Release ignored error contexts

CMakeLists.txt

@@ -158,18 +158,10 @@ add_custom_command(
   VERBATIM
 )
 
-# More than one library target consumes the generated sources below. Route
-# them through one explicit prerequisite so parallel Make builds cannot invoke
-# the same generator twice and interleave writes to errno.c.
-add_custom_target(akerror_generated
-  DEPENDS ${GENERATED_ERRNO_C} ${GENERATED_AKERROR_H}
-)
-
 add_library(akerror SHARED
   src/error.c
   ${GENERATED_ERRNO_C}
 )
-add_dependencies(akerror akerror_generated)
 
 target_include_directories(akerror PUBLIC
   $<BUILD_INTERFACE:${GENERATED_DIR}/include>
@@ -208,32 +200,6 @@ set_target_properties(akerror PROPERTIES
 akerr_instrument_for_coverage(akerror)
 akerr_instrument_for_sanitizers(akerror)
 
-# akerr_init() must terminate if it cannot reserve the library-owned status
-# band. The production table sizes are deliberately PRIVATE, so exercise that
-# otherwise unreachable startup failure with a second library target whose
-# private registries cannot accept even the first reservation. Keeping this a
-# distinct target is the test: no compile definition leaks into consumers or
-# weakens the production library.
-add_library(akerror_init_failure SHARED
-  src/error.c
-  ${GENERATED_ERRNO_C}
-)
-add_dependencies(akerror_init_failure akerror_generated)
-target_include_directories(akerror_init_failure PUBLIC
-  ${GENERATED_DIR}/include
-)
-target_compile_definitions(akerror_init_failure
-  PUBLIC AKERR_USE_STDLIB=${AKERR_USE_STDLIB}
-  PRIVATE AKERR_STATUS_NAME_SLOTS=8
-  PRIVATE AKERR_MAX_RESERVED_STATUS_RANGES=0
-  PRIVATE ${AKERR_THREADS_DEFINE}
-)
-if(AKERR_THREAD_SAFE)
-    target_link_libraries(akerror_init_failure PRIVATE Threads::Threads)
-endif()
-akerr_instrument_for_coverage(akerror_init_failure)
-akerr_instrument_for_sanitizers(akerror_init_failure)
-
 # Each test is one source file in tests/ built into test_<name> and registered
 # as CTest <name>. Tests expected to abort (unhandled error / contract
 # violation) go in AKERR_WILL_FAIL_TESTS; all others must exit 0.
@@ -261,7 +227,6 @@ set(AKERR_TESTS
     err_registry_init_order
     err_status_exception
     err_copy_string
-    err_init_reservation_fatal
     err_library_status_fatal
     err_refcount_double_fail
     err_stacktrace_bounds
@@ -289,18 +254,13 @@ endif()
 set(AKERR_WILL_FAIL_TESTS
     err_trace
     err_improper_closure
-    err_init_reservation_fatal
     err_library_status_fatal
 )
 
 foreach(_test IN LISTS AKERR_TESTS)
     add_executable(test_${_test} tests/${_test}.c)
     target_include_directories(test_${_test} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/tests)
-    if(_test STREQUAL "err_init_reservation_fatal")
-        target_link_libraries(test_${_test} PRIVATE akerror_init_failure)
-    else()
     target_link_libraries(test_${_test} PRIVATE akerror)
-    endif()
     if(AKERR_THREAD_SAFE)
         target_link_libraries(test_${_test} PRIVATE Threads::Threads)
     endif()
@@ -345,14 +305,7 @@ if(Python3_FOUND)
     # The script configures and drives its own instrumented build tree (under
     # ${CMAKE_BINARY_DIR}/coverage) so this build's binaries and its coverage
     # counters can never be stale or half-instrumented. Reports via gcov.
-    # Keep the convenient generic name at the top level, but namespace it when
+    add_custom_target(coverage
-    # embedded so a parent project can provide its own coverage target.
-    if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-        set(AKERR_COVERAGE_TARGET coverage)
-    else()
-        set(AKERR_COVERAGE_TARGET akerror_coverage)
-    endif()
-    add_custom_target(${AKERR_COVERAGE_TARGET}
         COMMAND ${Python3_EXECUTABLE}
                 ${CMAKE_CURRENT_SOURCE_DIR}/scripts/coverage.py
                 --source-root ${CMAKE_CURRENT_SOURCE_DIR}
@@ -384,6 +337,7 @@ if(Python3_FOUND)
     )
 endif()
 
