Basic tests implemented using cmocka

.clang-format

@@ -51,7 +51,7 @@ AllowShortEnumsOnASingleLine: true
 AllowShortFunctionsOnASingleLine: All
 AllowShortIfStatementsOnASingleLine: Never
 AllowShortLambdasOnASingleLine: All
-AllowShortLoopsOnASingleLine: false
+AllowShortLoopsOnASingleLine: true
 AlwaysBreakAfterDefinitionReturnType: All
 AlwaysBreakAfterReturnType: AllDefinitions
 AlwaysBreakBeforeMultilineStrings: false

.gitignore

@@ -4,3 +4,6 @@
 *.a
 build
 driver
+*.elf
+*.json
+.cache

Makefile

@@ -1,19 +1,21 @@
 # SPDX-License-Identifier: MIT
 
 CC = gcc
-CFLAGS = -Wall -Wextra -Werror -Wno-unused-parameter 
-CFLAGS += -Wno-unused-variable -Wno-unused-function 
+CFLAGS = -Wall -Wextra -Werror -Wno-unused-parameter
+CFLAGS += -Wno-unused-variable -Wno-unused-function
 CFLAGS += -Wno-unused-but-set-variable -Wno-unused-value -Wno-unused-label
 CFLAGS += -Wno-unused-result -Wno-unused-const-variable
 
-ifneq ($(DEBUG), 1)
+CFLAGS += -I.
+
+ifneq ($(RELEASE), 1)
+CFLAGS += -g -O0 -std=c99 -march=native -mtune=native
+CFLAGS += -DDEBUG
+else
 CFLAGS += -fno-exceptions -fno-asynchronous-unwind-tables -fno-ident
 CFLAGS += -fno-unwind-tables -fno-stack-protector -fno-plt -fno-pic
 CFLAGS += -O3 -std=c99 -march=native -mtune=native -fomit-frame-pointer
 CFLAGS += -fshort-enums
-else
-CFLAGS += -g -O0 -std=c99 -march=native -mtune=native
-CFLAGS += -DDEBUG
 endif # DEBUG
 
 LDFLAGS = -lm
@@ -25,6 +27,9 @@ ASMS = $(C_SOURCES:.c=.s)
 
 all: $(OBJECTS)
 
+test: test/test.elf
+	./test/test.elf
+
 %.o: %.c $(C_HEADERS)
 	@echo "CC $<"
 	@$(CC) $(CFLAGS) -c $< -o $@
@@ -39,6 +44,9 @@ driver: $(OBJECTS)
 run: driver
 	@./driver
 
+test/test.elf: test/test_ringbuf.o ringbuf.o
+	@$(CC) $(CFLAGS) $^ -o $@ -lpthread -lcmocka
+
 lib: $(OBJECTS)
 	@ar rcs librbuf.a ringbuf.o
 
@@ -50,7 +58,7 @@ install:
 	@cp ringbuf.h /usr/local/include
 
 clean:
-	rm -f $(OBJECTS) $(ASMS) driver librbuf.a librbuf.so
+	rm -f $(OBJECTS) $(ASMS) driver librbuf.a librbuf.so **/*.o **/*.elf
 
 asm: $(ASMS) $(OBJECTS)
 	wc -l $(ASMS)
@@ -62,4 +70,4 @@ tidy:
 format:
 	clang-format -i $(C_SOURCES) $(C_HEADERS)
 
