[MPlayer-dev-eng] [PATCH] compile as PIE by default

[Reimar Döffinger]

Hello,
below patch would compile MPlayer as PIE on x86 by default.
On 32 bit, the cost would only be in a larger binary size and having to do
relocations at startup, but no real cost at runtime.
On 64 bit, there is almost no size or runtime overhead, mostly that
in some cases PIC-relative addressing has to be used.
I believe that none of the assembler code will be disabled by either.
I have not made any changes to other architectures since I can't
judge the impact.
A side effect of the 64 bit case is that MPlayer will refuse to link
against some static libraries (those not compiled with PIC and thus violating
the ABI), one example (which only exists as static library) is LIVE555
as provided by Debian.
Another point is that backtraces without debug info will probably be
even less useful.
Any comments? My belief is that there is negligible if any disadvantage
for a sometimes significant win in security.

Index: configure
===================================================================
--- configure	(revision 34955)
+++ configure	(working copy)
@@ -2643,6 +2643,22 @@
 fi
 
 
+# try to create a relocatable binary by default
+echocheck "relocatable binary"
+if x86_32 && cflag_check -pie ; then
+  extra_ldflags="$extra_ldflags -pie"
+  relocatable=yes
+  res_comment="non-PIC"
+elif x86_64 && cflag_check -fpie -pie ; then
+  extra_ldflags="$extra_ldflags -fpie -pie"
+  extra_cflags="$extra_cflags -fpie"
+  relocatable=yes
+  res_comment="fast PIC"
+else
+  relocatable=no
+  res_comment="unavailable or untested architecture"
+fi
+echores $relocatable
 
 if x86_32 ; then
   # Checking assembler (_as) compatibility...