+set(main_lib_dest "lib/my_library-${MY_LIBRARY_VERSION}")
 install(TARGETS akerror
   EXPORT akerrorTargets
   ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
@@ -407,17 +361,8 @@ configure_package_config_file(
     INSTALL_DESTINATION ${akerror_install_cmakedir}
 )
 
-# The SOVERSION is the project major version, so packages with the same major
-# are ABI-compatible and a different major must be rejected.
-write_basic_package_version_file(
-    "${CMAKE_CURRENT_BINARY_DIR}/akerrorConfigVersion.cmake"
-    VERSION ${PROJECT_VERSION}
-    COMPATIBILITY SameMajorVersion
-)
-
 install(FILES
     "${CMAKE_CURRENT_BINARY_DIR}/akerrorConfig.cmake"
-    "${CMAKE_CURRENT_BINARY_DIR}/akerrorConfigVersion.cmake"
     DESTINATION ${akerror_install_cmakedir}
 )
 

UPGRADING.md

@@ -132,11 +132,6 @@ One recursive lock covers both the pool and the registry, so error
 correctness there is worth more than throughput, but a program that raises
 errors in a hot loop will feel it.
 
-Releasing the last reference to a context remains serialized under that same
-pool lock, but it now resets only the handled/status/reported state, the string
-heads, and the stack-trace cursor. It no longer wipes the whole context buffer,
-so release is a fixed handful of stores rather than a tens-of-kilobytes write.
-
 The per-thread last-ditch context is a whole `akerr_ErrorContext` (tens of
 kilobytes) in thread-local storage, allocated per thread on first use of the
 library from that thread.

docs/thread-safety.md

@@ -14,9 +14,11 @@ What that covers:
   against each other and against lookups. Two threads reserving the same range
   cannot both win — exactly one gets `NULL` and the other gets
   `AKERR_STATUS_RANGE_OVERLAP` naming the winner.
-* **Per-thread state.** The context behind `IGNORE` (`__akerr_last_ignored`) and
+* **Per-thread state.** `IGNORE` uses `__akerr_last_ignored` as a scratch pointer
-  the last-ditch context used to report `akerr_release_error(NULL)` are
+  while it logs an error, then releases the context and clears the pointer.
-  thread-local, so one thread's ignored error is never another's.
+  That scratch pointer and the last-ditch context used to report
+  `akerr_release_error(NULL)` are thread-local, so concurrent calls cannot
+  overwrite each other's state.
 * **Handing a context from one thread to another.** A context is not thread
   state — it lives in `AKERR_ARRAY_ERROR`, which is process-global — so it
   outlives the thread that raised it. The reference count is the only field the

include/akerror.tmpl.h

@@ -173,9 +173,10 @@ extern akerr_ErrorContext AKERR_ARRAY_ERROR[AKERR_MAX_ARRAY_ERROR];
 extern akerr_ErrorUnhandledErrorHandler akerr_handler_unhandled_error;
 extern akerr_ErrorLogFunction akerr_log_method;
 /*
- * The error IGNORE() last swallowed, per thread: an ignored error is a fact
+ * IGNORE()'s per-thread scratch pointer. It is non-NULL only while IGNORE()
- * about the thread that ignored it, and one shared slot would have two threads
+ * logs the swallowed error; IGNORE() releases the context and clears this
- * overwriting each other's. Thread local only when AKERR_THREAD_SAFE is 1.
+ * pointer before returning to its caller. Thread local only when
+ * AKERR_THREAD_SAFE is 1.
  */
 extern AKERR_THREAD_LOCAL akerr_ErrorContext *__akerr_last_ignored;
 
@@ -437,6 +438,7 @@ akerr_ErrorContext AKERR_NOIGNORE *__akerr_copy_string(char *destination, int ca
     __akerr_last_ignored = __stmt;					\
     if ( __akerr_last_ignored != NULL ) {				\
 	LOG_ERROR_WITH_MESSAGE(__akerr_last_ignored, "** IGNORED ERROR **"); \
+	RELEASE_ERROR(__akerr_last_ignored);				\
     }
 
