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1130 lines (946 loc) · 29.6 KB
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/*******************************************************
HIDAPI - Multi-Platform library for
communication with HID devices.
Alan Ott
Signal 11 Software
8/22/2009
Linux Version - 6/2/2009
Copyright 2009, 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
/* 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 it's 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 it's 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;
struct pollfd fds;
fds.fd = dev->device_handle;
fds.events = POLLIN;
fds.revents = 0;
ret = poll(&fds, 1, milliseconds);
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