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joystick: Split out Linux opening code for reuse by querying code. 

This prevents an assertion whem LINUX_JoystickGetGamepadMapping tried to
open the stick temporarily and messed with global state by doing so. Now
the global state is only set in LINUX_JoystickOpen, but the common code
is shared by both interfaces.

Fixes #4198.
This commit is contained in:
Ryan C. Gordon 2021-07-24 17:44:35 -04:00
parent 6c92bf540c
commit 5ae0dd4b52
No known key found for this signature in database
GPG Key ID: FA148B892AB48044
1 changed files with 62 additions and 35 deletions
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93
src/joystick/linux/SDL_sysjoystick.c
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@ -965,6 +965,47 @@ ConfigJoystick(SDL_Joystick *joystick, int fd)
}
/* This is used to do the heavy lifting for LINUX_JoystickOpen and
also LINUX_JoystickGetGamepadMapping, so we can query the hardware
without adding an opened SDL_Joystick object to the system.
This expects `joystick->hwdata` to be allocated and will not free it
on error. Returns -1 on error, 0 on success. */
static int
PrepareJoystickHwdata(SDL_Joystick *joystick, SDL_joylist_item *item)
{
joystick->hwdata->item = item;
joystick->hwdata->guid = item->guid;
joystick->hwdata->effect.id = -1;
joystick->hwdata->m_bSteamController = item->m_bSteamController;
SDL_memset(joystick->hwdata->abs_map, 0xFF, sizeof(joystick->hwdata->abs_map));
if (item->m_bSteamController) {
joystick->hwdata->fd = -1;
SDL_GetSteamControllerInputs(&joystick->nbuttons,
&joystick->naxes,
&joystick->nhats);
} else {
const int fd = open(item->path, O_RDWR, 0);
if (fd < 0) {
return SDL_SetError("Unable to open %s", item->path);
}
joystick->hwdata->fd = fd;
joystick->hwdata->fname = SDL_strdup(item->path);
if (joystick->hwdata->fname == NULL) {
close(fd);
return SDL_OutOfMemory();
}
/* Set the joystick to non-blocking read mode */
fcntl(fd, F_SETFL, O_NONBLOCK);
/* Get the number of buttons and axes on the joystick */
ConfigJoystick(joystick, fd);
}
}
/* Function to open a joystick for use.
The joystick to open is specified by the device index.
This should fill the nbuttons and naxes fields of the joystick structure.
@ -985,39 +1026,11 @@ LINUX_JoystickOpen(SDL_Joystick *joystick, int device_index)
if (joystick->hwdata == NULL) {
return SDL_OutOfMemory();
}
joystick->hwdata->item = item;
joystick->hwdata->guid = item->guid;
joystick->hwdata->effect.id = -1;
joystick->hwdata->m_bSteamController = item->m_bSteamController;
SDL_memset(joystick->hwdata->abs_map, 0xFF, sizeof(joystick->hwdata->abs_map));
if (item->m_bSteamController) {
joystick->hwdata->fd = -1;
SDL_GetSteamControllerInputs(&joystick->nbuttons,
&joystick->naxes,
&joystick->nhats);
} else {
int fd = open(item->path, O_RDWR, 0);
if (fd < 0) {
if (PrepareJoystickHwdata(joystick, item) == -1) {
SDL_free(joystick->hwdata);
joystick->hwdata = NULL;
return SDL_SetError("Unable to open %s", item->path);
}
joystick->hwdata->fd = fd;
joystick->hwdata->fname = SDL_strdup(item->path);
if (joystick->hwdata->fname == NULL) {
SDL_free(joystick->hwdata);
joystick->hwdata = NULL;
close(fd);
return SDL_OutOfMemory();
}
/* Set the joystick to non-blocking read mode */
fcntl(fd, F_SETFL, O_NONBLOCK);
/* Get the number of buttons and axes on the joystick */
ConfigJoystick(joystick, fd);
return -1; /* SDL_SetError will already have been called */
}
SDL_assert(item->hwdata == NULL);
@ -1026,7 +1039,7 @@ LINUX_JoystickOpen(SDL_Joystick *joystick, int device_index)
/* mark joystick as fresh and ready */
joystick->hwdata->fresh = SDL_TRUE;
return (0);
return 0;
}
static int
@ -1417,18 +1430,32 @@ LINUX_JoystickGetGamepadMapping(int device_index, SDL_GamepadMapping *out)
return SDL_TRUE;
}
/* We temporarily open the device to check how it's configured. Make
a fake SDL_Joystick object to do so. */
joystick = (SDL_Joystick *) SDL_calloc(sizeof(*joystick), 1);
if (joystick == NULL) {
SDL_OutOfMemory();
return SDL_FALSE;
}
/* We temporarily open the device to check how it's configured. */
if (LINUX_JoystickOpen(joystick, device_index) < 0) {
joystick->hwdata = (struct joystick_hwdata *)
SDL_calloc(1, sizeof(*joystick->hwdata));
if (joystick->hwdata == NULL) {
SDL_free(joystick);
SDL_OutOfMemory();
return SDL_FALSE;
}
if (PrepareJoystickHwdata(joystick, item) == -1) {
SDL_free(joystick->hwdata);
SDL_free(joystick);
return SDL_FALSE; /* SDL_SetError will already have been called */
}
/* don't assign `item->hwdata` so it's not in any global state. */
/* it is now safe to call LINUX_JoystickClose on this fake joystick. */
if (!joystick->hwdata->has_key[BTN_GAMEPAD]) {
/* Not a gamepad according to the specs. */
LINUX_JoystickClose(joystick);