SDL: If a mapping specifies a crc, don't match for controllers that don't have that CRC (e5024)

From e5024fae3decb724e397d3c9dbcb744d8c79aac1 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Thu, 14 Mar 2024 13:26:56 -0700
Subject: [PATCH] If a mapping specifies a crc, don't match for controllers
 that don't have that CRC

The CRC is used to distinguish between different controllers that have the same VID/PID, so if the CRC doesn't match, it's probably a different controller that we don't know about.

Fixes https://github.com/libsdl-org/SDL/issues/9265

(cherry picked from commit 30e93b40c2a6fd2219ad55e820f5d037e3619c2c)
(cherry picked from commit b8daf14fe550512c42d5e30bd696d52effc337e5)
---
 src/joystick/SDL_gamecontroller.c | 52 +++++++++++--------------------
 1 file changed, 19 insertions(+), 33 deletions(-)

diff --git a/src/joystick/SDL_gamecontroller.c b/src/joystick/SDL_gamecontroller.c
index 1cf8c2e417dba..410c985d46259 100644
--- a/src/joystick/SDL_gamecontroller.c
+++ b/src/joystick/SDL_gamecontroller.c
@@ -688,16 +688,14 @@ static ControllerMapping_t *SDL_CreateMappingForWGIController(SDL_JoystickGUID g
 /*
  * Helper function to scan the mappings database for a controller with the specified GUID
  */
-static ControllerMapping_t *SDL_PrivateMatchControllerMappingForGUID(SDL_JoystickGUID guid, SDL_bool match_crc, SDL_bool match_version)
+static ControllerMapping_t *SDL_PrivateMatchControllerMappingForGUID(SDL_JoystickGUID guid, SDL_bool match_version)
 {
-    ControllerMapping_t *mapping;
+    ControllerMapping_t *mapping, *best_match = NULL;
     Uint16 crc = 0;
 
     SDL_AssertJoysticksLocked();
 
-    if (match_crc) {
-        SDL_GetJoystickGUIDInfo(guid, NULL, NULL, NULL, &crc);
-    }
+    SDL_GetJoystickGUIDInfo(guid, NULL, NULL, NULL, &crc);
 
     /* Clear the CRC from the GUID for matching, the mappings never include it in the GUID */
     SDL_SetJoystickGUIDCRC(&guid, 0);
@@ -719,20 +717,26 @@ static ControllerMapping_t *SDL_PrivateMatchControllerMappingForGUID(SDL_Joystic
         }
 
         if (SDL_memcmp(&guid, &mapping_guid, sizeof(guid)) == 0) {
-            Uint16 mapping_crc = 0;
+            const char *crc_string = SDL_strstr(mapping->mapping, SDL_CONTROLLER_CRC_FIELD);
+            if (crc_string) {
+                Uint16 mapping_crc = (Uint16)SDL_strtol(crc_string + SDL_CONTROLLER_CRC_FIELD_SIZE, NULL, 16);
 
-            if (match_crc) {
-                const char *crc_string = SDL_strstr(mapping->mapping, SDL_CONTROLLER_CRC_FIELD);
-                if (crc_string) {
-                    mapping_crc = (Uint16)SDL_strtol(crc_string + SDL_CONTROLLER_CRC_FIELD_SIZE, NULL, 16);
+                if (mapping_crc != crc) {
+                    /* This mapping specified a CRC and they don't match */
+                    continue;
                 }
-            }
-            if (crc == mapping_crc) {
+
+                /* An exact match, including CRC */
                 return mapping;
             }
+
+
+            if (!best_match) {
+                best_match = mapping;
+            }
         }
     }
-    return NULL;
+    return best_match;
 }
 
 /*
@@ -741,19 +745,8 @@ static ControllerMapping_t *SDL_PrivateMatchControllerMappingForGUID(SDL_Joystic
 static ControllerMapping_t *SDL_PrivateGetControllerMappingForGUID(SDL_JoystickGUID guid, SDL_bool adding_mapping)
 {
     ControllerMapping_t *mapping;
-    Uint16 vendor, product, crc;
 
-    SDL_GetJoystickGUIDInfo(guid, &vendor, &product, NULL, &crc);
-    if (crc) {
-        /* First check for exact CRC matching */
-        mapping = SDL_PrivateMatchControllerMappingForGUID(guid, SDL_TRUE, SDL_TRUE);
-        if (mapping) {
-            return mapping;
-        }
-    }
-
-    /* Now check for a mapping without CRC */
-    mapping = SDL_PrivateMatchControllerMappingForGUID(guid, SDL_FALSE, SDL_TRUE);
+    mapping = SDL_PrivateMatchControllerMappingForGUID(guid, SDL_TRUE);
     if (mapping) {
         return mapping;
     }
@@ -767,14 +760,7 @@ static ControllerMapping_t *SDL_PrivateGetControllerMappingForGUID(SDL_JoystickG
 
     if (SDL_JoystickGUIDUsesVersion(guid)) {
         /* Try again, ignoring the version */
-        if (crc) {
-            mapping = SDL_PrivateMatchControllerMappingForGUID(guid, SDL_TRUE, SDL_FALSE);
-            if (mapping) {
-                return mapping;
-            }
-        }
-
-        mapping = SDL_PrivateMatchControllerMappingForGUID(guid, SDL_FALSE, SDL_FALSE);
+        mapping = SDL_PrivateMatchControllerMappingForGUID(guid, SDL_FALSE);
         if (mapping) {
             return mapping;
         }