On Feb 9 15:33, Tom Honermann wrote: > On 2/9/2019 9:51 AM, Corinna Vinschen wrote: > > On Feb 8 22:25, Tom Honermann wrote: > >> The following program demonstrates the problem. > >> [...] > >> Here is where things go bananas. If the program is run with stdout > >> initially redirected to a pipe, then the stderr output from the native > >> Windows program ends up overwriting the stdout output from the two > >> calls to echo: > >> > >> $ ./test | cat > >> $ cat out > >> The syntax of this command is: > >> > >> NET > >> [ ACCOUNTS | COMPUTER | CONFIG | CONTINUE | FILE | GROUP | HELP | > >> HELPMSG | LOCALGROUP | PAUSE | SESSION | SHARE | START | > >> STATISTICS | STOP | TIME | USE | USER | VIEW ] > >> > >> Note that the lines containing "first" and "second" are now absent in > >> the file. > > Thanks for the testcase. I tracked this down to a bug when calling > > native (non-Cygwin) apps. If the descriptor is in O_APPEND mode, we > > have to set the file offset to EOF before calling native apps. However, > > this only worked reliably for the first descriptor in O_APPEND mode, but > > only by chance for subsequent descriptors in O_APPEND mode. Your > > example code with the extra pipe to `cat' triggered the misbehaviour. > > > > I fixed that in git master: > > https://sourceware.org/git/?p=newlib-cygwin.git;a=commitdiff;h=0be0b8f0335e > > > > This will be in the 3.0.0 release. > > > > I just uploaded new developer snapshots to https://cygwin.com/snapshots/ > > You only need to replace the Cygwin DLL for testing. Please give it a try. > > Thank you, Corinna! This does appear to fix the problem. I verified > the snapshot with the original test case and the one above and both work > as expected now. We'll do some more extensive testing and report back > if we find any further issues. You are awesome!
Thanks for testing. I'll upload another 3.0.0 test release early next week and then I hope the release can be done a few days later. Corinna -- Corinna Vinschen Cygwin Maintainer
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