linux-kernel - [PATCH v1 01/19] lib/string_helpers: Introduce kasprintf

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Date:   Fri,  5 Nov 2021 14:42:24 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Jianqun Xu <jay.xu@...k-chips.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Sai Krishna Potthuri <lakshmi.sai.krishna.potthuri@...inx.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org
Cc:     Bamvor Jian Zhang <bamv2005@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Gregory Clement <gregory.clement@...tlin.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        Michal Simek <michal.simek@...inx.com>,
        Andy Shevchenko <andy@...nel.org>
Subject: [PATCH v1 01/19] lib/string_helpers: Introduce kasprintf_strarray()

We have a few users already that basically want to have array of
sequential strings to be allocated and filled.

Provide a helper for them (basically adjusted version from gpio-mockup.c).

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 include/linux/string_helpers.h |  1 +
 lib/string_helpers.c           | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 4ba39e1403b2..f67a94013c87 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -100,6 +100,7 @@ char *kstrdup_quotable(const char *src, gfp_t gfp);
 char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp);
 char *kstrdup_quotable_file(struct file *file, gfp_t gfp);
 
+char **kasprintf_strarray(gfp_t gfp, const char *prefix, size_t n);
 void kfree_strarray(char **array, size_t n);
 
 #endif
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index d5d008f5b1d9..9758997c465e 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -674,6 +674,39 @@ char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
 }
 EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
 
+/**
+ * kasprintf_strarray - allocate and fill array of sequential strings
+ * @gfp: flags for the slab allocator
+ * @prefix: prefix to be used
+ * @n: amount of lines to be allocated and filled
+ *
+ * Allocates and fills @n strings using pattern "%s-%zu", where prefix
+ * is provided by caller. The caller is responsible to free them with
+ * kfree_strarray() after use.
+ *
+ * Returns array of strings or NULL when memory can't be allocated.
+ */
+char **kasprintf_strarray(gfp_t gfp, const char *prefix, size_t n)
+{
+	char **names;
+	size_t i;
+
+	names = kcalloc(n + 1, sizeof(char *), gfp);
+	if (!names)
+		return NULL;
+
+	for (i = 0; i < n; i++) {
+		names[i] = kasprintf(gfp, "%s-%zu", prefix, i);
+		if (!names[i]) {
+			kfree_strarray(names, i);
+			return NULL;
+		}
+	}
+
+	return names;
+}
+EXPORT_SYMBOL_GPL(kasprintf_strarray);
+
 /**
  * kfree_strarray - free a number of dynamically allocated strings contained
  *                  in an array and the array itself
-- 
2.33.0