Commit Graph

5 Commits

Author SHA1 Message Date
Markus Armbruster 1f51470d04 Revert "qemu-char: Print strerror message on failure" and deps
The commit's purpose is laudable:

    The only way for chardev drivers to communicate an error was to
    return a NULL pointer, which resulted in an error message that
    said _that_ something went wrong, but not _why_.

It attempts to achieve it by changing the interface to return 0/-errno
and update qemu_chr_open_opts() to use strerror() to display a more
helpful error message.  Unfortunately, it has serious flaws:

1. Backends "socket" and "udp" return bogus error codes, because
qemu_chr_open_socket() and qemu_chr_open_udp() assume that
unix_listen_opts(), unix_connect_opts(), inet_listen_opts(),
inet_connect_opts() and inet_dgram_opts() fail with errno set
appropriately.  That assumption is wrong, and the commit turns
unspecific error messages into misleading error messages.  For
instance:

    $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx
    inet_connect: host and/or port not specified
    chardev: opening backend "socket" failed: No such file or directory

ENOENT is what happens to be in my errno when the backend returns
-errno.  Let's put ERANGE there just for giggles:

    $ qemu-system-x86_64 -nodefaults -vnc :0 -chardev socket,id=bar,host=xxx -drive if=none,iops=99999999999999999999
    inet_connect: host and/or port not specified
    chardev: opening backend "socket" failed: Numerical result out of range

Worse: when errno happens to be zero, return -errno erroneously
signals success, and qemu_chr_new_from_opts() dies dereferencing
uninitialized chr.  I observe this with "-serial unix:".

2. All qemu_chr_open_opts() knows about the error is an errno error
code.  That's simply not enough for a decent message.  For instance,
when inet_dgram() can't resolve the parameter host, which errno code
should it use?  What if it can't resolve parameter localaddr?

Clue: many backends already report errors in their open methods.
Let's revert the flawed commit along with its dependencies, and fix up
the silent error paths instead.

This reverts commit 6e1db57b2a.

Conflicts:

	console.c
	hw/baum.c
	qemu-char.c

This reverts commit aad04cd024.

The parts of commit db418a0a "Add stdio char device on windows" that
depend on the reverted change fixed up.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-02-24 09:06:56 -06:00
Blue Swirl aad04cd024 Fix chrdev return value conversion
6e1db57b2a didn't
convert brlapi or win32 chrdevs, breaking build for those.

Fix by converting the chrdevs.

Acked-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2011-07-24 14:48:57 +00:00
Gerd Hoffmann 2b0efdc3e1 usb-serial and braille: use qdev for -usbdevice
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-30 08:39:31 -05:00
Gerd Hoffmann dc1c21e60c convert braille chardev to QemuOpts.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-09-11 10:19:48 -05:00
aurel32 2e4d9fb126 Braille device support
(Samuel Thibault)


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@4173 c046a42c-6fe2-441c-8c8c-71466251a162
2008-04-08 06:01:02 +00:00