.value = whence->u.name;
	}
	switch (whence->u.value) {
	case QGA_SEEK_SET:
	return SEEK_SET;
	case QGA_SEEK_CUR:
	return SEEK_CUR;
	case QGA_SEEK_END:
	return SEEK_END;
	}
	error_setg(errp, "invalid whence code %"PRId64, whence->u.value);
	return -1;
	}