Re: [PATCH 2/2] mingw: fix mingw_open_append to work with named pipes
- Date: Mon, 10 Sep 2018 11:44:56 -0400
- From: Jeff Hostetler <git@xxxxxxxxxxxxxxxxx>
- Subject: Re: [PATCH 2/2] mingw: fix mingw_open_append to work with named pipes
On 9/8/2018 2:31 PM, Johannes Sixt wrote:
Am 08.09.2018 um 11:26 schrieb Johannes Sixt:
Am 07.09.2018 um 20:19 schrieb Jeff Hostetler via GitGitGadget:
diff --git a/compat/mingw.c b/compat/mingw.c
index 858ca14a57..ef03bbe5d2 100644
@@ -355,7 +355,7 @@ static int mingw_open_append(wchar_t const
*wfilename, int oflags, ...)
* FILE_SHARE_WRITE is required to permit child processes
* to append to the file.
- handle = CreateFileW(wfilename, FILE_APPEND_DATA,
+ handle = CreateFileW(wfilename, FILE_WRITE_DATA | FILE_APPEND_DATA,
FILE_SHARE_WRITE | FILE_SHARE_READ,
NULL, create, FILE_ATTRIBUTE_NORMAL, NULL);
if (handle == INVALID_HANDLE_VALUE)
I did not go with this version because the documentation
FILE_APPEND_DATA: For a file object, the right to append data to the
file. (For local files, write operations will not overwrite existing
data if this flag is specified without FILE_WRITE_DATA.) [...]
which could be interpreted as: Only if FILE_WRITE_DATA is not set, we
have the guarantee that existing data in local files is not
overwritten, i.e., new data is appended atomically.
Is this interpretation too narrow and we do get atomicity even when
FILE_WRITE_DATA is set?
Here is are some comments on stackoverflow which let me think that
FILE_APPEND_DATA with FILE_WRITE_DATA is no longer atomic:
Yeah, this whole thing is a little under-documented for my tastes.
Let's leave it as you have it. I'll re-roll with a fix to route
named pipes to the existing _wopen() code.