[PATCH] Don't call uname or getrlimit in libpthread init function

[PATCH] Don't call uname or getrlimit in libpthread init function

[Andreas Schwab]

The libpthread init function calls uname and getrlimit, which means they
are called just by being linked against it, even if the program does not
use any of the libpthread functions, thus may use the function names for
its own purpose.

Andreas.

2010-04-08  Andreas Schwab  <schwab@redhat.com>

	* sysdeps/unix/sysv/linux/i386/Versions: Export __uname under
	GLIBC_PRIVATE.
	* nptl/Versions: Export __getrlimit under GLIBC_PRIVATE.
	* sysdeps/unix/sysv/linux/i386/smp.h: Call __uname instead of uname.
	* nptl/nptl-init.c: Call __getrlimit instead of getrlimit.
---
 nptl/Versions                              |    1 +
 nptl/nptl-init.c                           |    2 +-
 nptl/sysdeps/unix/sysv/linux/i386/Versions |    6 ++++++
 nptl/sysdeps/unix/sysv/linux/i386/smp.h    |    2 +-
 4 files changed, 9 insertions(+), 2 deletions(-)
 create mode 100644 nptl/sysdeps/unix/sysv/linux/i386/Versions

diff --git a/nptl/Versions b/nptl/Versions
index 1f2de79..13ca357 100644
--- a/nptl/Versions
+++ b/nptl/Versions
@@ -29,6 +29,7 @@ libc {
   GLIBC_PRIVATE {
     # Internal libc interface to libpthread
     __libc_dl_error_tsd;
+    __getrlimit;
   }
 }
 
diff --git a/nptl/nptl-init.c b/nptl/nptl-init.c
index 851bab2..c663f21 100644
--- a/nptl/nptl-init.c
+++ b/nptl/nptl-init.c
@@ -396,7 +396,7 @@ __pthread_initialize_minimal_internal (void)
   /* Determine the default allowed stack size.  This is the size used
      in case the user does not specify one.  */
   struct rlimit limit;
-  if (getrlimit (RLIMIT_STACK, &limit) != 0
+  if (__getrlimit (RLIMIT_STACK, &limit) != 0
       || limit.rlim_cur == RLIM_INFINITY)
     /* The system limit is not usable.  Use an architecture-specific
        default.  */
diff --git a/nptl/sysdeps/unix/sysv/linux/i386/Versions b/nptl/sysdeps/unix/sysv/linux/i386/Versions
new file mode 100644
index 0000000..9d53804
--- /dev/null
+++ b/nptl/sysdeps/unix/sysv/linux/i386/Versions
@@ -0,0 +1,6 @@
+libc {
+  GLIBC_PRIVATE {
+    # Internal libc interface to libpthread
+    __uname;
+  }
+}
diff --git a/nptl/sysdeps/unix/sysv/linux/i386/smp.h b/nptl/sysdeps/unix/sysv/linux/i386/smp.h
index f68a0c0..bdff665 100644
--- a/nptl/sysdeps/unix/sysv/linux/i386/smp.h
+++ b/nptl/sysdeps/unix/sysv/linux/i386/smp.h
@@ -37,7 +37,7 @@ is_smp_system (void)
   char *cp;
 
   /* Try reading the number using `sysctl' first.  */
-  if (uname (&u.uts) == 0)
+  if (__uname (&u.uts) == 0)
     cp = u.uts.version;
   else
     {
-- 
1.7.0.1


-- 
Andreas Schwab, schwab@redhat.com
GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84  5EC7 45C6 250E 6F00 984E
"And now for something completely different."

Re: [PATCH] Don't call uname or getrlimit in libpthread init function

[Ulrich Drepper]

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On 04/08/2010 02:42 AM, Andreas Schwab wrote:
> The libpthread init function calls uname and getrlimit, which means they
> are called just by being linked against it, even if the program does not
> use any of the libpthread functions, thus may use the function names for
> its own purpose.

No, uname belongs to the namespace to the implementation.  You cannot
just overload it.  Why on earth should this be allowed?  Somebody
overloading the function has to know what s/he does.

- -- 
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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Re: [PATCH] Don't call uname or getrlimit in libpthread init function

[Ulrich Drepper]

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On 04/08/2010 04:16 PM, Andreas Schwab wrote:
> The last time I checked, uname was not in C99.

Neither is POSIX threads.  If you link with the DSO you're leaving ISO C
territory.

And moreover: when you define a function umask in your program (= the
executable) nothing bad will happen.  Preloading, as in this case, is
something completely different.

This is just another precedence for somebody doing stupid things and
expecting nothing to break.  It's just a bad idea to encourage this.  If
you replace a function then do it right and everything will work
correctly.  If the floodgates for these kinds of changes would be opened
we would have to add a whole lot of symbols to libc.so.  This doesn't
come without a cost.

- -- 
➧ Ulrich Drepper ➧ Red Hat, Inc. ➧ 444 Castro St ➧ Mountain View, CA ❖
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Re: [PATCH] Don't call uname or getrlimit in libpthread init function

[Andreas Schwab]

Ulrich Drepper <drepper@redhat.com> writes:

> If you replace a function then do it right and everything will work
> correctly.

So what's wrong with
<http://sourceware.org/ml/libc-alpha/2010-04/msg00017.html>?

Andreas.

-- 
Andreas Schwab, schwab@redhat.com
GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84  5EC7 45C6 250E 6F00 984E
"And now for something completely different."