-.PHONY: all clean format asm
+.PHONY: all clean format asm test

README.md

@@ -0,0 +1,44 @@
+# RingBuf
+
+RingBuf is an allocator-agnostic, non-overwriting circular/ring buffer
+implementation in C99.  
+See: [Circular Buffer (Wikipedia)](https://en.wikipedia.org/wiki/Circular_buffer)
+
+## Features
+- Space Efficiency
+The code is designed to be portable and flexible. The inspiration initially
+came to me when designing a network driver. When operating in memory
+constrained environments, every byte is of upmost importance. Traditional
+metaprogramming such as templating in C++ and template metaprogramming in C,
+although generic has the side effect of expanding into discrete machine code
+specific for the specialization applied, essentially scaling (spatially) linear
+with the amount of different datatypes we specialize on. This implementation
+circumvents this by treating all data as a void pointer with a length. This
+implies **no deep copies**.
+
+- Allocator Agnostic
+Another common characteristic of memory constrained environments are
+custom malloc implementations and/or variations.
+    - Signatures
+    - Arena
+
+## Design considerations
+- Holding a reference to malloc internally would make a tidier interface
+- Passing a user-defined function for deep-copies would enable certain applications
+
+## Usage
+In essence:
+```c
+int value = 42;
+struct RingBuf rb;
+rb_init(&rb, 10, malloc, sizeof(int));
+rb_push_back(&rb, (void *)&data, memcpy);
+rb_pop_front(&rb, &value, memcpy);
+```
+Most of these functions return Enum result types. See:
+[ringbuf.h](./ringbuf.h).
+
+## Future Improvements
+- Trim the code
+- Reduce boilerplate in tests
+- Reduce the number of tests in exchange for better test fit

driver.c

@@ -4,27 +4,16 @@
 #include <string.h>
 #include <stdio.h>
 
-#define rb_size_t size_t
+#ifndef DEBUG
+#define DEBUG
+#endif
+
+// #define rb_size_t size_t
 // #define rb_size_t int
 #include "ringbuf.h"
 
 typedef int DATATYPE;
 
-/**
- * @brief Debug print and empty the ringbuf
- */
-void
-rb_debug_empty(struct RingBuf *rb)
-{
-  int d;
-  if(rb->count == 0)
-    return;
-  printf("Debug Data: [");
-  while(rb_pop_front(rb, &d, memcpy) == ReadOk)
-    printf("%d,", d);
-  printf("\b]\n");
-}
-
 int
 main(void)
 {

ringbuf.c

@@ -4,6 +4,7 @@
 // #include <string.h>
 
 #include "ringbuf.h"
+#include <assert.h>
 #include <stdint.h>
 
 #ifdef DEBUG
@@ -29,7 +30,18 @@ rb_init(struct RingBuf *rb, rb_size_t capacity, ALLOC_T malloc_fn,
 void
 rb_destroy(struct RingBuf *rb, FREE_T free_fn)
 {
-  free_fn(rb->buffer);
+  if(rb->buffer) { // Prevent double-free
+    free_fn(rb->buffer);
+    rb->buffer = NULL;
+    rb->buffer_end = NULL;
+
+    rb->struct_size = 0;
+    rb->capacity = 0;
+    rb->count = 0;
+
+    rb->write_head = NULL;
+    rb->read_head = NULL;
+  }
 }
 
 void
@@ -46,6 +58,8 @@ rb_push_back(struct RingBuf *rb, const void *item, MEMCPY_T memcpy_fn)
   if(rb->count == rb->capacity)
     return Full;
 
+  assert(rb->buffer != NULL);
+
   memcpy_fn(rb->write_head, item, rb->struct_size);
 
   // Advance the write head
@@ -117,6 +131,21 @@ rb_pop_front(struct RingBuf *rb, void *item, MEMCPY_T memcpy_fn)
   return ReadOk;
 }
 
+#ifdef DEBUG
+#include <stdio.h>
+
+void
+rb_debug_empty(struct RingBuf *rb)
+{
+  int d;
+  if(rb->count == 0)
+    return;
+  printf("Debug Data: [");
+  while(rb_pop_front(rb, &d, memcpy) == ReadOk)
+    printf("%d,", d);
+  printf("\b]\n");
+}
+
 void
 rb_debug_print(struct RingBuf *rb)
 {
@@ -133,3 +162,5 @@ rb_debug_print(struct RingBuf *rb)
 
