The __linux__ version of qemu_chr_open_pp_fd() tries to claim the parport device with a PPCLAIM ioctl(). On success, it stores the file descriptor in the chardev object, and returns success. On failure, it closes the file descriptor, and returns failure. chardev_new() then passes the Chardev to object_unref(). This duly calls char_parallel_finalize(), which closes the file descriptor stored in the chardev object. Since qemu_chr_open_pp_fd() didn't store it, it's still zero, so this closes standard input. Ooopsie. To demonstate, add a unit test. With the bug above unfixed, running this test closes standard input. char_hotswap_test() happens to run next. It opens a socket, duly gets file descriptor 0, and since it tests for success with > 0 instead of >= 0, it fails. The test needs to be conditional exactly like the chardev it tests. Since the condition is rather complicated, steal the solution from the serial chardev: define HAVE_CHARDEV_PARALLEL in qemu/osdep.h. This also permits simplifying chardev/meson.build a bit. The bug fix is easy enough: store the file descriptor, and leave closing it to char_parallel_finalize(). Signed-off-by: Markus Armbruster <armbru(a)redhat.com&gt; --- include/qemu/osdep.h | 9 ++++++++- chardev/char-parallel.c | 7 +++++-- tests/unit/test-char.c | 21 +++++++++++++++++++++ chardev/meson.build | 4 +--- 4 files changed, 35 insertions(+), 6 deletions(-) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index c9692cc314..3b0f3389d3 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -508,11 +508,18 @@ void qemu_anon_ram_free(void *ptr, size_t size); #ifdef _WIN32 #define HAVE_CHARDEV_SERIAL 1 -#elif defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ +#define HAVE_CHARDEV_PARALLEL 1 +#else +#if defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \ || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \ || defined(__GLIBC__) || defined(__APPLE__) #define HAVE_CHARDEV_SERIAL 1 #endif +#if defined(__linux__) || defined(__FreeBSD__) \ + || defined(__FreeBSD_kernel__) || defined(__DragonFly__) +#define HAVE_CHARDEV_PARALLEL 1 +#endif +#endif #if defined(__HAIKU__) #define SIGIO SIGPOLL diff --git a/chardev/char-parallel.c b/chardev/char-parallel.c index a5164f975a..78697d7522 100644 --- a/chardev/char-parallel.c +++ b/chardev/char-parallel.c @@ -164,13 +164,13 @@ static void qemu_chr_open_pp_fd(Chardev *chr, { ParallelChardev *drv = PARALLEL_CHARDEV(chr); + drv->fd = fd; + if (ioctl(fd, PPCLAIM) < 0) { error_setg_errno(errp, errno, "not a parallel port"); - close(fd); return; } - drv->fd = fd; drv->mode = IEEE1284_MODE_COMPAT; } #endif /* __linux__ */ @@ -238,6 +238,7 @@ static void qemu_chr_open_pp_fd(Chardev *chr, } #endif +#ifdef HAVE_CHARDEV_PARALLEL static void qmp_chardev_open_parallel(Chardev *chr, ChardevBackend *backend, bool *be_opened, @@ -306,3 +307,5 @@ static void register_types(void) } type_init(register_types); + +#endif /* HAVE_CHARDEV_PARALLEL */ diff --git a/tests/unit/test-char.c b/tests/unit/test-char.c index 649fdf64e1..76946e6f90 100644 --- a/tests/unit/test-char.c +++ b/tests/unit/test-char.c @@ -1203,6 +1203,24 @@ static void char_serial_test(void) } #endif +#if defined(HAVE_CHARDEV_PARALLEL) && !defined(WIN32) +static void char_parallel_test(void) +{ + QemuOpts *opts; + Chardev *chr; + + opts = qemu_opts_create(qemu_find_opts("chardev"), "parallel-id", + 1, &error_abort); + qemu_opt_set(opts, "backend", "parallel", &error_abort); + qemu_opt_set(opts, "path", "/dev/null", &error_abort); + + chr = qemu_chr_new_from_opts(opts, NULL, NULL); + g_assert_null(chr); + + qemu_opts_del(opts); +} +#endif + #ifndef _WIN32 static void char_file_fifo_test(void) { @@ -1544,6 +1562,9 @@ int main(int argc, char **argv) g_test_add_func("/char/udp", char_udp_test); #if defined(HAVE_CHARDEV_SERIAL) && !defined(WIN32) g_test_add_func("/char/serial", char_serial_test); +#endif +#if defined(HAVE_CHARDEV_PARALLEL) && !defined(WIN32) + g_test_add_func("/char/parallel", char_parallel_test); #endif g_test_add_func("/char/hotswap", char_hotswap_test); g_test_add_func("/char/websocket", char_websock_test); diff --git a/chardev/meson.build b/chardev/meson.build index c80337d15f..b39028b7b0 100644 --- a/chardev/meson.build +++ b/chardev/meson.build @@ -21,11 +21,9 @@ if host_os == 'windows' else chardev_ss.add(files( 'char-fd.c', + 'char-parallel.c', 'char-pty.c', ), util) - if host_os in ['linux', 'gnu/kfreebsd', 'freebsd', 'dragonfly'] - chardev_ss.add(files('char-parallel.c')) - endif endif chardev_ss = chardev_ss.apply({}) -- 2.43.0

Eric Blake <eblake(a)redhat.com&gt; writes: I like this style, too. Will fix. Thanks!

