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b66ed23238
This patch implements a new chardev backend `hub` device, which aggregates input from multiple backend devices and forwards it to a single frontend device. Additionally, `hub` device takes the output from the frontend device and sends it back to all the connected backend devices. This allows for seamless interaction between different backend devices and a single frontend interface. The idea of the change is trivial: keep list of backend devices (up to 4), init them on demand and forward data buffer back and forth. The following is QEMU command line example: -chardev pty,path=/tmp/pty,id=pty0 \ -chardev vc,id=vc0 \ -chardev hub,id=hub0,chardevs.0=pty0,chardevs.1=vc0 \ -device virtconsole,chardev=hub0 \ -vnc 0.0.0.0:0 Which creates 2 backend devices: text virtual console (`vc0`) and a pseudo TTY (`pty0`) connected to the single virtio hvc console with the backend aggregator (`hub0`) help. `vc0` renders text to an image, which can be shared over the VNC protocol. `pty0` is a pseudo TTY backend which provides biderectional communication to the virtio hvc console. 'chardevs.N' list syntax is used for the sake of compatibility with the representation of JSON lists in 'key=val' pairs format of the util/keyval.c, despite the fact that modern QAPI way of parsing, namely qobject_input_visitor_new_str(), is not used. Choice of keeping QAPI list syntax may help to smoothly switch to modern parsing in the future. Signed-off-by: Roman Penyaev <r.peniaev@gmail.com> Reviewed-by: "Marc-André Lureau" <marcandre.lureau@redhat.com> Cc: qemu-devel@nongnu.org Message-ID: <20250123085327.965501-3-r.peniaev@gmail.com>
119 lines
4 KiB
C
119 lines
4 KiB
C
/*
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* QEMU Character device internals
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*
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* Copyright (c) 2003-2008 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef CHARDEV_INTERNAL_H
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#define CHARDEV_INTERNAL_H
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#include "chardev/char.h"
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#include "chardev/char-fe.h"
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#include "qom/object.h"
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#define MAX_HUB 4
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#define MAX_MUX 4
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#define MUX_BUFFER_SIZE 32 /* Must be a power of 2. */
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#define MUX_BUFFER_MASK (MUX_BUFFER_SIZE - 1)
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struct MuxChardev {
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Chardev parent;
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/* Linked frontends */
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CharBackend *backends[MAX_MUX];
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/* Linked backend */
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CharBackend chr;
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unsigned long mux_bitset;
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int focus;
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bool term_got_escape;
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/* Intermediate input buffer catches escape sequences even if the
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currently active device is not accepting any input - but only until it
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is full as well. */
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unsigned char buffer[MAX_MUX][MUX_BUFFER_SIZE];
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unsigned int prod[MAX_MUX];
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unsigned int cons[MAX_MUX];
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int timestamps;
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/* Protected by the Chardev chr_write_lock. */
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bool linestart;
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int64_t timestamps_start;
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};
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typedef struct MuxChardev MuxChardev;
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typedef struct HubChardev HubChardev;
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typedef struct HubCharBackend HubCharBackend;
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/*
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* Back-pointer on a hub, actual backend and its index in
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* `hub->backends` array
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*/
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struct HubCharBackend {
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HubChardev *hub;
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CharBackend be;
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unsigned int be_ind;
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};
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struct HubChardev {
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Chardev parent;
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/* Linked backends */
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HubCharBackend backends[MAX_HUB];
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/*
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* Number of backends attached to this hub. Once attached, a
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* backend can't be detached, so the counter is only increasing.
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* To safely remove a backend, hub has to be removed first.
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*/
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unsigned int be_cnt;
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/*
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* Number of CHR_EVEN_OPENED events from all backends. Needed to
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* send CHR_EVEN_CLOSED only when counter goes to zero.
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*/
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unsigned int be_event_opened_cnt;
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/*
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* Counters of written bytes from a single frontend device
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* to multiple backend devices.
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*/
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unsigned int be_written[MAX_HUB];
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unsigned int be_min_written;
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/*
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* Index of a backend device which got EAGAIN on last write,
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* -1 is invalid index.
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*/
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int be_eagain_ind;
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};
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typedef struct HubChardev HubChardev;
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DECLARE_INSTANCE_CHECKER(MuxChardev, MUX_CHARDEV,
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TYPE_CHARDEV_MUX)
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DECLARE_INSTANCE_CHECKER(HubChardev, HUB_CHARDEV,
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TYPE_CHARDEV_HUB)
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#define CHARDEV_IS_MUX(chr) \
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object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_MUX)
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#define CHARDEV_IS_HUB(chr) \
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object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_HUB)
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bool mux_chr_attach_frontend(MuxChardev *d, CharBackend *b,
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unsigned int *tag, Error **errp);
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bool mux_chr_detach_frontend(MuxChardev *d, unsigned int tag);
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void mux_set_focus(Chardev *chr, unsigned int focus);
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void mux_chr_send_all_event(Chardev *chr, QEMUChrEvent event);
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Object *get_chardevs_root(void);
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#endif /* CHARDEV_INTERNAL_H */
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