hush: add commented-out debug printouts in "memleak" built-in

Allocation addresses of malloc() are jittery,
thought I had a mem leak in hush, but it was malloc variability.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 17 insertions, 0 deletions

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index f760af2cb..2d01a3ae7 100644
--- a/libbb/appletlib.c
+++ b/libbb/appletlib.c
@@ -942,6 +942,14 @@ int main(int argc UNUSED_PARAM, char **argv)
          */
         mallopt(M_MMAP_THRESHOLD, 32 * 1024 - 256);
 #endif
+#if 0 /*def M_TOP_PAD*/
+        /* When the program break is increased, then M_TOP_PAD bytes are added
+         * to the sbrk(2) request. When the heap is trimmed because of free(3),
+         * this much free space is preserved at the top of the heap.
+         * glibc default seems to be way too big: 128k, but need to verify.
+         */
+        mallopt(M_TOP_PAD, 8 * 1024);
+#endif
 
 #if !BB_MMU
         /* NOMMU re-exec trick sets high-order bit in first byte of name */
diff --git a/shell/hush.c b/shell/hush.c
index 668b1f2b7..9b51f389e 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -9284,6 +9284,15 @@ static int FAST_FUNC builtin_memleak(char **argv UNUSED_PARAM)
         if (l < (unsigned long)p) l = (unsigned long)p;
         free(p);
 
+
+# if 0  /* debug */
+        {
+                struct mallinfo mi = mallinfo();
+                printf("top alloc:0x%lx malloced:%d+%d=%d\n", l,
+                        mi.arena, mi.hblkhd, mi.arena + mi.hblkhd);
+        }
+# endif
+
         if (!G.memleak_value)
                 G.memleak_value = l;