Hi On Tue, Feb 13, 2024 at 5:58 PM Markus Armbruster <armbru(a)redhat.com&gt; wrote: I am okay with a new PR. thanks

Character backends are actually QOM types. When a backend's compile-time conditional QOM type is not compiled in, creation fails with "'FOO' is not a valid char driver name". Okay, except introspecting chardev-add with query-qmp-schema doesn't work then: the backend type is there even though the QOM type isn't. A management application can work around this issue by using qom-list-types instead. Fix the issue anyway: add the conditionals to the QAPI schema. Signed-off-by: Markus Armbruster <armbru(a)redhat.com&gt; --- qapi/char.json | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/qapi/char.json b/qapi/char.json index 6c6ad3b10c..2d74e66746 100644 --- a/qapi/char.json +++ b/qapi/char.json @@ -472,8 +472,8 @@ ## { 'enum': 'ChardevBackendKind', 'data': [ 'file', - 'serial', - 'parallel', + { 'name': 'serial', 'if': 'HAVE_CHARDEV_SERIAL' }, + { 'name': 'parallel', 'if': 'HAVE_CHARDEV_PARALLEL' }, 'pipe', 'socket', 'udp', @@ -482,10 +482,10 @@ 'mux', 'msmouse', 'wctablet', - 'braille', + { 'name': 'braille', 'if': 'CONFIG_BRLAPI' }, 'testdev', 'stdio', - 'console', + { 'name': 'console', 'if': 'CONFIG_WIN32' }, { 'name': 'spicevmc', 'if': 'CONFIG_SPICE' }, { 'name': 'spiceport', 'if': 'CONFIG_SPICE' }, { 'name': 'qemu-vdagent', 'if': 'CONFIG_SPICE_PROTOCOL' }, @@ -614,8 +614,10 @@ 'base': { 'type': 'ChardevBackendKind' }, 'discriminator': 'type', 'data': { 'file': 'ChardevFileWrapper', - 'serial': 'ChardevHostdevWrapper', - 'parallel': 'ChardevHostdevWrapper', + 'serial': { 'type': 'ChardevHostdevWrapper', + 'if': 'HAVE_CHARDEV_SERIAL' }, + 'parallel': { 'type': 'ChardevHostdevWrapper', + 'if': 'HAVE_CHARDEV_PARALLEL' }, 'pipe': 'ChardevHostdevWrapper', 'socket': 'ChardevSocketWrapper', 'udp': 'ChardevUdpWrapper', @@ -624,10 +626,12 @@ 'mux': 'ChardevMuxWrapper', 'msmouse': 'ChardevCommonWrapper', 'wctablet': 'ChardevCommonWrapper', - 'braille': 'ChardevCommonWrapper', + 'braille': { 'type': 'ChardevCommonWrapper', + 'if': 'CONFIG_BRLAPI' }, 'testdev': 'ChardevCommonWrapper', 'stdio': 'ChardevStdioWrapper', - 'console': 'ChardevCommonWrapper', + 'console': { 'type': 'ChardevCommonWrapper', + 'if': 'CONFIG_WIN32' }, 'spicevmc': { 'type': 'ChardevSpiceChannelWrapper', 'if': 'CONFIG_SPICE' }, 'spiceport': { 'type': 'ChardevSpicePortWrapper', -- 2.43.0

It's an alias for "ringbuf" we kept for backward compatibility; see commit 3a1da42eb35 (qapi: Rename ChardevBackend member "memory" to "ringbuf"). Deprecation is long overdue. Signed-off-by: Markus Armbruster <armbru(a)redhat.com&gt; --- docs/about/deprecated.rst | 8 ++++++++ qapi/char.json | 8 +++++--- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst index d4492b9460..ae1a520c26 100644 --- a/docs/about/deprecated.rst +++ b/docs/about/deprecated.rst @@ -371,6 +371,14 @@ Specifying the iSCSI password in plain text on the command line using the used instead, to refer to a ``--object secret...`` instance that provides a password via a file, or encrypted. +Character device options +'''''''''''''''''''''''' + +Backend ``memory`` (since 9.0) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +``memory`` is a deprecated synonym for ``ringbuf``. + CPU device properties ''''''''''''''''''''' diff --git a/qapi/char.json b/qapi/char.json index 2d74e66746..75a7e057f0 100644 --- a/qapi/char.json +++ b/qapi/char.json @@ -468,6 +468,10 @@ # # @memory: Since 1.5 # +# Features: +# +# @deprecated: Member @memory is deprecated. Use @ringbuf instead. +# # Since: 1.4 ## { 'enum': 'ChardevBackendKind', @@ -492,8 +496,7 @@ { 'name': 'dbus', 'if': 'CONFIG_DBUS_DISPLAY' }, 'vc', 'ringbuf', - # next one is just for compatibility - 'memory' ] } + { 'name': 'memory', 'features': [ 'deprecated' ] } ] } ## # @ChardevFileWrapper: @@ -642,7 +645,6 @@ 'if': 'CONFIG_DBUS_DISPLAY' }, 'vc': 'ChardevVCWrapper', 'ringbuf': 'ChardevRingbufWrapper', - # next one is just for compatibility 'memory': 'ChardevRingbufWrapper' } } ## -- 2.43.0