src/libudev/libudev.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  This file is part of systemd.

  Copyright 2008-2014 Kay Sievers <kay@vrfy.org>

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <ctype.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "libudev.h"

#include "alloc-util.h"
#include "fd-util.h"
#include "libudev-private.h"
#include "missing.h"
#include "string-util.h"

/**
 * SECTION:libudev
 * @short_description: libudev context
 *
 * The context contains the default values read from the udev config file,
 * and is passed to all library operations.
 */

/**
 * udev:
 *
 * Opaque object representing the library context.
 */
struct udev {
        int refcount;
        void (*log_fn)(struct udev *udev,
                       int priority, const char *file, int line, const char *fn,
                       const char *format, va_list args);
        void *userdata;
};

/**
 * udev_get_userdata:
 * @udev: udev library context
 *
 * Retrieve stored data pointer from library context. This might be useful
 * to access from callbacks.
 *
 * Returns: stored userdata
 **/
_public_ void *udev_get_userdata(struct udev *udev) {
        if (udev == NULL)
                return NULL;
        return udev->userdata;
}

/**
 * udev_set_userdata:
 * @udev: udev library context
 * @userdata: data pointer
 *
 * Store custom @userdata in the library context.
 **/
_public_ void udev_set_userdata(struct udev *udev, void *userdata) {
        if (udev == NULL)
                return;
        udev->userdata = userdata;
}

/**
 * udev_new:
 *
 * Create udev library context. This reads the udev configuration
 * file, and fills in the default values.
 *
 * The initial refcount is 1, and needs to be decremented to
 * release the resources of the udev library context.
 *
 * Returns: a new udev library context
 **/
_public_ struct udev *udev_new(void) {
        struct udev *udev;

        udev = new0(struct udev, 1);
        if (!udev) {
                errno = ENOMEM;
                return NULL;
        }
        udev->refcount = 1;

        return udev;
}

/**
 * udev_ref:
 * @udev: udev library context
 *
 * Take a reference of the udev library context.
 *
 * Returns: the passed udev library context
 **/
_public_ struct udev *udev_ref(struct udev *udev) {
        if (udev == NULL)
                return NULL;
        udev->refcount++;
        return udev;
}

/**
 * udev_unref:
 * @udev: udev library context
 *
 * Drop a reference of the udev library context. If the refcount
 * reaches zero, the resources of the context will be released.
 *
 * Returns: the passed udev library context if it has still an active reference, or #NULL otherwise.
 **/
_public_ struct udev *udev_unref(struct udev *udev) {
        if (udev == NULL)
                return NULL;
        udev->refcount--;
        if (udev->refcount > 0)
                return udev;
        return mfree(udev);
}

/**
 * udev_set_log_fn:
 * @udev: udev library context
 * @log_fn: function to be called for log messages
 *
 * This function is deprecated.
 *
 **/
_public_ void udev_set_log_fn(struct udev *udev,
                     void (*log_fn)(struct udev *udev,
                                    int priority, const char *file, int line, const char *fn,
                                    const char *format, va_list args)) {
        return;
}

/**
 * udev_get_log_priority:
 * @udev: udev library context
 *
 * This function is deprecated.
 *
 **/
_public_ int udev_get_log_priority(struct udev *udev) {
        return log_get_max_level();
}

/**
 * udev_set_log_priority:
 * @udev: udev library context
 * @priority: the new log priority
 *
 * This function is deprecated.
 *
 **/
_public_ void udev_set_log_priority(struct udev *udev, int priority) {
        log_set_max_level(priority);
}