chardev/char-pty.c | 33 +++++++++++++++++++++++++++++++++ chardev/char.c | 5 +++++ qapi/char.json | 27 ++++++++++++++++++++++++++- qemu-options.hx | 33 +++++++++++++++++++++++++++------ 4 files changed, 91 insertions(+), 7 deletions(-)
Add path option to the pty char backend which will create a symbolic
link to the given path that points to the allocated PTY.
This avoids having to make QMP or HMP monitor queries to find out what
the new PTY device path is.
Based on patch from Paulo Neves:
https://patchew.org/QEMU/1548509635-15776-1-git-send-email-ptsneves@gmail.com/
Tested with the following invocations that the link is created and
removed when qemu stops:
qemu-system-x86_64 -nodefaults -mon chardev=compat_monitor \
-chardev pty,path=test,id=compat_monitor0
qemu-system-x86_64 -nodefaults -monitor pty:test
# check QMP invocation with path set
qemu-system-x86_64 -nodefaults -qmp tcp:localhost:4444,server=on,wait=off
nc localhost 4444
> {"execute": "qmp_capabilities"}
> {"execute": "chardev-add", "arguments": {"id": "bar", "backend": {
"type": "pty", "data": {"path": "test" }}}}
# check QMP invocation with path not set
qemu-system-x86_64 -nodefaults -qmp tcp:localhost:4444,server=on,wait=off
nc localhost 4444
> {"execute": "qmp_capabilities"}
> {"execute": "chardev-add", "arguments": {"id": "bar", "backend": {
"type": "pty", "data": {}}}}
Also tested that when a link path is not passed invocations still work, e.g.:
qemu-system-x86_64 -monitor pty
Co-authored-by: Paulo Neves <ptsneves@gmail.com>
Signed-off-by: Paulo Neves <ptsneves@gmail.com>
[OP: rebase and address original patch review comments]
Signed-off-by: Octavian Purdila <tavip@google.com>
---
Changes since v3:
* update documentation with note about user's resposability to check
and remove the symlink since it can't be removed on crashes or
certain startup errors
* use a dedicated ChardevPty structure instead of relying on
ChardevHostdev
Changes since v2:
* remove NULL path check, g_strdup() allows NULL inputs
Changes since v1:
* Keep the original Signed-off-by from Paulo and add one line
description with further changes
* Update commit message with justification for why the new
functionality is useful
* Don't close master_fd when symlink creation fails to avoid double
close
* Update documentation for clarity
chardev/char-pty.c | 33 +++++++++++++++++++++++++++++++++
chardev/char.c | 5 +++++
qapi/char.json | 27 ++++++++++++++++++++++++++-
qemu-options.hx | 33 +++++++++++++++++++++++++++------
4 files changed, 91 insertions(+), 7 deletions(-)
diff --git a/chardev/char-pty.c b/chardev/char-pty.c
index cc2f7617fe..cbb21b76ae 100644
--- a/chardev/char-pty.c
+++ b/chardev/char-pty.c
@@ -29,6 +29,7 @@
#include "qemu/sockets.h"
#include "qemu/error-report.h"
#include "qemu/module.h"
+#include "qemu/option.h"
#include "qemu/qemu-print.h"
#include "chardev/char-io.h"
@@ -41,6 +42,7 @@ struct PtyChardev {
int connected;
GSource *timer_src;
+ char *path;
};
typedef struct PtyChardev PtyChardev;
@@ -204,6 +206,12 @@ static void char_pty_finalize(Object *obj)
Chardev *chr = CHARDEV(obj);
PtyChardev *s = PTY_CHARDEV(obj);
+ /* unlink symlink */
+ if (s->path) {
+ unlink(s->path);
+ g_free(s->path);
+ }
+
pty_chr_state(chr, 0);
object_unref(OBJECT(s->ioc));
pty_chr_timer_cancel(s);
@@ -330,6 +338,7 @@ static void char_pty_open(Chardev *chr,
int master_fd, slave_fd;
char pty_name[PATH_MAX];
char *name;
+ char *path = backend->u.pty.data->path;
master_fd = qemu_openpty_raw(&slave_fd, pty_name);
if (master_fd < 0) {
@@ -354,12 +363,36 @@ static void char_pty_open(Chardev *chr,
g_free(name);
s->timer_src = NULL;
*be_opened = false;
+
+ /* create symbolic link */
+ if (path) {
+ int res = symlink(pty_name, path);
+
+ if (res != 0) {
+ error_setg_errno(errp, errno, "Failed to create PTY symlink");
+ } else {
+ s->path = g_strdup(path);
+ }
+ }
+}
+
+static void char_pty_parse(QemuOpts *opts, ChardevBackend *backend,
