Interrupt system implemented, some new programs.

makefile

@@ -11,6 +11,12 @@ PREFIX ?= /usr/local
 # editing a header rebuilds everything that includes it.
 DEPFLAGS = -MMD -MP
 
+# Both tools use POSIX interfaces that ISO C does not have: realpath, clock_gettime,
+# strdup, dirname and getopt. Asking for POSIX.1-2008 by name means the build does
+# not rely on the compiler happening to default to a mode where those are visible,
+# and it survives someone overriding CFLAGS, which is why it is kept separate.
+POSIXFLAGS = -D_POSIX_C_SOURCE=200809L
+
 # Directories
 SRC_DIR_EMU = Source/Emulator
 SRC_DIR_ASM = Source/Assembler
@@ -41,12 +47,12 @@ $(ASM_TARGET): $(ASM_OBJS)
 # Compile emulator source files to object files
 $(OBJ_DIR)/%.o: $(SRC_DIR_EMU)/%.c
 	mkdir -p $(OBJ_DIR)
-	$(CC) $(CFLAGS) $(DEPFLAGS) -c $< -o $@
+	$(CC) $(CFLAGS) $(POSIXFLAGS) $(DEPFLAGS) -c $< -o $@
 
 # Compile assembler source files to object files
 $(OBJ_DIR)/%.o: $(SRC_DIR_ASM)/%.c
 	mkdir -p $(OBJ_DIR)
-	$(CC) $(CFLAGS) $(DEPFLAGS) -c $< -o $@
+	$(CC) $(CFLAGS) $(POSIXFLAGS) $(DEPFLAGS) -c $< -o $@
 
 # Pull in the header dependencies written out by the compiler above.
 -include $(EMU_OBJS:.o=.d) $(ASM_OBJS:.o=.d)
@@ -55,6 +61,28 @@ $(OBJ_DIR)/%.o: $(SRC_DIR_ASM)/%.c
 test: $(EMU_TARGET) $(ASM_TARGET)
 	@./Tests/run.sh
 
+# Rebuild both tools with the address and undefined behaviour sanitizers and run
+# the test suite under them. Slower than 'make test', and worth running before a
+# release or after anything that touches memory handling.
+#
+# The sanitizers catch reads and writes off the end of an array, use after free,
+# leaks, and undefined arithmetic. They also fill fresh allocations with a junk
+# pattern, which is what turns a read of uninitialised memory from something that
+# quietly works into something the tests notice.
+#
+# If the suite fails, the sanitizer binaries are deliberately left in place so
+# that the failing case can be run again by hand. 'make' puts the normal ones back.
+SANITIZE_FLAGS = -Wall -Wextra -g -O1 -fsanitize=address,undefined -fno-omit-frame-pointer
+
+sanitize:
+	@$(MAKE) --no-print-directory clean
+	@$(MAKE) --no-print-directory CFLAGS="$(SANITIZE_FLAGS)"
+	@echo "Running the test suite under AddressSanitizer and UndefinedBehaviorSanitizer."
+	@./Tests/run.sh
+	@$(MAKE) --no-print-directory clean
+	@$(MAKE) --no-print-directory
+	@echo "Sanitizer run finished cleanly. Normal binaries rebuilt."
+
 # Record the current output of every test as the expected result.
 # Only do this when the current output is known to be correct.
 bless: $(EMU_TARGET) $(ASM_TARGET)
@@ -72,4 +100,4 @@ install: $(EMU_TARGET) $(ASM_TARGET)
 	install -m 755 $^ "$(PREFIX)/bin/"
 
 # Phony targets
-.PHONY: all clean install test bless
+.PHONY: all clean install test bless sanitize