libusb1/linux_google.c

/*
 * Linux-specific functions for libusb.
 */

#include "libusbi.h"

extern int sysfs_can_relate_devices;
extern int linux_get_device_address(
    struct libusb_context *ctx, int detached,
    uint8_t *busnum, uint8_t *devaddr,const char *dev_node,
    const char *sys_name);
extern int linux_enumerate_device(
    struct libusb_context *ctx,
    uint8_t busnum, uint8_t devaddr, const char *sysfs_dir);

/**
 * Returns a USB device currently attached to the system. This is
 * your entry point into connecting to that USB device.
 *
 * This return value of this function indicates whether the device was found or
 * not. Success is a 0, other values indicate failure.
 *
 * \param ctx the context to operate on, or NULL for the default context
 * \param devname SYSFS device name to check
 * \param device output location for the device. Must be later freed with
 * libusb_unref_device().
 * \returns 0 for success.
 * \ref libusb_error according to errors encountered by the backend.
 */
int libusb_ext_get_one_device(libusb_context *ctx, const char* devname,
                              libusb_device **device)
{
  if (!sysfs_can_relate_devices) {
    return LIBUSB_ERROR_NOT_SUPPORTED;
  }

  int r = 0;
  uint8_t busnum, devaddr;
  USBI_GET_CONTEXT(ctx);

  r = linux_get_device_address (ctx, 0, &busnum, &devaddr, NULL, devname);
  if (r < 0) {
    return r;
  }

  r = linux_enumerate_device(ctx, busnum & 0xff, devaddr & 0xff, devname);
  if (r < 0) {
    return r;
  }

  struct libusb_device *it;
  usbi_mutex_lock(&ctx->usb_devs_lock);
  list_for_each_entry(it, &ctx->usb_devs, list, struct libusb_device) {
    if (it->bus_number == busnum && it->device_address == devaddr) {
      *device = it;
    }
  }
  usbi_mutex_unlock(&ctx->usb_devs_lock);

  return LIBUSB_SUCCESS;
}