Kirill noticied that on recent versions on QEMU he was not able to trigger SysRq to invoke debug capabilites of Linux Kernel. He tracked it down to qemu_chr_be_event() ignoring CHR_EVENT_BREAK due s->be being NULL. The bug was introduced in 2.8, commita4afa548fc
("char: move front end handlers in CharBackend"). Since the commit, the qemu_chr_be_event() failed to deliver CHR_EVENT_BREAK due to qemu_chr_fe_init() does not set s->be in case of mux. Let's fix this by teaching mux to send an event to the frontend with the focus. Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Fixes:a4afa548fc
("char: move front end handlers in CharBackend") Message-Id: <20171103152824.21948-2-marcandre.lureau@redhat.com> Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
375 lines
10 KiB
C
375 lines
10 KiB
C
/*
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* QEMU System Emulator
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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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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "qemu-common.h"
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#include "chardev/char.h"
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#include "sysemu/block-backend.h"
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#include "chardev/char-mux.h"
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/* MUX driver for serial I/O splitting */
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/* Called with chr_write_lock held. */
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static int mux_chr_write(Chardev *chr, const uint8_t *buf, int len)
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{
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MuxChardev *d = MUX_CHARDEV(chr);
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int ret;
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if (!d->timestamps) {
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ret = qemu_chr_fe_write(&d->chr, buf, len);
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} else {
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int i;
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ret = 0;
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for (i = 0; i < len; i++) {
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if (d->linestart) {
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char buf1[64];
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int64_t ti;
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int secs;
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ti = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
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if (d->timestamps_start == -1) {
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d->timestamps_start = ti;
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}
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ti -= d->timestamps_start;
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secs = ti / 1000;
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snprintf(buf1, sizeof(buf1),
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"[%02d:%02d:%02d.%03d] ",
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secs / 3600,
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(secs / 60) % 60,
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secs % 60,
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(int)(ti % 1000));
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/* XXX this blocks entire thread. Rewrite to use
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* qemu_chr_fe_write and background I/O callbacks */
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qemu_chr_fe_write_all(&d->chr,
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(uint8_t *)buf1, strlen(buf1));
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d->linestart = 0;
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}
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ret += qemu_chr_fe_write(&d->chr, buf + i, 1);
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if (buf[i] == '\n') {
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d->linestart = 1;
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}
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}
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}
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return ret;
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}
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static const char * const mux_help[] = {
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"% h print this help\n\r",
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"% x exit emulator\n\r",
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"% s save disk data back to file (if -snapshot)\n\r",
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"% t toggle console timestamps\n\r",
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"% b send break (magic sysrq)\n\r",
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"% c switch between console and monitor\n\r",
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"% % sends %\n\r",
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NULL
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};
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int term_escape_char = 0x01; /* ctrl-a is used for escape */
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static void mux_print_help(Chardev *chr)
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{
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int i, j;
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char ebuf[15] = "Escape-Char";
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char cbuf[50] = "\n\r";
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if (term_escape_char > 0 && term_escape_char < 26) {
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snprintf(cbuf, sizeof(cbuf), "\n\r");
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snprintf(ebuf, sizeof(ebuf), "C-%c", term_escape_char - 1 + 'a');
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} else {
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snprintf(cbuf, sizeof(cbuf),
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"\n\rEscape-Char set to Ascii: 0x%02x\n\r\n\r",
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term_escape_char);
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}
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/* XXX this blocks entire thread. Rewrite to use
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* qemu_chr_fe_write and background I/O callbacks */
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qemu_chr_write_all(chr, (uint8_t *)cbuf, strlen(cbuf));
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for (i = 0; mux_help[i] != NULL; i++) {
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for (j = 0; mux_help[i][j] != '\0'; j++) {
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if (mux_help[i][j] == '%') {
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qemu_chr_write_all(chr, (uint8_t *)ebuf, strlen(ebuf));
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} else {
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qemu_chr_write_all(chr, (uint8_t *)&mux_help[i][j], 1);
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}
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}
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}
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}
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static void mux_chr_send_event(MuxChardev *d, int mux_nr, int event)
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{
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CharBackend *be = d->backends[mux_nr];
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if (be && be->chr_event) {
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be->chr_event(be->opaque, event);
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}
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}
