Add a new method to export the extent of the break, akin to return
value of sbrk(0) in UNIX. In terms of dlmalloc and our proprietary
contiguous mspace class, this is the highest address returned by its
morecore method.
diff --git a/include/cutils/mspace.h b/include/cutils/mspace.h
index e6e4047..93fe48e 100644
--- a/include/cutils/mspace.h
+++ b/include/cutils/mspace.h
@@ -87,6 +87,11 @@
size_t max_capacity, int locked, void *base);
size_t destroy_contiguous_mspace(mspace msp);
+
+/*
+ Returns the position of the "break" within the given mspace.
+*/
+void *contiguous_mspace_sbrk0(mspace msp);
#endif
/*
diff --git a/libcutils/mspace.c b/libcutils/mspace.c
index 63b199d..6d3b35c 100644
--- a/libcutils/mspace.c
+++ b/libcutils/mspace.c
@@ -271,4 +271,16 @@
}
return 0;
}
+
+void *contiguous_mspace_sbrk0(mspace msp) {
+ struct mspace_contig_state *cs;
+ mstate ms;
+ const unsigned int pagesize = PAGESIZE;
+
+ ms = (mstate)msp;
+ cs = (struct mspace_contig_state *)((uintptr_t)ms & ~(pagesize-1));
+ assert(cs->magic == CONTIG_STATE_MAGIC);
+ assert(cs->m == ms);
+ return cs->brk;
+}
#endif