From 508f51f5f41e1e7af50f5f215688ad77daec0f1a Mon Sep 17 00:00:00 2001
From: Eli Zaretskii <eliz@gnu.org>
Date: Mon, 5 Nov 2012 19:23:25 +0200
Subject: [PATCH] Fix bug #12774 with crashes in ralloc.c.
src/ralloc.c (relinquish): If real_morecore fails to return memory
to the system, don't crash; instead, leave the last heap
unchanged and return.
---
src/ChangeLog | 6 ++++++
src/ralloc.c | 34 +++++++++++++++++-----------------
2 files changed, 23 insertions(+), 17 deletions(-)
diff --git a/src/ChangeLog b/src/ChangeLog
index 3ae755f3d20..c49039a3cf9 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2012-11-05 Eli Zaretskii <eliz@gnu.org>
+
+ * ralloc.c (relinquish): If real_morecore fails to return memory
+ to the system, don't crash; instead, leave the last heap
+ unchanged and return. (Bug#12774)
+
2012-11-03 Eli Zaretskii <eliz@gnu.org>
* lisp.mk: Adjust comments to the fact that term/internal is now
diff --git a/src/ralloc.c b/src/ralloc.c
index 11897411930..e5bf76b0e6d 100644
--- a/src/ralloc.c
+++ b/src/ralloc.c
@@ -327,6 +327,8 @@ relinquish (void)
if ((char *)last_heap->end - (char *)last_heap->bloc_start <= excess)
{
+ heap_ptr lh_prev;
+
/* This heap should have no blocs in it. If it does, we
cannot return it to the system. */
if (last_heap->first_bloc != NIL_BLOC
@@ -335,28 +337,26 @@ relinquish (void)
/* Return the last heap, with its header, to the system. */
excess = (char *)last_heap->end - (char *)last_heap->start;
- last_heap = last_heap->prev;
- last_heap->next = NIL_HEAP;
+ lh_prev = last_heap->prev;
+ /* If the system doesn't want that much memory back, leave
+ last_heap unaltered to reflect that. This can occur if
+ break_value is still within the original data segment. */
+ if ((*real_morecore) (- excess) != 0)
+ {
+ last_heap = lh_prev;
+ last_heap->next = NIL_HEAP;
+ }
}
else
{
excess = (char *) last_heap->end
- (char *) ROUNDUP ((char *)last_heap->end - excess);
- last_heap->end = (char *) last_heap->end - excess;
- }
-
- if ((*real_morecore) (- excess) == 0)
- {
- /* If the system didn't want that much memory back, adjust
- the end of the last heap to reflect that. This can occur
- if break_value is still within the original data segment. */
- last_heap->end = (char *) last_heap->end + excess;
- /* Make sure that the result of the adjustment is accurate.
- It should be, for the else clause above; the other case,
- which returns the entire last heap to the system, seems
- unlikely to trigger this mode of failure. */
- if (last_heap->end != (*real_morecore) (0))
- emacs_abort ();
+ /* If the system doesn't want that much memory back, leave
+ the end of the last heap unchanged to reflect that. This
+ can occur if break_value is still within the original
+ data segment. */
+ if ((*real_morecore) (- excess) != 0)
+ last_heap->end = (char *) last_heap->end - excess;
}
}
}
--
2.39.5