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static void mux_chr_be_event(Chardev *chr, int event)
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{
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MuxChardev *d = MUX_CHARDEV(chr);
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if (d->focus != -1) {
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mux_chr_send_event(d, d->focus, event);
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}
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}
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static int mux_proc_byte(Chardev *chr, MuxChardev *d, int ch)
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{
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if (d->term_got_escape) {
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d->term_got_escape = 0;
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if (ch == term_escape_char) {
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goto send_char;
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}
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switch (ch) {
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case '?':
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case 'h':
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mux_print_help(chr);
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break;
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case 'x':
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{
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const char *term = "QEMU: Terminated\n\r";
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qemu_chr_write_all(chr, (uint8_t *)term, strlen(term));
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exit(0);
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break;
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}
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case 's':
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blk_commit_all();
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break;
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case 'b':
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qemu_chr_be_event(chr, CHR_EVENT_BREAK);
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break;
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case 'c':
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assert(d->mux_cnt > 0); /* handler registered with first fe */
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/* Switch to the next registered device */
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mux_set_focus(chr, (d->focus + 1) % d->mux_cnt);
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break;
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case 't':
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d->timestamps = !d->timestamps;
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d->timestamps_start = -1;
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d->linestart = 0;
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break;
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}
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} else if (ch == term_escape_char) {
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d->term_got_escape = 1;
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} else {
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send_char:
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return 1;
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}
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return 0;
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}
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static void mux_chr_accept_input(Chardev *chr)
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{
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MuxChardev *d = MUX_CHARDEV(chr);
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int m = d->focus;
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CharBackend *be = d->backends[m];
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while (be && d->prod[m] != d->cons[m] &&
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be->chr_can_read && be->chr_can_read(be->opaque)) {
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be->chr_read(be->opaque,
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&d->buffer[m][d->cons[m]++ & MUX_BUFFER_MASK], 1);
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}
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}
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static int mux_chr_can_read(void *opaque)
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{
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MuxChardev *d = MUX_CHARDEV(opaque);
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int m = d->focus;
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CharBackend *be = d->backends[m];
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if ((d->prod[m] - d->cons[m]) < MUX_BUFFER_SIZE) {
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return 1;
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}
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if (be && be->chr_can_read) {
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return be->chr_can_read(be->opaque);
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}
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return 0;
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}
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static void mux_chr_read(void *opaque, const uint8_t *buf, int size)
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{
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Chardev *chr = CHARDEV(opaque);
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MuxChardev *d = MUX_CHARDEV(opaque);
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int m = d->focus;
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CharBackend *be = d->backends[m];
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int i;
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mux_chr_accept_input(opaque);
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for (i = 0; i < size; i++)
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if (mux_proc_byte(chr, d, buf[i])) {
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if (d->prod[m] == d->cons[m] &&
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be && be->chr_can_read &&
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be->chr_can_read(be->opaque)) {
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be->chr_read(be->opaque, &buf[i], 1);
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} else {
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d->buffer[m][d->prod[m]++ & MUX_BUFFER_MASK] = buf[i];
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}
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}
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}
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bool muxes_realized;
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void mux_chr_send_all_event(Chardev *chr, int event)
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{
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MuxChardev *d = MUX_CHARDEV(chr);
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int i;
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if (!muxes_realized) {
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return;
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}
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/* Send the event to all registered listeners */
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for (i = 0; i < d->mux_cnt; i++) {
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mux_chr_send_event(d, i, event);
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}
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}
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static void mux_chr_event(void *opaque, int event)
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{
