From 7ea1b69dd4c76ba8368fac8e2eab55969adec3d3 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Tue, 5 Apr 2022 21:00:07 -0700
Subject: [PATCH] Sort controllers by the js* index on Linux
Also fixed the initial scan to directly scan devices instead of using
udev so they can be sorted, as intended.
Fixes https://github.com/libsdl-org/SDL/issues/4688
---
src/joystick/linux/SDL_sysjoystick.c | 95 ++++++++++++++++++++--------
1 file changed, 70 insertions(+), 25 deletions(-)
diff --git a/src/joystick/linux/SDL_sysjoystick.c b/src/joystick/linux/SDL_sysjoystick.c
index 39bd99139ed..b8cac5f0f81 100644
--- a/src/joystick/linux/SDL_sysjoystick.c
+++ b/src/joystick/linux/SDL_sysjoystick.c
@@ -606,6 +606,26 @@ LINUX_InotifyJoystickDetect(void)
}
#endif /* HAVE_INOTIFY */
+static int get_event_joystick_index(int event)
+{
+ int joystick_index = -1;
+ int i, count;
+ struct dirent **entries;
+ char path[PATH_MAX];
+
+ SDL_snprintf(path, SDL_arraysize(path), "/sys/class/input/event%d/device", event);
+ count = scandir(path, &entries, NULL, alphasort);
+ for (i = 0; i < count; ++i) {
+ if (SDL_strncmp(entries[i]->d_name, "js", 2) == 0) {
+ joystick_index = SDL_atoi(entries[i]->d_name+2);
+ }
+ free(entries[i]); /* This should NOT be SDL_free() */
+ }
+ free(entries); /* This should NOT be SDL_free() */
+
+ return joystick_index;
+}
+
/* Detect devices by reading /dev/input. In the inotify code path we
* have to do this the first time, to detect devices that already existed
* before we started; in the non-inotify code path we do this repeatedly
@@ -618,10 +638,35 @@ filter_entries(const struct dirent *entry)
static int
sort_entries(const struct dirent **a, const struct dirent **b)
{
- int numA = SDL_atoi((*a)->d_name+5);
- int numB = SDL_atoi((*b)->d_name+5);
+ int numA, numB;
+ int offset;
+
+ if (SDL_classic_joysticks) {
+ offset = 2; /* strlen("js") */
+ numA = SDL_atoi((*a)->d_name+offset);
+ numB = SDL_atoi((*b)->d_name+offset);
+ } else {
+ offset = 5; /* strlen("event") */
+ numA = SDL_atoi((*a)->d_name+offset);
+ numB = SDL_atoi((*b)->d_name+offset);
+
+ /* See if we can get the joystick ordering */
+ {
+ int jsA = get_event_joystick_index(numA);
+ int jsB = get_event_joystick_index(numB);
+ if (jsA >= 0 && jsB >= 0) {
+ numA = jsA;
+ numB = jsB;
+ } else if (jsA >= 0) {
+ return -1;
+ } else if (jsB >= 0) {
+ return 1;
+ }
+ }
+ }
return (numA - numB);
}
+
static void
LINUX_FallbackJoystickDetect(void)
{
@@ -684,29 +729,7 @@ LINUX_JoystickInit(void)
SDL_classic_joysticks = SDL_GetHintBoolean(SDL_HINT_LINUX_JOYSTICK_CLASSIC, SDL_FALSE);
-#if SDL_USE_LIBUDEV
- if (enumeration_method == ENUMERATION_UNSET) {
- if (SDL_GetHintBoolean("SDL_JOYSTICK_DISABLE_UDEV", SDL_FALSE)) {
- SDL_LogDebug(SDL_LOG_CATEGORY_INPUT,
- "udev disabled by SDL_JOYSTICK_DISABLE_UDEV");
- enumeration_method = ENUMERATION_FALLBACK;
-
- } else if (access("/.flatpak-info", F_OK) == 0
- || access("/run/host/container-manager", F_OK) == 0) {
- /* Explicitly check `/.flatpak-info` because, for old versions of
- * Flatpak, this was the only available way to tell if we were in
- * a Flatpak container. */
- SDL_LogDebug(SDL_LOG_CATEGORY_INPUT,
- "Container detected, disabling udev integration");
- enumeration_method = ENUMERATION_FALLBACK;
-
- } else {
- SDL_LogDebug(SDL_LOG_CATEGORY_INPUT,
- "Using udev for joystick device discovery");
- enumeration_method = ENUMERATION_LIBUDEV;
- }
- }
-#endif
+ enumeration_method = ENUMERATION_UNSET;
/* First see if the user specified one or more joysticks to use */
if (devices != NULL) {
@@ -735,6 +758,28 @@ LINUX_JoystickInit(void)
LINUX_JoystickDetect();
#if SDL_USE_LIBUDEV
+ if (enumeration_method == ENUMERATION_UNSET) {
+ if (SDL_GetHintBoolean("SDL_JOYSTICK_DISABLE_UDEV", SDL_FALSE)) {
+ SDL_LogDebug(SDL_LOG_CATEGORY_INPUT,
+ "udev disabled by SDL_JOYSTICK_DISABLE_UDEV");
+ enumeration_method = ENUMERATION_FALLBACK;
+
+ } else if (access("/.flatpak-info", F_OK) == 0
+ || access("/run/host/container-manager", F_OK) == 0) {
+ /* Explicitly check `/.flatpak-info` because, for old versions of
+ * Flatpak, this was the only available way to tell if we were in
+ * a Flatpak container. */
+ SDL_LogDebug(SDL_LOG_CATEGORY_INPUT,
+ "Container detected, disabling udev integration");
+ enumeration_method = ENUMERATION_FALLBACK;
+
+ } else {
+ SDL_LogDebug(SDL_LOG_CATEGORY_INPUT,
+ "Using udev for joystick device discovery");
+ enumeration_method = ENUMERATION_LIBUDEV;
+ }
+ }
+
if (enumeration_method == ENUMERATION_LIBUDEV) {
if (SDL_UDEV_Init() < 0) {
return SDL_SetError("Could not initialize UDEV");