lib/string_helpers: Introduce parse_int_array_user()

Merge series from Cezary Rojewski <cezary.rojewski@intel.com>:

Continuation of recent upstream discussion [1] regarding user string
tokenization.

First, parse_int_array_user() is introduced to allow for splitting
specified user string into a sequence of integers. Makes use of
get_options() internally so the parsing logic is not duplicated.

With that done, redundant parts of the sound driver are removed.

Originally similar functionality was added for the SOF sound driver. As
more users are on the horizon, it is desirable to update existing
string_helpers code and provide a unified solution.

1 files changed, 44 insertions, 0 deletions

diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 5ed3beb066e6..230020a2e076 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -131,6 +131,50 @@ void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
 }
 EXPORT_SYMBOL(string_get_size);
 
+/**
+ * parse_int_array_user - Split string into a sequence of integers
+ * @from:	The user space buffer to read from
+ * @count:	The maximum number of bytes to read
+ * @array:	Returned pointer to sequence of integers
+ *
+ * On success @array is allocated and initialized with a sequence of
+ * integers extracted from the @from plus an additional element that
+ * begins the sequence and specifies the integers count.
+ *
+ * Caller takes responsibility for freeing @array when it is no longer
+ * needed.
+ */
+int parse_int_array_user(const char __user *from, size_t count, int **array)
+{
+	int *ints, nints;
+	char *buf;
+	int ret = 0;
+
+	buf = memdup_user_nul(from, count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	get_options(buf, 0, &nints);
+	if (!nints) {
+		ret = -ENOENT;
+		goto free_buf;
+	}
+
+	ints = kcalloc(nints + 1, sizeof(*ints), GFP_KERNEL);
+	if (!ints) {
+		ret = -ENOMEM;
+		goto free_buf;
+	}
+
+	get_options(buf, nints + 1, ints);
+	*array = ints;
+
+free_buf:
+	kfree(buf);
+	return ret;
+}
+EXPORT_SYMBOL(parse_int_array_user);
+
 static bool unescape_space(char **src, char **dst)
 {
 	char *p = *dst, *q = *src;