+ Error **errp)
+{
+ const char *path = qemu_opt_get(opts, "path");
+ ChardevPty *pty;
+
+ backend->type = CHARDEV_BACKEND_KIND_PTY;
+ pty = backend->u.pty.data = g_new0(ChardevPty, 1);
+ qemu_chr_parse_common(opts, qapi_ChardevPty_base(pty));
+ pty->path = g_strdup(path);
}
static void char_pty_class_init(ObjectClass *oc, void *data)
{
ChardevClass *cc = CHARDEV_CLASS(oc);
+ cc->parse = char_pty_parse;
cc->open = char_pty_open;
cc->chr_write = char_pty_chr_write;
cc->chr_update_read_handler = pty_chr_update_read_handler;
diff --git a/chardev/char.c b/chardev/char.c
index 3c43fb1278..404c6b8a4f 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -428,6 +428,11 @@ QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename,
qemu_opt_set(opts, "path", p, &error_abort);
return opts;
}
+ if (strstart(filename, "pty:", &p)) {
+ qemu_opt_set(opts, "backend", "pty", &error_abort);
+ qemu_opt_set(opts, "path", p, &error_abort);
+ return opts;
+ }
if (strstart(filename, "tcp:", &p) ||
strstart(filename, "telnet:", &p) ||
strstart(filename, "tn3270:", &p) ||
diff --git a/qapi/char.json b/qapi/char.json
index 777dde55d9..953d519066 100644
--- a/qapi/char.json
+++ b/qapi/char.json
@@ -431,6 +431,20 @@
'base': 'ChardevCommon',
'if': 'CONFIG_SPICE_PROTOCOL' }
+##
+# @ChardevPty:
+#
+# Configuration info for pty implementation.
+#
+# @path: optional path to create a symbolic link that points to the
+# allocated PTY
+#
+# Since: 9.2
+##
+{ 'struct': 'ChardevPty',
+ 'data': { '*path': 'str' },
+ 'base': 'ChardevCommon' }
+
##
# @ChardevBackendKind:
#
@@ -630,6 +644,17 @@
{ 'struct': 'ChardevRingbufWrapper',
'data': { 'data': 'ChardevRingbuf' } }
+
+##
+# @ChardevPtyWrapper:
+#
+# @data: Configuration info for pty chardevs
+#
+# Since: 9.2
+##
+{ 'struct': 'ChardevPtyWrapper',
+ 'data': { 'data': 'ChardevPty' } }
+
##
# @ChardevBackend:
#
@@ -650,7 +675,7 @@
'pipe': 'ChardevHostdevWrapper',
'socket': 'ChardevSocketWrapper',
'udp': 'ChardevUdpWrapper',
- 'pty': 'ChardevCommonWrapper',
+ 'pty': 'ChardevPtyWrapper',
'null': 'ChardevCommonWrapper',
'mux': 'ChardevMuxWrapper',
'msmouse': 'ChardevCommonWrapper',
diff --git a/qemu-options.hx b/qemu-options.hx
index 8ca7f34ef0..08d8f8c559 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3569,7 +3569,7 @@ DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
"-chardev console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
"-chardev serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
#else
- "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
+ "-chardev pty,id=id[,path=path][,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
"-chardev stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
#endif
#ifdef CONFIG_BRLAPI
@@ -3808,12 +3808,22 @@ The available backends are:
``path`` specifies the name of the serial device to open.
-``-chardev pty,id=id``
- Create a new pseudo-terminal on the host and connect to it. ``pty``
- does not take any options.
+``-chardev pty,id=id[,path=path]``
+ Create a new pseudo-terminal on the host and connect to it.
``pty`` is not available on Windows hosts.
+ If ``path`` is specified, QEMU will create a symbolic link at
+ that location which points to the new PTY device.
+
+ This avoids having to make QMP or HMP monitor queries to find out
+ what the new PTY device path is.
+
+ Note that while QEMU will remove the symlink when it exits
+ gracefully, it will not do so in case of crashes or on certain
+ startup errors. It is recommended that the user checks and removes
+ the symlink after qemu terminates to account for this.
+
``-chardev stdio,id=id[,signal=on|off]``
Connect to standard input and standard output of the QEMU process.
@@ -4171,8 +4181,19 @@ SRST
vc:80Cx24C
- ``pty``
- [Linux only] Pseudo TTY (a new PTY is automatically allocated)
+ ``pty[:path]``
+ [Linux only] Pseudo TTY (a new PTY is automatically allocated).
