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Linux hidapi code dynamically loads udev
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@slouken
slouken committed Nov 23, 2019
1 parent 359ae75 commit 308e7f2
Showing 1 changed file with 48 additions and 36 deletions.
84 changes: 48 additions & 36 deletions src/hidapi/linux/hid.c
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Expand Up @@ -48,7 +48,8 @@
#include <linux/hidraw.h>
#include <linux/version.h>
#include <linux/input.h>
#include <libudev.h>
//#include <libudev.h>
#include "../../core/linux/SDL_udev.h"

#include "hidapi.h"

Expand All @@ -66,6 +67,8 @@ namespace NAMESPACE
#define HIDIOCGFEATURE(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x07, len)
#endif

static const SDL_UDEV_Symbols *udev_syms;

/* USB HID device property names */
const char *device_string_names[] = {
"manufacturer",
Expand Down Expand Up @@ -147,7 +150,7 @@ static wchar_t *utf8_to_wchar_t(const char *utf8)
string. The returned string must be freed with free() when done.*/
static wchar_t *copy_udev_string(struct udev_device *dev, const char *udev_name)
{
return utf8_to_wchar_t(udev_device_get_sysattr_value(dev, udev_name));
return utf8_to_wchar_t(udev_syms->udev_device_get_sysattr_value(dev, udev_name));
}

/* uses_numbered_reports() returns 1 if report_descriptor describes a device
Expand Down Expand Up @@ -277,7 +280,7 @@ static int is_bluetooth(hid_device *dev)
int ret = -1;

/* Create the udev object */
udev = udev_new();
udev = udev_syms->udev_new();
if (!udev) {
printf("Can't create udev\n");
return -1;
Expand All @@ -286,14 +289,14 @@ static int is_bluetooth(hid_device *dev)
/* Get the dev_t (major/minor numbers) from the file handle. */
ret = fstat(dev->device_handle, &s);
if (-1 == ret) {
udev_unref(udev);
udev_syms->udev_unref(udev);
return ret;
}

/* Open a udev device from the dev_t. 'c' means character device. */
udev_dev = udev_device_new_from_devnum(udev, 'c', s.st_rdev);
udev_dev = udev_syms->udev_device_new_from_devnum(udev, 'c', s.st_rdev);
if (udev_dev) {
hid_dev = udev_device_get_parent_with_subsystem_devtype(
hid_dev = udev_syms->udev_device_get_parent_with_subsystem_devtype(
udev_dev,
"hid",
NULL);
Expand All @@ -305,7 +308,7 @@ static int is_bluetooth(hid_device *dev)
char *product_name_utf8 = NULL;

ret = parse_uevent_info(
udev_device_get_sysattr_value(hid_dev, "uevent"),
udev_syms->udev_device_get_sysattr_value(hid_dev, "uevent"),
&bus_type,
&dev_vid,
&dev_pid,
Expand All @@ -319,10 +322,10 @@ static int is_bluetooth(hid_device *dev)
/* hid_dev doesn't need to be (and can't be) unref'd.
I'm not sure why, but it'll throw double-free() errors. */
}
udev_device_unref(udev_dev);
udev_syms->udev_device_unref(udev_dev);
}

udev_unref(udev);
udev_syms->udev_unref(udev);

return ret;
}
Expand All @@ -339,7 +342,7 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
char *tmp;

/* Create the udev object */
udev = udev_new();
udev = udev_syms->udev_new();
if (!udev) {
printf("Can't create udev\n");
return -1;
Expand All @@ -348,13 +351,13 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
/* Get the dev_t (major/minor numbers) from the file handle. */
ret = fstat(dev->device_handle, &s);
if (-1 == ret) {
udev_unref(udev);
udev_syms->udev_unref(udev);
return ret;
}
/* Open a udev device from the dev_t. 'c' means character device. */
udev_dev = udev_device_new_from_devnum(udev, 'c', s.st_rdev);
udev_dev = udev_syms->udev_device_new_from_devnum(udev, 'c', s.st_rdev);
if (udev_dev) {
hid_dev = udev_device_get_parent_with_subsystem_devtype(
hid_dev = udev_syms->udev_device_get_parent_with_subsystem_devtype(
udev_dev,
"hid",
NULL);
Expand All @@ -365,7 +368,7 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
size_t retm;

ret = parse_uevent_info(
udev_device_get_sysattr_value(hid_dev, "uevent"),
udev_syms->udev_device_get_sysattr_value(hid_dev, "uevent"),
&bus_type,
&dev_vid,
&dev_pid,
Expand Down Expand Up @@ -401,7 +404,7 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
}
else {
/* This is a USB device. Find its parent USB Device node. */
parent = udev_device_get_parent_with_subsystem_devtype(
parent = udev_syms->udev_device_get_parent_with_subsystem_devtype(
udev_dev,
"usb",
"usb_device");
Expand All @@ -416,7 +419,7 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
goto end;
}

str = udev_device_get_sysattr_value(parent, key_str);
str = udev_syms->udev_device_get_sysattr_value(parent, key_str);
if (str) {
/* Convert the string from UTF-8 to wchar_t */
retm = mbstowcs(string, str, maxlen);
Expand All @@ -432,10 +435,10 @@ static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t
free(serial_number_utf8);
free(product_name_utf8);

udev_device_unref(udev_dev);
udev_syms->udev_device_unref(udev_dev);
/* parent and hid_dev don't need to be (and can't be) unref'd.
I'm not sure why, but they'll throw double-free() errors. */
udev_unref(udev);
udev_syms->udev_unref(udev);

return ret;
}
Expand All @@ -451,11 +454,17 @@ int HID_API_EXPORT hid_init(void)

kernel_version = detect_kernel_version();

udev_syms = SDL_UDEV_GetUdevSyms();
if (!udev_syms)
return -1;

return 0;
}

int HID_API_EXPORT hid_exit(void)
{
SDL_UDEV_ReleaseUdevSyms();

