struct Window {
MMapCache *cache;
- unsigned keep_always;
+ bool keep_always;
bool in_unused;
int prot;
Hashmap *fds;
- Hashmap *contexts;
+ Context *contexts[MMAP_CACHE_MAX_CONTEXTS];
LIST_HEAD(Window, unused);
Window *last_unused;
};
#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
}
}
static Context *context_add(MMapCache *m, unsigned id) {
Context *c;
- int r;
assert(m);
- c = hashmap_get(m->contexts, UINT_TO_PTR(id + 1));
+ c = m->contexts[id];
if (c)
return c;
- r = hashmap_ensure_allocated(&m->contexts, NULL);
- if (r < 0)
- return NULL;
-
c = new0(Context, 1);
if (!c)
return NULL;
c->cache = m;
c->id = id;
- r = hashmap_put(m->contexts, UINT_TO_PTR(id + 1), c);
- if (r < 0) {
- free(c);
- return NULL;
- }
+ assert(!m->contexts[id]);
+ m->contexts[id] = c;
return c;
}
context_detach_window(c);
- if (c->cache)
- assert_se(hashmap_remove(c->cache->contexts, UINT_TO_PTR(c->id + 1)));
+ if (c->cache) {
+ assert(c->cache->contexts[c->id] == c);
+ c->cache->contexts[c->id] = NULL;
+ }
free(c);
}
}
static void mmap_cache_free(MMapCache *m) {
- Context *c;
FileDescriptor *f;
+ int i;
assert(m);
- while ((c = hashmap_first(m->contexts)))
- context_free(c);
-
- hashmap_free(m->contexts);
+ for (i = 0; i < MMAP_CACHE_MAX_CONTEXTS; i++)
+ if (m->contexts[i])
+ context_free(m->contexts[i]);
while ((f = hashmap_first(m->fds)))
fd_free(f);
bool keep_always,
uint64_t offset,
size_t size,
- void **ret,
- void **release_cookie) {
+ void **ret) {
Context *c;
assert(m->n_ref > 0);
assert(fd >= 0);
assert(size > 0);
+ assert(ret);
- c = hashmap_get(m->contexts, UINT_TO_PTR(context+1));
+ c = m->contexts[context];
if (!c)
return 0;
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);
- if (keep_always && release_cookie)
- *release_cookie = c->window;
+ *ret = (uint8_t*) c->window->ptr + (offset - c->window->offset);
return 1;
}
bool keep_always,
uint64_t offset,
size_t size,
- void **ret,
- void **release_cookie) {
+ void **ret) {
FileDescriptor *f;
Window *w;
context_attach_window(c, w);
w->keep_always += keep_always;
- if (ret)
- *ret = (uint8_t*) w->ptr + (offset - w->offset);
- if (keep_always && release_cookie)
- *release_cookie = c->window;
+ *ret = (uint8_t*) w->ptr + (offset - w->offset);
return 1;
}
uint64_t offset,
size_t size,
struct stat *st,
- void **ret,
- void **release_cookie) {
+ void **ret) {
uint64_t woffset, wsize;
Context *c;
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);
- if (keep_always && release_cookie)
- *release_cookie = c->window;
+ *ret = (uint8_t*) w->ptr + (offset - w->offset);
return 1;
outofmem:
uint64_t offset,
size_t size,
struct stat *st,
- void **ret,
- void **release_cookie) {
+ void **ret) {
int r;
assert(m->n_ref > 0);
assert(fd >= 0);
assert(size > 0);
+ assert(ret);
+ assert(context < MMAP_CACHE_MAX_CONTEXTS);
/* Check whether the current context is the right one already */
- r = try_context(m, fd, prot, context, keep_always, offset, size, ret, release_cookie);
+ r = try_context(m, fd, prot, context, keep_always, offset, size, ret);
if (r != 0) {
m->n_hit ++;
return r;
}
/* Search for a matching mmap */
- r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret, release_cookie);
+ r = find_mmap(m, fd, prot, context, keep_always, offset, size, ret);
if (r != 0) {
m->n_hit ++;
return r;
m->n_missed++;
/* Create a new mmap */
- return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret, release_cookie);
-}
-
-int mmap_cache_release(
- MMapCache *m,
- int fd,
- void *release_cookie) {
-
- FileDescriptor *f;
- Window *w;
-
- assert(m);
- assert(m->n_ref > 0);
- assert(fd >= 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 (w == release_cookie)
- break;
-
- if (!w)
- return -ENOENT;
-
- if (w->keep_always == 0)
- return -ENOLCK;
-
- w->keep_always -= 1;
- return 0;
+ return add_mmap(m, fd, prot, context, keep_always, offset, size, st, ret);
}
void mmap_cache_close_fd(MMapCache *m, int fd) {
fd_free(f);
}
-void mmap_cache_close_context(MMapCache *m, unsigned context) {
- Context *c;
-
- assert(m);
-
- c = hashmap_get(m->contexts, UINT_TO_PTR(context + 1));
- if (!c)
- return;
-
- context_free(c);
-}
-
unsigned mmap_cache_get_hit(MMapCache *m) {
assert(m);