Install the ThreadSanitizer ASLR runner

Co-authored-by: Andrew Kesterson <andrew@aklabs.net>

.gitea/workflows/ci.yaml

@@ -75,7 +75,7 @@ jobs:
       - name: dependencies
         run: |
           sudo apt-get update -y
-          sudo apt-get install -y cmake gcc moreutils
+          sudo apt-get install -y cmake gcc moreutils util-linux
       # The thread tests assert exclusive ownership of pool slots and reserved
       # ranges, which is checkable without tooling and runs in the job above.
       # This is the run that proves there is no data race underneath them.

CMakeLists.txt

@@ -107,6 +107,19 @@ if(AKERR_SANITIZE AND NOT CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
         "AKERR_SANITIZE requires GCC or Clang, not ${CMAKE_C_COMPILER_ID}")
 endif()
 
+if(AKERR_SANITIZE STREQUAL "thread" AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    # ThreadSanitizer reserves a fixed, very large virtual-address range. Linux
+    # ASLR can put a loader mapping inside it before the runtime starts, which
+    # makes every test fail with "unexpected memory mapping" before main().
+    # Run the instrumented tests under the normal util-linux ASLR wrapper.
+    find_program(AKERR_SETARCH_EXECUTABLE setarch)
+    if(NOT AKERR_SETARCH_EXECUTABLE)
+        message(FATAL_ERROR
+            "AKERR_SANITIZE=thread on Linux requires setarch (util-linux) to "
+            "start tests with ASLR disabled.")
+    endif()
+endif()
+
 function(akerr_instrument_for_sanitizers _target)
     if(AKERR_SANITIZE)
         target_compile_options(${_target} PRIVATE
@@ -252,7 +265,13 @@ foreach(_test IN LISTS AKERR_TESTS)
         target_link_libraries(test_${_test} PRIVATE Threads::Threads)
     endif()
     akerr_instrument_for_sanitizers(test_${_test})
-    add_test(NAME ${_test} COMMAND test_${_test})
+    if(AKERR_SANITIZE STREQUAL "thread" AND CMAKE_SYSTEM_NAME STREQUAL "Linux")
+        add_test(NAME ${_test}
+                 COMMAND ${AKERR_SETARCH_EXECUTABLE} ${CMAKE_SYSTEM_PROCESSOR}
+                         -R $<TARGET_FILE:test_${_test}>)
+    else()
+        add_test(NAME ${_test} COMMAND test_${_test})
+    endif()
     # A sanitizer report is a test failure. Without halt_on_error the runtime
     # prints and continues, which leaves a race to be noticed in the log by
     # somebody reading it -- and under a race storm the reporting itself is slow
@@ -263,6 +282,14 @@ foreach(_test IN LISTS AKERR_TESTS)
     endif()
 endforeach()
 
+# HANDLE_GROUP deliberately enters the next case label. Keep that public macro
+# compiling with the warning enabled, so a future macro edit cannot restore the
+# warning for consumers which adopt -Wextra.
+if(CMAKE_C_COMPILER_ID MATCHES "GNU|Clang")
+    target_compile_options(test_err_handle_group PRIVATE
+                           -Werror=implicit-fallthrough)
+endif()
+
 set_tests_properties(
     ${AKERR_WILL_FAIL_TESTS}
     PROPERTIES WILL_FAIL TRUE

docs/building.md

@@ -58,4 +58,6 @@ cmake --install build
 `PATH_MAX` and `NULL` are used unconditionally but only included under the
 stdlib branch, so the header's includes need untangling before
 `-DAKERR_USE_STDLIB=OFF` builds. The list above still states what a replacement
-must provide. See [TODO.md](../TODO.md).
+must provide. That configuration does not currently compile -- `bool`, `PATH_MAX` and `NULL`
+are used unconditionally but included only under the stdlib branch. See
+[issue #12](https://source.starfort.tech/andrew/libakerror/issues/12).

include/akerror.tmpl.h

@@ -391,6 +391,18 @@ akerr_ErrorContext AKERR_NOIGNORE *__akerr_copy_string(char *destination, int ca
  * Defines for the ATTEMPT/CATCH/CLEANUP/PROCESS/HANDLE/FINISH process
  */
 
+/*
+ * HANDLE_GROUP deliberately enters the next case label. GCC and clang both
+ * understand this spelling in the C modes supported by libakerror. Other
+ * compilers keep the established control flow without receiving an attribute
+ * they do not implement.
+ */
+#if defined(__GNUC__) || defined(__clang__)
+#define AKERR_FALLTHROUGH __attribute__((fallthrough));
+#else
+#define AKERR_FALLTHROUGH
+#endif
+
 #define ATTEMPT					\
     switch ( 0 ) {				\
     case 0:					\
@@ -443,6 +455,7 @@ akerr_ErrorContext AKERR_NOIGNORE *__akerr_copy_string(char *destination, int ca
     __err_context->handled = true;
 
 #define HANDLE_GROUP(__err_context, __err_status)			\
+    AKERR_FALLTHROUGH					\
     case __err_status:							\
     __err_context->stacktracebufptr = (char *)&__err_context->stacktracebuf; \
     __err_context->handled = true;