mingw: do not let ld strip relocations

This is the first step for enabling ASLR (Address Space Layout
Randomization) support. We want to enable ASLR for better protection
against exploiting security holes in Git: it makes it harder to attack
software by making code addresses unpredictable.

The problem fixed by this commit is that `ld.exe` seems to be stripping
relocations which in turn will break ASLR support. We just make sure
it's not stripping the main executable entry.

Signed-off-by: İsmail Dönmez <ismail@i10z.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/config.mak.uname b/config.mak.uname
index d916d1dc7ab90d954dcd25f89d09f7478053112a..01b390c04310e1ff05ed63691d4be63fbdb515b5 100644 (file)
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -578,10 +578,12 @@ else
                ifeq (MINGW32,$(MSYSTEM))
                        prefix = /mingw32
                        HOST_CPU = i686
                ifeq (MINGW32,$(MSYSTEM))
                        prefix = /mingw32
                        HOST_CPU = i686

+                       BASIC_LDFLAGS += -Wl,--pic-executable,-e,_mainCRTStartup

                endif
                ifeq (MINGW64,$(MSYSTEM))
                        prefix = /mingw64
                        HOST_CPU = x86_64
                endif
                ifeq (MINGW64,$(MSYSTEM))
                        prefix = /mingw64
                        HOST_CPU = x86_64

+                       BASIC_LDFLAGS += -Wl,--pic-executable,-e,mainCRTStartup

                else
                        COMPAT_CFLAGS += -D_USE_32BIT_TIME_T
                        BASIC_LDFLAGS += -Wl,--large-address-aware
                else
                        COMPAT_CFLAGS += -D_USE_32BIT_TIME_T
                        BASIC_LDFLAGS += -Wl,--large-address-aware