[PULL v2 0/4] Character device backend patches for 2024-02-12

[PULL v2 0/4] Character device backend patches for 2024-02-12

[Markus Armbruster]

I offered Marc-André to do this pull request, and he accepted.

The following changes since commit 5d1fc614413b10dd94858b07a1b2e26b1aa0296c:

  Merge tag 'migration-staging-pull-request' of https://gitlab.com/peterx/qemu into staging (2024-02-09 11:22:20 +0000)

are available in the Git repository at:

  https://repo.or.cz/qemu/armbru.git tags/pull-char-2024-02-12-v2

for you to fetch changes up to b04c12282b33e81ba29b54dd001667f5c4002252:

  qapi/char: Deprecate backend type "memory" (2024-02-14 07:45:08 +0100)

----------------------------------------------------------------
Character device backend patches for 2024-02-12

----------------------------------------------------------------
Markus Armbruster (4):
      chardev/parallel: Don't close stdin on inappropriate device
      tests/unit/test-char: Fix qemu_socket(), make_udp_socket() check
      qapi/char: Make backend types properly conditional
      qapi/char: Deprecate backend type "memory"

 docs/about/deprecated.rst |  8 ++++++++
 qapi/char.json            | 28 +++++++++++++++++-----------
 include/qemu/osdep.h      |  9 ++++++++-
 chardev/char-parallel.c   |  7 +++++--
 tests/unit/test-char.c    | 31 +++++++++++++++++++++++++++++--
 chardev/meson.build       |  4 +---
 6 files changed, 68 insertions(+), 19 deletions(-)

-- 
2.43.0

[PULL v2 1/4] chardev/parallel: Don't close stdin on inappropriate device

[Markus Armbruster]

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 new unit 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().

The next commit will fix char_hotswap_test()'s test for success.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240203080228.2766159-2-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[Test fixed up for BSDs, indentation fixed up, commit message improved]
---
 include/qemu/osdep.h    |  9 ++++++++-
 chardev/char-parallel.c |  7 +++++--
 tests/unit/test-char.c  | 27 +++++++++++++++++++++++++++
 chardev/meson.build     |  4 +---
 4 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 7d359dabc4..c7053cdc2b 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..2aea49c3b6 100644
--- a/tests/unit/test-char.c
+++ b/tests/unit/test-char.c
@@ -1203,6 +1203,30 @@ 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);
+#ifdef __linux__
+    /* fails to PPCLAIM, see qemu_chr_open_pp_fd() */
+    g_assert_null(chr);
+#else
+    g_assert_nonnull(chr);
+    object_unparent(OBJECT(chr));
+#endif
+
+    qemu_opts_del(opts);
+}
+#endif
+
 #ifndef _WIN32
 static void char_file_fifo_test(void)
 {
@@ -1544,6 +1568,9 @@ 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..70070a8279 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

[PULL v2 2/4] tests/unit/test-char: Fix qemu_socket(), make_udp_socket() check

[Markus Armbruster]

qemu_socket() and make_udp_socket() return a file descriptor on
success, -1 on failure.  The check misinterprets 0 as failure.  Fix
that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240203080228.2766159-3-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 tests/unit/test-char.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/unit/test-char.c b/tests/unit/test-char.c
index 2aea49c3b6..f273ce5226 100644
--- a/tests/unit/test-char.c
+++ b/tests/unit/test-char.c
@@ -556,7 +556,7 @@ static int make_udp_socket(int *port)
     socklen_t alen = sizeof(addr);
     int ret, sock = qemu_socket(PF_INET, SOCK_DGRAM, 0);
 
-    g_assert_cmpint(sock, >, 0);
+    g_assert_cmpint(sock, >=, 0);
     addr.sin_family = AF_INET ;
     addr.sin_addr.s_addr = htonl(INADDR_ANY);
     addr.sin_port = 0;
@@ -1407,7 +1407,7 @@ static void char_hotswap_test(void)
 
     int port;
     int sock = make_udp_socket(&port);
-    g_assert_cmpint(sock, >, 0);
+    g_assert_cmpint(sock, >=, 0);
 
     chr_args = g_strdup_printf("udp:127.0.0.1:%d", port);
 
-- 
2.43.0

[PULL v2 3/4] qapi/char: Make backend types properly conditional

[Markus Armbruster]

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@redhat.com>
Message-ID: <20240203080228.2766159-4-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 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

[PULL v2 4/4] qapi/char: Deprecate backend type "memory"

[Markus Armbruster]

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@redhat.com>
Message-ID: <20240203080228.2766159-5-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 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 c7b95e6068..7d9343676c 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -380,6 +380,14 @@ 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

Re: [PULL v2 0/4] Character device backend patches for 2024-02-12

[Peter Maydell]

On Wed, 14 Feb 2024 at 06:47, Markus Armbruster <armbru@redhat.com> wrote:
>
> I offered Marc-André to do this pull request, and he accepted.
>
> The following changes since commit 5d1fc614413b10dd94858b07a1b2e26b1aa0296c:
>
>   Merge tag 'migration-staging-pull-request' of https://gitlab.com/peterx/qemu into staging (2024-02-09 11:22:20 +0000)
>
> are available in the Git repository at:
>
>   https://repo.or.cz/qemu/armbru.git tags/pull-char-2024-02-12-v2
>
> for you to fetch changes up to b04c12282b33e81ba29b54dd001667f5c4002252:
>
>   qapi/char: Deprecate backend type "memory" (2024-02-14 07:45:08 +0100)
>
> ----------------------------------------------------------------
> Character device backend patches for 2024-02-12
>


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/9.0
for any user-visible changes.

-- PMM