Subject: Re: Re: [PATCH/RFC] send-pack.c: Allow to disable side-band-64k

From: Thomas Braun <[email-masked]>
Date: Tue, 20 May 2014 10:46:07 +0200

Am 19.05.2014 22:29, schrieb Erik Faye-Lund:
>>  [...]
>> Would we need to wrap both ends, shouldn't wrapping only reading be
>> good enough to prevent deadlocking?
>>
>> compat/poll/poll.c already contains a function called IsSocketHandle
>> that is able to tell if a HANDLE points to a socket or not.
>
> This very quick attempt did not work out :(
>
> diff --git a/compat/mingw.c b/compat/mingw.c
> index 0335958..ec1d81f 100644
> --- a/compat/mingw.c
> +++ b/compat/mingw.c
> @@ -370,6 +370,65 @@ int mingw_open (const char *filename, int oflags, ...)
>       return fd;
>   }
>
> +#define is_console_handle(h) (((long) (h) & 3) == 3)
> +
> +static int is_socket_handle(HANDLE h)
> +{
> +    WSANETWORKEVENTS ev;
> +
> +    if (is_console_handle(h))
> +        return 0;
> +
> +    /*
> +     * Under Wine, it seems that getsockopt returns 0 for pipes too.
> +     * WSAEnumNetworkEvents instead distinguishes the two correctly.
> +     */
> +    ev.lNetworkEvents = 0xDEADBEEF;
> +    WSAEnumNetworkEvents((SOCKET) h, NULL, &ev);
> +    return ev.lNetworkEvents != 0xDEADBEEF;
> +}
> +
> +#undef read
> +ssize_t mingw_read(int fd, void *buf, size_t count)
> +{
> +    int ret;
> +    HANDLE fh = (HANDLE)_get_osfhandle(fd);
> +
> +    if (fh == INVALID_HANDLE_VALUE) {
> +        errno = EBADF;
> +        return -1;
> +    }
> +
> +    if (!is_socket_handle(fh))
> +        return read(fd, buf, count);
> +
> +    ret = recv((SOCKET)fh, buf, count, 0);
> +    if (ret < 0)
> +        errno = WSAGetLastError();
> +    return ret;
> +}
> +
> +#undef write
> +ssize_t mingw_write(int fd, const void *buf, size_t count)
> +{
> +    int ret;
> +    HANDLE fh = (HANDLE)_get_osfhandle(fd);
> +
> +    if (fh == INVALID_HANDLE_VALUE) {
> +        errno = EBADF;
> +        return -1;
> +    }
> +
> +    if (!is_socket_handle(fh))
> +        return write(fd, buf, count);
> +
> +    return send((SOCKET)fh, buf, count, 0);
> +    if (ret < 0)
> +        errno = WSAGetLastError();
> +    return ret;
> +}
> +
> +
>   static BOOL WINAPI ctrl_ignore(DWORD type)
>   {
>       return TRUE;
> diff --git a/compat/mingw.h b/compat/mingw.h
> index 08b83fe..1690098 100644
> --- a/compat/mingw.h
> +++ b/compat/mingw.h
> @@ -177,6 +177,12 @@ int mingw_rmdir(const char *path);
>   int mingw_open (const char *filename, int oflags, ...);
>   #define open mingw_open
>
> +ssize_t mingw_read(int fd, void *buf, size_t count);
> +#define read mingw_read
> +
> +ssize_t mingw_write(int fd, const void *buf, size_t count);
> +#define write mingw_write
> +
>   int mingw_fgetc(FILE *stream);
>   #define fgetc mingw_fgetc

According to [1] you also have to pass WSA_FLAG_OVERLAPPED to avoid the deadlock.

With that change I don't get a hang anymore but a read error with 
errno 10054 aka WSAECONNRESET.

[1]: https://groups.google.com/forum/#!msg/msysgit/at8D7J-h7mw/PM9w-d41cDYJ

diff --git a/compat/mingw.c b/compat/mingw.c
index 383cafe..4a58135 100644
--- a/compat/mingw.c
+++ b/compat/mingw.c
@@ -366,6 +366,71 @@ int mingw_open (const char *filename, int oflags, ...)
 	return fd;
 }
 
+#define is_console_handle(h) (((long) (h) & 3) == 3)
+
+static int is_socket_handle(HANDLE h)
+{
+    WSANETWORKEVENTS ev;
+
+    if (is_console_handle(h))
+        return 0;
+
+    /*
+     * Under Wine, it seems that getsockopt returns 0 for pipes too.
+     * WSAEnumNetworkEvents instead distinguishes the two correctly.
+     */
+    ev.lNetworkEvents = 0xDEADBEEF;
+    WSAEnumNetworkEvents((SOCKET) h, NULL, &ev);
+    return ev.lNetworkEvents != 0xDEADBEEF;
+}
+
+#undef read
+ssize_t mingw_read(int fd, void *buf, size_t count)
+{
+    int ret;
+    HANDLE fh = (HANDLE)_get_osfhandle(fd);
+
+    if (fh == INVALID_HANDLE_VALUE) {
+        errno = EBADF;
+        return -1;
+    }
+
+    if (!is_socket_handle(fh))
+        return read(fd, buf, count);
+
+    ret = recv((SOCKET)fh, buf, count, 0);
+    if (ret < 0)
+    {
+        errno = WSAGetLastError();
+        warning("errno %d",errno);
+    }
+    return ret;
+}
+
+#undef write
+ssize_t mingw_write(int fd, const void *buf, size_t count)
+{
+    int ret;
+    HANDLE fh = (HANDLE)_get_osfhandle(fd);
+
+    if (fh == INVALID_HANDLE_VALUE) {
+        errno = EBADF;
+        return -1;
+    }
+
+    if (!is_socket_handle(fh))
+        return write(fd, buf, count);
+
+    ret = send((SOCKET)fh, buf, count, 0);
+    if (ret < 0)
+    {
+        errno = WSAGetLastError();
+        warning("errno %d",errno);
+    }
+    return ret;
+}
+
+
 static BOOL WINAPI ctrl_ignore(DWORD type)
 {
 	return TRUE;
@@ -1542,7 +1607,7 @@ int mingw_socket(int domain, int type, int protocol)
 	SOCKET s;
 
 	ensure_socket_initialization();
-	s = WSASocket(domain, type, protocol, NULL, 0, 0);
+	s = WSASocket(domain, type, protocol, NULL, 0, WSA_FLAG_OVERLAPPED);
 	if (s == INVALID_SOCKET) {
 		/*
 		 * WSAGetLastError() values are regular BSD error codes
diff --git a/compat/mingw.h b/compat/mingw.h
index 08b83fe..1690098 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -177,6 +177,12 @@ int mingw_rmdir(const char *path);
 int mingw_open (const char *filename, int oflags, ...);
 #define open mingw_open
 
+ssize_t mingw_read(int fd, void *buf, size_t count);
+#define read mingw_read
+
+ssize_t mingw_write(int fd, const void *buf, size_t count);
+#define write mingw_write
+
 int mingw_fgetc(FILE *stream);
 #define fgetc mingw_fgetc

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