Implement tmpfile with O_TMPFILE (bug 21530)
Commit Message
On 26/06/2017 08:47, Andreas Schwab wrote:
> If the kernel or the file system does not support O_TMPFILE fall back to
> creating a temporary file based on tmpnam.
>
> [BZ #21530]
> * stdio-common/tmpfile.c (tmpfile) [O_TMPFILE]: Try opening an
> unnamed file first.
> ---
> stdio-common/tmpfile.c | 51 ++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 37 insertions(+), 14 deletions(-)
I would prefer to compartmentalize Linuxism to linux sysdep folder, something
like:
Comments
On Jun 26 2017, Adhemerval Zanella <adhemerval.zanella@linaro.org> wrote:
> On 26/06/2017 08:47, Andreas Schwab wrote:
>> If the kernel or the file system does not support O_TMPFILE fall back to
>> creating a temporary file based on tmpnam.
>>
>> [BZ #21530]
>> * stdio-common/tmpfile.c (tmpfile) [O_TMPFILE]: Try opening an
>> unnamed file first.
>> ---
>> stdio-common/tmpfile.c | 51 ++++++++++++++++++++++++++++++++++++--------------
>> 1 file changed, 37 insertions(+), 14 deletions(-)
>
> I would prefer to compartmentalize Linuxism to linux sysdep folder, something
> like:
Perhaps it will be adopted by POSIX?
Andreas.
On 06/26/2017 04:53 PM, Adhemerval Zanella wrote:
> I would prefer to compartmentalize Linuxism to linux sysdep folder, something
> like:
Isn't O_TMPFILE part of the GNU API now?
Thanks,
Florian
On 06/26/2017 11:34 AM, Florian Weimer wrote:
> On 06/26/2017 04:53 PM, Adhemerval Zanella wrote:
>> I would prefer to compartmentalize Linuxism to linux sysdep folder, something
>> like:
>
> Isn't O_TMPFILE part of the GNU API now?
Part of the GNU/Linux API? Yes.
We export it under __USE_GNU in fcntl-linux.h.
Is that the same as the Generic GNU API?
We do talk about O_TMPFILE in GNU/Hurd open/openat
implementations, and O_TMPFILE seems like a generically
useful feature everyone would agree you want in an OS.
On 26/06/2017 13:37, Carlos O'Donell wrote:
> On 06/26/2017 11:34 AM, Florian Weimer wrote:
>> On 06/26/2017 04:53 PM, Adhemerval Zanella wrote:
>>> I would prefer to compartmentalize Linuxism to linux sysdep folder, something
>>> like:
>>
>> Isn't O_TMPFILE part of the GNU API now?
>
> Part of the GNU/Linux API? Yes.
>
> We export it under __USE_GNU in fcntl-linux.h.
>
> Is that the same as the Generic GNU API?
>
> We do talk about O_TMPFILE in GNU/Hurd open/openat
> implementations, and O_TMPFILE seems like a generically
> useful feature everyone would agree you want in an OS.
>
It can be adopted by POSIX in the future, but *currently* it only
exported on Linux-only headers and it would require kernel support
to have it implemented correctly (so trying to emulate it with a
generic code is not an option). So imho it is still Linux specific.
On 06/26/2017 06:37 PM, Carlos O'Donell wrote:
> On 06/26/2017 11:34 AM, Florian Weimer wrote:
>> On 06/26/2017 04:53 PM, Adhemerval Zanella wrote:
>>> I would prefer to compartmentalize Linuxism to linux sysdep folder, something
>>> like:
>> Isn't O_TMPFILE part of the GNU API now?
> Part of the GNU/Linux API? Yes.
>
> We export it under __USE_GNU in fcntl-linux.h.
>
> Is that the same as the Generic GNU API?
I assumed that Hurd provides it as well, but I seem to have confused it
with some other non-POSIX functionality provided by the port.
Thanks,
Florian
@@ -181,5 +181,8 @@ libc_hidden_proto (__obstack_vprintf_chk)
extern FILE * __fmemopen (void *buf, size_t len, const char *mode);
libc_hidden_proto (__fmemopen)
+extern int __gen_tempfd (int flags);
+libc_hidden_proto (__gen_tempfd)
+
# endif /* not _ISOMAC */
#endif /* stdio.h */
@@ -39,7 +39,7 @@ routines := \
flockfile ftrylockfile funlockfile \
isoc99_scanf isoc99_vscanf isoc99_fscanf isoc99_vfscanf isoc99_sscanf \
isoc99_vsscanf \
- psiginfo
+ psiginfo gentempfd
aux := errlist siglist printf-parsemb printf-parsewc fxprintf
new file mode 100644
@@ -0,0 +1,26 @@
+/* Generate a temporary file descriptor. Generic/POSIX version.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+
+int
+__gen_tempfd (int flags)
+{
+ return -1;
+}
+libc_hidden_def (__gen_tempfd)
@@ -26,7 +26,6 @@
# define tmpfile __new_tmpfile
#endif
-
/* This returns a new stream opened on a temporary file (generated
by tmpnam). The file is opened with mode "w+b" (binary read/write).
If we couldn't generate a unique filename or the file couldn't
@@ -34,23 +33,34 @@
FILE *
tmpfile (void)
{
- char buf[FILENAME_MAX];
int fd;
FILE *f;
-
- if (__path_search (buf, FILENAME_MAX, NULL, "tmpf", 0))
- return NULL;
int flags = 0;
#ifdef FLAGS
flags = FLAGS;
#endif
- fd = __gen_tempname (buf, 0, flags, __GT_FILE);
+
+ /* First try a system specific method. */
+ fd = __gen_tempfd (flags);
+
if (fd < 0)
- return NULL;
+ {
+ char buf[FILENAME_MAX];
- /* Note that this relies on the Unix semantics that
- a file is not really removed until it is closed. */
- (void) __unlink (buf);
+ if (__path_search (buf, sizeof buf, NULL, "tmpf", 0))
+ return NULL;
+
+ fd = __gen_tempname (buf, 0, flags, __GT_FILE);
+ if (fd < 0)
+ return NULL;
+
+ /* Note that this relies on the Unix semantics that
+ a file is not really removed until it is closed. */
+ (void) __unlink (buf);
+ }
+
+ if (fd < 0)
+ return NULL;
if ((f = __fdopen (fd, "w+b")) == NULL)
__close (fd);
new file mode 100644
@@ -0,0 +1,34 @@
+/* Generate a temporary file descriptor. Linux version.
+ Copyright (C) 2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <errno.h>
+
+int
+__gen_tempfd (int flags)
+{
+ int fd = __open (P_tmpdir, O_RDWR | O_TMPFILE | O_EXCL | flags,
+ S_IRUSR | S_IWUSR);
+ if (fd < 0 && errno == ENOENT && strcmp (P_tmpdir, "/tmp") != 0)
+ fd = __open ("/tmp", O_RDWR | O_TMPFILE | O_EXCL | flags,
+ S_IRUSR | S_IWUSR);
+
+ return fd;
+}
+libc_hidden_def (__gen_tempfd)