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

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;

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);