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From:   Cezary Rojewski <cezary.rojewski@intel.com>
To:     alsa-devel@alsa-project.org, broonie@kernel.org
Cc:     tiwai@suse.com, perex@perex.cz,
        amadeuszx.slawinski@linux.intel.com,
        pierre-louis.bossart@linux.intel.com, hdegoede@redhat.com,
        lgirdwood@gmail.com, kai.vehmanen@linux.intel.com,
        peter.ujfalusi@linux.intel.com, ranjani.sridharan@linux.intel.com,
        yung-chuan.liao@linux.intel.com, andy@kernel.org,
        linux-kernel@vger.kernel.org, willy@infradead.org,
        Cezary Rojewski <cezary.rojewski@intel.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: [PATCH v3 1/2] lib/string_helpers: Introduce tokenize_user_input()
Date:   Thu,  1 Sep 2022 19:50:21 +0200
Message-Id: <20220901175022.334824-2-cezary.rojewski@intel.com>
In-Reply-To: <20220901175022.334824-1-cezary.rojewski@intel.com>
References: <20220901175022.334824-1-cezary.rojewski@intel.com>
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Add new helper function to allow for splitting specified user string
into a sequence of integers. Internally it makes use of get_options() so
the returned sequence contains the integers extracted plus an additional
element that begins the sequence and specifies the integers count.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
---
 include/linux/string_helpers.h |  2 ++
 lib/string_helpers.c           | 45 ++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 4d72258d42fd..97583dae556f 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -21,6 +21,8 @@ enum string_size_units {
 void string_get_size(u64 size, u64 blk_size, enum string_size_units units,
 		     char *buf, int len);
 
+int tokenize_user_input(const char __user *from, size_t count, int **tkns);
+
 #define UNESCAPE_SPACE		BIT(0)
 #define UNESCAPE_OCTAL		BIT(1)
 #define UNESCAPE_HEX		BIT(2)
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 5ed3beb066e6..f878afccab4c 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -131,6 +131,51 @@ void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,
 }
 EXPORT_SYMBOL(string_get_size);
 
+/**
+ * tokenize_user_input - Split string into a sequence of integers
+ * @from:	The user space buffer to read from
+ * @ppos:	The current position in the buffer
+ * @count:	The maximum number of bytes to read
+ * @tkns:	Returned pointer to sequence of integers
+ *
+ * On success @tkns 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 @tkns when it is no longer
+ * needed.
+ */
+int tokenize_user_input(const char __user *from, size_t count, int **tkns)
+{
+	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);
+	*tkns = ints;
+
+free_buf:
+	kfree(buf);
+	return ret;
+}
+EXPORT_SYMBOL(tokenize_user_input);
+
 static bool unescape_space(char **src, char **dst)
 {
 	char *p = *dst, *q = *src;
-- 
2.25.1