diff mbox

[2/2] qga: set file descriptors in qmp_guest_file_open non-blocking on Win32

Message ID 1444215574-11895-3-git-send-email-den@openvz.org
State New
Headers show

Commit Message

Denis V. Lunev Oct. 7, 2015, 10:59 a.m. UTC 
From: Olga Krishtal <okrishtal@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 <okrishtal@virtuozzo.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
CC: Michael Roth <mdroth@linux.vnet.ibm.com>
CC: Stefan Weil <sw@weilnetz.de>
---
 qga/commands-win32.c |  6 ++++++
 util/oslib-win32.c   | 52 +++++++++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 53 insertions(+), 5 deletions(-)

Comments

Michael Roth Oct. 12, 2015, 5:38 p.m. UTC | #1 
Quoting Denis V. Lunev (2015-10-07 05:59:34)
> From: Olga Krishtal <okrishtal@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 <okrishtal@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> Reviewed-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
> CC: Michael Roth <mdroth@linux.vnet.ibm.com>
> CC: Stefan Weil <sw@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
>
Denis V. Lunev Oct. 12, 2015, 5:47 p.m. UTC | #2 
On 10/12/2015 08:38 PM, Michael Roth wrote:
> Quoting Denis V. Lunev (2015-10-07 05:59:34)
>> From: Olga Krishtal <okrishtal@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 <okrishtal@virtuozzo.com>
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> Reviewed-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
>> CC: Michael Roth <mdroth@linux.vnet.ibm.com>
>> CC: Stefan Weil <sw@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.

you are perfectly correct, I have missed this fact from previous discussion.
Sure this needs to be addressed.

Thank you for a review.

Den
Stefan Weil Oct. 12, 2015, 6:39 p.m. UTC | #3 
Hi,

please see my inline comments below.

Am 12.10.2015 um 19:38 schrieb Michael Roth:
> Quoting Denis V. Lunev (2015-10-07 05:59:34)
>> From: Olga Krishtal <okrishtal@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 <okrishtal@virtuozzo.com>
>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>> Reviewed-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
>> CC: Michael Roth <mdroth@linux.vnet.ibm.com>
>> CC: Stefan Weil <sw@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 */

... or an anonymous pipe.

>> +    if (GetNamedPipeHandleState(handle, &pipe_state, NULL,
>> +                                NULL, NULL, NULL, 0)) {
>> +        /* The fd is named pipe fd */

pipe_state could be declared here.

>> +        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;

The QEMU style still requires variable declarations at the beginning of
a code block.

>> +    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.

Yes.

> 
> 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.
> 
>>  }

I'm sorry that I cannot run any tests, but as far as I can see,
the code will be fine if all the notes are taken into account.

Regards
Stefan
Denis V. Lunev Oct. 12, 2015, 7:14 p.m. UTC | #4 
On 10/12/2015 09:39 PM, Stefan Weil wrote:
> Hi,
>
> please see my inline comments below.
>
> Am 12.10.2015 um 19:38 schrieb Michael Roth:
>> Quoting Denis V. Lunev (2015-10-07 05:59:34)
>>> From: Olga Krishtal <okrishtal@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 <okrishtal@virtuozzo.com>
>>> Signed-off-by: Denis V. Lunev <den@openvz.org>
>>> Reviewed-by: Yuri Pudgorodskiy <yur@virtuozzo.com>
>>> CC: Michael Roth <mdroth@linux.vnet.ibm.com>
>>> CC: Stefan Weil <sw@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 */
> ... or an anonymous pipe.
ok

>>> +    if (GetNamedPipeHandleState(handle, &pipe_state, NULL,
>>> +                                NULL, NULL, NULL, 0)) {
>>> +        /* The fd is named pipe fd */
> pipe_state could be declared here.

not ok. pipe_state is initialized in GetNamedPipeHandleState above,
which is in the main scope of the function


>>> +        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;
> The QEMU style still requires variable declarations at the beginning of
> a code block.
ok

>>> +    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.
> Yes.
sure :) already discussed


>> 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.
>>
>>>   }
> I'm sorry that I cannot run any tests, but as far as I can see,
> the code will be fine if all the notes are taken into account.
>
> Regards
> Stefan
>
diff mbox

Patch

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);
 }