static void qemu_char_open(Chardev *chr, ChardevBackend *backend,
                           bool *be_opened, Error **errp)
{
    ChardevClass *cc = CHARDEV_GET_CLASS(chr);
    /* Any ChardevCommon member would work */
    ChardevCommon *common = backend ? backend->u.null.data : NULL;

    if (common && common->has_logfile) {
        int flags = O_WRONLY | O_CREAT;
        if (common->has_logappend &&
            common->logappend) {
            flags |= O_APPEND;
        } else {
            flags |= O_TRUNC;
        }
        chr->logfd = qemu_open(common->logfile, flags, 0666);
        if (chr->logfd < 0) {
            error_setg_errno(errp, errno,
                             "Unable to open logfile %s",
                             common->logfile);
            return;
        }
    }

    if (cc->open) {
        cc->open(chr, backend, be_opened, errp);
    }
}

static void write_pidfile(void)
{
    int pidfd;
    char pidstr[32];

    pidfd = qemu_open(pidfile, O_CREAT|O_WRONLY, S_IRUSR|S_IWUSR);
    if (pidfd == -1) {
        error_report("Cannot open pid file, %s", strerror(errno));
        exit(EXIT_FAILURE);
    }

    if (lockf(pidfd, F_TLOCK, 0)) {
        error_report("Cannot lock pid file, %s", strerror(errno));
        goto fail;
    }
    if (ftruncate(pidfd, 0)) {
        error_report("Failed to truncate pid file");
        goto fail;
    }

    snprintf(pidstr, sizeof(pidstr), "%d\n", getpid());
    if (write(pidfd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
        error_report("Failed to write pid file");
        goto fail;
    }
    return;

fail:
    unlink(pidfile);
    close(pidfd);
    exit(EXIT_FAILURE);
}

static int raw_create(const char *filename, QEMUOptionParameter *options)
{
    int fd;
    int result = 0;
    int64_t total_size = 0;

    /* Read out options */
    while (options && options->name) {
        if (!strcmp(options->name, BLOCK_OPT_SIZE)) {
            total_size = options->value.n / BDRV_SECTOR_SIZE;
        }
        options++;
    }

    fd = qemu_open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,
                   0644);
    if (fd < 0) {
        result = -errno;
    } else {
        if (ftruncate(fd, total_size * BDRV_SECTOR_SIZE) != 0) {
            result = -errno;
        }
        if (qemu_close(fd) != 0) {
            result = -errno;
        }
    }
    return result;
}

static int floppy_probe_device(const char *filename)
{
    int fd, ret;
    int prio = 0;
    struct floppy_struct fdparam;
    struct stat st;

    if (strstart(filename, "/dev/fd", NULL) &&
        !strstart(filename, "/dev/fdset/", NULL)) {
        prio = 50;
    }

    fd = qemu_open(filename, O_RDONLY | O_NONBLOCK);
    if (fd < 0) {
        goto out;
    }
    ret = fstat(fd, &st);
    if (ret == -1 || !S_ISBLK(st.st_mode)) {
        goto outc;
    }

    /* Attempt to detect via a floppy specific ioctl */
    ret = ioctl(fd, FDGETPRM, &fdparam);
    if (ret >= 0)
        prio = 100;

outc:
    qemu_close(fd);
out:
    return prio;
}

static int rtc_start_timer(struct qemu_alarm_timer *t)
{
    int rtc_fd;
    unsigned long current_rtc_freq = 0;

    TFR(rtc_fd = qemu_open("/dev/rtc", O_RDONLY));
    if (rtc_fd < 0)
        return -1;
    ioctl(rtc_fd, RTC_IRQP_READ, &current_rtc_freq);
    if (current_rtc_freq != RTC_FREQ &&
        ioctl(rtc_fd, RTC_IRQP_SET, RTC_FREQ) < 0) {
        fprintf(stderr, "Could not configure '/dev/rtc' to have a 1024 Hz timer. This is not a fatal\n"
                "error, but for better emulation accuracy either use a 2.6 host Linux kernel or\n"
                "type 'echo 1024 > /proc/sys/dev/rtc/max-user-freq' as root.\n");
        goto fail;
    }
    if (ioctl(rtc_fd, RTC_PIE_ON, 0) < 0) {
    fail:
        close(rtc_fd);
        return -1;
    }

    enable_sigio_timer(rtc_fd);

    t->priv = (void *)(long)rtc_fd;

    return 0;
}

static bool ga_open_pidfile(const char *pidfile)
{
    int pidfd;
    char pidstr[32];

    pidfd = qemu_open(pidfile, O_CREAT|O_WRONLY, S_IRUSR|S_IWUSR);
    if (pidfd == -1 || lockf(pidfd, F_TLOCK, 0)) {
        g_critical("Cannot lock pid file, %s", strerror(errno));
        if (pidfd != -1) {
            close(pidfd);
        }
        return false;
    }

    if (ftruncate(pidfd, 0)) {
        g_critical("Failed to truncate pid file");
        goto fail;
    }
    snprintf(pidstr, sizeof(pidstr), "%d\n", getpid());
    if (write(pidfd, pidstr, strlen(pidstr)) != strlen(pidstr)) {
        g_critical("Failed to write pid file");
        goto fail;
    }