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mux_chr_send_all_event(CHARDEV(opaque), event);
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}
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static GSource *mux_chr_add_watch(Chardev *s, GIOCondition cond)
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{
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MuxChardev *d = MUX_CHARDEV(s);
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Chardev *chr = qemu_chr_fe_get_driver(&d->chr);
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ChardevClass *cc = CHARDEV_GET_CLASS(chr);
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if (!cc->chr_add_watch) {
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return NULL;
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}
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return cc->chr_add_watch(chr, cond);
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}
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static void char_mux_finalize(Object *obj)
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{
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MuxChardev *d = MUX_CHARDEV(obj);
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int i;
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for (i = 0; i < d->mux_cnt; i++) {
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CharBackend *be = d->backends[i];
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if (be) {
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be->chr = NULL;
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}
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}
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qemu_chr_fe_deinit(&d->chr, false);
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}
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void mux_chr_set_handlers(Chardev *chr, GMainContext *context)
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{
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MuxChardev *d = MUX_CHARDEV(chr);
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/* Fix up the real driver with mux routines */
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qemu_chr_fe_set_handlers(&d->chr,
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mux_chr_can_read,
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mux_chr_read,
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mux_chr_event,
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NULL,
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chr,
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context, true);
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}
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void mux_set_focus(Chardev *chr, int focus)
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{
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MuxChardev *d = MUX_CHARDEV(chr);
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assert(focus >= 0);
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assert(focus < d->mux_cnt);
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if (d->focus != -1) {
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mux_chr_send_event(d, d->focus, CHR_EVENT_MUX_OUT);
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}
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d->focus = focus;
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mux_chr_send_event(d, d->focus, CHR_EVENT_MUX_IN);
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}
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static void qemu_chr_open_mux(Chardev *chr,
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ChardevBackend *backend,
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bool *be_opened,
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Error **errp)
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{
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ChardevMux *mux = backend->u.mux.data;
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Chardev *drv;
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MuxChardev *d = MUX_CHARDEV(chr);
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drv = qemu_chr_find(mux->chardev);
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if (drv == NULL) {
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error_setg(errp, "mux: base chardev %s not found", mux->chardev);
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return;
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}
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d->focus = -1;
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/* only default to opened state if we've realized the initial
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* set of muxes
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*/
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*be_opened = muxes_realized;
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qemu_chr_fe_init(&d->chr, drv, errp);
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}
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static void qemu_chr_parse_mux(QemuOpts *opts, ChardevBackend *backend,
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Error **errp)
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{
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const char *chardev = qemu_opt_get(opts, "chardev");
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ChardevMux *mux;
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if (chardev == NULL) {
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error_setg(errp, "chardev: mux: no chardev given");
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return;
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}
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backend->type = CHARDEV_BACKEND_KIND_MUX;
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mux = backend->u.mux.data = g_new0(ChardevMux, 1);
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qemu_chr_parse_common(opts, qapi_ChardevMux_base(mux));
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mux->chardev = g_strdup(chardev);
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}
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static void char_mux_class_init(ObjectClass *oc, void *data)
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{
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ChardevClass *cc = CHARDEV_CLASS(oc);
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cc->parse = qemu_chr_parse_mux;
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cc->open = qemu_chr_open_mux;
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cc->chr_write = mux_chr_write;
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cc->chr_accept_input = mux_chr_accept_input;
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cc->chr_add_watch = mux_chr_add_watch;
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cc->chr_be_event = mux_chr_be_event;
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}
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static const TypeInfo char_mux_type_info = {
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.name = TYPE_CHARDEV_MUX,
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.parent = TYPE_CHARDEV,
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.class_init = char_mux_class_init,
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.instance_size = sizeof(MuxChardev),
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.instance_finalize = char_mux_finalize,
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};
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static void register_types(void)
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{
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type_register_static(&char_mux_type_info);
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}
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type_init(register_types);
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