Quoting Denis V. Lunev (2015-10-27 12:48:43)
> From: Olga Krishtal <okrish...@parallels.com>
>
> Set fd non-blocking to avoid common use cases (like reading from a
> named pipe) from hanging the agent. This was missed in the original
> code.
>
> The patch introduces analog of qemu_set_non/block for HANDLES.
> The usage of handles in qemu_set_non/block is impossible, because for
> win32 there is a difference between file discriptors and file handles,
> and all file ops are made via Win32 api.
If this is specific to HANDLEs, why do we need to cast back and forth
between int64_t and HANDLE? I haven't build tested, but it seems like
this would break for 32-bit mingw builds.
I would define these as qemu_set_*_by_handle(HANDLE fh, ...) instead
and make them win32 only. If someone wants to introduce a FILE*
variant for posix they can introduce it as
qemu_set_*_by_handle(FILE *fh, ...) rather than us needing to
abstract away the handle type.
>
> Signed-off-by: Olga Krishtal <okrish...@parallels.com>
> Signed-off-by: Denis V. Lunev <d...@openvz.org>
> CC: Michael Roth <mdr...@linux.vnet.ibm.com>
> CC: Stefan Weil <s...@weilnetz.de>
> ---
> include/qemu/sockets.h | 2 ++
> qga/commands-win32.c | 6 ++++++
> util/oslib-win32.c | 41 +++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 49 insertions(+)
>
> diff --git a/include/qemu/sockets.h b/include/qemu/sockets.h
> index 5a183c5..e2323f4 100644
> --- a/include/qemu/sockets.h
> +++ b/include/qemu/sockets.h
> @@ -39,6 +39,8 @@ int socket_set_cork(int fd, int v);
> int socket_set_nodelay(int fd);
> void qemu_set_block(int fd);
> void qemu_set_nonblock(int fd);
> +void qemu_set_nonblock_by_handle(int64_t fh);
> +void qemu_set_block_by_handle(int64_t fh);
> int socket_set_fast_reuse(int fd);
> int send_all(int fd, const void *buf, int len1);
> int recv_all(int fd, void *buf, int len1, bool single_read);
> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
> index 97f19d5..f959d75 100644
> --- a/qga/commands-win32.c
> +++ b/qga/commands-win32.c
> @@ -34,6 +34,7 @@
> #include "qapi/qmp/qerror.h"
> #include "qemu/queue.h"
> #include "qemu/host-utils.h"
> +#include "qemu/sockets.h"
>
> #ifndef SHTDN_REASON_FLAG_PLANNED
> #define SHTDN_REASON_FLAG_PLANNED 0x80000000
> @@ -158,6 +159,11 @@ int64_t qmp_guest_file_open(const char *path, bool
> has_mode,
> return -1;
> }
>
> + /* set fd non-blocking to avoid common use cases (like reading from a
> + * named pipe) from hanging the agent
> + */
> + qemu_set_nonblock_by_handle((int64_t)fh);
> +
> fd = guest_file_handle_add(fh, errp);
> if (fd < 0) {
> CloseHandle(fh);
> diff --git a/util/oslib-win32.c b/util/oslib-win32.c
> index 09f9e98..4a9fd8e 100644
> --- a/util/oslib-win32.c
> +++ b/util/oslib-win32.c
> @@ -121,6 +121,37 @@ struct tm *localtime_r(const time_t *timep, struct tm
> *result)
> }
> #endif /* CONFIG_LOCALTIME_R */
>
> +static void qemu_set_handle_nonblocking(int64_t fh, bool nonblocking)
> +{
> + DWORD file_type, pipe_state;
> + HANDLE handle = (HANDLE)fh;
> + file_type = GetFileType(handle);
> + if (file_type != FILE_TYPE_PIPE) {
> + return;
> + }
> + /* If file_type == FILE_TYPE_PIPE, according to msdn
> + * the specified file is socket or named pipe */
> + if (!GetNamedPipeHandleState(handle, &pipe_state, NULL,
> + NULL, NULL, NULL, 0)) {
> + return;
> + }
> + /* The fd is named pipe fd */
> + if (!nonblocking == !(pipe_state & PIPE_NOWAIT)) {
> + /* In this case we do not need perform any operation, because
> + * nonblocking = true and PIPE_NOWAIT is already set or
> + * nonblocking = false and PIPE_NOWAIT is not set */
> + return;
> + }
> +
> + if (nonblocking) {
> + pipe_state |= PIPE_NOWAIT;
> + } else {
> + pipe_state &= ~PIPE_NOWAIT;
> + }
> +
> + SetNamedPipeHandleState(handle, &pipe_state, NULL, NULL);
> +}
> +
> void qemu_set_block(int fd)
> {
> unsigned long opt = 0;
> @@ -135,6 +166,16 @@ void qemu_set_nonblock(int fd)
> qemu_fd_register(fd);
> }
>
> +void qemu_set_block_by_handle(int64_t fh)
> +{
> + qemu_set_handle_nonblocking(fh, false);
> +}
> +
> +void qemu_set_nonblock_by_handle(int64_t fh)
> +{
> + qemu_set_handle_nonblocking(fh, true);
> +}
> +
> int socket_set_fast_reuse(int fd)
> {
> /* Enabling the reuse of an endpoint that was used by a socket still in
> --
> 2.1.4
>
