Add memdebug module, a simple malloc debugger

2 files changed, 157 insertions, 0 deletions

diff --git a/memdebug/memdebug.c b/memdebug/memdebug.c
new file mode 100644
index 0000000..9725cb1
--- /dev/null
+++ b/memdebug/memdebug.c
@@ -0,0 +1,113 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+/* define/undef to enable tracing of errors */
+#define MEMDEBUG_TRACE
+/* define/undef to enable tracing of double free errors */
+#define MEMDEBUG_TRACE_DOUBLE_FREE
+
+#include "memdebug.h"
+
+static struct memdebug_heap_item *heap_head = NULL;
+static struct memdebug_heap_item *heap_tail = NULL;
+
+void *__memdebug_malloc(size_t size, const char *func,
+                        const char *file, const unsigned int line)
+{
+	void *ret;
+	struct memdebug_heap_item *hi = malloc(sizeof(struct memdebug_heap_item));
+
+	if (!hi)
+		goto out_err;
+
+	ret = malloc(size);
+	if (!ret) {
+		free(hi);
+		goto out_err;
+	}
+
+	hi->next = NULL;
+	hi->addr = ret;
+	hi->size = size;
+	hi->func = func;
+	hi->file = file;
+	hi->line = line;
+#ifdef MEMDEBUG_TRACE_DOUBLE_FREE
+	hi->freed_func = NULL;
+	hi->freed_file = NULL;
+	hi->line = 0;
+#endif
+
+	if (!heap_head)
+		heap_head = hi;
+	if (!heap_tail)
+		heap_tail = hi;
+	else {
+		heap_tail->next = hi;
+		heap_tail = hi;
+	}
+
+	return ret;
+
+out_err:
+	memdebug_trace("malloc failed (%s:%d:%s)", file, line, func);
+	return NULL;
+}
+
+void __memdebug_free(void *ptr, const char *func,
+                     const char *file, const unsigned int line)
+{
+	struct memdebug_heap_item *hi, *prev;
+
+	if (!ptr) {
+		memdebug_trace("trying to free NULL pointer (%s:%d:%s)", file, line, func);
+		return;
+	}
+
+	for (hi = heap_head, prev = NULL; hi; prev = hi, hi = hi->next)
+		if (hi->addr ==ptr)
+			break;
+
+	if (!hi) {
+		memdebug_trace("no memory allocated at %p (%s:%d:%s)", ptr, file, line, func);
+		return;
+	}
+
+#ifdef MEMDEBUG_TRACE_DOUBLE_FREE
+	if (hi->freed_func) {
+		memdebug_trace("double free at %p (%s:%d:%s)\nalready freed by %s:%d:%s",
+				ptr, file, line, func, hi->freed_file, hi->freed_line, hi->freed_func);
+		return;
+	}
+
+	hi->freed_func = func;
+	hi->freed_file = file;
+	hi->freed_line = line;
+#else
+	/* Delete the item from the linked list */
+	if (prev)
+		prev->next = hi->next;
+	else
+		heap_head = hi->next;
+	if (heap_tail == hi)
+		heap_tail = prev;
+
+	free(hi);
+#endif
+
+	free(ptr);
+}
+
+void memdebug_report(void)
+{
+	struct memdebug_heap_item *hi;
+	size_t total_size = 0;
+
+	fprintf(stderr, "\n\n*** Reporting allocated memory ***\n");
+	for (hi = heap_head; hi; hi = hi->next) {
+		fprintf(stderr, "  %zu bytes at %p (%s:%d:%s)\n", hi->size, hi->addr, hi->file, hi->line, hi->func);
+		total_size += hi->size;
+	}
+	fprintf(stderr, "Total size: %zu bytes\n\n", total_size);
+	fflush(stderr);
+}
diff --git a/memdebug/memdebug.h b/memdebug/memdebug.h
new file mode 100644
index 0000000..d96e356
--- /dev/null
+++ b/memdebug/memdebug.h
@@ -0,0 +1,44 @@
+#ifndef _MEMDEBUG_H_
+#define _MEMDEBUG_H_
+
+#include <stdlib.h>
+
+#ifdef MEMDEBUG_TRACE
+# define memdebug_trace(fmt, args...) \
+	({ \
+	 fprintf(stderr, "\n\n*** " fmt " ***\n\n", ##args); \
+	 fflush(stderr); \
+	 })
+#else
+# define memdebug_trace(fmt, args...)
+#endif
+
+struct memdebug_heap_item {
+	struct memdebug_heap_item *next;
+
+	void *addr;
+	size_t size;
+
+	const char *func;
+	const char *file;
+	unsigned int line;
+
+#ifdef MEMDEBUG_TRACE_DOUBLE_FREE
+	const char *freed_func;
+	const char *freed_file;
+	unsigned int freed_line;
+#endif
+};
+
+#define memdebug_malloc(size) \
+	__memdebug_malloc(size, __func__, __FILE__, __LINE__)
+#define memdebug_free(ptr) \
+	__memdebug_free(ptr, __func__, __FILE__, __LINE__)
+
+void *__memdebug_malloc(size_t size, const char *func,
+                        const char *file, const unsigned int line);
+void __memdebug_free(void *ptr, const char *func,
+                   const char *file, const unsigned int line);
+void memdebug_report(void);
+
+#endif /* _MEMDEBUG_H_ */