Merge "Don't write to /sys/class/android_usb/android0/enable with configfs." am: 7cb1b796

#include <sys/wait.h>

#include <unistd.h>

#include <android-base/file.h>

#include <android-base/logging.h>

#include <android-base/properties.h>

#include <android-base/unique_fd.h>

#include "common.h"

#include "fuse_sideload.h"

#include "ui.h"

static void set_usb_driver(bool enabled) {

  int fd = open("/sys/class/android_usb/android0/enable", O_WRONLY);

  if (fd < 0) {

    ui->Print("failed to open driver control: %s\n", strerror(errno));

  // USB configfs doesn't use /s/c/a/a/enable.

  if (android::base::GetBoolProperty("sys.usb.configfs", false)) {

    return;

  }

  if (TEMP_FAILURE_RETRY(write(fd, enabled ? "1" : "0", 1)) == -1) {

    ui->Print("failed to set driver control: %s\n", strerror(errno));

  static constexpr const char* USB_DRIVER_CONTROL = "/sys/class/android_usb/android0/enable";

  android::base::unique_fd fd(open(USB_DRIVER_CONTROL, O_WRONLY));

  if (fd == -1) {

    PLOG(ERROR) << "Failed to open driver control";

    return;

  }

  if (close(fd) < 0) {

    ui->Print("failed to close driver control: %s\n", strerror(errno));

  // Not using android::base::WriteStringToFile since that will open with O_CREAT and give EPERM

  // when USB_DRIVER_CONTROL doesn't exist. When it gives EPERM, we don't know whether that's due

  // to non-existent USB_DRIVER_CONTROL or indeed a permission issue.

  if (!android::base::WriteStringToFd(enabled ? "1" : "0", fd)) {

    PLOG(ERROR) << "Failed to set driver control";

  }

}