qemu-io.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
qemu-io puts the TTY into non-canonical mode, which means no EOF processing is
done and thus getchar() will never return the EOF constant. Instead we have to
check for an explicit Ctrl-D, aka 0x4, to detect EOF and exit the qemu-io
shell. This fixes the regression that prevented Ctrl-D from triggering an exit
of qemu-io that has existed since readline was first added in
commit 0cf17e181798063c3824c8200ba46f25f54faa1a
Author: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu Nov 14 11:54:17 2013 +0100
qemu-io: use readline.c
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
qemu-io.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/qemu-io.c b/qemu-io.c
index c70bde3eb1..2ea0bfbaf8 100644
--- a/qemu-io.c
+++ b/qemu-io.c
@@ -322,7 +322,9 @@ static char *fetchline_readline(void)
readline_start(readline_state, get_prompt(), 0, readline_func, &line);
while (!line) {
int ch = getchar();
- if (ch == EOF) {
+ /* In non-canon tty mode we get 0x4 (Ctrl-D), not the stdio "EOF"
+ * constant */
+ if (ch == 0x4) {
break;
}
readline_handle_byte(readline_state, ch);
--
2.14.3
On 12/06/2017 05:57 AM, Daniel P. Berrange wrote:
> qemu-io puts the TTY into non-canonical mode, which means no EOF processing is
> done and thus getchar() will never return the EOF constant. Instead we have to
> check for an explicit Ctrl-D, aka 0x4, to detect EOF and exit the qemu-io
> shell. This fixes the regression that prevented Ctrl-D from triggering an exit
> of qemu-io that has existed since readline was first added in
>
> commit 0cf17e181798063c3824c8200ba46f25f54faa1a
> Author: Stefan Hajnoczi <stefanha@redhat.com>
> Date: Thu Nov 14 11:54:17 2013 +0100
>
> qemu-io: use readline.c
>
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
> qemu-io.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
> while (!line) {
> int ch = getchar();
> - if (ch == EOF) {
> + /* In non-canon tty mode we get 0x4 (Ctrl-D), not the stdio "EOF"
> + * constant */
> + if (ch == 0x4) {
Should we instead be looking for a match against the current termios()
c_cc[VEOF] setting, in case the user prefers something other than ^D via
stty? Does readline provide any functionality for automating this?
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
On Wed, Dec 06, 2017 at 08:22:35AM -0600, Eric Blake wrote:
> On 12/06/2017 05:57 AM, Daniel P. Berrange wrote:
> > qemu-io puts the TTY into non-canonical mode, which means no EOF processing is
> > done and thus getchar() will never return the EOF constant. Instead we have to
> > check for an explicit Ctrl-D, aka 0x4, to detect EOF and exit the qemu-io
> > shell. This fixes the regression that prevented Ctrl-D from triggering an exit
> > of qemu-io that has existed since readline was first added in
> >
> > commit 0cf17e181798063c3824c8200ba46f25f54faa1a
> > Author: Stefan Hajnoczi <stefanha@redhat.com>
> > Date: Thu Nov 14 11:54:17 2013 +0100
> >
> > qemu-io: use readline.c
> >
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> > qemu-io.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
>
> > while (!line) {
> > int ch = getchar();
> > - if (ch == EOF) {
> > + /* In non-canon tty mode we get 0x4 (Ctrl-D), not the stdio "EOF"
> > + * constant */
> > + if (ch == 0x4) {
>
> Should we instead be looking for a match against the current termios()
> c_cc[VEOF] setting, in case the user prefers something other than ^D via
> stty? Does readline provide any functionality for automating this?
I was afraid someone was going to suggest doing that. I was being lazy by
hardcoding Ctrl-D, but yes the real readline() library will honour the
VEOF value. QEMU though is using a home-grown reimpl of readline...
