Some requested additional malloc entry points

1 files changed, 31 insertions, 0 deletions

diff --git a/libc/stdlib/malloc-standard/free.c b/libc/stdlib/malloc-standard/free.c
index 4277767fa..ec4debd56 100644
--- a/libc/stdlib/malloc-standard/free.c
+++ b/libc/stdlib/malloc-standard/free.c
@@ -17,6 +17,37 @@
 #include "malloc.h"
 
 
+/* ------------------------- malloc_trim -------------------------
+  malloc_trim(size_t pad);
+
+  If possible, gives memory back to the system (via negative
+  arguments to sbrk) if there is unused memory at the `high' end of
+  the malloc pool. You can call this after freeing large blocks of
+  memory to potentially reduce the system-level memory requirements
+  of a program. However, it cannot guarantee to reduce memory. Under
+  some allocation patterns, some large free blocks of memory will be
+  locked between two used chunks, so they cannot be given back to
+  the system.
+  
+  The `pad' argument to malloc_trim represents the amount of free
+  trailing space to leave untrimmed. If this argument is zero,
+  only the minimum amount of memory to maintain internal data
+  structures will be left (one page or less). Non-zero arguments
+  can be supplied to maintain enough trailing space to service
+  future expected allocations without having to re-obtain memory
+  from the system.
+  
+  Malloc_trim returns 1 if it actually released any memory, else 0.
+  On systems that do not support "negative sbrks", it will always
+  return 0.
+*/
+int malloc_trim(size_t pad)
+{
+  mstate av = get_malloc_state();
+  __malloc_consolidate(av);
+  return __malloc_trim(pad, av);
+}
+
 /* ------------------------- __malloc_trim -------------------------
    __malloc_trim is an inverse of sorts to __malloc_alloc.  It gives memory
    back to the system (via negative arguments to sbrk) if there is unused