 #define CLEANUP					\

src/error.c

@@ -88,10 +88,7 @@ typedef struct
 
 static akerr_StatusName akerr_status_names[AKERR_STATUS_NAME_SLOTS];
 static int akerr_status_name_count;
-/* C has no portable zero-length arrays. Keep one unused physical slot when a
+static akerr_StatusRange akerr_status_ranges[AKERR_MAX_RESERVED_STATUS_RANGES];
- * test build sets the logical capacity to zero to drive init's fatal path. */
-static akerr_StatusRange akerr_status_ranges[
-    AKERR_MAX_RESERVED_STATUS_RANGES > 0 ? AKERR_MAX_RESERVED_STATUS_RANGES : 1];
 static int akerr_status_range_count;
 
 akerr_ErrorContext AKERR_ARRAY_ERROR[AKERR_MAX_ARRAY_ERROR];
@@ -380,10 +377,10 @@ akerr_ErrorContext *akerr_next_error()
 }
 
 /*
- * The reset returns the slot to the pool, so it and the decrement that triggers
+ * The wipe returns the slot to the pool, so it and the decrement that triggers
  * it are one operation under the lock. Otherwise a thread that saw the count
  * reach zero could be handed the slot by akerr_next_error() and start writing
- * its error into it while the releasing thread was still resetting it.
+ * its error into it while the releasing thread was still memsetting it.
  */
 akerr_ErrorContext *akerr_release_error(akerr_ErrorContext *err)
 {
@@ -401,13 +398,7 @@ akerr_ErrorContext *akerr_release_error(akerr_ErrorContext *err)
     }
     if ( err->refcount == 0 ) {
 	oldid = err->arrayid;
-	err->handled = false;
+	memset(err, 0x00, sizeof(akerr_ErrorContext));
-	err->status = 0;
-	err->reported = false;
-	err->message[0] = '\0';
-	err->fname[0] = '\0';
-	err->function[0] = '\0';
-	err->stacktracebuf[0] = '\0';
 	err->stacktracebufptr = (char *)&err->stacktracebuf;
 	err->arrayid = oldid;
 	remaining = NULL;

tests/err_ignore.c

@@ -1,11 +1,7 @@
 #include "akerror.h"
 #include "err_capture.h"
 
-/*
+/* IGNORE logs and releases an error, then lets execution continue. */
- * IGNORE deliberately swallows an error: it records the context in
- * __akerr_last_ignored, logs it with an "IGNORED ERROR" marker, and lets
- * execution continue.
- */
 
 akerr_ErrorContext *boom(void)
 {
@@ -21,11 +17,15 @@ int main(void)
     PREPARE_ERROR(e);
     (void)e;
 
+    /* More failures than the pool has slots must remain safe: a leaking
+     * IGNORE used to exhaust the pool and terminate the process here. */
+    for ( int i = 0; i < AKERR_MAX_ARRAY_ERROR + 1; i++ ) {
 	IGNORE(boom());
+	AKERR_CHECK(__akerr_last_ignored == NULL);
+	AKERR_CHECK(akerr_slots_in_use() == 0);
+    }
     reached_after_ignore = 1;
 
-    AKERR_CHECK(__akerr_last_ignored != NULL);
-    AKERR_CHECK(__akerr_last_ignored->status == AKERR_VALUE);
     AKERR_CHECK(reached_after_ignore == 1);
     AKERR_CHECK_CONTAINS("IGNORED ERROR");
     AKERR_CHECK_CONTAINS("this error is ignored on purpose");

tests/err_init_reservation_fatal.c

@@ -1,20 +0,0 @@
-#include "akerror.h"
-
-#include <stdio.h>
-
-/*
- * This executable links to akerror_init_failure, a test-only library target
- * with no status-range slots. The first reservation in akerr_init() must be
- * terminal: continuing would leave every library status unowned and make all
- * subsequent name registrations invalid.
- *
- * CTest marks this WILL_FAIL. Reaching the message and returning zero means
- * initialization swallowed its own reservation failure.
- */
-int main(void)
-{
-    akerr_init();
-
-    fprintf(stderr, "err_init_reservation_fatal: akerr_init did not terminate\n");
-    return 0;
-}

tests/err_release_clears.c

@@ -1,32 +1,24 @@
 #include "akerror.h"
 #include "err_capture.h"
+#include <string.h>
 
