struct Window {
MMapCache *cache;
- unsigned keep_always;
+ bool keep_always;
bool in_unused;
int prot;
};
#define WINDOWS_MIN 64
-#define WINDOW_SIZE (8ULL*1024ULL*1024ULL)
+
+#ifdef ENABLE_DEBUG_MMAP_CACHE
+/* Tiny windows increase mmap activity and the chance of exposing unsafe use. */
+# define WINDOW_SIZE (page_size())
+#else
+# define WINDOW_SIZE (8ULL*1024ULL*1024ULL)
+#endif
MMapCache* mmap_cache_new(void) {
MMapCache *m;
c->window = NULL;
LIST_REMOVE(by_window, w->contexts, c);
- if (!w->contexts && w->keep_always == 0) {
+ if (!w->contexts && !w->keep_always) {
/* Not used anymore? */
+#ifdef ENABLE_DEBUG_MMAP_CACHE
+ /* Unmap unused windows immediately to expose use-after-unmap
+ * by SIGSEGV. */
+ window_free(w);
+#else
LIST_PREPEND(unused, c->cache->unused, w);
if (!c->cache->last_unused)
c->cache->last_unused = w;
w->in_unused = true;
+#endif
}
}
assert(m->n_ref > 0);
assert(fd >= 0);
assert(size > 0);
+ assert(ret);
c = hashmap_get(m->contexts, UINT_TO_PTR(context+1));
if (!c)
return 0;
}
- c->window->keep_always += keep_always;
+ c->window->keep_always |= keep_always;
- if (ret)
- *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
+ *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
return 1;
}
context_attach_window(c, w);
w->keep_always += keep_always;
- if (ret)
- *ret = (uint8_t*) w->ptr + (offset - w->offset);
+ *ret = (uint8_t*) w->ptr + (offset - w->offset);
return 1;
}
assert(m->n_ref > 0);
assert(fd >= 0);
assert(size > 0);
+ assert(ret);
woffset = offset & ~((uint64_t) page_size() - 1ULL);
wsize = size + (offset - woffset);
c->window = w;
LIST_PREPEND(by_window, w->contexts, c);
- if (ret)
- *ret = (uint8_t*) w->ptr + (offset - w->offset);
+ *ret = (uint8_t*) w->ptr + (offset - w->offset);
return 1;
outofmem:
assert(m->n_ref > 0);
assert(fd >= 0);
assert(size > 0);
+ assert(ret);
/* Check whether the current context is the right one already */
r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);
}
-int mmap_cache_release(
- MMapCache *m,
- int fd,
- int prot,
- unsigned context,
- uint64_t offset,
- size_t size) {
-
- FileDescriptor *f;
- Window *w;
-
- assert(m);
- assert(m->n_ref > 0);
- assert(fd >= 0);
- assert(size > 0);
-
- f = hashmap_get(m->fds, INT_TO_PTR(fd + 1));
- if (!f)
- return -EBADF;
-
- assert(f->fd == fd);
-
- LIST_FOREACH(by_fd, w, f->windows)
- if (window_matches(w, fd, prot, offset, size))
- break;
-
- if (!w)
- return -ENOENT;
-
- if (w->keep_always == 0)
- return -ENOLCK;
-
- w->keep_always -= 1;
- return 0;
-}
-
void mmap_cache_close_fd(MMapCache *m, int fd) {
FileDescriptor *f;