cifs: cleanup misc.c

misc.c was getting a little large, move two of the UNC parsing relating
functions to a new C file unc.c which makes the coding of the
upcoming witness protocol patch series a little cleaner as well.

Suggested-by: Rafal Szczesniak <rafal@elbingbrewery.org>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 67 insertions, 0 deletions

diff --git a/fs/cifs/unc.c b/fs/cifs/unc.c
new file mode 100644
index 000000000000..2c5665f5543a
--- /dev/null
+++ b/fs/cifs/unc.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *   Copyright (C) 2020, Microsoft Corporation.
+ *
+ *   Author(s): Steve French <stfrench@microsoft.com>
+ *              Suresh Jayaraman <sjayaraman@suse.de>
+ *              Jeff Layton <jlayton@kernel.org>
+ */
+
+#include <linux/slab.h>
+#include "cifsproto.h"
+
+/* extract the host portion of the UNC string */
+char *extract_hostname(const char *unc)
+{
+	const char *src;
+	char *dst, *delim;
+	unsigned int len;
+
+	/* skip double chars at beginning of string */
+	/* BB: check validity of these bytes? */
+	if (strlen(unc) < 3)
+		return ERR_PTR(-EINVAL);
+	for (src = unc; *src && *src == '\\'; src++)
+		;
+	if (!*src)
+		return ERR_PTR(-EINVAL);
+
+	/* delimiter between hostname and sharename is always '\\' now */
+	delim = strchr(src, '\\');
+	if (!delim)
+		return ERR_PTR(-EINVAL);
+
+	len = delim - src;
+	dst = kmalloc((len + 1), GFP_KERNEL);
+	if (dst == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(dst, src, len);
+	dst[len] = '\0';
+
+	return dst;
+}
+
+char *extract_sharename(const char *unc)
+{
+	const char *src;
+	char *delim, *dst;
+	int len;
+
+	/* skip double chars at the beginning */
+	src = unc + 2;
+
+	/* share name is always preceded by '\\' now */
+	delim = strchr(src, '\\');
+	if (!delim)
+		return ERR_PTR(-EINVAL);
+	delim++;
+	len = strlen(delim);
+
+	/* caller has to free the memory */
+	dst = kstrndup(delim, len, GFP_KERNEL);
+	if (!dst)
+		return ERR_PTR(-ENOMEM);
+
+	return dst;
+}