+
+ If ``path`` is specified, QEMU will create a symbolic link at
+ that location which points to the new PTY device.
+
+ This avoids having to make QMP or HMP monitor queries to find
+ out what the new PTY device path is.
+
+ Note that while QEMU will remove the symlink when it exits
+ gracefully, it will not do so in case of crashes or on certain
+ startup errors. It is recommended that the user checks and
+ removes the symlink after qemu terminates to account for this.
``none``
No device is allocated. Note that for machine types which
--
2.46.0.rc2.264.g509ed76dc8-googOn Tue, Aug 6, 2024 at 5:09 AM Octavian Purdila <tavip@google.com> wrote:
> Add path option to the pty char backend which will create a symbolic
> link to the given path that points to the allocated PTY.
>
> This avoids having to make QMP or HMP monitor queries to find out what
> the new PTY device path is.
>
> Based on patch from Paulo Neves:
>
>
> https://patchew.org/QEMU/1548509635-15776-1-git-send-email-ptsneves@gmail.com/
>
> Tested with the following invocations that the link is created and
> removed when qemu stops:
>
> qemu-system-x86_64 -nodefaults -mon chardev=compat_monitor \
> -chardev pty,path=test,id=compat_monitor0
>
> qemu-system-x86_64 -nodefaults -monitor pty:test
>
> # check QMP invocation with path set
> qemu-system-x86_64 -nodefaults -qmp tcp:localhost:4444,server=on,wait=off
> nc localhost 4444
> > {"execute": "qmp_capabilities"}
> > {"execute": "chardev-add", "arguments": {"id": "bar", "backend": {
> "type": "pty", "data": {"path": "test" }}}}
>
> # check QMP invocation with path not set
> qemu-system-x86_64 -nodefaults -qmp tcp:localhost:4444,server=on,wait=off
> nc localhost 4444
> > {"execute": "qmp_capabilities"}
> > {"execute": "chardev-add", "arguments": {"id": "bar", "backend": {
> "type": "pty", "data": {}}}}
>
> Also tested that when a link path is not passed invocations still work,
> e.g.:
>
> qemu-system-x86_64 -monitor pty
>
> Co-authored-by: Paulo Neves <ptsneves@gmail.com>
> Signed-off-by: Paulo Neves <ptsneves@gmail.com>
> [OP: rebase and address original patch review comments]
> Signed-off-by: Octavian Purdila <tavip@google.com>
>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
> Changes since v3:
>
> * update documentation with note about user's resposability to check
> and remove the symlink since it can't be removed on crashes or
> certain startup errors
>
> * use a dedicated ChardevPty structure instead of relying on
> ChardevHostdev
>
> Changes since v2:
>
> * remove NULL path check, g_strdup() allows NULL inputs
>
> Changes since v1:
>
> * Keep the original Signed-off-by from Paulo and add one line
> description with further changes
>
> * Update commit message with justification for why the new
> functionality is useful
>
> * Don't close master_fd when symlink creation fails to avoid double
> close
>
> * Update documentation for clarity
>
> chardev/char-pty.c | 33 +++++++++++++++++++++++++++++++++
> chardev/char.c | 5 +++++
> qapi/char.json | 27 ++++++++++++++++++++++++++-
> qemu-options.hx | 33 +++++++++++++++++++++++++++------
> 4 files changed, 91 insertions(+), 7 deletions(-)
>
> diff --git a/chardev/char-pty.c b/chardev/char-pty.c
> index cc2f7617fe..cbb21b76ae 100644
> --- a/chardev/char-pty.c
> +++ b/chardev/char-pty.c
> @@ -29,6 +29,7 @@
> #include "qemu/sockets.h"
> #include "qemu/error-report.h"
> #include "qemu/module.h"
> +#include "qemu/option.h"
> #include "qemu/qemu-print.h"
>
> #include "chardev/char-io.h"
> @@ -41,6 +42,7 @@ struct PtyChardev {
>
> int connected;
> GSource *timer_src;
> + char *path;
> };
> typedef struct PtyChardev PtyChardev;
>
> @@ -204,6 +206,12 @@ static void char_pty_finalize(Object *obj)
> Chardev *chr = CHARDEV(obj);
> PtyChardev *s = PTY_CHARDEV(obj);
>
> + /* unlink symlink */
> + if (s->path) {
> + unlink(s->path);
> + g_free(s->path);
> + }
