systemd/src/libudev-device-private.c

/*
 * libudev - interface to udev device information
 *
 * Copyright (C) 2008-2010 Kay Sievers <kay.sievers@vrfy.org>
 *
 * This library 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.
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stddef.h>
#include <stdbool.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>

#include "libudev.h"
#include "libudev-private.h"

static void udev_device_tag(struct udev_device *dev, const char *tag, bool add)
{
        const char *id;
        struct udev *udev = udev_device_get_udev(dev);
        char filename[UTIL_PATH_SIZE];

        id = udev_device_get_id_filename(dev);
        if (id == NULL)
                return;
        util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev), "/tags/", tag, "/", id, NULL);

        if (add) {
                int fd;

                util_create_path(udev, filename);
                fd = open(filename, O_WRONLY|O_CREAT|O_CLOEXEC|O_TRUNC|O_NOFOLLOW, 0444);
                if (fd >= 0)
                        close(fd);
        } else {
                unlink(filename);
        }
}

int udev_device_tag_index(struct udev_device *dev, struct udev_device *dev_old, bool add)
{
        struct udev_list_entry *list_entry;
        bool found;

        if (add && dev_old != NULL) {
                /* delete possible left-over tags */
                udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(dev_old)) {
                        const char *tag_old = udev_list_entry_get_name(list_entry);
                        struct udev_list_entry *list_entry_current;

                        found = false;
                        udev_list_entry_foreach(list_entry_current, udev_device_get_tags_list_entry(dev)) {
                                const char *tag = udev_list_entry_get_name(list_entry_current);

                                if (strcmp(tag, tag_old) == 0) {
                                        found = true;
                                        break;
                                }
                        }
                        if (!found)
                                udev_device_tag(dev_old, tag_old, false);
                }
        }

        udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(dev))
                udev_device_tag(dev, udev_list_entry_get_name(list_entry), add);

        return 0;
}

static bool device_has_info(struct udev_device *udev_device)
{
        struct udev_list_entry *list_entry;

        if (udev_device_get_devlinks_list_entry(udev_device) != NULL)
                return true;
        if (udev_device_get_devlink_priority(udev_device) != 0)
                return true;
        udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(udev_device))
                if (udev_list_entry_get_num(list_entry))
                        return true;
        if (udev_device_get_tags_list_entry(udev_device) != NULL)
                return true;
        if (udev_device_get_watch_handle(udev_device) >= 0)
                return true;
        return false;
}

int udev_device_update_db(struct udev_device *udev_device)
{
        bool has_info;
        const char *id;
        struct udev *udev = udev_device_get_udev(udev_device);
        char filename[UTIL_PATH_SIZE];
        char filename_tmp[UTIL_PATH_SIZE];
        FILE *f;

        id = udev_device_get_id_filename(udev_device);
        if (id == NULL)
                return -1;

        has_info = device_has_info(udev_device);
        util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev), "/data/", id, NULL);

        /* do not store anything for otherwise empty devices */
        if (!has_info &&
            major(udev_device_get_devnum(udev_device)) == 0 &&
            udev_device_get_ifindex(udev_device) == 0) {
                unlink(filename);
                return 0;
        }

        /* write a database file */
        util_strscpyl(filename_tmp, sizeof(filename_tmp), filename, ".tmp", NULL);
        util_create_path(udev, filename_tmp);
        f = fopen(filename_tmp, "we");
        if (f == NULL) {
                err(udev, "unable to create temporary db file '%s': %m\n", filename_tmp);
                return -1;
        }

        /*
         * set 'sticky' bit to indicate that we should not clean the
         * database when we transition from initramfs to the real root
         */
        if (udev_device_get_db_persist(udev_device))
                fchmod(fileno(f), 01644);

        if (has_info) {
                struct udev_list_entry *list_entry;

                if (major(udev_device_get_devnum(udev_device)) > 0) {
                        size_t devlen = strlen(udev_get_dev_path(udev))+1;

                        udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(udev_device))
                                fprintf(f, "S:%s\n", &udev_list_entry_get_name(list_entry)[devlen]);
                        if (udev_device_get_devlink_priority(udev_device) != 0)
                                fprintf(f, "L:%i\n", udev_device_get_devlink_priority(udev_device));
                        if (udev_device_get_watch_handle(udev_device) >= 0)
                                fprintf(f, "W:%i\n", udev_device_get_watch_handle(udev_device));
                }

                if (udev_device_get_usec_initialized(udev_device) > 0)
                        fprintf(f, "I:%llu\n", udev_device_get_usec_initialized(udev_device));

                udev_list_entry_foreach(list_entry, udev_device_get_properties_list_entry(udev_device)) {
                        if (!udev_list_entry_get_num(list_entry))
                                continue;
                        fprintf(f, "E:%s=%s\n",
                                udev_list_entry_get_name(list_entry),
                                udev_list_entry_get_value(list_entry));
                }

                udev_list_entry_foreach(list_entry, udev_device_get_tags_list_entry(udev_device))
                        fprintf(f, "G:%s\n", udev_list_entry_get_name(list_entry));
        }

        fclose(f);
        rename(filename_tmp, filename);
        info(udev, "created %s file '%s' for '%s'\n", has_info ? "db" : "empty",
             filename, udev_device_get_devpath(udev_device));
        return 0;
}

int udev_device_delete_db(struct udev_device *udev_device)
{
        const char *id;
        struct udev *udev = udev_device_get_udev(udev_device);
        char filename[UTIL_PATH_SIZE];

        id = udev_device_get_id_filename(udev_device);
        if (id == NULL)
                return -1;
        util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev), "/data/", id, NULL);
        unlink(filename);
        return 0;
}