/* Nothing to do for this in the Linux/hidraw implementation. */
return 0;
}
Expand All @@ -474,20 +483,23 @@ struct hid_device_info HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
hid_init();

/* Create the udev object */
udev = udev_new();
udev = udev_syms->udev_new();
if (!udev) {
printf("Can't create udev\n");
return NULL;
}

/* Create a list of the devices in the 'hidraw' subsystem. */
enumerate = udev_enumerate_new(udev);
udev_enumerate_add_match_subsystem(enumerate, "hidraw");
udev_enumerate_scan_devices(enumerate);
devices = udev_enumerate_get_list_entry(enumerate);
enumerate = udev_syms->udev_enumerate_new(udev);
udev_syms->udev_enumerate_add_match_subsystem(enumerate, "hidraw");
udev_syms->udev_enumerate_scan_devices(enumerate);
devices = udev_syms->udev_enumerate_get_list_entry(enumerate);
/* For each item, see if it matches the vid/pid, and if so
create a udev_device record for it */
udev_list_entry_foreach(dev_list_entry, devices) {
for (dev_list_entry = devices;
dev_list_entry;
dev_list_entry = udev_syms->udev_list_entry_get_next(dev_list_entry)) {

const char *sysfs_path;
const char *dev_path;
const char *str;
Expand All @@ -504,11 +516,11 @@ struct hid_device_info HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,

/* Get the filename of the /sys entry for the device
and create a udev_device object (dev) representing it */
sysfs_path = udev_list_entry_get_name(dev_list_entry);
raw_dev = udev_device_new_from_syspath(udev, sysfs_path);
dev_path = udev_device_get_devnode(raw_dev);
sysfs_path = udev_syms->udev_list_entry_get_name(dev_list_entry);
raw_dev = udev_syms->udev_device_new_from_syspath(udev, sysfs_path);
dev_path = udev_syms->udev_device_get_devnode(raw_dev);

hid_dev = udev_device_get_parent_with_subsystem_devtype(
hid_dev = udev_syms->udev_device_get_parent_with_subsystem_devtype(
raw_dev,
"hid",
NULL);
Expand All @@ -519,7 +531,7 @@ struct hid_device_info HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
}

result = parse_uevent_info(
udev_device_get_sysattr_value(hid_dev, "uevent"),
udev_syms->udev_device_get_sysattr_value(hid_dev, "uevent"),
&bus_type,
&dev_vid,
&dev_pid,
Expand Down Expand Up @@ -582,7 +594,7 @@ struct hid_device_info HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
subsystem/devtype pair of "usb"/"usb_device". This will
be several levels up the tree, but the function will find
it. */
usb_dev = udev_device_get_parent_with_subsystem_devtype(
usb_dev = udev_syms->udev_device_get_parent_with_subsystem_devtype(
raw_dev,
"usb",
"usb_device");
Expand Down Expand Up @@ -610,16 +622,16 @@ struct hid_device_info HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
cur_dev->product_string = copy_udev_string(usb_dev, device_string_names[DEVICE_STRING_PRODUCT]);

/* Release Number */
str = udev_device_get_sysattr_value(usb_dev, "bcdDevice");
str = udev_syms->udev_device_get_sysattr_value(usb_dev, "bcdDevice");
cur_dev->release_number = (str)? strtol(str, NULL, 16): 0x0;

/* Get a handle to the interface's udev node. */
intf_dev = udev_device_get_parent_with_subsystem_devtype(
intf_dev = udev_syms->udev_device_get_parent_with_subsystem_devtype(
raw_dev,
"usb",
"usb_interface");
if (intf_dev) {
str = udev_device_get_sysattr_value(intf_dev, "bInterfaceNumber");
str = udev_syms->udev_device_get_sysattr_value(intf_dev, "bInterfaceNumber");
cur_dev->interface_number = (str)? strtol(str, NULL, 16): -1;
}

Expand All @@ -642,14 +654,14 @@ struct hid_device_info HID_API_EXPORT *hid_enumerate(unsigned short vendor_id,
next:
free(serial_number_utf8);
free(product_name_utf8);
udev_device_unref(raw_dev);
udev_syms->udev_device_unref(raw_dev);
/* hid_dev, usb_dev and intf_dev don't need to be (and can't be)
unref()d. It will cause a double-free() error. I'm not
sure why. */
}
/* Free the enumerator and udev objects. */
udev_enumerate_unref(enumerate);
udev_unref(udev);
udev_syms->udev_enumerate_unref(enumerate);
udev_syms->udev_unref(udev);

return root;
}
Expand Down

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