add stubs for Android extensions

Makefile

@@ -1,5 +1,5 @@
 CPPFLAGS := -D_GNU_SOURCE
-CFLAGS := -std=c11 -Wall -Wextra -O2 -flto -fPIC -fvisibility=hidden -fno-plt
+CFLAGS := -std=c11 -Wall -Wextra -Wmissing-prototypes -O2 -flto -fPIC -fvisibility=hidden -fno-plt
 LDFLAGS := -Wl,-z,defs,-z,relro,-z,now,-z,nodlopen,-z,text
 OBJECTS := chacha.o malloc.o memory.o pages.o random.o util.o
 

malloc.c

@@ -978,7 +978,7 @@ EXPORT int h_malloc_trim(UNUSED size_t pad) {
 EXPORT void h_malloc_stats(void) {}
 
 EXPORT struct mallinfo h_mallinfo(void) {
-    return (struct mallinfo){0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+    return (struct mallinfo){0};
 }
 
 EXPORT int h_malloc_info(UNUSED int options, UNUSED FILE *fp) {
@@ -993,3 +993,35 @@ COLD EXPORT void *h_malloc_get_state(void) {
 COLD EXPORT int h_malloc_set_state(UNUSED void *state) {
     return -2;
 }
+
+#ifdef __ANDROID__
+EXPORT size_t __mallinfo_narenas(void) {
+    return 0;
+}
+
+EXPORT size_t __mallinfo_nbins(void) {
+    return 0;
+}
+
+EXPORT struct mallinfo __mallinfo_arena_info(UNUSED size_t arena) {
+    return (struct mallinfo){0};
+}
+
+EXPORT struct mallinfo __mallinfo_bin_info(UNUSED size_t arena, UNUSED size_t bin) {
+    return (struct mallinfo){0};
+}
+
+COLD EXPORT int h_iterate(UNUSED uintptr_t base, UNUSED size_t size,
+                          UNUSED void (*callback)(uintptr_t ptr, size_t size, void *arg),
+                          UNUSED void *arg) {
+    fatal_error("not implemented");
+}
+
+COLD EXPORT void h_malloc_disable(void) {
+    fatal_error("not implemented");
+}
+
+COLD EXPORT void h_malloc_enable(void) {
+    fatal_error("not implemented");
+}
+#endif

malloc.h

@@ -52,6 +52,18 @@ void *h_valloc(size_t size);
 void *h_pvalloc(size_t size);
 void h_cfree(void *ptr);
 
+// Android extensions
+#ifdef __ANDROID__
+size_t __mallinfo_narenas(void);
+size_t __mallinfo_nbins(void);
+struct mallinfo __mallinfo_arena_info(size_t arena);
+struct mallinfo __mallinfo_bin_info(size_t arena, size_t bin);
+int h_iterate(uintptr_t base, size_t size, void (*callback)(uintptr_t ptr, size_t size, void *arg),
+              void *arg);
+void h_malloc_disable(void);
+void h_malloc_enable(void);
+#endif
+
 // custom extensions
 
 // return an upper bound on object size for any pointer based on malloc metadata