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hid.c
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hid.c
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/*******************************************************
HIDAPI - Multi-Platform library for
communication with HID devices.
Alan Ott
Signal 11 Software
libusb/hidapi Team
Copyright 2022, All Rights Reserved.
At the discretion of the user of this library,
this software may be licensed under the terms of the
GNU General Public License v3, a BSD-Style license, or the
original HIDAPI license as outlined in the LICENSE.txt,
LICENSE-gpl3.txt, LICENSE-bsd.txt, and LICENSE-orig.txt
files located at the root of the source distribution.
These files may also be found in the public source
code repository located at:
https://github.com/libusb/hidapi .
********************************************************/
/* C */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <locale.h>
#include <errno.h>
/* Unix */
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/utsname.h>
#include <fcntl.h>
#include <poll.h>
/* Linux */
#include <linux/hidraw.h>
#include <linux/version.h>
#include <linux/input.h>
#include <libudev.h>
#include "hidapi.h"
#ifdef HIDAPI_ALLOW_BUILD_WORKAROUND_KERNEL_2_6_39
/* This definitions first appeared in Linux Kernel 2.6.39 in linux/hidraw.h.
hidapi doesn't support kernels older than that,
so we don't define macros below explicitly, to fail builds on old kernels.
For those who really need this as a workaround (e.g. to be able to build on old build machines),
can workaround by defining the macro above.
*/
#ifndef HIDIOCSFEATURE
#define HIDIOCSFEATURE(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x06, len)
#endif
#ifndef HIDIOCGFEATURE
#define HIDIOCGFEATURE(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x07, len)
#endif
#endif
// HIDIOCGINPUT is not defined in Linux kernel headers < 5.11.
// This definition is from hidraw.h in Linux >= 5.11.
// https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f43d3870cafa2a0f3854c1819c8385733db8f9ae
#ifndef HIDIOCGINPUT
#define HIDIOCGINPUT(len) _IOC(_IOC_WRITE|_IOC_READ, 'H', 0x0A, len)
#endif
/* USB HID device property names */
const char *device_string_names[] = {
"manufacturer",
"product",
"serial",
};
/* Symbolic names for the properties above */
enum device_string_id {
DEVICE_STRING_MANUFACTURER,
DEVICE_STRING_PRODUCT,
DEVICE_STRING_SERIAL,
DEVICE_STRING_COUNT,
};
struct hid_device_ {
int device_handle;
int blocking;
int uses_numbered_reports;
wchar_t *last_error_str;
};
static struct hid_api_version api_version = {
.major = HID_API_VERSION_MAJOR,
.minor = HID_API_VERSION_MINOR,
.patch = HID_API_VERSION_PATCH
};
/* Global error message that is not specific to a device, e.g. for
hid_open(). It is thread-local like errno. */
__thread wchar_t *last_global_error_str = NULL;
static hid_device *new_hid_device(void)
{
hid_device *dev = (hid_device*) calloc(1, sizeof(hid_device));
dev->device_handle = -1;
dev->blocking = 1;
dev->uses_numbered_reports = 0;
dev->last_error_str = NULL;
return dev;
}
/* The caller must free the returned string with free(). */
static wchar_t *utf8_to_wchar_t(const char *utf8)
{
wchar_t *ret = NULL;
if (utf8) {
size_t wlen = mbstowcs(NULL, utf8, 0);
if ((size_t) -1 == wlen) {
return wcsdup(L"");
}
ret = (wchar_t*) calloc(wlen+1, sizeof(wchar_t));
mbstowcs(ret, utf8, wlen+1);
ret[wlen] = 0x0000;
}
return ret;
}
/* Set the last global error to be reported by hid_error(NULL).
* The given error message will be copied (and decoded according to the
* currently locale, so do not pass in string constants).
* The last stored global error message is freed.
* Use register_global_error(NULL) to indicate "no error". */
static void register_global_error(const char *msg)
{
if (last_global_error_str)
free(last_global_error_str);
last_global_error_str = utf8_to_wchar_t(msg);
}
/* See register_global_error, but you can pass a format string into this function. */
static void register_global_error_format(const char *format, ...)
{
va_list args;
va_start(args, format);
char msg[100];
vsnprintf(msg, sizeof(msg), format, args);
va_end(args);
register_global_error(msg);
}
/* Set the last error for a device to be reported by hid_error(device).
* The given error message will be copied (and decoded according to the
* currently locale, so do not pass in string constants).
* The last stored global error message is freed.
