[Bug libc/14327] New: pthread uses mktemp(), causing link-time warning

[Bug libc/14327] New: pthread uses mktemp(), causing link-time warning

[nyh at math dot technion.ac.il]

http://sourceware.org/bugzilla/show_bug.cgi?id=14327

             Bug #: 14327
           Summary: pthread uses mktemp(), causing link-time warning
           Product: glibc
           Version: 2.15
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: unassigned@sourceware.org
        ReportedBy: nyh@math.technion.ac.il
                CC: drepper.fsp@gmail.com
    Classification: Unclassified


When *statically* linking a program with -lpthread, I get the following
warning:

/usr/lib/gcc/x86_64-redhat-linux/4.7.0/../../../../lib64/libpthread.a(libpthread.o):
In function `sem_open':
(.text+0x67f8): warning: the use of `mktemp' is dangerous, better use `mkstemp'

This warning is annoying, because it implies there something wrong with
libpthread. Can glibc use mkstemp like the warning suggests? Or do something
else to avoid this warning from the linker?

I'm seeing this problem on Fedora 17, gcc 4.7.0, glibc 2.15.

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[Bug libc/14327] pthread uses mktemp(), causing link-time warning

[polacek at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14327

Marek Polacek <polacek at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |polacek at redhat dot com

--- Comment #1 from Marek Polacek <polacek at redhat dot com> 2012-07-03 13:54:35 UTC ---
Well, no, the comment above mktemp says:
"We really want to use mktemp here.  We cannot use mkstemp since the file must
be opened with a specific mode.  The mode cannot later be set since then we
cannot apply the file create mask."

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[Bug libc/14327] pthread uses mktemp(), causing link-time warning

[aj at suse dot de]

http://sourceware.org/bugzilla/show_bug.cgi?id=14327

Andreas Jaeger <aj at suse dot de> changed:

           What    |Removed                     |Added
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                 CC|                            |aj at suse dot de

--- Comment #2 from Andreas Jaeger <aj at suse dot de> 2012-07-03 14:02:29 UTC ---
Initial analysis:
nptl/sem_open.c contains:

       {
          /* Add the suffix for mktemp.  */
          strcpy (xxxxxx, "XXXXXX");

          /* We really want to use mktemp here.  We cannot use mkstemp
             since the file must be opened with a specific mode.  The
             mode cannot later be set since then we cannot apply the
             file create mask.  */
          if (mktemp (tmpfname) == NULL)
            return SEM_FAILED;

          /* Open the file.  Make sure we do not overwrite anything.  */
          fd = __libc_open (tmpfname, O_RDWR | O_CREAT | O_EXCL, mode);


There's no function that does this directly. mktemp is short, we could use the
implementation directly in sem_open just avoiding the warning, I just don't
like duplication of code.

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[Bug libc/14327] pthread uses mktemp(), causing link-time warning

[nyh at math dot technion.ac.il]

http://sourceware.org/bugzilla/show_bug.cgi?id=14327

--- Comment #3 from Nadav Har'El <nyh at math dot technion.ac.il> 2012-07-03 14:16:23 UTC ---
I have another possible (even is twisted) workaround.

In glibc, rename the current function mktemp() to _mktemp(), and have mktemp()
call _mktemp(). Users that use mktemp() will be warned, as usual. But the
libpthread code, aware of _mktemp(), will "extern" it (it won't be in any
header file) and use it.

Another, cleaner, option is to invent a new function, say mkomstemp(), which is
like mkostemp() but adds a mode parameter, and then (?) libpthread could use
that (though I'm not sure - I don't know what is __libc_open).

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[Bug libc/14327] pthread uses mktemp(), causing link-time warning

[bugdal at aerifal dot cx]

http://sourceware.org/bugzilla/show_bug.cgi?id=14327

Rich Felker <bugdal at aerifal dot cx> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bugdal at aerifal dot cx

--- Comment #4 from Rich Felker <bugdal at aerifal dot cx> 2012-07-03 23:15:16 UTC ---
This bug needs to be fixed anyway since calling mktemp is a namespace
violation. mktemp was removed from POSIX in 2008. So calling __mktemp or
similar instead would be the perfect fix.

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[Bug libc/14327] pthread uses mktemp(), causing link-time warning

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=14327

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |2.18

--- Comment #5 from Andreas Schwab <schwab@linux-m68k.org> 2013-01-16 14:58:52 UTC ---
Fixed in 2.18.

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[Bug libc/14327] pthread uses mktemp(), causing link-time warning

[schwab@linux-m68k.org]

http://sourceware.org/bugzilla/show_bug.cgi?id=14327

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
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                 CC|                            |geir at cray dot com

--- Comment #6 from Andreas Schwab <schwab@linux-m68k.org> 2013-05-15 09:45:18 UTC ---
*** Bug 15137 has been marked as a duplicate of this bug. ***

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[Bug libc/14327] pthread uses mktemp(), causing link-time warning

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=14327

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
              Flags|                            |security-

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