 /*
- * Releasing an error context back to the pool must reset the state that affects
+ * Releasing an error context back to the pool must wipe it, so the next caller
- * the next caller. In particular, a handled error must not make a fresh error
+ * that checks it out never sees stale status/message/stacktrace from a previous
- * look handled when its slot is recycled.
+ * error. Mutation testing showed the clearing memset in akerr_release_error
+ * could be deleted without any test noticing.
  */
 
-static int unhandled_calls = 0;
-static int unhandled_status = 0;
-
-static void test_unhandled_handler(akerr_ErrorContext *errctx)
-{
-    unhandled_calls++;
-    unhandled_status = (errctx != NULL) ? errctx->status : 0;
-}
-
 akerr_ErrorContext *boom(void)
 {
     PREPARE_ERROR(e);
-    FAIL_RETURN(e, AKERR_VALUE, "first error is handled");
+    FAIL_RETURN(e, AKERR_VALUE, "stale dirty message that must not survive");
 }
 
 int main(void)
 {
     akerr_capture_install();
     akerr_init();
-    akerr_handler_unhandled_error = &test_unhandled_handler;
 
     /* Raise and fully handle an error; FINISH_NORETURN releases it to the pool. */
     PREPARE_ERROR(e);
@@ -40,31 +32,13 @@ int main(void)
 
     AKERR_CHECK(e == NULL);
 
-    /* A fresh error in the recycled slot must not inherit handled=true. */
+    /* The next context handed out is the slot we just released: it must be clean. */
-    PREPARE_ERROR(fresh);
-    ATTEMPT {
-	CATCH(fresh, boom());
-    } CLEANUP {
-    } PROCESS(fresh) {
-    } FINISH_NORETURN(fresh);
-
-    AKERR_CHECK(unhandled_calls == 1);
-    AKERR_CHECK(unhandled_status == AKERR_VALUE);
-    AKERR_CHECK(fresh == NULL);
-
-    /* The next context handed out is the same slot, with recycle state reset. */
     akerr_ErrorContext *slot = akerr_next_error();
     AKERR_CHECK(slot != NULL);
-    AKERR_CHECK(slot->handled == false);
     AKERR_CHECK(slot->status == 0);
-    AKERR_CHECK(slot->reported == false);
     AKERR_CHECK(slot->message[0] == '\0');
-    AKERR_CHECK(slot->fname[0] == '\0');
-    AKERR_CHECK(slot->function[0] == '\0');
     AKERR_CHECK(slot->stacktracebuf[0] == '\0');
-    AKERR_CHECK(slot->stacktracebufptr == (char *)&slot->stacktracebuf);
+    AKERR_CHECK(strstr(slot->message, "stale dirty message") == NULL);
-    RELEASE_ERROR(slot);
-    AKERR_CHECK(akerr_slots_in_use() == 0);
 
     fprintf(stderr, "err_release_clears ok\n");
     return 0;

tests/err_threads_pool.c

@@ -90,9 +90,6 @@ static void one_checkout(akerr_ThreadArg *arg)
 static void *pool_body(void *raw)
 {
     akerr_ThreadArg *arg = raw;
-    char expected[64];
-
-    snprintf(expected, sizeof(expected), "ignored by thread %d", arg->id);
     pthread_barrier_wait(arg->barrier);
 
     for ( int i = 0; i < ITERATIONS; i++ ) {
@@ -100,17 +97,10 @@ static void *pool_body(void *raw)
 	one_checkout(arg);
     }
 
-    /* An ignored error is a fact about the thread that ignored it: each thread
+    /* IGNORE's scratch pointer is thread-local while logging and cleared after
-     * must see its own, not the last one any thread swallowed. */
+     * release. Concurrent ignored errors must all return their pool slots. */
     IGNORE(ignorable(arg));
-    AKERR_TCHECK(arg, __akerr_last_ignored != NULL);
+    AKERR_TCHECK(arg, __akerr_last_ignored == NULL);
-    if ( __akerr_last_ignored != NULL ) {
-	AKERR_TCHECK(arg, __akerr_last_ignored->status == AKERR_IO);
-	AKERR_TCHECK(arg, strcmp(__akerr_last_ignored->message, expected) == 0);
-    }
-    /* IGNORE keeps the reference by design; hand it back so the pool is empty
-     * at the end of the test. */
-    RELEASE_ERROR(__akerr_last_ignored);
 
     return NULL;
 }