* Use register_device_error(device, NULL) to indicate "no error". */
static void register_device_error(hid_device *dev, const char *msg)
{
if (dev->last_error_str)
free(dev->last_error_str);
dev->last_error_str = utf8_to_wchar_t(msg);
}
/* See register_device_error, but you can pass a format string into this function. */
static void register_device_error_format(hid_device *dev, const char *format, ...)
{
va_list args;
va_start(args, format);
char msg[100];
vsnprintf(msg, sizeof(msg), format, args);
va_end(args);
register_device_error(dev, msg);
}
/* Get an attribute value from a udev_device and return it as a whar_t
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));
}
/*
* Gets the size of the HID item at the given position
* Returns 1 if successful, 0 if an invalid key
* Sets data_len and key_size when successful
*/
static int get_hid_item_size(__u8 *report_descriptor, unsigned int pos, __u32 size, int *data_len, int *key_size)
{
int key = report_descriptor[pos];
int size_code;
/*
* This is a Long Item. The next byte contains the
* length of the data section (value) for this key.
* See the HID specification, version 1.11, section
* 6.2.2.3, titled "Long Items."
*/
if ((key & 0xf0) == 0xf0) {
if (pos + 1 < size)
{
*data_len = report_descriptor[pos + 1];
*key_size = 3;
return 1;
}
*data_len = 0; /* malformed report */
*key_size = 0;
}
/*
* This is a Short Item. The bottom two bits of the
* key contain the size code for the data section
* (value) for this key. Refer to the HID
* specification, version 1.11, section 6.2.2.2,
* titled "Short Items."
*/
size_code = key & 0x3;
switch (size_code) {
case 0:
case 1:
case 2:
*data_len = size_code;
*key_size = 1;
return 1;
case 3:
*data_len = 4;
*key_size = 1;
return 1;
default:
/* Can't ever happen since size_code is & 0x3 */
*data_len = 0;
*key_size = 0;
break;
};
/* malformed report */
return 0;
}
/* uses_numbered_reports() returns 1 if report_descriptor describes a device
which contains numbered reports. */
static int uses_numbered_reports(__u8 *report_descriptor, __u32 size) {
unsigned int i = 0;
int data_len, key_size;
while (i < size) {
int key = report_descriptor[i];
/* Check for the Report ID key */
if (key == 0x85/*Report ID*/) {
/* This device has a Report ID, which means it uses
numbered reports. */
return 1;
}
/* Determine data_len and key_size */
if (!get_hid_item_size(report_descriptor, i, size, &data_len, &key_size))
return 0; /* malformed report */
/* Skip over this key and its associated data */
i += data_len + key_size;
}
/* Didn't find a Report ID key. Device doesn't use numbered reports. */
return 0;
}
/*
* Get bytes from a HID Report Descriptor.
* Only call with a num_bytes of 0, 1, 2, or 4.
*/
static __u32 get_hid_report_bytes(__u8 *rpt, size_t len, size_t num_bytes, size_t cur)
{
/* Return if there aren't enough bytes. */
if (cur + num_bytes >= len)
return 0;
if (num_bytes == 0)
return 0;
else if (num_bytes == 1)
return rpt[cur + 1];
else if (num_bytes == 2)
return (rpt[cur + 2] * 256 + rpt[cur + 1]);
else if (num_bytes == 4)
return (
rpt[cur + 4] * 0x01000000 +
rpt[cur + 3] * 0x00010000 +
rpt[cur + 2] * 0x00000100 +
rpt[cur + 1] * 0x00000001
);
else
return 0;
}
/*
* Retrieves the device's Usage Page and Usage from the report descriptor.
* The algorithm returns the current Usage Page/Usage pair whenever a new
* Collection is found and a Usage Local Item is currently in scope.
* Usage Local Items are consumed by each Main Item (See. 6.2.2.8).
* The algorithm should give similar results as Apple's:
* https://developer.apple.com/documentation/iokit/kiohiddeviceusagepairskey?language=objc
* Physical Collections are also matched (macOS does the same).
*
* This function can be called repeatedly until it returns non-0
* Usage is found. pos is the starting point (initially 0) and will be updated
* to the next search position.
*
* The return value is 0 when a pair is found.
* 1 when finished processing descriptor.
* -1 on a malformed report.
