Simplify/restrict shortcut mods

app/scrcpy.1

@@ -424,9 +424,9 @@ Turn the device screen off immediately.
 .BI "\-\-shortcut\-mod " key\fR[+...]][,...]
 Specify the modifiers to use for scrcpy shortcuts. Possible keys are "lctrl", "rctrl", "lalt", "ralt", "lsuper" and "rsuper".
 
-A shortcut can consist in several keys, separated by '+'. Several shortcuts can be specified, separated by ','.
+Several shortcut modifiers can be specified, separated by ','.
 
-For example, to use either LCtrl+LAlt or LSuper for scrcpy shortcuts, pass "lctrl+lalt,lsuper".
+For example, to use either LCtrl or LSuper for scrcpy shortcuts, pass "lctrl,lsuper".
 
 Default is "lalt,lsuper" (left-Alt or left-Super).
 

app/src/cli.c

@@ -716,10 +716,10 @@ static const struct sc_option options[] = {
         .text = "Specify the modifiers to use for scrcpy shortcuts.\n"
                 "Possible keys are \"lctrl\", \"rctrl\", \"lalt\", \"ralt\", "
                 "\"lsuper\" and \"rsuper\".\n"
-                "A shortcut can consist in several keys, separated by '+'. "
-                "Several shortcuts can be specified, separated by ','.\n"
-                "For example, to use either LCtrl+LAlt or LSuper for scrcpy "
-                "shortcuts, pass \"lctrl+lalt,lsuper\".\n"
+                "Several shortcut modifiers can be specified, separated by "
+                "','.\n"
+                "For example, to use either LCtrl or LSuper for scrcpy "
+                "shortcuts, pass \"lctrl,lsuper\".\n"
                 "Default is \"lalt,lsuper\" (left-Alt or left-Super).",
     },
     {
@@ -1687,82 +1687,62 @@ parse_log_level(const char *s, enum sc_log_level *log_level) {
     return false;
 }
 
-// item is a list of mod keys separated by '+' (e.g. "lctrl+lalt")
-// returns a bitwise-or of SC_SHORTCUT_MOD_* constants (or 0 on error)
-static unsigned
+static enum sc_shortcut_mod
 parse_shortcut_mods_item(const char *item, size_t len) {
-    unsigned mod = 0;
-
-    for (;;) {
-        char *plus = strchr(item, '+');
-        // strchr() does not consider the "len" parameter, to it could find an
-        // occurrence too far in the string (there is no strnchr())
-        bool has_plus = plus && plus < item + len;
-
-        assert(!has_plus || plus > item);
-        size_t key_len = has_plus ? (size_t) (plus - item) : len;
-
 #define STREQ(literal, s, len) \
     ((sizeof(literal)-1 == len) && !memcmp(literal, s, len))
 
-        if (STREQ("lctrl", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_LCTRL;
-        } else if (STREQ("rctrl", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_RCTRL;
-        } else if (STREQ("lalt", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_LALT;
-        } else if (STREQ("ralt", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_RALT;
-        } else if (STREQ("lsuper", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_LSUPER;
-        } else if (STREQ("rsuper", item, key_len)) {
-            mod |= SC_SHORTCUT_MOD_RSUPER;
-        } else {
-            LOGE("Unknown modifier key: %.*s "
-                 "(must be one of: lctrl, rctrl, lalt, ralt, lsuper, rsuper)",
-                 (int) key_len, item);
-            return 0;
-        }
+    if (STREQ("lctrl", item, len)) {
+        return SC_SHORTCUT_MOD_LCTRL;
+    }
+    if (STREQ("rctrl", item, len)) {
+        return SC_SHORTCUT_MOD_RCTRL;
+    }
+    if (STREQ("lalt", item, len)) {
+        return SC_SHORTCUT_MOD_LALT;
+    }
+    if (STREQ("ralt", item, len)) {
+        return SC_SHORTCUT_MOD_RALT;
+    }
+    if (STREQ("lsuper", item, len)) {
+        return SC_SHORTCUT_MOD_LSUPER;
+    }
+    if (STREQ("rsuper", item, len)) {
+        return SC_SHORTCUT_MOD_RSUPER;
+    }
 #undef STREQ
 
