Exceptions in C!

src/CMakeLists.txt

@@ -20,3 +20,4 @@ add_subdirectory(./BinaryTree)
 add_subdirectory(./Subprocess)
 add_subdirectory(./TracingHeap)
 add_subdirectory(./Complex)
+add_subdirectory(./ExceptionalScope)

src/ExceptionalScope/CMakeLists.txt

@@ -0,0 +1 @@
+add_library(ExceptionalScope STATIC ExceptionalScope.c)

src/ExceptionalScope/ExceptionalScope.c

@@ -0,0 +1,51 @@
+#include "ExceptionalScope.h"
+#include "../errorcodes.h"
+
+#include <setjmp.h>
+#include <stdlib.h>
+#include <string.h>
+
+
+int  ExceptionalScope_Create(ExceptionalScope* self)
+{
+	memset(self, 0, sizeof(*self));
+
+	return EXIT_SUCCESS;
+}
+
+void ExceptionalScope_ActivateCleaners(ExceptionalScope* self)
+{
+	while (self->cleaners != NULL) {
+		self->cleaners->action(self->cleaners->arg);
+		self->cleaners = self->cleaners->next;
+	}
+}
+
+void ExceptionalScope_Destroy(ExceptionalScope* self)
+{
+	ExceptionalScope_ActivateCleaners(self);
+}
+
+void ExceptionalScope_PushCleaner(ExceptionalScope* self, ExceptionalScopeCleaner* cleaner)
+{
+	cleaner->next = self->cleaners;
+	self->cleaners = cleaner;
+}
+
+int ExceptionalScope_PopCleaner(ExceptionalScope* self, ExceptionalScopeCleaner* cleaner)
+{
+	if (self->cleaners != cleaner) return ENOTFOUND;
+
+	self->cleaners = self->cleaners->next;
+
+	return EXIT_SUCCESS;
+}
+
+[[noreturn]] void ExceptionalScope_Throw(ExceptionalScope* self, void* exception)
+{
+	self->exception = exception;
+
+	ExceptionalScope_ActivateCleaners(self);
+
+	longjmp(self->handler, 1);
+}

src/ExceptionalScope/ExceptionalScope.h

@@ -0,0 +1,33 @@
+#ifndef UTILITIEC_EXCEPTIONALSCOPE_H
+#define UTILITIEC_EXCEPTIONALSCOPE_H
+
+#include <setjmp.h>
+
+#define withScopedCleaner(scope, cleaner) for (int __cleanerDone##cleaner = (ExceptionalScope_PushCleaner(scope, &cleaner), 1); __cleanerDone##cleaner--; ExceptionalScope_PopCleaner(scope, &cleaner))
+#define try(scope) if (setjmp((scope)->handler) == 0)
+#define catch else
+
+typedef void (*ExceptionalScopeCleanerFunction) (void* arg);
+
+typedef struct ExceptionalScopeCleaner_s {
+	ExceptionalScopeCleanerFunction action;
+	void* arg;
+
+	struct ExceptionalScopeCleaner_s* next;
+} ExceptionalScopeCleaner;
+
+typedef struct ExceptionalScope_s {
+	jmp_buf handler; // jump here when the exception is thrown
+	ExceptionalScopeCleaner* cleaners; // execute all these before the jumping to the handler
+	void* exception;
+} ExceptionalScope;
+
+int  ExceptionalScope_Create(ExceptionalScope* self);
+void ExceptionalScope_Destroy(ExceptionalScope* self);
+
+void ExceptionalScope_PushCleaner(ExceptionalScope* self, ExceptionalScopeCleaner* cleaner);
+int  ExceptionalScope_PopCleaner(ExceptionalScope* self, ExceptionalScopeCleaner* cleaner);
+
+[[noreturn]] void ExceptionalScope_Throw(ExceptionalScope* self, void* exception);
+
+#endif

tests/CMakeLists.txt

@@ -60,4 +60,8 @@ target_link_libraries(QuadTree-test
 	rand
 	pointers
 	allocator-interface
+
+add_executable(ExceptionalScope-test ExceptionalScope.test.c)
+target_link_libraries(ExceptionalScope-test
+	ExceptionalScope
 )

tests/ExceptionalScope.test.c

@@ -0,0 +1,44 @@
+#include "../src/ExceptionalScope/ExceptionalScope.h"
+#include <stdio.h>
+
+#define unsafe
+
+void print(const char* s)
+{
+	unsafe {
+		puts(s);
+	}
+}
+
+int main()
+{
+	ExceptionalScope scope;
+	ExceptionalScope_Create(&scope);
+	scope.exception = (void*) 0xCAFEBABE;
+
+	try(&scope) {
+		ExceptionalScopeCleaner outerCleaner = {
+			.next = NULL,
+			.arg = "Unwinding the cleaner stack #2",
+			.action = (ExceptionalScopeCleanerFunction) print,
+		};
+		withScopedCleaner(&scope, outerCleaner) {
+			ExceptionalScopeCleaner innerCleaner = {
+				.next = NULL,
+				.arg = "Unwinding the cleaner stack #1",
+				.action = (ExceptionalScopeCleanerFunction) print,
+			};
+
+			withScopedCleaner(&scope, innerCleaner) {
+
+				ExceptionalScope_Throw(&scope, (void*) 0xDEADBEEF);
+				puts("After the throw");
+
+			}
+		}
+	} catch {
+		printf("Caught an exception: %p\n", scope.exception);
+	}
+
+	ExceptionalScope_Destroy(&scope);
+}