*/
static int get_next_hid_usage(__u8 *report_descriptor, __u32 size, unsigned int *pos, unsigned short *usage_page, unsigned short *usage)
{
int data_len, key_size;
int initial = *pos == 0; /* Used to handle case where no top-level application collection is defined */
int usage_pair_ready = 0;
/* Usage is a Local Item, it must be set before each Main Item (Collection) before a pair is returned */
int usage_found = 0;
while (*pos < size) {
int key = report_descriptor[*pos];
int key_cmd = key & 0xfc;
/* Determine data_len and key_size */
if (!get_hid_item_size(report_descriptor, *pos, size, &data_len, &key_size))
return -1; /* malformed report */
switch (key_cmd) {
case 0x4: /* Usage Page 6.2.2.7 (Global) */
*usage_page = get_hid_report_bytes(report_descriptor, size, data_len, *pos);
break;
case 0x8: /* Usage 6.2.2.8 (Local) */
*usage = get_hid_report_bytes(report_descriptor, size, data_len, *pos);
usage_found = 1;
break;
case 0xa0: /* Collection 6.2.2.4 (Main) */
/* A Usage Item (Local) must be found for the pair to be valid */
if (usage_found)
usage_pair_ready = 1;
/* Usage is a Local Item, unset it */
usage_found = 0;
break;
case 0x80: /* Input 6.2.2.4 (Main) */
case 0x90: /* Output 6.2.2.4 (Main) */
case 0xb0: /* Feature 6.2.2.4 (Main) */
case 0xc0: /* End Collection 6.2.2.4 (Main) */
/* Usage is a Local Item, unset it */
usage_found = 0;
break;
}
/* Skip over this key and its associated data */
*pos += data_len + key_size;
/* Return usage pair */
if (usage_pair_ready)
return 0;
}
/* If no top-level application collection is found and usage page/usage pair is found, pair is valid
https://docs.microsoft.com/en-us/windows-hardware/drivers/hid/top-level-collections */
if (initial && usage_found)
return 0; /* success */
return 1; /* finished processing */
}
/*
* Retrieves the hidraw report descriptor from a file.
* When using this form, <sysfs_path>/device/report_descriptor, elevated priviledges are not required.
*/
static int get_hid_report_descriptor(const char *rpt_path, struct hidraw_report_descriptor *rpt_desc)
{
int rpt_handle;
ssize_t res;
rpt_handle = open(rpt_path, O_RDONLY);
if (rpt_handle < 0) {
register_global_error_format("open failed (%s): %s", rpt_path, strerror(errno));
return -1;
}
/*
* Read in the Report Descriptor
* The sysfs file has a maximum size of 4096 (which is the same as HID_MAX_DESCRIPTOR_SIZE) so we should always
* be ok when reading the descriptor.
* In practice if the HID descriptor is any larger I suspect many other things will break.
*/
memset(rpt_desc, 0x0, sizeof(*rpt_desc));
res = read(rpt_handle, rpt_desc->value, HID_MAX_DESCRIPTOR_SIZE);
if (res < 0) {
register_global_error_format("read failed (%s): %s", rpt_path, strerror(errno));
}
rpt_desc->size = (__u32) res;
close(rpt_handle);
return (int) res;
}
static int get_hid_report_descriptor_from_sysfs(const char *sysfs_path, struct hidraw_report_descriptor *rpt_desc)
{
int res = -1;
/* Construct <sysfs_path>/device/report_descriptor */
size_t rpt_path_len = strlen(sysfs_path) + 25 + 1;
char* rpt_path = (char*) calloc(1, rpt_path_len);
snprintf(rpt_path, rpt_path_len, "%s/device/report_descriptor", sysfs_path);
res = get_hid_report_descriptor(rpt_path, rpt_desc);
free(rpt_path);
return res;
}
/*
* The caller is responsible for free()ing the (newly-allocated) character
* strings pointed to by serial_number_utf8 and product_name_utf8 after use.