Regards,
Daniel
--
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On 12/06/2017 08:25 AM, Daniel P. Berrange wrote: >> Should we instead be looking for a match against the current termios() >> c_cc[VEOF] setting, in case the user prefers something other than ^D via >> stty? Does readline provide any functionality for automating this? > > I was afraid someone was going to suggest doing that. I was being lazy by > hardcoding Ctrl-D, but yes the real readline() library will honour the > VEOF value. QEMU though is using a home-grown reimpl of readline... I understand why we can't use modern libreadline (it is licensed GPLv3+, making it impossible to use with our GPLv2-only code) - but doesn't BSD have a readline-alike library with BSD licensing that we could use instead of implementing readline ourselves? (Was it named libinput?) -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org
Eric Blake <eblake@redhat.com> writes: > On 12/06/2017 08:25 AM, Daniel P. Berrange wrote: > >>> Should we instead be looking for a match against the current termios() >>> c_cc[VEOF] setting, in case the user prefers something other than ^D via >>> stty? Does readline provide any functionality for automating this? >> >> I was afraid someone was going to suggest doing that. I was being lazy by >> hardcoding Ctrl-D, but yes the real readline() library will honour the >> VEOF value. QEMU though is using a home-grown reimpl of readline... > > I understand why we can't use modern libreadline (it is licensed GPLv3+, > making it impossible to use with our GPLv2-only code) - but doesn't BSD > have a readline-alike library with BSD licensing that we could use > instead of implementing readline ourselves? (Was it named libinput?) We've discussed this before. Short story: we can't use the original due to our foolish licensing mistake, and the clones don't cut the mustard. Long story: http://lists.gnu.org/archive/html/qemu-devel/2016-10/msg02697.html
* Daniel P. Berrange (berrange@redhat.com) wrote:
> qemu-io puts the TTY into non-canonical mode, which means no EOF processing is
> done and thus getchar() will never return the EOF constant. Instead we have to
> check for an explicit Ctrl-D, aka 0x4, to detect EOF and exit the qemu-io
> shell. This fixes the regression that prevented Ctrl-D from triggering an exit
> of qemu-io that has existed since readline was first added in
>
> commit 0cf17e181798063c3824c8200ba46f25f54faa1a
> Author: Stefan Hajnoczi <stefanha@redhat.com>
> Date: Thu Nov 14 11:54:17 2013 +0100
>
> qemu-io: use readline.c
>
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
> qemu-io.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/qemu-io.c b/qemu-io.c
> index c70bde3eb1..2ea0bfbaf8 100644
> --- a/qemu-io.c
> +++ b/qemu-io.c
> @@ -322,7 +322,9 @@ static char *fetchline_readline(void)
> readline_start(readline_state, get_prompt(), 0, readline_func, &line);
> while (!line) {
> int ch = getchar();
> - if (ch == EOF) {
> + /* In non-canon tty mode we get 0x4 (Ctrl-D), not the stdio "EOF"
> + * constant */
> + if (ch == 0x4) {
Personally I'd have made that EOF or 0x4 - but that's fine
(I don't see the point of reading the ioctl to figure out which EOF
char we're using; it seems to turn a trivial check into something much
more complex)
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> break;
> }
> readline_handle_byte(readline_state, ch);
> --
> 2.14.3
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
On Fri, Dec 08, 2017 at 12:15:21PM +0000, Dr. David Alan Gilbert wrote:
> * Daniel P. Berrange (berrange@redhat.com) wrote:
> > qemu-io puts the TTY into non-canonical mode, which means no EOF processing is
> > done and thus getchar() will never return the EOF constant. Instead we have to
> > check for an explicit Ctrl-D, aka 0x4, to detect EOF and exit the qemu-io
> > shell. This fixes the regression that prevented Ctrl-D from triggering an exit
> > of qemu-io that has existed since readline was first added in
> >
> > commit 0cf17e181798063c3824c8200ba46f25f54faa1a
> > Author: Stefan Hajnoczi <stefanha@redhat.com>
> > Date: Thu Nov 14 11:54:17 2013 +0100
> >
> > qemu-io: use readline.c
> >
> > Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> > ---
> > qemu-io.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/qemu-io.c b/qemu-io.c
> > index c70bde3eb1..2ea0bfbaf8 100644
> > --- a/qemu-io.c
> > +++ b/qemu-io.c
> > @@ -322,7 +322,9 @@ static char *fetchline_readline(void)
> > readline_start(readline_state, get_prompt(), 0, readline_func, &line);
> > while (!line) {
> > int ch = getchar();
> > - if (ch == EOF) {
> > + /* In non-canon tty mode we get 0x4 (Ctrl-D), not the stdio "EOF"
> > + * constant */
> > + if (ch == 0x4) {
>
> Personally I'd have made that EOF or 0x4 - but that's fine
I thought about that, but it is impossible to get 'EOF' when the terminal
is in raw mode, so there's little point.
> (I don't see the point of reading the ioctl to figure out which EOF
> char we're using; it seems to turn a trivial check into something much
> more complex)
I'd already done the work to read termios settings by time I read this
comment, so I've sent a v2 anyway :-)
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Regards,
Daniel
--
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