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Re: [Qemu-devel] [PATCH 5/5] qga: guest-exec simple stdin/stdout/stderr
From: |
Michael Roth |
Subject: |
Re: [Qemu-devel] [PATCH 5/5] qga: guest-exec simple stdin/stdout/stderr redirection |
Date: |
Mon, 12 Oct 2015 23:05:08 -0500 |
User-agent: |
alot/0.3.6 |
Quoting Denis V. Lunev (2015-10-07 05:32:21)
> From: Yuri Pudgorodskiy <address@hidden>
>
> Implemented with base64-encoded strings in qga json protocol.
> Glib portable GIOChannel is used for data I/O.
>
> Optinal stdin parameter of guest-exec command is now used as
> stdin content for spawned subprocess.
>
> If capture-output bool flag is specified, guest-exec redirects out/err
> file descriptiors internally to pipes and collects subprocess
> output.
>
> Guest-exe-status is modified to return this collected data to requestor
> in base64 encoding.
>
> Signed-off-by: Yuri Pudgorodskiy <address@hidden>
> Signed-off-by: Denis V. Lunev <address@hidden>
> CC: Michael Roth <address@hidden>
For capture-output mode, win32 guests appear to spin forever on EOF and
the exec'd process never gets reaped as a result. The below patch
seems to fix this issue. If this seems reasonable I can squash it
into the patch directly, but you might want to check I didn't break one
of your !capture-output use-cases (I assume this is still mainly focused
on redirecting to virtio-serial for stdio).
Another issue I noticed is that glib relies on
gspawn-win{32,64}-helper[-console].exe for g_spawn*() interface, so guest
exec won't work for .msi distributables unless those are added. This can
probably be addressed during soft-freeze though.
diff --git a/qga/commands.c b/qga/commands.c
index 27c06c5..fbf8abd 100644
--- a/qga/commands.c
+++ b/qga/commands.c
@@ -318,7 +318,7 @@ static gboolean guest_exec_output_watch(GIOChannel *ch,
struct GuestExecIOData *p = (struct GuestExecIOData *)p_;
gsize bytes_read = 0;
- if (cond == G_IO_HUP) {
+ if (cond == G_IO_HUP || cond == G_IO_ERR) {
g_io_channel_unref(ch);
g_atomic_int_set(&p->closed, 1);
return FALSE;
@@ -330,10 +330,18 @@ static gboolean guest_exec_output_watch(GIOChannel *ch,
t = g_try_realloc(p->data, p->size + GUEST_EXEC_IO_SIZE);
}
if (t == NULL) {
+ GIOStatus gstatus = 0;
p->truncated = true;
/* ignore truncated output */
gchar buf[GUEST_EXEC_IO_SIZE];
- g_io_channel_read_chars(ch, buf, sizeof(buf), &bytes_read, NULL);
+ gstatus = g_io_channel_read_chars(ch, buf, sizeof(buf),
+ &bytes_read, NULL);
+ if (gstatus == G_IO_STATUS_EOF || gstatus == G_IO_STATUS_ERROR) {
+ g_io_channel_unref(ch);
+ g_atomic_int_set(&p->closed, 1);
+ return false;
+ }
+
return TRUE;
}
p->size += GUEST_EXEC_IO_SIZE;
@@ -342,8 +350,14 @@ static gboolean guest_exec_output_watch(GIOChannel *ch,
/* Calling read API once.
* On next available data our callback will be called again */
- g_io_channel_read_chars(ch, (gchar *)p->data + p->length,
+ GIOStatus gstatus = 0;
+ 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) {
+ g_io_channel_unref(ch);
+ g_atomic_int_set(&p->closed, 1);
+ return false;
+ }
> ---
> qga/commands.c | 175
> ++++++++++++++++++++++++++++++++++++++++++++++++---
> qga/qapi-schema.json | 11 +++-
> 2 files changed, 175 insertions(+), 11 deletions(-)
>
> diff --git a/qga/commands.c b/qga/commands.c
> index b487324..740423f 100644
> --- a/qga/commands.c
> +++ b/qga/commands.c
> @@ -15,6 +15,11 @@
> #include "qga-qmp-commands.h"
> #include "qapi/qmp/qerror.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,
> @@ -71,10 +76,23 @@ struct GuestAgentInfo *qmp_guest_info(Error **errp)
> return info;
> }
>
> +struct GuestExecIOData {
> + guchar *data;
> + gsize size;
> + gsize length;
> + gint closed;
> + bool truncated;
> + const char *name;
> +};
> +
> struct GuestExecInfo {
> GPid pid;
> gint status;
> - bool finished;
> + bool has_output;
> + gint finished;
> + struct GuestExecIOData in;
> + struct GuestExecIOData out;
> + struct GuestExecIOData err;
> QTAILQ_ENTRY(GuestExecInfo) next;
> };
> typedef struct GuestExecInfo GuestExecInfo;
> @@ -123,9 +141,18 @@ GuestExecStatus *qmp_guest_exec_status(int64_t pid,
> Error **err)
> }
>
> ges = g_new0(GuestExecStatus, 1);
> - ges->exited = gei->finished;
>
> - if (gei->finished) {
> + bool finished = g_atomic_int_get(&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 && g_atomic_int_get(&gei->out.closed);
> + finished = finished && g_atomic_int_get(&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.
