* [PATCH] Cygwin: Have tmpfile(3) use O_TMPFILE
@ 2021-02-09 10:50 Mark Geisert
2021-02-09 15:25 ` Corinna Vinschen
0 siblings, 1 reply; 4+ messages in thread
From: Mark Geisert @ 2021-02-09 10:50 UTC (permalink / raw)
To: cygwin-patches
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");
+ if (!dir)
+ dir = P_tmpdir;
+ int fd = open (dir, O_RDWR | O_CREAT | O_BINARY | O_TMPFILE,
+ S_IRUSR | S_IWUSR);
+ if (fd < 0)
+ return NULL;
+ FILE *fp = fdopen (fd, "wb+");
+ int e = errno;
+ if (!fp)
+ close (fd); // ..will remove file
+ set_errno (e);
+ return fp;
+}
+
+EXPORT_ALIAS (tmpfile, tmpfile64);
--
2.30.0
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Cygwin: Have tmpfile(3) use O_TMPFILE
2021-02-09 10:50 [PATCH] Cygwin: Have tmpfile(3) use O_TMPFILE Mark Geisert
@ 2021-02-09 15:25 ` Corinna Vinschen
2021-02-10 9:07 ` Mark Geisert
0 siblings, 1 reply; 4+ messages in thread
From: Corinna Vinschen @ 2021-02-09 15:25 UTC (permalink / raw)
To: cygwin-patches
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".
> + 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.
Thanks,
Corinna
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Cygwin: Have tmpfile(3) use O_TMPFILE
2021-02-09 15:25 ` Corinna Vinschen
@ 2021-02-10 9:07 ` Mark Geisert
2021-02-10 10:12 ` Corinna Vinschen
0 siblings, 1 reply; 4+ messages in thread
From: Mark Geisert @ 2021-02-10 9:07 UTC (permalink / raw)
To: cygwin-patches
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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] Cygwin: Have tmpfile(3) use O_TMPFILE
2021-02-10 9:07 ` Mark Geisert
@ 2021-02-10 10:12 ` Corinna Vinschen
0 siblings, 0 replies; 4+ messages in thread
From: Corinna Vinschen @ 2021-02-10 10:12 UTC (permalink / raw)
To: cygwin-patches
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
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-02-10 10:12 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-02-09 10:50 [PATCH] Cygwin: Have tmpfile(3) use O_TMPFILE Mark Geisert
2021-02-09 15:25 ` Corinna Vinschen
2021-02-10 9:07 ` Mark Geisert
2021-02-10 10:12 ` Corinna Vinschen
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).