[PATCH v3 06/36] qemu-keymap: properly check return from xkb_keymap_mod_get_index

["Alex Bennée" <alex.bennee@linaro.org>]

We can return XKB_MOD_INVALID for AltGr which rightly gets flagged by
sanitisers as an overly wide shift attempt. Properly check the return
type and leave the bitmap as zero in that case. Tested output before
and after is unchanged with the gb and ara keymaps.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
---
 qemu-keymap.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/qemu-keymap.c b/qemu-keymap.c
index 229866e004..8c80f7a4ed 100644
--- a/qemu-keymap.c
+++ b/qemu-keymap.c
@@ -140,6 +140,18 @@ static void usage(FILE *out)
             names.options ?: "-");
 }
 
+static xkb_mod_mask_t get_mod(struct xkb_keymap *map, const char *name)
+{
+    xkb_mod_index_t mod;
+    xkb_mod_mask_t mask = 0;
+
+    mod = xkb_keymap_mod_get_index(map, name);
+    if (mod != XKB_MOD_INVALID) {
+        mask = (1 << mod);
+    }
+    return mask;
+}
+
 int main(int argc, char *argv[])
 {
     struct xkb_context *ctx;
@@ -215,14 +227,10 @@ int main(int argc, char *argv[])
                 mod, xkb_keymap_mod_get_name(map, mod));
     }
 
-    mod = xkb_keymap_mod_get_index(map, "Shift");
-    shift = (1 << mod);
-    mod = xkb_keymap_mod_get_index(map, "Control");
-    ctrl = (1 << mod);
-    mod = xkb_keymap_mod_get_index(map, "AltGr");
-    altgr = (1 << mod);
-    mod = xkb_keymap_mod_get_index(map, "NumLock");
-    numlock = (1 << mod);
+    shift = get_mod(map, "Shift");
+    ctrl = get_mod(map, "Control");
+    altgr = get_mod(map, "AltGr");
+    numlock = get_mod(map, "NumLock");
 
     state = xkb_state_new(map);
     xkb_keymap_key_for_each(map, walk_map, state);
-- 
2.39.2