Add our own version of qsort, because the one from ORCA/C is recursive and can use thousands of KB of stack space.

The new version is a heap sort implementation adapted from musl libc.

Makefile

@@ -53,7 +53,8 @@ LIBBB_C_SRC = \
 	libbb/safe.poll.c \
 	libbb/parse.mode.c \
 	libbb/poll.c \
-	libbb/pgrp.c
+	libbb/pgrp.c \
+	libbb/qsort.c
 
 LIBBB_D_SRC = \
 	libbb/xfuncs.printf.c \

Makefile.gmake

@@ -52,7 +52,8 @@ SRCS = \
 	libbb/vfork.and.run.c \
 	libbb/poll.c \
 	libbb/get.exec.path.c \
-	libbb/pgrp.c
+	libbb/pgrp.c \
+	libbb/qsort.c
 OBJS = $(SRCS:.c=.o)
 
 INCLUDES = -I include -I shell -I libbb

libbb/qsort.c

@@ -0,0 +1,57 @@
+/* We use our own version of qsort because ORCA/C's version is recursive and
+ * can take up quite a bit of stack space (at least several thousand KB).
+ * 
+ * This implementation is adapted from (an old version of) musl libc.
+ * 
+ * Copyright (c) 2005-2011 Rich Felker
+ * Originally licensed under the GNU LGPL version 2.1 or later.
+ * Licensed under GPLv2 (pursuant to clause 3 of the LGPL version 2.1), 
+ * see file LICENSE in this source tree.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+/* A simple heap sort implementation.. only in-place O(nlogn) sort I know. */
+
+#define MIN(a, b) ((a)<(b) ? (a) : (b))
+
+static void swap(char *a, char *b, size_t len)
+{
+	char tmp;
+	char *a_end = a + len;
+	while (a != a_end) {
+		tmp = *a;
+		*a++ = *b;
+		*b++ = tmp;
+	}
+}
+
+static void sift(char *base, size_t root, size_t nel, size_t width, int (*cmp)(const void *, const void *))
+{
+	size_t max;
+
+	while (2*root <= nel) {
+		max = 2*root;
+		if (max < nel && cmp(base+max*width, base+(max+1)*width) < 0)
+			max++;
+		if (max && cmp(base+root*width, base+max*width) < 0) {
+			swap(base+root*width, base+max*width, width);
+			root = max;
+		} else break;
+	}
+}
+
+void qsort(void *_base, size_t nel, size_t width, int (*cmp)(const void *, const void *))
+{
+	char *base = _base;
+	size_t i;
+
+	if (!nel) return;
+	for (i=(nel+1)/2; i; i--)
+		sift(base, i-1, nel-1, width, cmp);
+	for (i=nel-1; i; i--) {
+		swap(base, base+i*width, width);
+		sift(base, 0, i-1, width, cmp);
+	}
+}