1 files changed, 104 insertions, 0 deletions
diff --git a/lib/libc/sys/brk.c b/lib/libc/sys/brk.c
new file mode 100644
index 000000000000..b3e6abdac981
--- /dev/null
+++ b/lib/libc/sys/brk.c
@@ -0,0 +1,104 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2018 Mark Johnston <markj@FreeBSD.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/syscall.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+void *__sys_break(char *nsize);
+
+static uintptr_t curbrk, minbrk;
+static int curbrk_initted;
+
+static int
+initbrk(void)
+{
+	void *newbrk;
+
+	if (!curbrk_initted) {
+		newbrk = __sys_break(NULL);
+		if (newbrk == (void *)-1)
+			return (-1);
+		curbrk = minbrk = (uintptr_t)newbrk;
+		curbrk_initted = 1;
+	}
+	return (0);
+}
+
+static void *
+mvbrk(void *addr)
+{
+	uintptr_t oldbrk;
+
+	if ((uintptr_t)addr < minbrk) {
+		/* Emulate legacy error handling in the syscall. */
+		errno = EINVAL;
+		return ((void *)-1);
+	}
+	if (__sys_break(addr) == (void *)-1)
+		return ((void *)-1);
+	oldbrk = curbrk;
+	curbrk = (uintptr_t)addr;
+	return ((void *)oldbrk);
+}
+
+int
+brk(const void *addr)
+{
+
+	if (initbrk() == -1)
+		return (-1);
+	if ((uintptr_t)addr < minbrk)
+		addr = (void *)minbrk;
+	return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
+}
+
+int
+_brk(const void *addr)
+{
+
+	if (initbrk() == -1)
+		return (-1);
+	return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0);
+}
+
+void *
+sbrk(intptr_t incr)
+{
+
+	if (initbrk() == -1)
+		return ((void *)-1);
+	if ((incr > 0 && curbrk + incr < curbrk) ||
+	    (incr < 0 && curbrk + incr > curbrk)) {
+		/* Emulate legacy error handling in the syscall. */
+		errno = EINVAL;
+		return ((void *)-1);
+	}
+	return (mvbrk((void *)(curbrk + incr)));
+}