    /* keep pidfile open & locked forever */
    return true;

fail:
    unlink(pidfile);
    close(pidfd);
    return false;
}

int qemu_create_pidfile(const char *filename)
{
    char buffer[128];
    int len;
    int fd;

    fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
    if (fd == -1) {
        return -1;
    }
#ifndef __ANDROID__
    if (lockf(fd, F_TLOCK, 0) == -1) {
        close(fd);
        return -1;
    }
    len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
    if (write(fd, buffer, len) != len) {
        close(fd);
        return -1;
    }
#endif // __ANDROID__

    /* keep pidfile open & locked forever */
    return 0;
}

static int hdev_create(const char *filename, QEMUOptionParameter *options)
{
    int fd;
    int ret = 0;
    struct stat stat_buf;
    int64_t total_size = 0;

    /* Read out options */
    while (options && options->name) {
        if (!strcmp(options->name, "size")) {
            total_size = options->value.n / BDRV_SECTOR_SIZE;
        }
        options++;
    }

    fd = qemu_open(filename, O_WRONLY | O_BINARY);
    if (fd < 0)
        return -errno;

    if (fstat(fd, &stat_buf) < 0)
        ret = -errno;
    else if (!S_ISBLK(stat_buf.st_mode) && !S_ISCHR(stat_buf.st_mode))
        ret = -ENODEV;
    else if (lseek(fd, 0, SEEK_END) < total_size * BDRV_SECTOR_SIZE)
        ret = -ENOSPC;

    qemu_close(fd);
    return ret;
}

static int cdrom_probe_device(const char *filename)
{
    int fd, ret;
    int prio = 0;
    struct stat st;

    fd = qemu_open(filename, O_RDONLY | O_NONBLOCK);
    if (fd < 0) {
        goto out;
    }
    ret = fstat(fd, &st);
    if (ret == -1 || !S_ISBLK(st.st_mode)) {
        goto outc;
    }

    /* Attempt to detect via a CDROM specific ioctl */
    ret = ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
    if (ret >= 0)
        prio = 100;

outc:
    qemu_close(fd);
out:
    return prio;
}

static int raw_open_common(BlockDriverState *bs, QDict *options,
                           int bdrv_flags, int open_flags)
{
    BDRVRawState *s = bs->opaque;
    QemuOpts *opts;
    Error *local_err = NULL;
    const char *filename;
    int fd, ret;

    opts = qemu_opts_create_nofail(&raw_runtime_opts);
    qemu_opts_absorb_qdict(opts, options, &local_err);
    if (error_is_set(&local_err)) {
        qerror_report_err(local_err);
        error_free(local_err);
        ret = -EINVAL;
        goto fail;
    }

    filename = qemu_opt_get(opts, "filename");

    ret = raw_normalize_devicepath(&filename);
    if (ret != 0) {
        goto fail;
    }

    s->open_flags = open_flags;
    raw_parse_flags(bdrv_flags, &s->open_flags);

    s->fd = -1;
    fd = qemu_open(filename, s->open_flags, 0644);
    if (fd < 0) {
        ret = -errno;
        if (ret == -EROFS) {
            ret = -EACCES;
        }
        goto fail;
    }
    s->fd = fd;

#ifdef CONFIG_LINUX_AIO
    if (raw_set_aio(&s->aio_ctx, &s->use_aio, bdrv_flags)) {
        qemu_close(fd);
        ret = -errno;
        goto fail;
    }
#endif

    s->has_discard = 1;
#ifdef CONFIG_XFS
    if (platform_test_xfs_fd(s->fd)) {
        s->is_xfs = 1;
    }
#endif

    ret = 0;
fail:
    qemu_opts_del(opts);
    return ret;
}

int qmp_chardev_open_file_source(char *src, int flags, Error **errp)
{
    int fd = -1;

    TFR(fd = qemu_open(src, flags, 0666));
    if (fd == -1) {
        error_setg_file_open(errp, errno, src);
    }
    return fd;
}

static void rng_random_opened(RngBackend *b, Error **errp)
{
    RndRandom *s = RNG_RANDOM(b);

    if (s->filename == NULL) {
        error_set(errp, QERR_INVALID_PARAMETER_VALUE,
                  "filename", "a valid filename");
    } else {
        s->fd = qemu_open(s->filename, O_RDONLY | O_NONBLOCK);
        if (s->fd == -1) {
            error_setg_file_open(errp, errno, s->filename);
        }
    }
}