-        if (!has_plus) {
-            break;
-        }
-
-        item = plus + 1;
-        assert(len >= key_len + 1);
-        len -= key_len + 1;
+    bool has_plus = strchr(item, '+');
+    if (has_plus) {
+        LOGE("Shortcut mod combination with '+' is not supported anymore: "
+             "'%.*s' (see #4741)", (int) len, item);
+        return 0;
     }
 
-    return mod;
+    LOGE("Unknown modifier key: %.*s "
+         "(must be one of: lctrl, rctrl, lalt, ralt, lsuper, rsuper)",
+         (int) len, item);
+
+    return 0;
 }
 
 static bool
-parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods) {
-    unsigned count = 0;
-    unsigned current = 0;
+parse_shortcut_mods(const char *s, uint8_t *shortcut_mods) {
+    uint8_t mods = 0;
 
-    // LCtrl+LAlt or RCtrl or LCtrl+RSuper: "lctrl+lalt,rctrl,lctrl+rsuper"
+    // A list of shortcut modifiers, for example "lctrl,rctrl,rsuper"
 
     for (;;) {
         char *comma = strchr(s, ',');
-        if (comma && count == SC_MAX_SHORTCUT_MODS - 1) {
-            assert(count < SC_MAX_SHORTCUT_MODS);
-            LOGW("Too many shortcut modifiers alternatives");
-            return false;
-        }
-
         assert(!comma || comma > s);
         size_t limit = comma ? (size_t) (comma - s) : strlen(s);
 
-        unsigned mod = parse_shortcut_mods_item(s, limit);
+        enum sc_shortcut_mod mod = parse_shortcut_mods_item(s, limit);
         if (!mod) {
-            LOGE("Invalid modifier keys: %.*s", (int) limit, s);
             return false;
         }
 
-        mods->data[current++] = mod;
-        ++count;
+        mods |= mod;
 
         if (!comma) {
             break;
@@ -1771,15 +1751,15 @@ parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods) {
         s = comma + 1;
     }
 
-    mods->count = count;
+    *shortcut_mods = mods;
 
     return true;
 }
 
 #ifdef SC_TEST
 // expose the function to unit-tests
 bool
-sc_parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods) {
+sc_parse_shortcut_mods(const char *s, uint8_t *mods) {
     return parse_shortcut_mods(s, mods);
 }
 #endif

app/src/cli.h

@@ -28,7 +28,7 @@ scrcpy_parse_args(struct scrcpy_cli_args *args, int argc, char *argv[]);
 
 #ifdef SC_TEST
 bool
-sc_parse_shortcut_mods(const char *s, struct sc_shortcut_mods *mods);
+sc_parse_shortcut_mods(const char *s, uint8_t *shortcut_mods);
 #endif
 
 #endif

app/src/input_manager.c

@@ -10,7 +10,7 @@
 #define SC_SDL_SHORTCUT_MODS_MASK (KMOD_CTRL | KMOD_ALT | KMOD_GUI)
 
 static inline uint16_t
-to_sdl_mod(unsigned shortcut_mod) {
+to_sdl_mod(uint8_t shortcut_mod) {
     uint16_t sdl_mod = 0;
     if (shortcut_mod & SC_SHORTCUT_MOD_LCTRL) {
         sdl_mod |= KMOD_LCTRL;
@@ -38,15 +38,18 @@ is_shortcut_mod(struct sc_input_manager *im, uint16_t sdl_mod) {
     // keep only the relevant modifier keys
     sdl_mod &= SC_SDL_SHORTCUT_MODS_MASK;
 
-    assert(im->sdl_shortcut_mods.count);
-    assert(im->sdl_shortcut_mods.count < SC_MAX_SHORTCUT_MODS);
-    for (unsigned i = 0; i < im->sdl_shortcut_mods.count; ++i) {
-        if (im->sdl_shortcut_mods.data[i] == sdl_mod) {
-            return true;
-        }
-    }
+    // at least one shortcut mod pressed?
+    return sdl_mod & im->sdl_shortcut_mods;
+}
 