*/
static int
parse_uevent_info(const char *uevent, unsigned *bus_type,
unsigned short *vendor_id, unsigned short *product_id,
char **serial_number_utf8, char **product_name_utf8)
{
char *tmp = strdup(uevent);
char *saveptr = NULL;
char *line;
char *key;
char *value;
int found_id = 0;
int found_serial = 0;
int found_name = 0;
line = strtok_r(tmp, "\n", &saveptr);
while (line != NULL) {
/* line: "KEY=value" */
key = line;
value = strchr(line, '=');
if (!value) {
goto next_line;
}
*value = '\0';
value++;
if (strcmp(key, "HID_ID") == 0) {
/**
* type vendor product
* HID_ID=0003:000005AC:00008242
**/
int ret = sscanf(value, "%x:%hx:%hx", bus_type, vendor_id, product_id);
if (ret == 3) {
found_id = 1;
}
} else if (strcmp(key, "HID_NAME") == 0) {
/* The caller has to free the product name */
*product_name_utf8 = strdup(value);
found_name = 1;
} else if (strcmp(key, "HID_UNIQ") == 0) {
/* The caller has to free the serial number */
*serial_number_utf8 = strdup(value);
found_serial = 1;
}
next_line:
line = strtok_r(NULL, "\n", &saveptr);
}
free(tmp);
return (found_id && found_name && found_serial);
}
static int get_device_string(hid_device *dev, enum device_string_id key, wchar_t *string, size_t maxlen)
{
struct udev *udev;
struct udev_device *udev_dev, *parent, *hid_dev;
struct stat s;
int ret = -1;
char *serial_number_utf8 = NULL;
char *product_name_utf8 = NULL;
/* Create the udev object */
udev = udev_new();
if (!udev) {
register_global_error("Couldn't create udev context");
return -1;
}
/* Get the dev_t (major/minor numbers) from the file handle. */
ret = fstat(dev->device_handle, &s);
if (-1 == ret)
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);
if (udev_dev) {
hid_dev = udev_device_get_parent_with_subsystem_devtype(
udev_dev,
"hid",
NULL);
if (hid_dev) {
unsigned short dev_vid;
unsigned short dev_pid;
unsigned bus_type;
size_t retm;
ret = parse_uevent_info(
udev_device_get_sysattr_value(hid_dev, "uevent"),
&bus_type,
&dev_vid,
&dev_pid,
&serial_number_utf8,
&product_name_utf8);
/* Standard USB device */
if (bus_type == BUS_USB) {
/* This is a USB device. Find its parent USB Device node. */
parent = udev_device_get_parent_with_subsystem_devtype(
udev_dev,
"usb",
"usb_device");
if (parent) {
const char *str;
const char *key_str = NULL;
if (key >= 0 && key < DEVICE_STRING_COUNT) {
key_str = device_string_names[key];
} else {
ret = -1;
goto end;
}
str = udev_device_get_sysattr_value(parent, key_str);
if (str) {
/* Convert the string from UTF-8 to wchar_t */
retm = mbstowcs(string, str, maxlen);
ret = (retm == (size_t)-1)? -1: 0;
}
/* USB information parsed */
goto end;
}
else {
/* Correctly handled below */
}
}
/* USB information not available (uhid) or another type of HID bus */
switch (bus_type) {
case BUS_BLUETOOTH:
case BUS_I2C:
case BUS_USB:
switch (key) {
case DEVICE_STRING_MANUFACTURER:
wcsncpy(string, L"", maxlen);
ret = 0;
break;
case DEVICE_STRING_PRODUCT:
retm = mbstowcs(string, product_name_utf8, maxlen);
ret = (retm == (size_t)-1)? -1: 0;
break;
case DEVICE_STRING_SERIAL:
retm = mbstowcs(string, serial_number_utf8, maxlen);
ret = (retm == (size_t)-1)? -1: 0;
break;
case DEVICE_STRING_COUNT:
default:
ret = -1;
break;
}
}
}
}
end:
free(serial_number_utf8);
free(product_name_utf8);
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);
return ret;
}
HID_API_EXPORT const struct hid_api_version* HID_API_CALL hid_version()
{
return &api_version;
}
HID_API_EXPORT const char* HID_API_CALL hid_version_str()
{
return HID_API_VERSION_STR;
}
int HID_API_EXPORT hid_init(void)
{
const char *locale;
/* Set the locale if it's not set. */
locale = setlocale(LC_CTYPE, NULL);
if (!locale)
setlocale(LC_CTYPE, "");
return 0;
}
int HID_API_EXPORT hid_exit(void)
{
/* Free global error message */
register_global_error(NULL);
return 0;
}
struct hid_device_info HID_API_EXPORT *hid_enumerate(unsigned short vendor_id, unsigned short product_id)
{
struct udev *udev;
struct udev_enumerate *enumerate;
struct udev_list_entry *devices, *dev_list_entry;
