kerneldevice,generic: input pattern to string match is not regex

The input pattern given to the string_match() method is not a regex
pattern and we cannot use it as that, because all the special
characters (e.g. '.') would not be treated correctly.

Also, the prefix matching with the wildcard at the end of the string
needs to be converted to a proper regex wildcard, i.e. '.*'.

This logic also adds support for suffix matching, with a wildcard at
the beginning of the string, e.g. as the ones used for the wwan kernel
device name matching rules (i.e. '*MBIM').

Unit tests are added to cover all cases, most of these tests were
failing without the fixes implemented here.

src/tests/Makefile.am

@@ -58,6 +58,7 @@ noinst_PROGRAMS = \
 	test-sms-part-cdma \
 	test-udev-rules \
 	test-error-helpers \
+	test-kernel-device-helpers \
 	$(NULL)
 
 if WITH_QMI

src/tests/meson.build

@@ -5,6 +5,7 @@ test_units = {
   'at-serial-port': libport_dep,
   'charsets': libhelpers_dep,
   'error-helpers': libhelpers_dep,
+  'kernel-device-helpers': libkerneldevice_dep,
   'modem-helpers': libhelpers_dep,
   'sms-part-3gpp': libhelpers_dep,
   'sms-part-cdma': libhelpers_dep,

src/tests/test-kernel-device-helpers.c

@@ -0,0 +1,118 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details:
+ *
+ * Copyright (C) 2021 Aleksander Morgado <aleksander@aleksander.es>
+ */
+
+#include <glib.h>
+#include <glib-object.h>
+#include <string.h>
+#include <stdlib.h>
+#include <locale.h>
+
+#define _LIBMM_INSIDE_MM
+#include <libmm-glib.h>
+
+#include "mm-kernel-device-helpers.h"
+#include "mm-log-test.h"
+
+/*****************************************************************************/
+
+typedef struct {
+    const gchar *pattern;
+    const gchar *str;
+    gboolean     match;
+} StringMatchTest;
+
+static const StringMatchTest string_match_tests[] = {
+    {
+        .pattern = "/sys/devices/pci0000:00/0000:00:1f.6/net/eno1",
+        .str     = "/sys/devices/pci0000:00/0000:00:1f.6/net/eno1",
+        .match   = TRUE,
+    },
+    {
+        .pattern = "/sys/devices/pci0000:00/0000:00:1f.6/net/*",
+        .str     = "/sys/devices/pci0000:00/0000:00:1f.6/net/eno1",
+        .match   = TRUE,
+    },
+    {
+        .pattern = "*MBIM",
+        .str     = "wwan0p1MBIM",
+        .match   = TRUE,
+    },
+    /* Don't match leading extra characters */
+    {
+        .pattern = "/sys/devices/pci0000:00/0000:00:1f.6/net",
+        .str     = "aaaaa/sys/devices/pci0000:00/0000:00:1f.6/net",
+        .match   = FALSE,
+    },
+    /* Don't match trailing extra characters */
+    {
+        .pattern = "/sys/devices/pci0000:00/0000:00:1f.6/net",
+        .str     = "/sys/devices/pci0000:00/0000:00:1f.6/netaaa",
+        .match   = FALSE,
+    },
+    /* The ASTERISK in a pattern given must be treated as a wildcard by
+     * itself, not as "the previous character 0-N times", as the input
+     * pattern is not a regex pattern. */
+    {
+        .pattern = "/sys/devices/pci0000:00/0000:00:1f.6/net/*",
+        .str     = "/sys/devices/pci0000:00/0000:00:1ff6/net",
+        .match   = FALSE,
+    },
+    {
+        .pattern = "/sys/devices/pci0000:00/0000:00:1f.6/net/*",
+        .str     = "/sys/devices/pci0000:00/0000:00:1f.6/netaaa",
+        .match   = FALSE,
+    },
+    /* The DOT in a pattern given must match the exact DOT character,
+     * as the input pattern is not a regex pattern. */
+    {
+        .pattern = "/sys/devices/pci0000:00/0000:00:1f.6/net/eno1",
+        .str     = "/sys/devices/pci0000:00/0000:00:1ff6/net/eno1",
+        .match   = FALSE,
+    },
+};
+
+static void
+test_string_match (void)
+{
+    guint i;
+
+    for (i = 0; i < G_N_ELEMENTS (string_match_tests); i++) {
+        gboolean match;
+
+        match = mm_kernel_device_generic_string_match (string_match_tests[i].str,
+                                                       string_match_tests[i].pattern,
+                                                       NULL);
+        if (match != string_match_tests[i].match)
+            mm_obj_warn (NULL, "string match failure: pattern '%s' should%s match str '%s'",
+                         string_match_tests[i].pattern,
+                         string_match_tests[i].match ? "" : " NOT",
+                         string_match_tests[i].str);
+
+        g_assert_cmpuint (match, ==, string_match_tests[i].match);
+    }
+}
+
+/*****************************************************************************/
+
+int main (int argc, char **argv)
+{
+    setlocale (LC_ALL, "");
+
+    g_test_init (&argc, &argv, NULL);
+
+    g_test_add_func ("/MM/kernel-device-helpers/string-match", test_string_match);
+
+    return g_test_run ();
+}