[git commit] hush: add commented-out debug printouts in "memleak" built-in

[Denys Vlasenko]

commit: https://git.busybox.net/busybox/commit/?id=7f0ebbc69ed14b2f35e8bc62b03612b94e270955
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

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 at googlemail.com>
---
 libbb/appletlib.c | 8 ++++++++
 shell/hush.c      | 9 +++++++++
 2 files changed, 17 insertions(+)

diff --git a/libbb/appletlib.c b/libbb/appletlib.c
index f760af2..2d01a3a 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 668b1f2..9b51f38 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;