   DEBUG_PRINT("============%s\n", "");
 }
+
+#endif

ringbuf.h

@@ -111,12 +111,25 @@ enum ReadResult rb_pop_front(struct RingBuf *rb, void *item,
 
 /**
  * @brief Free the ring buffer
+ *
+ * @details This function is idempotent, consecutive calls will not result in a
+ * double free.
+ *
  * @param rb The ring buffer
  * @param free The free function
  */
 void rb_destroy(struct RingBuf *rb, void(free)());
 
+#ifdef DEBUG
+
 /**
  * @brief Debug print
  */
 void rb_debug_print(struct RingBuf *rb);
+
+/**
+ * @brief Debug print and empty the ringbuf
+ */
+void rb_debug_empty(struct RingBuf *rb);
+
+#endif

test/test_ringbuf.c

@@ -0,0 +1,101 @@
+#include <setjmp.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <cmocka.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "ringbuf.h"
+
+/** Tests initialization */
+static void
+test_rb_init_empty(void **state) {
+  struct RingBuf rb;
+  rb_size_t      capacity = 10;
+  rb_size_t      struct_size = sizeof(int);
+
+  rb_init(&rb, capacity, malloc, struct_size);
+
+  assert_int_equal(rb.capacity, capacity);
+  assert_int_equal(rb.count, 0);
+}
+
+/** Tests push_back */
+static void
+test_rb_push_back(void **state) {
+  struct RingBuf rb;
+  rb_size_t      capacity = 10;
+  rb_size_t      struct_size = sizeof(int);
+
+  rb_init(&rb, capacity, malloc, struct_size);
+
+  int data = 10;
+
+  enum WriteResult wr = rb_push_back(&rb, (void *)&data, memcpy);
+  assert_int_equal(wr, WriteOk);
+
+  assert_int_equal(rb.capacity, capacity);
+  assert_int_equal(rb.count, 1);
+}
+
+/** Tests the destroy function */
+static void
+test_rb_init_destroy(void **state) {
+  struct RingBuf rb = { 0, 0, 0, NULL, NULL, NULL, NULL };
+  rb_size_t      capacity = 10;
+  rb_size_t      struct_size = sizeof(int);
+
+  rb_init(&rb, capacity, malloc, struct_size);
+
+  int data = 10;
+
+  rb_push_back(&rb, (void *)&data, memcpy);
+
+  assert_int_equal(rb.capacity, capacity);
+  assert_int_equal(rb.count, 1);
+
+  rb_destroy(&rb, free);
+
+  assert_null(rb.buffer);
+}
+
+/** Tests fill, but not overflow/wrap-around */
+static void
+test_rb_push_back_fill(void **state) {
+  struct RingBuf rb = { 0, 0, 0, NULL, NULL, NULL, NULL };
+  rb_size_t      capacity = 10;
+  rb_size_t      struct_size = sizeof(int);
+
+  rb_init(&rb, capacity, malloc, struct_size);
+
+  const int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
+
+  // Insert them all sequentially
+  for(int i = 0; rb_push_back(&rb, &arr[i], memcpy) == WriteOk; i++);
+  assert_int_equal(rb.count, 10);
+  assert_int_equal(rb.capacity, capacity);
+
+  // Read them out and assert expected value
+  for(int i = 0, d = __INT_MAX__; rb_pop_front(&rb, &d, memcpy) == ReadOk;
+      i++) {
+    assert_int_equal(d, arr[i]);
+  }
+
+  assert_int_equal(rb.capacity, capacity);
+  assert_int_equal(rb.count, 0);
+
+  rb_destroy(&rb, free);
+
+  assert_null(rb.buffer);
+}
+
+int
+main(void) {
+  const struct CMUnitTest tests[] = {
+    cmocka_unit_test(test_rb_init_empty),
+    cmocka_unit_test(test_rb_push_back),
+    cmocka_unit_test(test_rb_init_destroy),
+    cmocka_unit_test(test_rb_push_back_fill),
+  };
+
+  return cmocka_run_group_tests(tests, NULL, NULL);
+}