[PATCH 1/3] cifs: introduce smb3_options_for_each() helper

[Paulo Alcantara <pc@cjr.nz>]

Introduce a new helper to walk through the mount options and avoid
duplicating it all over the cifs code.

Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
---
 fs/cifs/cifsglob.h | 16 ++++++++++++++++
 fs/cifs/misc.c     | 48 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index ea90c53386b8..6c65e39f0509 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1960,4 +1960,20 @@ static inline bool is_tcon_dfs(struct cifs_tcon *tcon)
 		tcon->share_flags & (SHI1005_FLAGS_DFS | SHI1005_FLAGS_DFS_ROOT);
 }
 
+char *smb3_parse_option(char *options, char sep, char **nkey, char **nval);
+
+static inline char *smb3_parse_options_sep(char *options, char *sep, char **nkey, char **nval)
+{
+	*sep = ',';
+	if (!strncmp(options, "sep=", 4)) {
+		*sep = options[4];
+		options += 5;
+	}
+	return smb3_parse_option(options, *sep, nkey, nval);
+}
+
+#define smb3_options_for_each(opts, nopts, sep, key, val) \
+	for (nopts = (opts), nopts = smb3_parse_options_sep(nopts, &sep, &(key), &(val)); \
+	     (key); nopts = smb3_parse_option(nopts, sep, &(key), &(val)))
+
 #endif	/* _CIFS_GLOB_H */
diff --git a/fs/cifs/misc.c b/fs/cifs/misc.c
index cd705f8a4e31..7b3b1ea76baf 100644
--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -1284,3 +1284,51 @@ int update_super_prepath(struct cifs_tcon *tcon, char *prefix)
 	cifs_put_tcon_super(sb);
 	return rc;
 }
+
+/**
+ * Parse a string that is in key[=val][,key[=val]]* form.
+ *
+ * @options: The options to parse
+ * @sep: The options separator
+ * @nkey: The next key pointer
+ * @nval: The next value pointer
+ *
+ * Returns next key-value pair to be parsed, otherwise NULL.
+ */
+char *smb3_parse_option(char *options, char sep, char **nkey, char **nval)
+{
+	char *key, *value;
+	char sepstr[2] = {sep, '\0'};
+
+	*nkey = NULL;
+	*nval = NULL;
+
+	if (!options || !options[0])
+		return NULL;
+
+	while ((key = strsep(&options, sepstr)) != NULL) {
+		size_t len;
+
+		if (*key == 0)
+			return NULL;
+
+		while (options && options[0] == sep) {
+			len = strlen(key);
+			strcpy(key + len, options);
+			options = strchr(options, sep);
+			if (options)
+				*options++ = 0;
+		}
+
+		value = strchr(key, '=');
+		if (value) {
+			if (value == key)
+				continue;
+			*value++ = 0;
+		}
+		break;
+	}
+	*nkey = key;
+	*nval = value;
+	return options;
+}
-- 
2.31.1