Re: [Qemu-devel] [PULL 52/53] char: Remove unwanted crlf conversion

[Greg Kurz]

On Thu, 31 May 2018 19:16:05 +0200
Paolo Bonzini <address@hidden> wrote:

> From: Patryk Olszewski <address@hidden>
> 
> This patch fixes a bug in serial that made it almost impossible for guest
> to communicate with devices through host's serial.
> 
> OPOST flag in c_oflag enables output processing letting other flags in
> c_oflag take effect. Usually in c_oflag ONLCR flag is also set, which
> causes crlf to be sent in place of lf. This breaks binary transmissions.
> Unsetting OPOST flag turns off any output processing which fixes the bug.
> 

But it damages error reporting...

Without this patch:

$ qemu-system-ppc64 -serial stdio -kernel foo
foo: No such file or directory
qemu-system-ppc64: error loading foo: Failed to load ELF
$

With this patch:

$ .mbuild-ppc-for-3.0/obj/ppc64-softmmu/qemu-system-ppc64 -serial stdio -kernel 
foo
foo: No such file or directory
                              qemu-system-ppc64: error loading foo: Failed to 
load ELF
                                                                                
      $

It is possible to patch vreport() to append an explicit CR:

     error_vprintf(fmt, ap);
-    error_printf("\n");
+    error_printf("\n\r");
 }

but it only fixes the trailing newline of error_report(). Any other newline,
eg when using error_append_hint(), will lack the CR... Not sure how to fix
this :-\

> Bug reports related:
> https://bugs.launchpad.net/qemu/+bug/1772086
> https://bugs.launchpad.net/qemu/+bug/1407813
> https://bugs.launchpad.net/qemu/+bug/1715296
> also
> https://lists.nongnu.org/archive/html/qemu-devel/2006-06/msg00196.html
> 
> Signed-off-by: Patryk Olszewski <address@hidden>
> Message-Id: <address@hidden>
> Reviewed-by: Markus Armbruster <address@hidden>
> Reviewed-by: Thomas Huth <address@hidden>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  chardev/char-serial.c | 2 +-
>  chardev/char-stdio.c  | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/chardev/char-serial.c b/chardev/char-serial.c
> index feb52e559d..ae548d28da 100644
> --- a/chardev/char-serial.c
> +++ b/chardev/char-serial.c
> @@ -139,7 +139,7 @@ static void tty_serial_init(int fd, int speed,
>  
>      tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
>                       | INLCR | IGNCR | ICRNL | IXON);
> -    tty.c_oflag |= OPOST;
> +    tty.c_oflag &= ~OPOST;
>      tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
>      tty.c_cflag &= ~(CSIZE | PARENB | PARODD | CRTSCTS | CSTOPB);
>      switch (data_bits) {
> diff --git a/chardev/char-stdio.c b/chardev/char-stdio.c
> index 96375f2ab8..d83e60e787 100644
> --- a/chardev/char-stdio.c
> +++ b/chardev/char-stdio.c
> @@ -59,7 +59,7 @@ static void qemu_chr_set_echo_stdio(Chardev *chr, bool echo)
>      if (!echo) {
>          tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
>                           | INLCR | IGNCR | ICRNL | IXON);
> -        tty.c_oflag |= OPOST;
> +        tty.c_oflag &= ~OPOST;
>          tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
>          tty.c_cflag &= ~(CSIZE | PARENB);
>          tty.c_cflag |= CS8;