On Feb 10 01:07, Mark Geisert wrote: > Hi Corinna, > > Corinna Vinschen via Cygwin-patches wrote: > > Hi Mark, > > > > On Feb 9 02:50, Mark Geisert wrote: > > > Per discussion on cygwin-developers, a Cygwin tmpfile(3) implementation > > > has been added to syscalls.cc. This overrides the one supplied by > > > newlib. Then the open(2) flag O_TMPFILE was added to the open call that > > > tmpfile internally makes. > > > --- > > > winsup/cygwin/release/3.2.0 | 4 ++++ > > > winsup/cygwin/syscalls.cc | 20 ++++++++++++++++++++ > > > 2 files changed, 24 insertions(+) > > > > > > diff --git a/winsup/cygwin/release/3.2.0 b/winsup/cygwin/release/3.2.0 > > > index f748a9bc8..d02d16863 100644 > > > --- a/winsup/cygwin/release/3.2.0 > > > +++ b/winsup/cygwin/release/3.2.0 > > > @@ -19,6 +19,10 @@ What changed: > > > - A few FAQ updates. > > > +- Have tmpfile(3) make use of Win32 FILE_ATTRIBUTE_TEMPORARY via open(2) > > > + flag O_TMPFILE. > > > + Addresses: https://cygwin.com/pipermail/cygwin/2021-January/247304.html > > > + > > > Bug Fixes > > > --------- > > > diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc > > > index 52a020f07..b79c1c7cd 100644 > > > --- a/winsup/cygwin/syscalls.cc > > > +++ b/winsup/cygwin/syscalls.cc > > > @@ -5225,3 +5225,23 @@ pipe2 (int filedes[2], int mode) > > > syscall_printf ("%R = pipe2([%d, %d], %y)", res, read, write, mode); > > > return res; > > > } > > > + > > > +extern "C" FILE * > > > +tmpfile (void) > > > +{ > > > + char *dir = getenv ("TMPDIR"); > > > > This isn't what Linux tmpfile does. Per the man page, it tries to > > create the file in P_tmpdir first, and if that fails, it tries > > "/tmp". > > Oops, I was following newlib's code here. I'll adjust this.
Oops, I didn't check with newlib, sorry. Hmm, so we're stuck with either Linux-compat or backward-compat but not both. Decisions, decisions... Let's stick to backward-compat then, so no changes here. > > > + if (!dir) > > > + dir = P_tmpdir; > > > + int fd = open (dir, O_RDWR | O_CREAT | O_BINARY | O_TMPFILE, > > > > You have to specify O_EXCL here. The idea is that this file cannot be > > made permanent, and missing the O_EXCL flag allows exactly that. See > > https://man7.org/linux/man-pages/man2/open.2.html, the lengthy > > description in terms of O_TMPFILE. > > I started out with O_EXCL as you suggested, but found syscalls.cc:1504 > reporting EEXIST. Is there some clash there between fh->exists() and > O_TMPFILE? Hmm. You specify O_CREAT as well. O_TMPFILE replaces O_CREAT. The combination O_CREAT|O_EXCL still checks for existence of the file, in that case, the dir. Thanks, Corinna