/*
 * Unless path or file descriptor set has been provided by user,
 * determine the sysfs cancel file following kernel documentation
 * in Documentation/ABI/stable/sysfs-class-tpm.
 * From /dev/tpm0 create /sys/class/misc/tpm0/device/cancel
 */
static int tpm_passthrough_open_sysfs_cancel(TPMBackend *tb)
{
    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
    int fd = -1;
    char *dev;
    char path[PATH_MAX];

    if (tb->cancel_path) {
        fd = qemu_open(tb->cancel_path, O_WRONLY);
        if (fd < 0) {
            error_report("Could not open TPM cancel path : %s",
                         strerror(errno));
        }
        return fd;
    }

    dev = strrchr(tpm_pt->tpm_dev, '/');
    if (dev) {
        dev++;
        if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
                     dev) < sizeof(path)) {
            fd = qemu_open(path, O_WRONLY);
            if (fd >= 0) {
                tb->cancel_path = g_strdup(path);
            } else {
                error_report("tpm_passthrough: Could not open TPM cancel "
                             "path %s : %s", path, strerror(errno));
            }
        }
    } else {
       error_report("tpm_passthrough: Bad TPM device path %s",
                    tpm_pt->tpm_dev);
    }

    return fd;
}

static void floppy_eject(BlockDriverState *bs, bool eject_flag)
{
    BDRVRawState *s = bs->opaque;
    int fd;

    if (s->fd >= 0) {
        qemu_close(s->fd);
        s->fd = -1;
    }
    fd = qemu_open(bs->filename, s->open_flags | O_NONBLOCK);
    if (fd >= 0) {
        if (ioctl(fd, FDEJECT, 0) < 0)
            perror("FDEJECT");
        qemu_close(fd);
    }
}

static int tpm_passthrough_handle_device_opts(QemuOpts *opts, TPMBackend *tb)
{
    TPMPassthruState *tpm_pt = TPM_PASSTHROUGH(tb);
    const char *value;

    value = qemu_opt_get(opts, "cancel-path");
    if (value) {
        tb->cancel_path = g_strdup(value);
    }

    value = qemu_opt_get(opts, "path");
    if (!value) {
        value = TPM_PASSTHROUGH_DEFAULT_DEVICE;
    }

    tpm_pt->tpm_dev = g_strdup(value);

    tb->path = g_strdup(tpm_pt->tpm_dev);

    tpm_pt->tpm_fd = qemu_open(tpm_pt->tpm_dev, O_RDWR);
    if (tpm_pt->tpm_fd < 0) {
        error_report("Cannot access TPM device using '%s': %s\n",
                     tpm_pt->tpm_dev, strerror(errno));
        goto err_free_parameters;
    }

    if (tpm_passthrough_test_tpmdev(tpm_pt->tpm_fd)) {
        error_report("'%s' is not a TPM device.\n",
                     tpm_pt->tpm_dev);
        goto err_close_tpmdev;
    }

    return 0;

 err_close_tpmdev:
    qemu_close(tpm_pt->tpm_fd);
    tpm_pt->tpm_fd = -1;

 err_free_parameters:
    g_free(tb->path);
    tb->path = NULL;

    g_free(tpm_pt->tpm_dev);
    tpm_pt->tpm_dev = NULL;

    return 1;
}

int qemu_create_pidfile(const char *filename)
{
    char buffer[128];
    int len;
#ifndef _WIN32
    int fd;

    fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
    if (fd == -1)
        return -1;

    if (lockf(fd, F_TLOCK, 0) == -1)
        return -1;

    len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid());
    if (write(fd, buffer, len) != len)
        return -1;
#else
    HANDLE file;
    DWORD flags;
    OVERLAPPED overlap;
    BOOL ret;

    /* Open for writing with no sharing. */
    file = CreateFile(filename, GENERIC_WRITE, 0, NULL,
		      OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

    if (file == INVALID_HANDLE_VALUE)
      return -1;

    flags = LOCKFILE_EXCLUSIVE_LOCK | LOCKFILE_FAIL_IMMEDIATELY;
    overlap.hEvent = 0;
    /* Lock 1 byte. */
    ret = LockFileEx(file, flags, 0, 0, 1, &overlap);
    if (ret == 0)
      return -1;

    /* Write PID to file. */
    len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid());
    ret = WriteFileEx(file, (LPCVOID)buffer, (DWORD)len,
		      &overlap, NULL);
    if (ret == 0)
      return -1;
#endif
    return 0;
}

static int hdev_open(BlockDriverState *bs, const char *filename, int flags)
{
    BDRVRawState *s = bs->opaque;