struct hid_device_info *root = NULL; /* return object */
struct hid_device_info *cur_dev = NULL;
struct hid_device_info *prev_dev = NULL; /* previous device */
hid_init();
/* Create the udev object */
udev = udev_new();
if (!udev) {
register_global_error("Couldn't create udev context");
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);
/* 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) {
const char *sysfs_path;
const char *dev_path;
const char *str;
struct udev_device *raw_dev; /* The device's hidraw udev node. */
struct udev_device *hid_dev; /* The device's HID udev node. */
struct udev_device *usb_dev; /* The device's USB udev node. */
struct udev_device *intf_dev; /* The device's interface (in the USB sense). */
unsigned short dev_vid;
unsigned short dev_pid;
char *serial_number_utf8 = NULL;
char *product_name_utf8 = NULL;
unsigned bus_type;
int result;
struct hidraw_report_descriptor report_desc;
/* 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);
hid_dev = udev_device_get_parent_with_subsystem_devtype(
raw_dev,
"hid",
NULL);
if (!hid_dev) {
/* Unable to find parent hid device. */
goto next;
}
result = parse_uevent_info(
udev_device_get_sysattr_value(hid_dev, "uevent"),
&bus_type,
&dev_vid,
&dev_pid,
&serial_number_utf8,
&product_name_utf8);
if (!result) {
/* parse_uevent_info() failed for at least one field. */
goto next;
}
/* Filter out unhandled devices right away */
switch (bus_type) {
case BUS_BLUETOOTH:
case BUS_I2C:
case BUS_USB:
break;
default:
goto next;
}
/* Check the VID/PID against the arguments */
if ((vendor_id == 0x0 || vendor_id == dev_vid) &&
(product_id == 0x0 || product_id == dev_pid)) {
struct hid_device_info *tmp;
/* VID/PID match. Create the record. */
tmp = (struct hid_device_info*) calloc(1, sizeof(struct hid_device_info));
if (cur_dev) {
cur_dev->next = tmp;
}
else {
root = tmp;
}
prev_dev = cur_dev;
cur_dev = tmp;
/* Fill out the record */
cur_dev->next = NULL;
cur_dev->path = dev_path? strdup(dev_path): NULL;
/* VID/PID */
cur_dev->vendor_id = dev_vid;
cur_dev->product_id = dev_pid;
/* Serial Number */
cur_dev->serial_number = utf8_to_wchar_t(serial_number_utf8);
/* Release Number */
cur_dev->release_number = 0x0;
/* Interface Number */
cur_dev->interface_number = -1;
switch (bus_type) {
case BUS_USB:
/* The device pointed to by raw_dev contains information about
the hidraw device. In order to get information about the
USB device, get the parent device with the
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(
raw_dev,
"usb",
"usb_device");
/* uhid USB devices
Since this is a virtual hid interface, no USB information will
be available. */
if (!usb_dev) {
/* Manufacturer and Product strings */
cur_dev->manufacturer_string = wcsdup(L"");
cur_dev->product_string = utf8_to_wchar_t(product_name_utf8);
break;
}
/* Manufacturer and Product strings */
cur_dev->manufacturer_string = copy_udev_string(usb_dev, device_string_names[DEVICE_STRING_MANUFACTURER]);
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");
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(
raw_dev,
"usb",
"usb_interface");
if (intf_dev) {
str = udev_device_get_sysattr_value(intf_dev, "bInterfaceNumber");
cur_dev->interface_number = (str)? strtol(str, NULL, 16): -1;
}
break;
case BUS_BLUETOOTH:
case BUS_I2C:
/* Manufacturer and Product strings */
cur_dev->manufacturer_string = wcsdup(L"");
cur_dev->product_string = utf8_to_wchar_t(product_name_utf8);
break;
default:
/* Unknown device type - this should never happen, as we
* check for USB and Bluetooth devices above */
break;
}
/* Usage Page and Usage */
result = get_hid_report_descriptor_from_sysfs(sysfs_path, &report_desc);
if (result >= 0) {
unsigned short page = 0, usage = 0;
unsigned int pos = 0;
/*
* Parse the first usage and usage page
* out of the report descriptor.
*/
if (!get_next_hid_usage(report_desc.value, report_desc.size, &pos, &page, &usage)) {
cur_dev->usage_page = page;
cur_dev->usage = usage;
}
/*
* Parse any additional usage and usage pages
* out of the report descriptor.
