Quoting Denis V. Lunev (2015-10-07 05:59:34) > From: Olga Krishtal <okrish...@virtuozzo.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. > > Restore compatibility with Posix implementation. > > The patch adds Win32 specific implementation of qemu_set_nonblock. > > On Windows OS there is a separate API for changing flags of file, pipes > and sockets. Portable way to change file descriptor flags requires > to detect file descriptor type and proper actions depending of that > type. The patch adds wrapper qemu_set_fd_nonblocking into Windows specific > code to handle this stuff properly. > > The only problem is that qemu_set_nonblock is void but this should not > be a big deal. > > Signed-off-by: Olga Krishtal <okrish...@virtuozzo.com> > Signed-off-by: Denis V. Lunev <d...@openvz.org> > Reviewed-by: Yuri Pudgorodskiy <y...@virtuozzo.com> > CC: Michael Roth <mdr...@linux.vnet.ibm.com> > CC: Stefan Weil <s...@weilnetz.de> > --- > qga/commands-win32.c | 6 ++++++ > util/oslib-win32.c | 52 > +++++++++++++++++++++++++++++++++++++++++++++++----- > 2 files changed, 53 insertions(+), 5 deletions(-) > > diff --git a/qga/commands-win32.c b/qga/commands-win32.c > index 3374678..3274417 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(fileno(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 08f5a9c..f19aed5 100644 > --- a/util/oslib-win32.c > +++ b/util/oslib-win32.c > @@ -121,17 +121,59 @@ struct tm *localtime_r(const time_t *timep, struct tm > *result) > } > #endif /* CONFIG_LOCALTIME_R */ > > -void qemu_set_block(int fd) > +static void qemu_set_fd_nonblocking(int fd, bool nonblocking) > { > - unsigned long opt = 0; > - WSAEventSelect(fd, NULL, 0); > + HANDLE handle; > + DWORD file_type, pipe_state; > + > + handle = (HANDLE)_get_osfhandle(fd); > + if (handle == INVALID_HANDLE_VALUE) { > + return; > + } > + > + 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)) { > + /* 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); > + return; > + } > + > + /* The fd is socket fd */ > + unsigned long opt = (unsigned long)nonblocking; > + if (!nonblocking) { > + WSAEventSelect(fd, NULL, 0); > + } > ioctlsocket(fd, FIONBIO, &opt); > } > > +void qemu_set_block(int fd) > +{ > + qemu_set_fd_nonblocking(fd, false); > +} > + > void qemu_set_nonblock(int fd) > { > - unsigned long opt = 1; > - ioctlsocket(fd, FIONBIO, &opt); > + qemu_set_fd_nonblocking(fd, true); > qemu_fd_register(fd);
This still potentially calls qemu_fd_register() on a non-socket FD as noted in prior review. I think the fix is trivial, but if you can change and re-test that would be ideal. Since guest-file* already supports reading/writing to w32 pipes I can pick this up during soft-freeze if it comes to that. Since we're still taking the approach of generalizing qemu_set_nonblock() for win32 I'd really prefer to get Stefan's Ack/Reviewed-by before applying. > } > > -- > 2.1.4 >