Hi,
the below patches are supposed to help with an annoying DLL problem on
Cygwin. Since Windows doesn't provide a native fork implementation,
Cygwin emulates fork by creating a new process and overwrites the
forkee's memory with data from the forker. This method only works if
the OS doesn't randomly decide where to put DLLs into the memory of the
new process. However, DLLs are linked with a default image base of
0x10000000, thus requiring the runtime loader to relocate the DLLs to
some other memory base, which sometimes results in different locations
for DLLs in forker and forkee. This in turn breaks fork.
One way to ease the pain is to rebase the DLLs manually, using a tool
called rebase. If all DLLs in a Cygwin installation are based on
different memory locations the problem is much less frequently observed,
next to never. The disadvantage of this approach is that it requires
the manual intervention.
What we're trying to do now in Cygwin is this: Binutils' ld allows to
create pseudo-random image base addresses by giving the command line
option --enable-auto-image-base. It chooses the image base for the DLL
by creating a hash value from the DLL's name. This lowers the chance of
DLL collisions a lot, and manual rebasing is most of the time not
necessary anymore.
The below two patches change Makefile.shared so that the shared libs
on Cygwin are built with --enable-auto-image-base. The first patch is
against current CVS, the second patch is against the 0.9.8 release.
I hope both are ok for inclusion.
Thanks in advance,
Corinna
=== Current CVS ===
Index: Makefile.shared
===================================================================
RCS file: /home/cvs/cvsroot/src/openssl/Makefile.shared,v
retrieving revision 1.63
diff -p -u -r1.63 Makefile.shared
--- Makefile.shared 25 Mar 2007 15:20:35 -0000 1.63
+++ Makefile.shared 29 Mar 2007 09:34:02 -0000
@@ -255,7 +255,7 @@ link_o.cygwin:
SHLIB_SOVER=${LIBVERSION:+"-$(LIBVERSION)"}; \
ALLSYMSFLAGS='-Wl,--whole-archive'; \
NOALLSYMSFLAGS='-Wl,--no-whole-archive'; \
- SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared -Wl,-s,-Bsymbolic"; \
+ SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared
-Wl,--enable-auto-image-base -Wl,-s,-Bsymbolic"; \
$(LINK_SO_O)
link_a.cygwin:
@ $(CALC_VERSIONS); \
@@ -273,8 +273,7 @@ link_a.cygwin:
extras="$$extras rc.o"; \
ALLSYMSFLAGS='-Wl,--whole-archive'; \
NOALLSYMSFLAGS='-Wl,--no-whole-archive'; \
- base=; [ $(LIBNAME) = "crypto" ] && base=-Wl,--image-base,0x63000000; \
- SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared $$base
-Wl,-s,-Bsymbolic -Wl,--out-implib,lib$(LIBNAME).dll.a $$extras"; \
+ SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared
-Wl,--enable-auto-image-base -Wl,-s,-Bsymbolic
-Wl,--out-implib,lib$(LIBNAME).dll.a $$extras"; \
[ -f apps/$$dll_name ] && rm apps/$$dll_name; \
[ -f test/$$dll_name ] && rm test/$$dll_name; \
$(LINK_SO_A) || exit 1; \
=== 0.9.8 ===
--- Makefile.shared 2007-01-18 17:05:21.540291400 +0100
+++ Makefile.shared 2007-03-29 11:38:48.552858700 +0200
@@ -242,7 +242,7 @@ link_o.cygwin:
SHLIB_SOVER=${LIBVERSION:+"-$(LIBVERSION)"}; \
ALLSYMSFLAGS='-Wl,--whole-archive'; \
NOALLSYMSFLAGS='-Wl,--no-whole-archive'; \
- SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared -Wl,-Bsymbolic
-Wl,--out-implib,lib$(LIBNAME).dll.a"; \
+ SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared
-Wl,--enable-auto-image-base -Wl,-Bsymbolic
-Wl,--out-implib,lib$(LIBNAME).dll.a"; \
$(LINK_SO_O)
link_a.cygwin:
@ $(CALC_VERSIONS); \
@@ -253,8 +253,7 @@ link_a.cygwin:
SHLIB_SOVER=-$(LIBVERSION); \
ALLSYMSFLAGS='-Wl,--whole-archive'; \
NOALLSYMSFLAGS='-Wl,--no-whole-archive'; \
- base=; [ $(LIBNAME) = "crypto" ] && base=-Wl,--image-base,0x63000000; \
- SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared $$base -Wl,-Bsymbolic
-Wl,--out-implib,lib$(LIBNAME).dll.a"; \
+ SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS) -shared
-Wl,--enable-auto-image-base -Wl,-Bsymbolic
-Wl,--out-implib,lib$(LIBNAME).dll.a"; \
[ -f apps/$$SHLIB$$SHLIB_SUFFIX ] && rm apps/$$SHLIB$$SHLIB_SUFFIX; \
[ -f test/$$SHLIB$$SHLIB_SUFFIX ] && rm test/$$SHLIB$$SHLIB_SUFFIX; \
$(LINK_SO_A) || exit 1; \
=== end ===
--
Corinna Vinschen
Cygwin Project Co-Leader
Red Hat
______________________________________________________________________
OpenSSL Project http://www.openssl.org
Development Mailing List openssl-dev@openssl.org
Automated List Manager [EMAIL PROTECTED]
______________________________________________________________________
OpenSSL Project http://www.openssl.org
Development Mailing List openssl-dev@openssl.org
Automated List Manager [EMAIL PROTECTED]