#if defined(__APPLE__) && defined(__MACH__)
    if (strstart(filename, "/dev/cdrom", NULL)) {
        kern_return_t kernResult;
        io_iterator_t mediaIterator;
        char bsdPath[ MAXPATHLEN ];
        int fd;

        kernResult = FindEjectableCDMedia( &mediaIterator );
        kernResult = GetBSDPath( mediaIterator, bsdPath, sizeof( bsdPath ) );

        if ( bsdPath[ 0 ] != '\0' ) {
            strcat(bsdPath,"s0");
            /* some CDs don't have a partition 0 */
            fd = qemu_open(bsdPath, O_RDONLY | O_BINARY | O_LARGEFILE);
            if (fd < 0) {
                bsdPath[strlen(bsdPath)-1] = '1';
            } else {
                qemu_close(fd);
            }
            filename = bsdPath;
        }

        if ( mediaIterator )
            IOObjectRelease( mediaIterator );
    }
#endif

    s->type = FTYPE_FILE;
#if defined(__linux__)
    {
        char resolved_path[ MAXPATHLEN ], *temp;

        temp = realpath(filename, resolved_path);
        if (temp && strstart(temp, "/dev/sg", NULL)) {
            bs->sg = 1;
        }
    }
#endif

    return raw_open_common(bs, filename, flags, 0);
}

/* Note: we do not have a reliable method to detect if the floppy is
   present. The current method is to try to open the floppy at every
   I/O and to keep it opened during a few hundreds of ms. */
static int fd_open(BlockDriverState *bs)
{
    BDRVRawState *s = bs->opaque;
    int last_media_present;

    if (s->type != FTYPE_FD)
        return 0;
    last_media_present = (s->fd >= 0);
    if (s->fd >= 0 &&
        (get_clock() - s->fd_open_time) >= FD_OPEN_TIMEOUT) {
        qemu_close(s->fd);
        s->fd = -1;
#ifdef DEBUG_FLOPPY
        printf("Floppy closed\n");
#endif
    }
    if (s->fd < 0) {
        if (s->fd_got_error &&
            (get_clock() - s->fd_error_time) < FD_OPEN_TIMEOUT) {
#ifdef DEBUG_FLOPPY
            printf("No floppy (open delayed)\n");
#endif
            return -EIO;
        }
        s->fd = qemu_open(bs->filename, s->open_flags & ~O_NONBLOCK);
        if (s->fd < 0) {
            s->fd_error_time = get_clock();
            s->fd_got_error = 1;
            if (last_media_present)
                s->fd_media_changed = 1;
#ifdef DEBUG_FLOPPY
            printf("No floppy\n");
#endif
            return -EIO;
        }
#ifdef DEBUG_FLOPPY
        printf("Floppy opened\n");
#endif
    }
    if (!last_media_present)
        s->fd_media_changed = 1;
    s->fd_open_time = get_clock();
    s->fd_got_error = 0;
    return 0;
}

int qemu_create_pidfile(const char *filename)
{
    char buffer[128];
    int len;
    int fd;

    fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
    if (fd == -1) {
        return -1;
    }
    if (lockf(fd, F_TLOCK, 0) == -1) {
        return -1;
    }
    len = snprintf(buffer, sizeof(buffer), "%ld\n", (long)getpid());
    if (write(fd, buffer, len) != len) {
        return -1;
    }

    return 0;
}

static int hpet_start_timer(struct qemu_alarm_timer *t)
{
    struct hpet_info info;
    int r, fd;

    fd = qemu_open("/dev/hpet", O_RDONLY);
    if (fd < 0)
        return -1;

    /* Set frequency */
    r = ioctl(fd, HPET_IRQFREQ, RTC_FREQ);
    if (r < 0) {
        fprintf(stderr, "Could not configure '/dev/hpet' to have a 1024Hz timer. This is not a fatal\n"
                "error, but for better emulation accuracy type:\n"
                "'echo 1024 > /proc/sys/dev/hpet/max-user-freq' as root.\n");
        goto fail;
    }

    /* Check capabilities */
    r = ioctl(fd, HPET_INFO, &info);
    if (r < 0)
        goto fail;

    /* Enable periodic mode */
    r = ioctl(fd, HPET_EPI, 0);
    if (info.hi_flags && (r < 0))
        goto fail;

    /* Enable interrupt */
    r = ioctl(fd, HPET_IE_ON, 0);
    if (r < 0)
        goto fail;

    enable_sigio_timer(fd);
    t->priv = (void *)(long)fd;

    return 0;
fail:
    close(fd);
    return -1;
}