Re: [Qemu-devel] [PATCH v2] qemu-io: fix EOF Ctrl-D handling in qemu-io readline code

["Daniel P. Berrangé" <berrange@redhat.com>]

ping, does any block maintainer want to queue this one ?

On Fri, Dec 08, 2017 at 01:34:16PM +0000, 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
> query the TTY attributes to determine the configured EOF character (usually
> Ctrl-D / 0x4), and then explicitly check for that value. 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>
> ---
> Changed in v2:
> 
>   - Query termios settings for EOF character
> 
>  qemu-io.c | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/qemu-io.c b/qemu-io.c
> index c70bde3eb1..fa4972d734 100644
> --- a/qemu-io.c
> +++ b/qemu-io.c
> @@ -10,6 +10,9 @@
>  #include "qemu/osdep.h"
>  #include <getopt.h>
>  #include <libgen.h>
> +#ifndef _WIN32
> +#include <termios.h>
> +#endif
>  
>  #include "qapi/error.h"
>  #include "qemu-io.h"
> @@ -41,6 +44,26 @@ static bool imageOpts;
>  
>  static ReadLineState *readline_state;
>  
> +static int ttyEOF;
> +
> +static int get_eof_char(void)
> +{
> +#ifdef _WIN32
> +    return 0x4; /* Ctrl-D */
> +#else
> +    struct termios tty;
> +    if (tcgetattr(STDIN_FILENO, &tty) != 0) {
> +        if (errno == ENOTTY) {
> +            return 0x0; /* just expect read() == 0 */
> +        } else {
> +            return 0x4; /* Ctrl-D */
> +        }
> +    }
> +
> +    return tty.c_cc[VEOF];
> +#endif
> +}
> +
>  static int close_f(BlockBackend *blk, int argc, char **argv)
>  {
>      blk_unref(qemuio_blk);
> @@ -322,7 +345,7 @@ static char *fetchline_readline(void)
>      readline_start(readline_state, get_prompt(), 0, readline_func, &line);
>      while (!line) {
>          int ch = getchar();
> -        if (ch == EOF) {
> +        if (ttyEOF != 0x0 && ch == ttyEOF) {
>              break;
>          }
>          readline_handle_byte(readline_state, ch);
> @@ -592,6 +615,7 @@ int main(int argc, char **argv)
>      qemuio_add_command(&close_cmd);
>  
>      if (isatty(STDIN_FILENO)) {
> +        ttyEOF = get_eof_char();
>          readline_state = readline_init(readline_printf_func,
>                                         readline_flush_func,
>                                         NULL,
> -- 
> 2.14.3
> 

Regards,
Daniel
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