Re: [PATCH v3 1/2] util: Introduce qemu_get_host_name()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 6/22/20 8:19 PM, Michal Privoznik wrote:
> This function offers operating system agnostic way to fetch host
> name. It is implemented for both POSIX-like and Windows systems.
> 
> Signed-off-by: Michal Privoznik <mprivozn@redhat.com>

Thanks for the updates!

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

> ---
>  include/qemu/osdep.h | 10 ++++++++++
>  util/oslib-posix.c   | 35 +++++++++++++++++++++++++++++++++++
>  util/oslib-win32.c   | 13 +++++++++++++
>  3 files changed, 58 insertions(+)
> 
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index ff7c17b857..a795d46b28 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -607,4 +607,14 @@ static inline void qemu_reset_optind(void)
>  #endif
>  }
>  
> +/**
> + * qemu_get_host_name:
> + * @errp: Error object
> + *
> + * Operating system agnostic way of querying host name.
> + *
> + * Returns allocated hostname (caller should free), NULL on failure.
> + */
> +char *qemu_get_host_name(Error **errp);
> +
>  #endif
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index 916f1be224..3997ee0442 100644
> --- a/util/oslib-posix.c
> +++ b/util/oslib-posix.c
> @@ -761,3 +761,38 @@ void sigaction_invoke(struct sigaction *action,
>      }
>      action->sa_sigaction(info->ssi_signo, &si, NULL);
>  }
> +
> +#ifndef HOST_NAME_MAX
> +# ifdef _POSIX_HOST_NAME_MAX
> +#  define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
> +# else
> +#  define HOST_NAME_MAX 255
> +# endif
> +#endif
> +
> +char *qemu_get_host_name(Error **errp)
> +{
> +    long len = -1;
> +    g_autofree char *hostname = NULL;
> +
> +#ifdef _SC_HOST_NAME_MAX
> +    len = sysconf(_SC_HOST_NAME_MAX);
> +#endif /* _SC_HOST_NAME_MAX */
> +
> +    if (len < 0) {
> +        len = HOST_NAME_MAX;
> +    }
> +
> +    /* Unfortunately, gethostname() below does not guarantee a
> +     * NULL terminated string. Therefore, allocate one byte more
> +     * to be sure. */
> +    hostname = g_new0(char, len + 1);
> +
> +    if (gethostname(hostname, len) < 0) {
> +        error_setg_errno(errp, errno,
> +                         "cannot get hostname");
> +        return NULL;
> +    }
> +
> +    return g_steal_pointer(&hostname);
> +}
> diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> index e9b14ab178..3b49d27297 100644
> --- a/util/oslib-win32.c
> +++ b/util/oslib-win32.c
> @@ -808,3 +808,16 @@ bool qemu_write_pidfile(const char *filename, Error **errp)
>      }
>      return true;
>  }
> +
> +char *qemu_get_host_name(Error **errp)
> +{
> +    wchar_t tmp[MAX_COMPUTERNAME_LENGTH + 1];
> +    DWORD size = G_N_ELEMENTS(tmp);
> +
> +    if (GetComputerNameW(tmp, &size) == 0) {
> +        error_setg_win32(errp, GetLastError(), "failed close handle");
> +        return NULL;
> +    }
> +
> +    return g_utf16_to_utf8(tmp, size, NULL, NULL, NULL);
> +}
>