Lei Li <li...@linux.vnet.ibm.com> writes:
> When controlling a qemu instance from another program, it's
> hard to know which serial port or monitor device is redirected
> to which pty. With more than one device using "pty" a lot of
> guesswork is involved.
>
> $ ./x86_64-softmmu/qemu-system-x86_64 -serial pty -serial pty -monitor pty
> char device redirected to /dev/pts/5
> char device redirected to /dev/pts/6
> char device redirected to /dev/pts/7
>
> Although we can find out what everything else is connected to
> by the "info chardev" with "-monitor stdio" in the command line,
> It'd be very useful to be able to have qemu inherit pseudo-tty
> file descriptors so they could just be specified on the command
> line like:
>
> $ ./x86_64-softmmu/qemu-system-x86_64 -serial pty -serial pty -monitor pty
> char device compat_monitor0 redirected to /dev/pts/5
> char device serial0 redirected to /dev/pts/6
> char device serial1 redirected to /dev/pts/7
>
> Referred link: https://bugs.launchpad.net/qemu/+bug/938552
>
> Reported-by: Craig Ringer <ring...@gmail.com>
> Signed-off-by: Lei Li <li...@linux.vnet.ibm.com>
> ---
> qemu-char.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/qemu-char.c b/qemu-char.c
> index 242b799..2b0f5f4 100644
> --- a/qemu-char.c
> +++ b/qemu-char.c
> @@ -981,6 +981,7 @@ static CharDriverState *qemu_chr_open_pty(QemuOpts *opts)
> CharDriverState *chr;
> PtyCharDriver *s;
> struct termios tty;
> + char *label;
> int master_fd, slave_fd, len;
> #if defined(__OpenBSD__) || defined(__DragonFly__)
> char pty_name[PATH_MAX];
> @@ -1006,7 +1007,8 @@ static CharDriverState *qemu_chr_open_pty(QemuOpts
> *opts)
> chr->filename = g_malloc(len);
> snprintf(chr->filename, len, "pty:%s", q_ptsname(master_fd));
> qemu_opt_set(opts, "path", q_ptsname(master_fd));
> - fprintf(stderr, "char device redirected to %s\n", q_ptsname(master_fd));
> + label = g_strdup(qemu_opts_id(opts));
> + fprintf(stderr, "char device %s redirected to %s\n", label,
> q_ptsname(master_fd));
>
> s = g_malloc0(sizeof(PtyCharDriver));
> chr->opaque = s;
qemu_opts_id() may return null. g_strdup() then also returns null.
Printing null with %s crashes on some systems.
You leak label. Best fixed by not allocating in the first place.
Try this:
label = qemu_opts_id(opts)
fprintf(stderr, "char device%S%s redirected to %s\n",
label ? " " : "",
label ?: , "",
q_ptsname(master_fd));
Don't forget to imporve your subject :)
