Added malloc wrapper and ./configure --with-fixed-allocator and --wit…

…h-malloc-wrapper flags.

Makefile.am

@@ -5,7 +5,12 @@ lib_LTLIBRARIES = libcsptr.la
 WARNINGS = -Wall -Wextra \
 	-Wno-unused-result -Wno-missing-field-initializers
 
-libcsptr_la_CFLAGS = $(WARNINGS) -std=gnu11 -fplan9-extensions
+libcsptr_la_CFLAGS = \
+	$(WARNINGS) \
+	-std=gnu11 \
+	-fplan9-extensions
+
+libcsptr_la_LDFLAGS = $(FLAG_WRAP_MALLOC)
 
 EXTRA_DIST = LICENSE README.md
 
@@ -18,6 +23,7 @@ subdirinclude_HEADERS = \
 	src/smart_ptr.h
 
 libcsptr_la_SOURCES = \
-	src/mman.c
+	src/mman.c \
+	src/wrap_malloc.c
 
 man3_MANS = doc/csptr.3

configure.ac

@@ -8,6 +8,7 @@ AC_CANONICAL_SYSTEM
 
 AM_INIT_AUTOMAKE([dist-bzip2 no-dist-gzip foreign subdir-objects])
 LT_INIT
+AC_CONFIG_MACRO_DIR([m4])
 
 AC_PROG_CC
 AM_PROG_CC_C_O
@@ -19,6 +20,19 @@ AC_PROG_LN_S
 AC_PROG_MAKE_SET
 AC_SUBST([LIBTOOL_DEPS])
 
+AC_ARG_WITH([fixed-allocator],
+    [AS_HELP_STRING([--with-fixed-allocator], [Always use malloc/free as the allocation system])],
+    [AC_DEFINE([SMALLOC_FIXED_ALLOCATOR], [1], [Define if malloc should always be used.])],
+    [])
+
+AC_ARG_WITH([malloc-wrapper],
+    [AS_HELP_STRING([--with-malloc-wrapper], [Make smart pointers compatible with a pass to free(), and malloc() return a smart pointer.])],
+    [AC_DEFINE([SMALLOC_WRAP_MALLOC], [1], [Define if malloc should be wrapped])
+     FLAG_WRAP_MALLOC="-Wl,--no-as-needed -ldl"
+     AC_SUBST([FLAG_WRAP_MALLOC])
+    ],
+    [])
+
 AC_CONFIG_HEADERS([src/config.h])
 AC_CONFIG_FILES([Makefile])
 

src/mman.c

@@ -28,8 +28,10 @@
 #include <string.h>
 #include <assert.h>
 
+#include "config.h"
 #include "mman.h"
 #include "array.h"
+#include "wrap_malloc.h"
 #undef smalloc
 
 #define INLINE __attribute__ ((always_inline)) inline
@@ -80,10 +82,15 @@ void *sref(void *ptr) {
 
 __attribute__ ((malloc))
 INLINE static void *alloc_entry(size_t head, size_t size, size_t metasize) {
+    const size_t totalsize = head + size + metasize + sizeof (size_t);
 #ifdef SMALLOC_FIXED_ALLOCATOR
-    return malloc(head + size + metasize + sizeof (size_t));
+# ifdef SMALLOC_WRAP_MALLOC
+    return real_malloc(totalsize);
+# else /* !SMALLOC_WRAP_MALLOC */
+    return malloc(totalsize);
+# endif /* !SMALLOC_WRAP_MALLOC */
 #else /* !SMALLOC_FIXED_ALLOCATOR */
-    return smalloc_allocator.alloc(head + size + metasize + sizeof (size_t));
+    return smalloc_allocator.alloc(totalsize);
 #endif /* !SMALLOC_FIXED_ALLOCATOR */
 }
 
@@ -99,7 +106,11 @@ INLINE static void dealloc_entry(s_meta *meta, void *ptr) {
     }
 
 #ifdef SMALLOC_FIXED_ALLOCATOR
+# ifdef SMALLOC_WRAP_MALLOC
+    real_free(meta);
+# else /* !SMALLOC_WRAP_MALLOC */
     free(meta);
+# endif /* !SMALLOC_WRAP_MALLOC */
 #else /* !SMALLOC_FIXED_ALLOCATOR */
     smalloc_allocator.dealloc(meta);
 #endif /* !SMALLOC_FIXED_ALLOCATOR */

src/wrap_malloc.c

@@ -0,0 +1,42 @@
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "config.h"
+#include "mman.h"
+#undef smalloc
+
+#ifdef SMALLOC_WRAP_MALLOC
+void *(*real_malloc)(size_t) = NULL;
+void (*real_free)(void *) = NULL;
+
+__attribute__ ((constructor))
+static void initialize_handles(void) {
+# if defined(__APPLE__)
+    void *handle = dlopen("libc.dylib", RTLD_NOW);
+    real_malloc = (__typeof__(real_malloc)) dlsym(handle, "malloc");
+    real_free   = (__typeof__(real_free))   dlsym(handle, "free");
+# elif defined(__unix__)
+    real_malloc = (__typeof__(real_malloc)) dlsym(RTLD_NEXT, "malloc");
+    real_free   = (__typeof__(real_free))   dlsym(RTLD_NEXT, "free");
+# else
+#  error malloc wrapping not supported on non-*nix systems.
+# endif
+    if (real_malloc == NULL || real_free == NULL) {
+        puts("Failed to locate original malloc or free; aborting.\n");
+        exit(-1);
+    }
+
+    smalloc_allocator = (s_allocator) {real_malloc, real_free};
+}
+
+__attribute__ ((malloc))
+void *malloc(size_t size) {
+    return smalloc(size, 0, UNIQUE, 0);
+}
+
+void free(void *ptr) {
+    sfree(ptr);
+}
+#endif /* !SMALLOC_WRAP_MALLOC */

src/wrap_malloc.h

@@ -0,0 +1,9 @@
+#ifndef WRAP_MALLOC_H_
+# define WRAP_MALLOC_H_
+
+#ifdef SMALLOC_WRAP_MALLOC
+extern void *(*real_malloc)(size_t);
+extern void (*real_free)(void *);
+#endif /* !SMALLOC_WRAP_MALLOC */
+
+#endif /* !WRAP_MALLOC_H_ */