Forum OpenACS Development: Re: NaviServer on Windows: [ns_info threads] returning unbalanced braces

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43: Re: NaviServer on Windows: [ns_info threads] returning unbalanced braces (response to 42)
Posted by Maurizio Martignano on 03/21/17 02:41 PM
Dear Gustaf,
I've tried all combinations... here's the result:

the original code was:

DWORD n1;
if (WSASend(sock, (LPWSABUF)bufs, nbufs, &n1, flags,
NULL, NULL) != 0) {
n1 = -1;
}
n = n1;

and it DOES NOT WOK

I then used the readability improvement modification you posted this morning at 09:57:40
DWORD bytesReceived;
int rc;

rc = WSASend(sock, (LPWSABUF)bufs, nbufs, &bytesReceived, flags,
NULL, NULL);

if (rc == 0) {
n = bytesReceived;
} else {
n = -1;
}
and it DOES WORK

My original fix was to use a plain send
# if _MSC_VER < 1900
DWORD n1;
if (WSASend(sock, (LPWSABUF)bufs, nbufs, &n1, flags,
NULL, NULL) != 0) {
n1 = -1;
}
n = n1;
#else
n = send(sock, (LPWSABUF)bufs[0].iov_base, bufs[0].iov_len, flags);

#endif

and it DOES WORK

I will include your modification in my distribution, though I cannot see any difference between the first two implementations, but the code is here if anyone wants to check.

Thank you very much,
Maurizio

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44: Re: NaviServer on Windows: [ns_info threads] returning unbalanced braces (response to 43)
Posted by Gustaf Neumann on 03/22/17 09:20 AM
Do i read your mail correctly that now all know issues are gone? That would be great.

Concerning the change around WSAsend(): The difference is not easy to spot but due to a type conversion, since n1 (type DWORD) was originally assigned -1 in error conditions. Since DWORD is defined as unsigned 32bit quantity, bad things happen when its value is assigned to a type of a different size and signedness (here: ssize_t; probably not an issue in 32bit versions). Interestingly, this type issue is not flagged by sonarsrv: the current version of nssock.c in sonarsrv is still the "old" code and shows 0 issues [1]. I've cleaned this code yesterday to prepare for debugging return-codes from WSASend().

Concerning send(): When send() is used as shown in your snippet, the code will produce incorrect results when nbufs <> 1. The reason for using WSAsend() instead of send() is that the former supports the more efficient scatter/gather interface.

all the best
-gn

[1] http://sonarsrv.spazioit.com/code/index?id=my%3Anaviserver#/my%3Anaviserver%3Ansd%2Fsock.c

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45: Re: NaviServer on Windows: [ns_info threads] returning unbalanced braces (response to 44)
Posted by Maurizio Martignano on 03/22/17 01:00 PM
Dear Gustaf,
I believe all issues we have been facing are gone.
They were caused by two errors:
1. memory allocation problem (in dstring.c)
2. bad handling of the WSASend call.

I do not know if you saw it or not. But looking into possible causes for these problems I noticed that EINTR is not handled in a generic way as EWOULDBLOCK and EINPROGRESS. Perhaps it would make sense to normalize also EINTR.

Thank you,
Maurizio