Linux: Fix path buffer length warning

Fixes #1025.

README.md

@@ -182,6 +182,7 @@ information on what to include when reporting a bug.
 - [X11] Bugfix: Gamma ramp setting via RandR did not validate ramp size
 - [X11] Bugfix: Key name string encoding depended on current locale (#981,#983)
 - [Linux] Bugfix: Event processing did not detect joystick disconnection (#932)
+- [Linux] Bugfix: The joystick device path could be truncated (#1025)
 - [Cocoa] Added support for Vulkan window surface creation via
           [MoltenVK](https://moltengl.com/moltenvk/) (#870)
 - [Cocoa] Added support for loading a `MainMenu.nib` when available

src/linux_joystick.c

@@ -160,15 +160,24 @@ GLFWbool _glfwInitJoysticksLinux(void)
 
         while ((entry = readdir(dir)))
         {
-            char path[20];
             regmatch_t match;
+            char* path = NULL;
 
             if (regexec(&_glfw.linjs.regex, entry->d_name, 1, &match, 0) != 0)
                 continue;
 
-            snprintf(path, sizeof(path), "%s/%s", dirname, entry->d_name);
+            if (asprintf(&path, "%s/%s", dirname, entry->d_name) < 0)
+            {
+                _glfwInputError(GLFW_PLATFORM_ERROR,
+                                "Linux: Failed to construct device path: %s",
+                                strerror(errno));
+                continue;
+            }
+
             if (openJoystickDevice(path))
                 count++;
+
+            free(path);
         }
 
         closedir(dir);