> +
> pty_chr_state(chr, 0);
> object_unref(OBJECT(s->ioc));
> pty_chr_timer_cancel(s);
> @@ -330,6 +338,7 @@ static void char_pty_open(Chardev *chr,
> int master_fd, slave_fd;
> char pty_name[PATH_MAX];
> char *name;
> + char *path = backend->u.pty.data->path;
>
> master_fd = qemu_openpty_raw(&slave_fd, pty_name);
> if (master_fd < 0) {
> @@ -354,12 +363,36 @@ static void char_pty_open(Chardev *chr,
> g_free(name);
> s->timer_src = NULL;
> *be_opened = false;
> +
> + /* create symbolic link */
> + if (path) {
> + int res = symlink(pty_name, path);
> +
> + if (res != 0) {
> + error_setg_errno(errp, errno, "Failed to create PTY symlink");
> + } else {
> + s->path = g_strdup(path);
> + }
> + }
> +}
> +
> +static void char_pty_parse(QemuOpts *opts, ChardevBackend *backend,
> + Error **errp)
> +{
> + const char *path = qemu_opt_get(opts, "path");
> + ChardevPty *pty;
> +
> + backend->type = CHARDEV_BACKEND_KIND_PTY;
> + pty = backend->u.pty.data = g_new0(ChardevPty, 1);
> + qemu_chr_parse_common(opts, qapi_ChardevPty_base(pty));
> + pty->path = g_strdup(path);
> }
>
> static void char_pty_class_init(ObjectClass *oc, void *data)
> {
> ChardevClass *cc = CHARDEV_CLASS(oc);
>
> + cc->parse = char_pty_parse;
> cc->open = char_pty_open;
> cc->chr_write = char_pty_chr_write;
> cc->chr_update_read_handler = pty_chr_update_read_handler;
> diff --git a/chardev/char.c b/chardev/char.c
> index 3c43fb1278..404c6b8a4f 100644
> --- a/chardev/char.c
> +++ b/chardev/char.c
> @@ -428,6 +428,11 @@ QemuOpts *qemu_chr_parse_compat(const char *label,
> const char *filename,
> qemu_opt_set(opts, "path", p, &error_abort);
> return opts;
> }
> + if (strstart(filename, "pty:", &p)) {
> + qemu_opt_set(opts, "backend", "pty", &error_abort);
> + qemu_opt_set(opts, "path", p, &error_abort);
> + return opts;
> + }
> if (strstart(filename, "tcp:", &p) ||
> strstart(filename, "telnet:", &p) ||
> strstart(filename, "tn3270:", &p) ||
> diff --git a/qapi/char.json b/qapi/char.json
> index 777dde55d9..953d519066 100644
> --- a/qapi/char.json
> +++ b/qapi/char.json
> @@ -431,6 +431,20 @@
> 'base': 'ChardevCommon',
> 'if': 'CONFIG_SPICE_PROTOCOL' }
>
> +##
> +# @ChardevPty:
> +#
> +# Configuration info for pty implementation.
> +#
> +# @path: optional path to create a symbolic link that points to the
> +# allocated PTY
> +#
> +# Since: 9.2
> +##
> +{ 'struct': 'ChardevPty',
> + 'data': { '*path': 'str' },
> + 'base': 'ChardevCommon' }
> +
> ##
> # @ChardevBackendKind:
> #
> @@ -630,6 +644,17 @@
> { 'struct': 'ChardevRingbufWrapper',
> 'data': { 'data': 'ChardevRingbuf' } }
>
> +
> +##
> +# @ChardevPtyWrapper:
> +#
> +# @data: Configuration info for pty chardevs
> +#
> +# Since: 9.2
> +##
> +{ 'struct': 'ChardevPtyWrapper',
> + 'data': { 'data': 'ChardevPty' } }
> +
> ##
> # @ChardevBackend:
> #
> @@ -650,7 +675,7 @@
> 'pipe': 'ChardevHostdevWrapper',
> 'socket': 'ChardevSocketWrapper',
> 'udp': 'ChardevUdpWrapper',
> - 'pty': 'ChardevCommonWrapper',
> + 'pty': 'ChardevPtyWrapper',
> 'null': 'ChardevCommonWrapper',
> 'mux': 'ChardevMuxWrapper',
> 'msmouse': 'ChardevCommonWrapper',
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 8ca7f34ef0..08d8f8c559 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -3569,7 +3569,7 @@ DEF("chardev", HAS_ARG, QEMU_OPTION_chardev,
> "-chardev
> console,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
> "-chardev
> serial,id=id,path=path[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
> #else
> - "-chardev pty,id=id[,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
> + "-chardev
> pty,id=id[,path=path][,mux=on|off][,logfile=PATH][,logappend=on|off]\n"
> "-chardev
> stdio,id=id[,mux=on|off][,signal=on|off][,logfile=PATH][,logappend=on|off]\n"
> #endif
> #ifdef CONFIG_BRLAPI
> @@ -3808,12 +3808,22 @@ The available backends are:
>
> ``path`` specifies the name of the serial device to open.