-    return false;
+static bool
+is_shortcut_key(struct sc_input_manager *im, SDL_Keycode keycode) {
+    return (im->sdl_shortcut_mods & KMOD_LCTRL && keycode == SDLK_LCTRL)
+        || (im->sdl_shortcut_mods & KMOD_RCTRL && keycode == SDLK_RCTRL)
+        || (im->sdl_shortcut_mods & KMOD_LALT  && keycode == SDLK_LALT)
+        || (im->sdl_shortcut_mods & KMOD_RALT  && keycode == SDLK_RALT)
+        || (im->sdl_shortcut_mods & KMOD_LGUI  && keycode == SDLK_LGUI)
+        || (im->sdl_shortcut_mods & KMOD_RGUI  && keycode == SDLK_RGUI);
 }
 
 void
@@ -68,15 +71,7 @@ sc_input_manager_init(struct sc_input_manager *im,
     im->legacy_paste = params->legacy_paste;
     im->clipboard_autosync = params->clipboard_autosync;
 
-    const struct sc_shortcut_mods *shortcut_mods = params->shortcut_mods;
-    assert(shortcut_mods->count);
-    assert(shortcut_mods->count < SC_MAX_SHORTCUT_MODS);
-    for (unsigned i = 0; i < shortcut_mods->count; ++i) {
-        uint16_t sdl_mod = to_sdl_mod(shortcut_mods->data[i]);
-        assert(sdl_mod);
-        im->sdl_shortcut_mods.data[i] = sdl_mod;
-    }
-    im->sdl_shortcut_mods.count = shortcut_mods->count;
+    im->sdl_shortcut_mods = to_sdl_mod(params->shortcut_mods);
 
     im->vfinger_down = false;
     im->vfinger_invert_x = false;
@@ -412,7 +407,12 @@ sc_input_manager_process_key(struct sc_input_manager *im,
     bool shift = event->keysym.mod & KMOD_SHIFT;
     bool repeat = event->repeat;
 
-    bool smod = is_shortcut_mod(im, mod);
+    // Either the modifier includes a shortcut modifier, or the key
+    // press/release is a modifier key.
+    // The second condition is necessary to ignore the release of the modifier
+    // key (because in this case mod is 0).
+    bool is_shortcut = is_shortcut_mod(im, mod)
+                    || is_shortcut_key(im, keycode);
 
     if (down && !repeat) {
         if (keycode == im->last_keycode && mod == im->last_mod) {
@@ -424,8 +424,7 @@ sc_input_manager_process_key(struct sc_input_manager *im,
         }
     }
 
-    // The shortcut modifier is pressed
-    if (smod) {
+    if (is_shortcut) {
         enum sc_action action = down ? SC_ACTION_DOWN : SC_ACTION_UP;
         switch (keycode) {
             case SDLK_h:

app/src/input_manager.h

@@ -26,10 +26,7 @@ struct sc_input_manager {
     bool legacy_paste;
     bool clipboard_autosync;
 
-    struct {
-        unsigned data[SC_MAX_SHORTCUT_MODS];
-        unsigned count;
-    } sdl_shortcut_mods;
+    uint16_t sdl_shortcut_mods;
 
     bool vfinger_down;
     bool vfinger_invert_x;
@@ -55,7 +52,7 @@ struct sc_input_manager_params {
     bool forward_all_clicks;
     bool legacy_paste;
     bool clipboard_autosync;
-    const struct sc_shortcut_mods *shortcut_mods;
+    uint8_t shortcut_mods; // OR of enum sc_shortcut_mod values
 };
 
 void

app/src/options.c

@@ -30,10 +30,7 @@ const struct scrcpy_options scrcpy_options_default = {
     },
     .tunnel_host = 0,
     .tunnel_port = 0,
-    .shortcut_mods = {
-        .data = {SC_SHORTCUT_MOD_LALT, SC_SHORTCUT_MOD_LSUPER},
-        .count = 2,
-    },
+    .shortcut_mods = SC_SHORTCUT_MOD_LALT | SC_SHORTCUT_MOD_LSUPER,
     .max_size = 0,
     .video_bit_rate = 0,
     .audio_bit_rate = 0,

app/src/options.h

@@ -169,8 +169,6 @@ enum sc_key_inject_mode {
     SC_KEY_INJECT_MODE_RAW,
 };
 
-#define SC_MAX_SHORTCUT_MODS 8
-
 enum sc_shortcut_mod {
     SC_SHORTCUT_MOD_LCTRL = 1 << 0,
     SC_SHORTCUT_MOD_RCTRL = 1 << 1,
@@ -180,11 +178,6 @@ enum sc_shortcut_mod {
     SC_SHORTCUT_MOD_RSUPER = 1 << 5,
 };
 
