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Previously, cygwin read pipe used non-blocking mode although non- cygwin app uses blocking-mode by default. Despite this requirement, if a cygwin app is executed from a non-cygwin app and the cygwin app exits, read pipe remains on non-blocking mode because of the commit fc691d0246b9. Due to this behaviour, the non-cygwin app cannot read the pipe correctly after that. Similarly, if a non- cygwin app is executed from a cygwin app and the non-cygwin app exits, the read pipe mode remains on blocking mode although cygwin read pipe should be non-blocking mode. These bugs were provoked by pipe mode toggling between cygwin and non-cygwin apps. To make management of pipe mode simpler, this patch has re-designed the pipe implementation. In this new implementation, both read and write pipe basically use only blocking mode and the behaviour corresponding to the pipe mode is simulated in raw_read() and raw_write(). Only when NtQueryInformationFile (FilePipeLocalInformation) fails for some reasons, the raw_read()/ raw_write() cannot simulate non-blocking access. Therefore, the pipe mode is temporarily changed to non-blocking mode. Moreover, because the fact that NtSetInformationFile() in set_pipe_non_blocking(true) fails with STATUS_PIPE_BUSY if the pipe is not empty has been found, query handle is not necessary anymore. This allows the implementation much simpler than before. Addresses: https://github.com/git-for-windows/git/issues/5115 Fixes: fc691d0246b9 ("Cygwin: pipe: Make sure to set read pipe non-blocking for cygwin apps."); Reported-by: isaacag, Johannes Schindelin <Johannes.Schindelin@gmx.de> Reviewed-by: Corinna Vinschen <corinna@vinschen.de>, Ken Brown <kbrown@cornell.edu> Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>