>
> -``-chardev pty,id=id``
> - Create a new pseudo-terminal on the host and connect to it. ``pty``
> - does not take any options.
> +``-chardev pty,id=id[,path=path]``
> + Create a new pseudo-terminal on the host and connect to it.
>
> ``pty`` is not available on Windows hosts.
>
> + If ``path`` is specified, QEMU will create a symbolic link at
> + that location which points to the new PTY device.
> +
> + This avoids having to make QMP or HMP monitor queries to find out
> + what the new PTY device path is.
> +
> + Note that while QEMU will remove the symlink when it exits
> + gracefully, it will not do so in case of crashes or on certain
> + startup errors. It is recommended that the user checks and removes
> + the symlink after qemu terminates to account for this.
> +
> ``-chardev stdio,id=id[,signal=on|off]``
> Connect to standard input and standard output of the QEMU process.
>
> @@ -4171,8 +4181,19 @@ SRST
>
> vc:80Cx24C
>
> - ``pty``
> - [Linux only] Pseudo TTY (a new PTY is automatically allocated)
> + ``pty[:path]``
> + [Linux only] Pseudo TTY (a new PTY is automatically allocated).
> +
> + If ``path`` is specified, QEMU will create a symbolic link at
> + that location which points to the new PTY device.
> +
> + This avoids having to make QMP or HMP monitor queries to find
> + out what the new PTY device path is.
> +
> + Note that while QEMU will remove the symlink when it exits
> + gracefully, it will not do so in case of crashes or on certain
> + startup errors. It is recommended that the user checks and
> + removes the symlink after qemu terminates to account for this.
>
> ``none``
> No device is allocated. Note that for machine types which
> --
> 2.46.0.rc2.264.g509ed76dc8-goog
>
>
>
--
Marc-André Lureau
On Tue, Sep 3, 2024 at 12:14 AM Marc-André Lureau
<marcandre.lureau@gmail.com> wrote:
>
>
>
> On Tue, Aug 6, 2024 at 5:09 AM Octavian Purdila <tavip@google.com> wrote:
>>
>> Add path option to the pty char backend which will create a symbolic
>> link to the given path that points to the allocated PTY.
>>
>> This avoids having to make QMP or HMP monitor queries to find out what
>> the new PTY device path is.
>>
>> Based on patch from Paulo Neves:
>>
>> https://patchew.org/QEMU/1548509635-15776-1-git-send-email-ptsneves@gmail.com/
>>
>> Tested with the following invocations that the link is created and
>> removed when qemu stops:
>>
>> qemu-system-x86_64 -nodefaults -mon chardev=compat_monitor \
>> -chardev pty,path=test,id=compat_monitor0
>>
>> qemu-system-x86_64 -nodefaults -monitor pty:test
>>
>> # check QMP invocation with path set
>> qemu-system-x86_64 -nodefaults -qmp tcp:localhost:4444,server=on,wait=off
>> nc localhost 4444
>> > {"execute": "qmp_capabilities"}
>> > {"execute": "chardev-add", "arguments": {"id": "bar", "backend": {
>> "type": "pty", "data": {"path": "test" }}}}
>>
>> # check QMP invocation with path not set
>> qemu-system-x86_64 -nodefaults -qmp tcp:localhost:4444,server=on,wait=off
>> nc localhost 4444
>> > {"execute": "qmp_capabilities"}
>> > {"execute": "chardev-add", "arguments": {"id": "bar", "backend": {
>> "type": "pty", "data": {}}}}
>>
>> Also tested that when a link path is not passed invocations still work, e.g.:
>>
>> qemu-system-x86_64 -monitor pty
>>
>> Co-authored-by: Paulo Neves <ptsneves@gmail.com>
>> Signed-off-by: Paulo Neves <ptsneves@gmail.com>
>> [OP: rebase and address original patch review comments]
>> Signed-off-by: Octavian Purdila <tavip@google.com>
>
>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
>
Ping, it looks like this got lost.
https://patchew.org/QEMU/20240605185050.1678102-1-tavip@google.com/
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