-struct sc_shortcut_mods {
-    unsigned data[SC_MAX_SHORTCUT_MODS];
-    unsigned count;
-};
-
 struct sc_port_range {
     uint16_t first;
     uint16_t last;
@@ -219,7 +212,7 @@ struct scrcpy_options {
     struct sc_port_range port_range;
     uint32_t tunnel_host;
     uint16_t tunnel_port;
-    struct sc_shortcut_mods shortcut_mods;
+    uint8_t shortcut_mods; // OR of enum sc_shortcut_mod values
     uint16_t max_size;
     uint32_t video_bit_rate;
     uint32_t audio_bit_rate;

app/src/scrcpy.c

@@ -715,7 +715,7 @@ scrcpy(struct scrcpy_options *options) {
             .forward_all_clicks = options->forward_all_clicks,
             .legacy_paste = options->legacy_paste,
             .clipboard_autosync = options->clipboard_autosync,
-            .shortcut_mods = &options->shortcut_mods,
+            .shortcut_mods = options->shortcut_mods,
             .window_title = window_title,
             .always_on_top = options->always_on_top,
             .window_x = options->window_x,

app/src/screen.h

@@ -82,7 +82,7 @@ struct sc_screen_params {
     bool forward_all_clicks;
     bool legacy_paste;
     bool clipboard_autosync;
-    const struct sc_shortcut_mods *shortcut_mods;
+    uint8_t shortcut_mods; // OR of enum sc_shortcut_mod values
 
     const char *window_title;
     bool always_on_top;

app/tests/test_cli.c

@@ -124,32 +124,22 @@ static void test_options2(void) {
 }
 
 static void test_parse_shortcut_mods(void) {
-    struct sc_shortcut_mods mods;
+    uint8_t mods;
     bool ok;
 
     ok = sc_parse_shortcut_mods("lctrl", &mods);
     assert(ok);
-    assert(mods.count == 1);
-    assert(mods.data[0] == SC_SHORTCUT_MOD_LCTRL);
-
-    ok = sc_parse_shortcut_mods("lctrl+lalt", &mods);
-    assert(ok);
-    assert(mods.count == 1);
-    assert(mods.data[0] == (SC_SHORTCUT_MOD_LCTRL | SC_SHORTCUT_MOD_LALT));
+    assert(mods == SC_SHORTCUT_MOD_LCTRL);
 
     ok = sc_parse_shortcut_mods("rctrl,lalt", &mods);
     assert(ok);
-    assert(mods.count == 2);
-    assert(mods.data[0] == SC_SHORTCUT_MOD_RCTRL);
-    assert(mods.data[1] == SC_SHORTCUT_MOD_LALT);
+    assert(mods == (SC_SHORTCUT_MOD_RCTRL | SC_SHORTCUT_MOD_LALT));
 
-    ok = sc_parse_shortcut_mods("lsuper,rsuper+lalt,lctrl+rctrl+ralt", &mods);
+    ok = sc_parse_shortcut_mods("lsuper,rsuper,lctrl", &mods);
     assert(ok);
-    assert(mods.count == 3);
-    assert(mods.data[0] == SC_SHORTCUT_MOD_LSUPER);
-    assert(mods.data[1] == (SC_SHORTCUT_MOD_RSUPER | SC_SHORTCUT_MOD_LALT));
-    assert(mods.data[2] == (SC_SHORTCUT_MOD_LCTRL | SC_SHORTCUT_MOD_RCTRL |
-                            SC_SHORTCUT_MOD_RALT));
+    assert(mods == (SC_SHORTCUT_MOD_LSUPER
+                  | SC_SHORTCUT_MOD_RSUPER
+                  | SC_SHORTCUT_MOD_LCTRL));
 
     ok = sc_parse_shortcut_mods("", &mods);
     assert(!ok);

doc/shortcuts.md

@@ -13,8 +13,8 @@ It can be changed using `--shortcut-mod`. Possible keys are `lctrl`, `rctrl`,
 # use RCtrl for shortcuts
 scrcpy --shortcut-mod=rctrl
 
-# use either LCtrl+LAlt or LSuper for shortcuts
-scrcpy --shortcut-mod=lctrl+lalt,lsuper
+# use either LCtrl or LSuper for shortcuts
+scrcpy --shortcut-mod=lctrl,lsuper
 ```
 
 _<kbd>[Super]</kbd> is typically the <kbd>Windows</kbd> or <kbd>Cmd</kbd> key._