rules: Resolve relative include statements using XKB paths

Contrary to keymap files, the `! include` statement in rules does not
lookup include paths added to `xkb_context`. So it is not possible e.g.
to import another file in the same folder without using an absolute path.

- Added path utils: `is_absolute(path)`.
- Added XKB paths lookup to enable e.g. `! include evdev` to work.
- Added test.

changes/api/501.rules-includes.feature.md

@@ -0,0 +1 @@
+rules: Use XKB paths to resolve relative paths in include statements.

meson.build

@@ -255,9 +255,11 @@ libxkbcommon_sources = [
     'src/text.h',
     'src/utf8.c',
     'src/utf8.h',
-    'src/util-mem.h',
     'src/utils.c',
     'src/utils.h',
+    'src/util-mem.h',
+    'src/utils-paths.c',
+    'src/utils-paths.h',
 ]
 libxkbcommon_link_args = []
 libxkbcommon_link_deps = []

src/utils-paths.c

@@ -0,0 +1,50 @@
+/*
+ * Copyright © 2024 Pierre Le Marre
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "config.h"
+
+#include "utils.h"
+#include "utils-paths.h"
+
+
+bool
+is_absolute(const char *path)
+{
+    const size_t len = strlen_safe(path);
+#ifdef _WIN32
+    /*
+     * A file name is relative to the current directory if it does not begin with
+     * one of the following:
+     * - A UNC name of any format, which always start with two backslash characters ("\\").
+     * - A disk designator with a backslash, for example "C:\" or "d:\".
+     * - A single backslash, for example, "\directory" or "\file.txt".
+     * See: https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file
+     */
+    return len >= 1 &&
+           ((path[0] == PATH_SEPARATOR || path[0] == ALT_PATH_SEPARATOR) ||
+            (len >= 3 && path[1] == ':' &&
+             (path[2] == PATH_SEPARATOR || path[2] == ALT_PATH_SEPARATOR)));
+#else
+    return len >= 1 && path[0] == PATH_SEPARATOR;
+#endif
+}

src/utils-paths.h

@@ -0,0 +1,16 @@
+#ifndef UTILS_PATHS_H
+#define UTILS_PATHS_H
+
+#include <stdbool.h>
+
+#ifdef _WIN32
+#define PATH_SEPARATOR '\\'
+#define ALT_PATH_SEPARATOR '/'
+#else
+#define PATH_SEPARATOR '/'
+#endif
+
+bool
+is_absolute(const char *path);
+
+#endif

src/xkbcomp/rules.c

@@ -53,6 +53,7 @@
 #include "rules.h"
 #include "include.h"
 #include "scanner-utils.h"
+#include "utils-paths.h"
 
 #define MAX_INCLUDE_DEPTH 5
 
@@ -369,7 +370,6 @@ matcher_include(struct matcher *m, struct scanner *parent_scanner,
                 struct sval inc)
 {
     struct scanner s; /* parses the !include value */
-    FILE *file;
 
     scanner_init(&s, m->ctx, inc.start, inc.len,
                  parent_scanner->file_name, NULL);
@@ -383,6 +383,7 @@ matcher_include(struct matcher *m, struct scanner *parent_scanner,
         return;
     }
 
+    /* Proceed to %-expansion */
     while (!scanner_eof(&s) && !scanner_eol(&s)) {
         if (scanner_chr(&s, '%')) {
             if (scanner_chr(&s, '%')) {
@@ -427,19 +428,34 @@ matcher_include(struct matcher *m, struct scanner *parent_scanner,
         return;
     }
 
-    file = fopen(s.buf, "rb");
-    if (file) {
+    /* Lookup rules file in XKB paths only if the include path is relative */
+    unsigned int offset = 0;
+    FILE *file;
+    bool absolute_path = is_absolute(s.buf);
+    if (absolute_path)
+        file = fopen(s.buf, "rb");
+    else
+        file = FindFileInXkbPath(m->ctx, s.buf, FILE_TYPE_RULES, NULL, &offset);
+
+    while (file) {
         bool ret = read_rules_file(m->ctx, m, include_depth + 1, file, s.buf);
-        if (!ret)
-            log_err(m->ctx, XKB_LOG_MESSAGE_NO_ID,
-                    "No components returned from included XKB rules \"%s\"\n",
-                    s.buf);
         fclose(file);
-    } else {
+        if (ret)
+            return;
+        /* Failed to parse rules or get all the components */
         log_err(m->ctx, XKB_LOG_MESSAGE_NO_ID,
-                "Failed to open included XKB rules \"%s\"\n",
+                "No components returned from included XKB rules \"%s\"\n",
                 s.buf);
+        if (absolute_path)
+            break;
+        /* Try next XKB path */
+        offset++;
+        file = FindFileInXkbPath(m->ctx, s.buf, FILE_TYPE_RULES, NULL, &offset);
     }
+
+    log_err(m->ctx, XKB_LOG_MESSAGE_NO_ID,
+            "Failed to open included XKB rules \"%s\"\n",
+            s.buf);
 }
 
 static void

test/data/rules/inc-src-relative-path

@@ -0,0 +1,4 @@
+! layout        = symbols
+  my_layout     = my_symbols
+
+! include inc-dst-simple

test/rules-file-includes.c

@@ -167,6 +167,16 @@ main(int argc, char *argv[])
     };
     assert(test_rules(ctx, &test7));
 
+    struct test_data test8 = {
+        .rules = "inc-src-relative-path",
+
+        .model = "my_model", .layout = "my_layout", .variant = "", .options = "",
+
+        .keycodes = "my_keycodes", .types = "default_types",
+        .compat = "default_compat", .symbols = "my_symbols",
+    };
+    assert(test_rules(ctx, &test8));
+
     xkb_context_unref(ctx);
     return 0;
 }

test/utils.c

@@ -30,14 +30,13 @@
 
 #include "test.h"
 #include "utils.h"
+#include "utils-paths.h"
 
-int
-main(void)
+static void
+test_string_functions(void)
 {
     char buffer[10];
 
-    test_init();
-
     assert(!snprintf_safe(buffer, 0, "foo"));
     assert(!snprintf_safe(buffer, 1, "foo"));
     assert(!snprintf_safe(buffer, 3, "foo"));
@@ -53,6 +52,37 @@ main(void)
     assert(!streq_null("foobar", NULL));
     assert(!streq_null(NULL, "foobar"));
     assert(streq_null(NULL, NULL));
+}
+
+static void
+test_path_functions(void)
+{
+    /* Absolute paths */
+#ifdef _WIN32
+    assert(!is_absolute("path\\test"));
+    assert(is_absolute("c:\\test"));
+    assert(!is_absolute("c:test"));
+    assert(is_absolute("c:\\"));
+    assert(is_absolute("c:/"));
+    assert(!is_absolute("c:"));
+    assert(is_absolute("\\\\foo"));
+    assert(is_absolute("\\\\?\\foo"));
+    assert(is_absolute("\\\\?\\UNC\\foo"));
+    assert(is_absolute("/foo"));
+    assert(is_absolute("\\foo"));
+#else
+    assert(!is_absolute("test/path"));
+    assert(is_absolute("/test" ));
+    assert(is_absolute("/" ));
+#endif
+}
+
+int
+main(void)
+{
+    test_init();
+    test_string_functions();
+    test_path_functions();
 
     return 0;
 }