Fixed the apr_mmap_dup ownership problem for disjoint pools by getting

rid of the is_owner thing completely.  Instead, we place all of the dup'ed
apr_mmap_t's in a ring with each other (essentially the same as refcounting
the mmaped region but without the where-do-you-store-it pitfall).


git-svn-id: http://svn.apache.org/repos/asf/apr/apr/trunk@64067 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 29 insertions, 43 deletions

diff --git a/mmap/unix/mmap.c b/mmap/unix/mmap.c
index 4a54b860e..707702662 100644
--- a/mmap/unix/mmap.c
+++ b/mmap/unix/mmap.c
@@ -83,13 +83,17 @@
 static apr_status_t mmap_cleanup(void *themmap)
 {
     apr_mmap_t *mm = themmap;
-    int rv;
+    apr_mmap_t *next = APR_RING_NEXT(mm,link);
+    int rv = 0;
 
-    if (!mm->is_owner) {
-        return APR_EINVAL;
-    }
-    else if (mm->mm == (void *)-1) {
-        return APR_ENOENT;
+    /* we no longer refer to the mmaped region */
+    APR_RING_REMOVE(mm,link);
+    APR_RING_NEXT(mm,link) = NULL;
+    APR_RING_PREV(mm,link) = NULL;
+
+    if (next != mm) {
+        /* more references exist, so we're done */
+        return APR_SUCCESS;
     }
 
 #ifdef BEOS
@@ -163,7 +167,7 @@ APR_DECLARE(apr_status_t) apr_mmap_create(apr_mmap_t **new,
     (*new)->mm = mm;
     (*new)->size = size;
     (*new)->cntxt = cont;
-    (*new)->is_owner = 1;
+    APR_RING_ELEM_INIT(*new, link);
 
     /* register the cleanup... */
     apr_pool_cleanup_register((*new)->cntxt, (void*)(*new), mmap_cleanup,
@@ -179,21 +183,10 @@ APR_DECLARE(apr_status_t) apr_mmap_dup(apr_mmap_t **new_mmap,
     *new_mmap = (apr_mmap_t *)apr_pmemdup(p, old_mmap, sizeof(apr_mmap_t));
     (*new_mmap)->cntxt = p;
 
-    /* The old_mmap can transfer ownership only if the old_mmap itself
-     * is an owner of the mmap'ed segment.
-     */
-    if (old_mmap->is_owner) {
-        if (transfer_ownership) {
-            (*new_mmap)->is_owner = 1;
-            old_mmap->is_owner = 0;
-            apr_pool_cleanup_kill(old_mmap->cntxt, old_mmap, mmap_cleanup);
-            apr_pool_cleanup_register(p, *new_mmap, mmap_cleanup,
-                                      apr_pool_cleanup_null);
-        }
-        else {
-            (*new_mmap)->is_owner = 0;
-        }
-    }
+    APR_RING_INSERT_AFTER(old_mmap, *new_mmap, link);
+
+    apr_pool_cleanup_register(p, *new_mmap, mmap_cleanup,
+                              apr_pool_cleanup_null);
     return APR_SUCCESS;
 }
 
diff --git a/mmap/win32/mmap.c b/mmap/win32/mmap.c
index a113ecfcf..4053ab868 100644
--- a/mmap/win32/mmap.c
+++ b/mmap/win32/mmap.c
@@ -66,13 +66,17 @@
 static apr_status_t mmap_cleanup(void *themmap)
 {
     apr_mmap_t *mm = themmap;
+    apr_mmap_t *next = APR_RING_NEXT(mm,link);
     apr_status_t rv = 0;
 
-    if (!mm->is_owner) {
-        return APR_EINVAL;
-    }
-    else if (!mm->mhandle) {
-        return APR_ENOENT;
+    /* we no longer refer to the mmaped region */
+    APR_RING_REMOVE(mm,link);
+    APR_RING_NEXT(mm,link) = NULL;
+    APR_RING_PREV(mm,link) = NULL;
+
+    if (next != mm) {
+        /* more references exist, so we're done */
+        return APR_SUCCESS;
     }
 
     if (mm->mv) {
@@ -163,7 +167,7 @@ APR_DECLARE(apr_status_t) apr_mmap_create(apr_mmap_t **new, apr_file_t *file,
     (*new)->mm = (char*)((*new)->mv) + (*new)->poffset;
     (*new)->size = size;
     (*new)->cntxt = cont;
-    (*new)->is_owner = 1;
+    APR_RING_ELEM_INIT(*new, link);
 
     /* register the cleanup... */
     apr_pool_cleanup_register((*new)->cntxt, (void*)(*new), mmap_cleanup,
@@ -179,21 +183,10 @@ APR_DECLARE(apr_status_t) apr_mmap_dup(apr_mmap_t **new_mmap,
     *new_mmap = (apr_mmap_t *)apr_pmemdup(p, old_mmap, sizeof(apr_mmap_t));
     (*new_mmap)->cntxt = p;
 
-    /* The old_mmap can transfer ownership only if the old_mmap itself
-     * is an owner of the mmap'ed segment.
-     */
-    if (old_mmap->is_owner) {
-        if (transfer_ownership) {
-            (*new_mmap)->is_owner = 1;
-            old_mmap->is_owner = 0;
-            apr_pool_cleanup_kill(old_mmap->cntxt, old_mmap, mmap_cleanup);
-            apr_pool_cleanup_register(p, *new_mmap, mmap_cleanup,
-                                      apr_pool_cleanup_null);
-        }
-        else {
-            (*new_mmap)->is_owner = 0;
-        }
-    }
+    APR_RING_INSERT_AFTER(old_mmap, *new_mmap, link);
+
+    apr_pool_cleanup_register(p, *new_mmap, mmap_cleanup,
+                              apr_pool_cleanup_null);
     return APR_SUCCESS;
 }