From 6563b66a92c770e6eb0db1f75e64f0167d086348 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Tue, 22 Apr 2025 14:16:05 +1000
Subject: [PATCH] utils: add strv_find()

Finds and optionally returns the index of a string in a strv

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1193>
---
 src/util-strings.c | 21 +++++++++++++++++++++
 src/util-strings.h |  2 ++
 test/test-utils.c  | 41 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+)

diff --git a/src/util-strings.c b/src/util-strings.c
index e7e68163..9a6a15e0 100644
--- a/src/util-strings.c
+++ b/src/util-strings.c
@@ -290,6 +290,27 @@ int strv_for_each(const char **strv, strv_foreach_callback_t func, void *data)
 	return strv_for_each_n(strv, SIZE_MAX, func, data);
 }
 
+bool
+strv_find(char **strv, const char *needle, size_t *index_out)
+{
+	if (!strv)
+		return false;
+
+	size_t index = 0;
+	char **s = strv;
+	while (*s != NULL) {
+		if (streq(*s, needle)) {
+			if (index_out)
+				*index_out = index;
+			return true;
+		}
+		s++;
+		index++;
+	}
+
+	return false;
+}
+
 /**
  * Return a pointer to the basename within filename.
  * If the filename the empty string or a directory (i.e. the last char of
diff --git a/src/util-strings.h b/src/util-strings.h
index c245f9d3..b3139289 100644
--- a/src/util-strings.h
+++ b/src/util-strings.h
@@ -315,6 +315,8 @@ char **strv_append_printf(char **strv, const char *fmt, ...);
 __attribute__ ((format (printf, 2, 0)))
 char **strv_append_vprintf(char **strv, const char *fmt, va_list args);
 
+bool strv_find(char **strv, const char *needle, size_t *index_out);
+
 typedef int (*strv_foreach_callback_t)(const char *str, size_t index, void *data);
 int strv_for_each(const char **strv, strv_foreach_callback_t func, void *data);
 int strv_for_each_n(const char **strv, size_t max, strv_foreach_callback_t func, void *data);
diff --git a/test/test-utils.c b/test/test-utils.c
index f5a7bbf8..77e5cdf0 100644
--- a/test/test-utils.c
+++ b/test/test-utils.c
@@ -1279,6 +1279,46 @@ START_TEST(strv_append_test)
 }
 END_TEST
 
+START_TEST(strv_find_test)
+{
+	char *strv[] = {"a", "b", "c", NULL};
+
+	bool rc;
+	size_t index;
+
+	rc = strv_find(strv, "a", &index);
+	litest_assert(rc);
+	litest_assert_int_eq(index, 0U);
+
+	rc = strv_find(strv, "b", &index);
+	litest_assert(rc);
+	litest_assert_int_eq(index, 1U);
+
+	rc = strv_find(strv, "a", NULL);
+	litest_assert(rc);
+
+	index = 0xffff;
+	rc = strv_find(strv, "d", &index);
+	litest_assert(!rc);
+	litest_assert_int_eq(index, 0xffffU);
+
+	rc = strv_find(strv, "d", NULL);
+	litest_assert(!rc);
+
+	rc = strv_find(NULL, "a", &index);
+	litest_assert(!rc);
+	litest_assert_int_eq(index, 0xffffU);
+
+	rc = strv_find(NULL, NULL, &index);
+	litest_assert(!rc);
+	litest_assert_int_eq(index, 0xffffU);
+
+	rc = strv_find(strv, NULL, &index);
+	litest_assert(!rc);
+	litest_assert_int_eq(index, 0xffffU);
+}
+END_TEST
+
 START_TEST(double_array_from_string_test)
 {
 	struct double_array_from_string_test {
@@ -2228,6 +2268,7 @@ int main(void)
 	ADD_TEST(strsplit_test);
 	ADD_TEST(strv_for_each_test);
 	ADD_TEST(strv_append_test);
+	ADD_TEST(strv_find_test);
 	ADD_TEST(double_array_from_string_test);
 	ADD_TEST(strargv_test);
 	ADD_TEST(kvsplit_double_test);