*/
while (!get_next_hid_usage(report_desc.value, report_desc.size, &pos, &page, &usage)) {
/* Create new record for additional usage pairs */
tmp = (struct hid_device_info*) calloc(1, sizeof(struct hid_device_info));
cur_dev->next = tmp;
prev_dev = cur_dev;
cur_dev = tmp;
/* Update fields */
cur_dev->path = strdup(dev_path);
cur_dev->vendor_id = dev_vid;
cur_dev->product_id = dev_pid;
cur_dev->serial_number = prev_dev->serial_number? wcsdup(prev_dev->serial_number): NULL;
cur_dev->release_number = prev_dev->release_number;
cur_dev->interface_number = prev_dev->interface_number;
cur_dev->manufacturer_string = prev_dev->manufacturer_string? wcsdup(prev_dev->manufacturer_string): NULL;
cur_dev->product_string = prev_dev->product_string? wcsdup(prev_dev->product_string): NULL;
cur_dev->usage_page = page;
cur_dev->usage = usage;
}
}
}
next:
free(serial_number_utf8);
free(product_name_utf8);
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);
return root;
}
void HID_API_EXPORT hid_free_enumeration(struct hid_device_info *devs)
{
struct hid_device_info *d = devs;
while (d) {
struct hid_device_info *next = d->next;
free(d->path);
free(d->serial_number);
free(d->manufacturer_string);
free(d->product_string);
free(d);
d = next;
}
}
hid_device * hid_open(unsigned short vendor_id, unsigned short product_id, const wchar_t *serial_number)
{
/* Set global error to none */
register_global_error(NULL);
struct hid_device_info *devs, *cur_dev;
const char *path_to_open = NULL;
hid_device *handle = NULL;
devs = hid_enumerate(vendor_id, product_id);
cur_dev = devs;
while (cur_dev) {
if (cur_dev->vendor_id == vendor_id &&
cur_dev->product_id == product_id) {
if (serial_number) {
if (wcscmp(serial_number, cur_dev->serial_number) == 0) {
path_to_open = cur_dev->path;
break;
}
}
else {
path_to_open = cur_dev->path;
break;
}
}
cur_dev = cur_dev->next;
}
if (path_to_open) {
/* Open the device */
handle = hid_open_path(path_to_open);
} else {
register_global_error("No such device");
}
hid_free_enumeration(devs);
return handle;
}
hid_device * HID_API_EXPORT hid_open_path(const char *path)
{
/* Set global error to none */
register_global_error(NULL);
hid_device *dev = NULL;
hid_init();
dev = new_hid_device();
/* OPEN HERE */
dev->device_handle = open(path, O_RDWR);
/* If we have a good handle, return it. */
if (dev->device_handle >= 0) {
/* Set device error to none */
register_device_error(dev, NULL);
/* Get the report descriptor */
int res, desc_size = 0;
struct hidraw_report_descriptor rpt_desc;
memset(&rpt_desc, 0x0, sizeof(rpt_desc));
/* Get Report Descriptor Size */
res = ioctl(dev->device_handle, HIDIOCGRDESCSIZE, &desc_size);
if (res < 0)
register_device_error_format(dev, "ioctl (GRDESCSIZE): %s", strerror(errno));
/* Get Report Descriptor */
rpt_desc.size = desc_size;
res = ioctl(dev->device_handle, HIDIOCGRDESC, &rpt_desc);
if (res < 0) {
register_device_error_format(dev, "ioctl (GRDESC): %s", strerror(errno));
} else {
/* Determine if this device uses numbered reports. */
dev->uses_numbered_reports =
uses_numbered_reports(rpt_desc.value,
rpt_desc.size);
}
return dev;
}
else {
/* Unable to open any devices. */
register_global_error(strerror(errno));
free(dev);
return NULL;
}
}
int HID_API_EXPORT hid_write(hid_device *dev, const unsigned char *data, size_t length)
{
int bytes_written;
if (!data || (length == 0)) {
errno = EINVAL;
register_device_error(dev, strerror(errno));
return -1;
}
bytes_written = write(dev->device_handle, data, length);
register_device_error(dev, (bytes_written == -1)? strerror(errno): NULL);
return bytes_written;
}
int HID_API_EXPORT hid_read_timeout(hid_device *dev, unsigned char *data, size_t length, int milliseconds)
{
/* Set device error to none */
register_device_error(dev, NULL);
int bytes_read;
if (milliseconds >= 0) {
/* Milliseconds is either 0 (non-blocking) or > 0 (contains
a valid timeout). In both cases we want to call poll()
and wait for data to arrive. Don't rely on non-blocking
operation (O_NONBLOCK) since some kernels don't seem to
properly report device disconnection through read() when
in non-blocking mode. */
int ret;