xkbcomp: handle empty keymaps

We should handle empty xkb_keycode and xkb_symbol sections, since
xkbcomp handles them, and apparently XQuartz uses it. There are also
files for it in xkeyboard-config (rules=base model=empty layout=empty,
which translate to keycodes/empty and symbols/empty).

https://bugs.freedesktop.org/show_bug.cgi?id=67654

Reported-By: Gatis Paeglis <gatis.paeglis@digia.com>
Signed-off-by: Ran Benita <ran234@gmail.com>

6 files changed, 36 insertions, 10 deletions

diff --git a/src/xkbcomp/keycodes.c b/src/xkbcomp/keycodes.c
index 44e11bc..59916b7 100644
--- a/src/xkbcomp/keycodes.c
+++ b/src/xkbcomp/keycodes.c
@@ -231,7 +231,10 @@ InitKeyNamesInfo(KeyNamesInfo *info, struct xkb_context *ctx)
 {
     memset(info, 0, sizeof(*info));
     info->ctx = ctx;
-    info->min_key_code = XKB_KEYCODE_MAX;
+    info->min_key_code = XKB_KEYCODE_INVALID;
+#if XKB_KEYCODE_INVALID < XKB_KEYCODE_MAX
+#error "Hey, you can't be changing stuff like that."
+#endif
 }
 
 static xkb_keycode_t
@@ -606,15 +609,26 @@ CopyKeyNamesToKeymap(struct xkb_keymap *keymap, KeyNamesInfo *info)
     keymap->keycodes_section_name = strdup_safe(info->name);
     XkbEscapeMapName(keymap->keycodes_section_name);
 
-    keymap->min_key_code = info->min_key_code;
-    keymap->max_key_code = info->max_key_code;
+    if (info->min_key_code != XKB_KEYCODE_INVALID) {
+        keymap->min_key_code = info->min_key_code;
+        keymap->max_key_code = info->max_key_code;
+    }
+    else {
+        /*
+         * If the keymap has no keys, let's just use the safest pair
+         * we know.
+         */
+        keymap->min_key_code = 8;
+        keymap->max_key_code = 255;
+    }
 
-    /* Copy key names. */
-    keymap->keys = calloc(info->max_key_code + 1, sizeof(*keymap->keys));
-    for (kc = info->min_key_code; kc <= info->max_key_code; kc++) {
+    keymap->keys = calloc(keymap->max_key_code + 1, sizeof(*keymap->keys));
+    for (kc = keymap->min_key_code; kc <= keymap->max_key_code; kc++)
         keymap->keys[kc].keycode = kc;
+
+    /* Copy key names. */
+    for (kc = info->min_key_code; kc <= info->max_key_code; kc++)
         keymap->keys[kc].name = darray_item(info->key_names, kc);
-    }
 
     /*
      * Do some sanity checking on the aliases. We can't do it before
diff --git a/src/xkbcomp/symbols.c b/src/xkbcomp/symbols.c
index 5cf68d9..6033264 100644
--- a/src/xkbcomp/symbols.c
+++ b/src/xkbcomp/symbols.c
@@ -1619,9 +1619,6 @@ CompileSymbols(XkbFile *file, struct xkb_keymap *keymap,
 
     HandleSymbolsFile(&info, file, merge);
 
-    if (darray_empty(info.keys))
-        goto err_info;
-
     if (info.errorCount != 0)
         goto err_info;
 
diff --git a/test/data/keycodes/empty b/test/data/keycodes/empty
new file mode 100644
index 0000000..eedc943
--- /dev/null
+++ b/test/data/keycodes/empty
@@ -0,0 +1,4 @@
+default xkb_keycodes "empty" {
+    minimum= 8;
+    maximum= 255;
+};
diff --git a/test/data/symbols/empty b/test/data/symbols/empty
new file mode 100644
index 0000000..cae3303
--- /dev/null
+++ b/test/data/symbols/empty
@@ -0,0 +1,4 @@
+default partial alphanumeric_keys modifier_keys
+xkb_symbols "basic" {
+    name[Group1]= "Empty";
+};
diff --git a/test/data/sync.sh b/test/data/sync.sh
index 7f2538a..12ed434 100755
--- a/test/data/sync.sh
+++ b/test/data/sync.sh
@@ -32,9 +32,12 @@ for file in \
     symbols/rupeesign \
     symbols/kpdl \
     symbols/de \
+    symbols/ch \
+    symbols/empty \
     keycodes/xfree86 \
     keycodes/aliases \
     keycodes/evdev \
+    keycodes/empty \
     types/complete \
     types/pc \
     types/basic \
diff --git a/test/rulescomp.c b/test/rulescomp.c
index 97b4315..60e7a4c 100644
--- a/test/rulescomp.c
+++ b/test/rulescomp.c
@@ -231,6 +231,10 @@ main(int argc, char *argv[])
     assert(!test_rmlvo_env(ctx, "broken", "what-on-earth", "invalid", "", "",
                            KEY_A,          BOTH, XKB_KEY_a,               FINISH));
 
+    /* Ensure a keymap with an empty xkb_keycodes compiles fine. */
+    assert(test_rmlvo_env(ctx, "base", "empty", "empty", "", "",
+                          KEY_A,          BOTH, XKB_KEY_NoSymbol,         FINISH));
+
     xkb_context_unref(ctx);
 
     ctx = test_get_context(0);