build: Add a way to set CFLAGS for AddressSanitizer etc.

We don't want to set these globally via the normal CFLAGS, because if
we did, AddressSanitizer would catch test-segfault deliberately
segfaulting, and "helpfully" turn it into exit status 1, which in turn
makes our test fail because it asserts that the segfault is reported
as a segfault.

A typical use with gcc as compiler, on a reasonably recent Debian,
would be:

    ./configure SANITIZE_CFLAGS="-fsanitize=address -fsanitize=undefined -fPIE -pie"

Signed-off-by: Simon McVittie <smcv@collabora.com>

bus/Makefile.am

@@ -38,6 +38,7 @@ AM_LDFLAGS = @R_DYNAMIC_LDFLAG@
 
 AM_CFLAGS = \
 	$(CODE_COVERAGE_CFLAGS) \
+	$(SANITIZE_CFLAGS) \
 	$(NULL)
 
 EFENCE=

configure.ac

@@ -1224,6 +1224,9 @@ CFLAGS="$EXTRA_CFLAGS $CFLAGS"
 CXXFLAGS="$EXTRA_CXXFLAGS $CXXFLAGS"
 LDFLAGS="$EXTRA_LDFLAGS $LDFLAGS"
 
+AC_ARG_VAR([SANITIZE_CFLAGS],
+           [Extra CFLAGS for modules that are instrumented for error-checking])
+
 case $host_os in
     solaris*)
         # Solaris' C library apparently needs these runes to be threadsafe...

dbus/Makefile.am

@@ -17,6 +17,7 @@ AM_CPPFLAGS = \
 
 AM_CFLAGS = \
 	$(CODE_COVERAGE_CFLAGS) \
+	$(SANITIZE_CFLAGS) \
 	$(NULL)
 
 if HAVE_VISIBILITY

test/Makefile.am

@@ -23,6 +23,7 @@ AM_LDFLAGS = @R_DYNAMIC_LDFLAG@
 
 AM_CFLAGS = \
 	$(CODE_COVERAGE_CFLAGS) \
+	$(SANITIZE_CFLAGS) \
 	$(NULL)
 
 noinst_LTLIBRARIES = libdbus-testutils.la
@@ -91,6 +92,12 @@ endif !DBUS_ENABLE_EMBEDDED_TESTS
 
 noinst_PROGRAMS= $(TEST_BINARIES)
 
+# This helper is meant to crash, so if we're compiling the rest with
+# AddressSanitizer, we need to stop it from catching the SIGSEGV and
+# turning it into _exit(1); so don't give it SANITIZE_CFLAGS.
+# CODE_COVERAGE_CFLAGS are fairly pointless here, too.
+test_segfault_CFLAGS =
+
 test_service_LDADD = libdbus-testutils.la
 test_names_LDADD = libdbus-testutils.la
 ## break_loader_LDADD = $(top_builddir)/dbus/libdbus-internal.la

test/name-test/Makefile.am

@@ -7,6 +7,7 @@ AM_CPPFLAGS = \
 
 AM_CFLAGS = \
 	$(CODE_COVERAGE_CFLAGS) \
+	$(SANITIZE_CFLAGS) \
 	$(NULL)
 
 # if assertions are enabled, improve backtraces

tools/Makefile.am

@@ -8,6 +8,7 @@ AM_CPPFLAGS = \
 
 AM_CFLAGS = \
 	$(CODE_COVERAGE_CFLAGS) \
+	$(SANITIZE_CFLAGS) \
 	$(NULL)
 
 # if assertions are enabled, improve backtraces