journal: remove journal_file_object_keep/release functions

[elogind.git] / src / journal / mmap-cache.c

diff --git a/src/journal/mmap-cache.c b/src/journal/mmap-cache.c
index 908562da27a45e922f5ddccfe31de12d0934a98b..f34d260856127e6493ff08db3ba5052515f25f47 100644 (file)
--- a/src/journal/mmap-cache.c
+++ b/src/journal/mmap-cache.c
@@ -38,7 +38,7 @@ typedef struct FileDescriptor FileDescriptor;
 struct Window {
         MMapCache *cache;
 
-        unsigned keep_always;
+        bool keep_always;
         bool in_unused;
 
         int prot;
@@ -83,7 +83,13 @@ struct MMapCache {
 };
 
 #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;
@@ -185,13 +191,19 @@ static void context_detach_window(Context *c) {
         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
         }
 }
 
@@ -227,7 +239,7 @@ static Context *context_add(MMapCache *m, unsigned id) {
         if (c)
                 return c;
 
-        r = hashmap_ensure_allocated(&m->contexts, trivial_hash_func, trivial_compare_func);
+        r = hashmap_ensure_allocated(&m->contexts, NULL);
         if (r < 0)
                 return NULL;
 
@@ -281,7 +293,7 @@ static FileDescriptor* fd_add(MMapCache *m, int fd) {
         if (f)
                 return f;
 
-        r = hashmap_ensure_allocated(&m->fds, trivial_hash_func, trivial_compare_func);
+        r = hashmap_ensure_allocated(&m->fds, NULL);
         if (r < 0)
                 return NULL;
 
@@ -360,6 +372,7 @@ static int try_context(
         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)
@@ -377,10 +390,9 @@ static int try_context(
                 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;
 }
 
@@ -423,8 +435,7 @@ static int find_mmap(
         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;
 }
 
@@ -450,6 +461,7 @@ static int add_mmap(
         assert(m->n_ref > 0);
         assert(fd >= 0);
         assert(size > 0);
+        assert(ret);
 
         woffset = offset & ~((uint64_t) page_size() - 1ULL);
         wsize = size + (offset - woffset);
@@ -519,8 +531,7 @@ static int add_mmap(
         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:
@@ -545,6 +556,7 @@ int mmap_cache_get(
         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);
@@ -566,42 +578,6 @@ int mmap_cache_get(
         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;