util: add some extra strv helpers

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1178>

src/util-strings.c

@@ -62,6 +62,63 @@ next_word(const char **state, size_t *len, const char *separators)
 	return next;
 }
 
+size_t
+strv_len(char **strv)
+{
+	if (!strv)
+		return 0;
+
+	size_t size = 1;
+	while (*strv) {
+		size++;
+		strv++;
+	}
+	return size;
+}
+
+char **
+strv_append_vprintf(char **strv, const char *fmt, va_list args)
+{
+	char *dup = strdup_vprintf(fmt, args);
+	char **s = strv_append_take(strv, &dup);
+	return s;
+}
+
+char **
+strv_append_printf(char **strv, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	char **s = strv_append_vprintf(strv, fmt, args);
+	va_end(args);
+	return s;
+}
+
+char **
+strv_append_strdup(char **strv, const char *str)
+{
+	char *dup = safe_strdup(str);
+	return strv_append_take(strv, &dup);
+}
+
+char **
+strv_append_take(char **strv, char **str)
+{
+	if (str && *str) {
+		size_t len = max(strv_len(strv) + 1, 2);
+
+		char **s = realloc(strv, len * sizeof(*strv));
+		if (!s)
+			abort();
+		s[len - 1] = NULL;
+		s[len - 2] = *str;
+		*str = NULL;
+		return s;
+	} else {
+		return strv;
+	}
+}
+
 /**
  * Return a null-terminated string array with the contents of argv
  * duplicated.

src/util-strings.h

@@ -301,9 +301,18 @@ safe_atod(const char *str, double *val)
 	return true;
 }
 
+/* Returns the length of the strv, including the terminating NULL */
+size_t strv_len(char **strv);
 char **strv_from_argv(int argc, char **argv);
 char **strv_from_string(const char *in, const char *separator, size_t *num_elements);
 char *strv_join(char **strv, const char *joiner);
+char **strv_append_strdup(char **strv, const char *s);
+/* Takes ownership of the string and appends it to strv, s is set to NULL */
+char **strv_append_take(char **strv, char **s);
+__attribute__ ((format (printf, 2, 3)))
+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);
 
 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);

test/test-utils.c

@@ -1207,6 +1207,77 @@ START_TEST(strv_for_each_test)
 }
 END_TEST
 
+__attribute__ ((format (printf, 1, 0)))
+static char **
+test_strv_appendv(char *format, ...)
+{
+	va_list args;
+	va_start(args, format);
+	char **strv = NULL;
+	strv = strv_append_vprintf(strv, "%s %d", args);
+	va_end(args);
+	return strv;
+}
+
+START_TEST(strv_append_test)
+{
+	{
+		char *test_strv1[] = {"a", "b", "c", NULL};
+		char **test_strv2 = NULL;
+
+		litest_assert_int_eq(strv_len(test_strv1), 4U);
+		litest_assert_int_eq(strv_len(test_strv2), 0U);
+	}
+	{
+		char **strv = NULL;
+		char *dup = safe_strdup("test");
+		strv = strv_append_take(strv, &dup);
+		litest_assert_ptr_null(dup);
+		litest_assert_ptr_notnull(strv);
+		litest_assert_str_eq(strv[0], "test");
+		litest_assert_ptr_eq(strv[1], NULL);
+		litest_assert_int_eq(strv_len(strv), 2U);
+
+		char *dup2 = safe_strdup("test2");
+		strv = strv_append_take(strv, &dup2);
+		litest_assert_ptr_null(dup2);
+		litest_assert_str_eq(strv[1], "test2");
+		litest_assert_ptr_eq(strv[2], NULL);
+		litest_assert_int_eq(strv_len(strv), 3U);
+
+		strv = strv_append_take(strv, NULL);
+		litest_assert_int_eq(strv_len(strv), 3U);
+		strv_free(strv);
+	}
+	{
+		char **strv = NULL;
+		strv = strv_append_strdup(strv, "banana");
+		litest_assert(strv != NULL);
+		litest_assert_str_eq(strv[0], "banana");
+		litest_assert_ptr_null(strv[1]);
+		litest_assert_int_eq(strv_len(strv), 2U);
+		strv_free(strv);
+	}
+	{
+		char **strv = test_strv_appendv("%s %d", "apple", 2);
+		litest_assert_ptr_notnull(strv);
+		litest_assert_str_eq(strv[0], "apple 2");
+		litest_assert_ptr_null(strv[1]);
+		litest_assert_int_eq(strv_len(strv), 2U);
+		strv_free(strv);
+	}
+	{
+		char **strv = NULL;
+		strv = strv_append_printf(strv, "coco%s", "nut");
+		litest_assert_ptr_notnull(strv);
+		litest_assert_str_eq(strv[0], "coconut");
+		litest_assert_ptr_null(strv[1]);
+		litest_assert_int_eq(strv_len(strv), 2U);
+		strv_free(strv);
+	}
+}
+END_TEST
+
 START_TEST(double_array_from_string_test)
 {
 	struct double_array_from_string_test {
@@ -2092,6 +2163,7 @@ int main(void)
 	ADD_TEST(safe_atod_test);
 	ADD_TEST(strsplit_test);
 	ADD_TEST(strv_for_each_test);
+	ADD_TEST(strv_append_test);
 	ADD_TEST(double_array_from_string_test);
 	ADD_TEST(strargv_test);
 	ADD_TEST(kvsplit_double_test);