> @@ -160,6 +187,20 @@ GuestExecStatus *qmp_guest_exec_status(int64_t pid,
> Error **err)
> 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);
> }
> @@ -230,6 +271,85 @@ static void guest_exec_task_setup(gpointer data)
> #endif
> }
>
> +static gboolean guest_exec_input_watch(GIOChannel *ch,
> + GIOCondition cond, gpointer p_)
> +{
> + struct GuestExecIOData *p = (struct 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 inp_data channel: %s",
> + gerr->message);
> + g_error_free(gerr);
> + }
> +
> +done:
> + g_io_channel_shutdown(ch, true, NULL);
> + g_io_channel_unref(ch);
> + g_atomic_int_set(&p->closed, 1);
> + g_free(p->data);
> +
> + return FALSE;
> +}
> +
> +static gboolean guest_exec_output_watch(GIOChannel *ch,
> + GIOCondition cond, gpointer p_)
> +{
> + struct GuestExecIOData *p = (struct GuestExecIOData *)p_;
> + gsize bytes_read = 0;
> +
> + if (cond == G_IO_HUP) {
> + g_io_channel_unref(ch);
> + g_atomic_int_set(&p->closed, 1);
> + return FALSE;
> + }
> +
> + 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) {
> + p->truncated = true;
> + /* ignore truncated output */
> + gchar buf[GUEST_EXEC_IO_SIZE];
> + g_io_channel_read_chars(ch, buf, sizeof(buf), &bytes_read, NULL);
> + 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 */
> + g_io_channel_read_chars(ch, (gchar *)p->data + p->length,
> + p->size - p->length, &bytes_read, NULL);
> +
> + p->length += bytes_read;
> +
> + return TRUE;
> +}
> +
> GuestExec *qmp_guest_exec(const char *path,
> bool has_arg, strList *arg,
> bool has_env, strList *env,
> @@ -244,6 +364,10 @@ GuestExec *qmp_guest_exec(const char *path,
> 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);
>
> arglist.value = (char *)path;
> arglist.next = has_arg ? arg : NULL;
> @@ -251,11 +375,14 @@ GuestExec *qmp_guest_exec(const char *path,
> 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,
> - guest_exec_task_setup, NULL, &pid, NULL, NULL, NULL, &gerr);
> + flags = G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD;
> + 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_inp_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);
> @@ -266,8 +393,40 @@ GuestExec *qmp_guest_exec(const char *path,
> ge->pid = (int64_t)pid;
>
> gei = guest_exec_info_add(pid);
> + gei->has_output = has_output;
> g_child_watch_add(pid, guest_exec_child_watch, gei);
>
> + if (has_inp_data) {
> + gei->in.data = g_base64_decode(inp_data, &gei->in.size);
> +#ifdef G_OS_WIN32
> + in_ch = g_io_channel_win32_new_fd(in_ch);
> +#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_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_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);
> diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
> index da6b64f..6f5ea50 100644
> --- a/qga/qapi-schema.json
> +++ b/qga/qapi-schema.json
> @@ -941,12 +941,17 @@
> # @err-data: #optional base64-encoded stderr of the process
> # Note: @out-data and @err-data are present only
> # if 'capture-output' was specified for 'guest-exec'
> +# @out-truncated: #optional true if stdout was not fully captured
> +# due to size limitation.
> +# @err-truncated: #optional true if stderr was not fully captured
> +# due to size limitation.
> #
> # Since: 2.5
> ##
> { 'struct': 'GuestExecStatus',
> 'data': { 'exited': 'bool', '*exitcode': 'int', '*signal': 'int',
> - '*out-data': 'str', '*err-data': 'str' }}
> + '*out-data': 'str', '*err-data': 'str',
> + '*out-truncated': 'bool', '*err-truncated': 'bool' }}
> ##
> # @guest-exec-status
> #
> @@ -955,9 +960,9 @@
> #
> # @pid: pid returned from guest-exec
> #
> -# Returns: @GuestExecStatus on success.
> +# Returns: GuestExecStatus on success.
> #
> -# Since 2.3
> +# Since 2.5
> ##
> { 'command': 'guest-exec-status',
> 'data': { 'pid': 'int' },
> --
> 2.1.4
>