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 -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
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 -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
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