if (! connect(...)) { handle error }

[ovidiuadam]

Hello, It seems to me that the statement in https://github.com/FastCGI-Archives/fcgi2/blob/master/libfcgi/os_win32.c, function int OS_FcgiConnect(char *bindPath), line 850 should be changed to:
if (connect(sock, (struct sockaddr *) &sockAddr, sockLen) < 0) { ...
Best regards,
Ovidiu Adam

[mcarbonneaux]

i think is ok like is writen!

if (! connect(sock, (struct sockaddr *) &sockAddr, sockLen)) 

in man of connect https://man7.org/linux/man-pages/man2/connect.2.html.
connect return:

• 0 (connection ok),
• -1 (connection ko).

in c language (https://c-for-dummies.com/blog/?p=1188)

• 0 = false,
• not 0 (>0 or <0) = true.

this if condition try to check if connect is ko...

• connect return -1 in ko case,
• and is true (<0),
• and with ! (reverse the boolean value) is true...
• and is match the ko case...
• and go to closesocket and return -1...

if need to bee changed, the prefered condition while be != 0...

if (connect(sock, (struct sockaddr *) &sockAddr, sockLen)!=0) 

[ovidiuadam]

Hello Mathieu - I beg to differ
The way the current code is written (!connect()) {error}, when connect() succeeds, it returns 0 forcing the execution into handling an error which does not exist, and closing an innocent socket.
For the error case the man says "On error, -1 is returned", hence my suggestion for the "<0 " test
Best regards, Ovidiu

[mcarbonneaux]

no return 0 (equal to false) is inverted and then come false then not entering in closingsocket brace.
and then return anything differant than 0 in the case -1 (equal to true) then inverted is now false, then enter to the brace.

[ovidiuadam]

.. and yes, changing the test to "the preferred condition while be != 0", will work too. Note that (connect() != 0) is different than (!connect()).

[mcarbonneaux]

Note that (connect() != 0) is different than (!connect()).

is equivalent, but more readable.

[ovidiuadam]

Not equivalent. Different. (!connect()) is equivalent to (connect() == 0)

[mcarbonneaux]

no i not ok with that!

• connect() == 0 is matching connect ok and is equivalent to if (!connect())
• connect() != 0 or more specificly connect == -1 is matching connect ko and is equivalent to if (connect())

in c language, 0 = false and not 0 is true....

[ovidiuadam]

No. it is not working. This is how I noticed it.

[mcarbonneaux]

is used in many project.... if the condition not worked any project on unix using this framework while not work at all...

[ovidiuadam]

[Ovidiu has revised this post, to match the mcarbonneaux post above. After the edits, the 2 posts are now in agreement]
No, I (Ovidiu) contend that:
connect() == 0 is matching connect success (according to man) is equivalent to if (!connect())
connect() != 0 or more specifically connect == -1 is matching connect failure and is equivalent to if (connect())

[mcarbonneaux]

then if (!connect()) is equivalent to connect() != 0....

[ovidiuadam]

This happens on Windows, not unix.

[ovidiuadam]

"0 is false in c langage" . Yes. (!connect()) --> false --> 0 --> and man says that 0 is the return value for success, but the Windows if(!connect()) executes the failure branch, in case of success

[mcarbonneaux]

are you sure that connect on windows return 0 on success ?
this as been more tested on unix...i think...

because this function is the first function that are call when you use this framework... i'm suprise that not work on windows...

on unix part is checking differently.
https://github.com/FastCGI-Archives/fcgi2/blob/master/libfcgi/os_unix.c#L459

connectStatus = connect(resultSock, (struct sockaddr *) &sa.unixVariant, len);
if(connectStatus >= 0) {
    return resultSock;
} 
else {
    /*
     * Most likely (errno == ENOENT || errno == ECONNREFUSED)
     * and no FCGI application server is running.
     */
    close(resultSock);
    return -1;
}

on windows the connect fonction seem to work like on unix:
https://learn.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-connect

• 0 when ok
• SOCKET_ERROR when ko (seem to be -1)

but the check are not the same (i ok with you but i don't understand why none as send feedback for that):
https://github.com/FastCGI-Archives/fcgi2/blob/master/libfcgi/os_win32.c#L850

if (! connect(sock, (struct sockaddr *) &sockAddr, sockLen)) 
{
	closesocket(sock);
	return -1;
}

but is possible that the most used case on windows is using pipe....

[mcarbonneaux]

i sayed erronous:

the if condition try to check if connect is ko...

when connect return -1 in ko case:

• and is true (!=0),
• and with ! (reverse the boolean value) is false...
• and is not match the ko case...
• and not go to closesocket and return -1...

when connect return 0 in ok case:

• and is false (=0),
• and with ! (reverse the boolean value) is true...
• and is match the ok case...
• and go to closesocket and return -1...

and simple (connect()) or (connect()!=0) or (connect()<0) (like you sayed) while be ok.

[ovidiuadam]

Bingo! - Yes, connect() in Windows works the same as in unix (it returns 0 for success and -1 for error).
Thank you, Ovidiu