[PATCH][BZ #16046] Static dlopen correction fallout fixes

[Maciej W. Rozycki]

On Fri, 31 Jan 2014, Roland McGrath wrote:

> >  Thinking more about the test case I have concluded that maybe a 
> > path-of-least-resistance check like below would do.  It verifies that 
> > there's exactly one link map whose file name is null, as is the case with 
> > the main executable only.  This approach may not be particularly robust, 
> > but it does cover what BZ #16046 is about.
> 
> It's a start.  Ideal would be to look at all the places you had to change
> and figure out what user-visible effects those changes had.

 Only elf/dl-iteratephdr.c (covered here) and elf/dl-load.c (default lib 
search path) changes can have any user-visible effect.  The rest are 
internal consistency updates, e.g. you can't really test an assertion 
unless there's a separate bug to be fixed.  I'll see if I can think of a 
test case covering the default lib search path for static executables.

> > +static int count;
> 
> Why have a static instead of passing the address of a local in the void *?

 I didn't want to overcomplicate code, however if you prefer using the 
iterator's argument, then I'm fine with that.

> > +static int
> > +callback (struct dl_phdr_info *info, size_t size, void *data)
> > +{
> > +  if (!*info->dlpi_name)
> 
> No implicit Boolean coercion please: (info->dlpi_name[0] == '\0') is the
> canonical way to write this expression.
> 
> > +int
> > +main(void)
> 
> Space before paren.
> 
> It's also good to have a comment simply explaining what it's verifying,
> even though it is fairly obvious in this case.

 The rest I agree make the piece a little bit better.  I took the 
opportunity and made further adjustments, specifically wrapped the case in 
the test skeleton in case it loops or something and removed the unneeded 
_GNU_SOURCE definition (already provided by include/libc-symbols.h).  
Here's the resulting new version.  Any further suggestions or comments?

2014-02-03  Maciej W. Rozycki  <macro@codesourcery.com>

	[BZ #16046]
	elf/tst-dl-iter-static.c: New file.
	elf/Makefile (tests-static): Add tst-dl-iter-static.

  Maciej

glibc-static-dlopen-16046-test.diff
Index: glibc-fsf-trunk-quilt/elf/Makefile
===================================================================
--- glibc-fsf-trunk-quilt.orig/elf/Makefile	2014-01-29 12:29:54.000000000 +0000
+++ glibc-fsf-trunk-quilt/elf/Makefile	2014-01-31 18:09:48.501960005 +0000
@@ -123,7 +123,7 @@ tests = tst-tls1 tst-tls2 tst-tls9 tst-l
 	tst-auxv
 tests-static = tst-tls1-static tst-tls2-static tst-stackguard1-static \
 	       tst-leaks1-static tst-array1-static tst-array5-static \
-	       tst-ptrguard1-static
+	       tst-ptrguard1-static tst-dl-iter-static
 ifeq (yes,$(build-shared))
 tests-static += tst-tls9-static
 tst-tls9-static-ENV = \
Index: glibc-fsf-trunk-quilt/elf/tst-dl-iter-static.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ glibc-fsf-trunk-quilt/elf/tst-dl-iter-static.c	2014-02-03 11:31:51.541961661 +0000
@@ -0,0 +1,52 @@
+/* BZ #16046 dl_iterate_phdr static executable test.
+   Copyright (C) 2014 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 <link.h>
+
+/* Check that the link map of the static executable itself is iterated
+   over exactly once.  */
+
+static int
+callback (struct dl_phdr_info *info, size_t size, void *data)
+{
+  union
+    {
+      void *data;
+      int *count;
+    }
+  u = { .data = data };
+
+  if (info->dlpi_name[0] == '\0')
+    (*u.count)++;
+
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  int count = 0;
+  int status;
+
+  status = dl_iterate_phdr (callback, &count);
+
+  return status || count != 1;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"