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.
+ 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.
..mark
