Обсуждение: Wonky rename semantics on Windows
Hi, I saw this failure: https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=bowerbird&dt=2018-11-21%2000%3A51%3A32 I think there may be more than one thing going wrong there, but one things I noticed was this: 2018-11-20 21:49:50.935 EST [9700:18] LOG: could not rename temporary statistics file "pg_stat_tmp/global.tmp" to "pg_stat_tmp/global.stat": Permission denied That probably has to do with rename() not behaving like Unix, and I see there have been threads about this before[1]. Googling led me to some recently posted clues on SO and elsewhere about a flag FILE_RENAME_FLAG_POSIX_SEMANTICS which can be used with SetFileInformationByHandle(), that wasn't mentioned in the earlier -hackers threads. I tried it on AppVeyor. It appears to work, even when both source and target file name exist and both files currently have an open handle. Perhaps they needed this for the Windows 10 WSL stuff? https://github.com/macdice/hello-windows/blob/rename-test/test.c https://ci.appveyor.com/project/macdice/hello-windows/builds/20450990 I wonder if they also have a new secret fully POSIX unlink() hidden in there somewhere too. [1] https://www.postgresql.org/message-id/flat/CAPpHfds9trA6ipezK3BsuuOSQwEmESiqj8pkOxACFJpoLpcoNw%40mail.gmail.com#9b04576b717175e9dbf03cc991977d3f -- Thomas Munro http://www.enterprisedb.com
On Wed, Nov 21, 2018 at 5:43 PM Thomas Munro <thomas.munro@enterprisedb.com> wrote: > Googling led me to some recently posted clues on SO and elsewhere > about a flag FILE_RENAME_FLAG_POSIX_SEMANTICS which can be used with > SetFileInformationByHandle(), that wasn't mentioned in the earlier > -hackers threads. I tried it on AppVeyor. It appears to work, even > when both source and target file name exist and both files currently > have an open handle. Perhaps they needed this for the Windows 10 WSL > stuff? Erm, looks like I posted too soon. My 5 minute hack didn't check the return code correctly (it's zero for failure). Oh well. I don't actually plan to investigate this any further myself, being non-Windows-enabled, but it looks like there might still be something promising here. -- Thomas Munro http://www.enterprisedb.com