src/udev/udev-builtin-path_id.c

/*
 * compose persistent device path
 *
 * Copyright (C) 2009-2011 Kay Sievers <kay@vrfy.org>
 *
 * Logic based on Hannes Reinecke's shell script.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <fcntl.h>
#include <errno.h>
#include <dirent.h>
#include <getopt.h>

#include "udev.h"

static int path_prepend(char **path, const char *fmt, ...)
{
        va_list va;
        char *pre;
        int err = 0;

        va_start(va, fmt);
        err = vasprintf(&pre, fmt, va);
        va_end(va);
        if (err < 0)
                goto out;

        if (*path != NULL) {
                char *new;

                err = asprintf(&new, "%s-%s", pre, *path);
                free(pre);
                if (err < 0)
                        goto out;
                free(*path);
                *path = new;
        } else {
                *path = pre;
        }
out:
        return err;
}

/*
** Linux only supports 32 bit luns.
** See drivers/scsi/scsi_scan.c::scsilun_to_int() for more details.
*/
static int format_lun_number(struct udev_device *dev, char **path)
{
        unsigned long lun = strtoul(udev_device_get_sysnum(dev), NULL, 10);

        /* address method 0, peripheral device addressing with bus id of zero */
        if (lun < 256)
                return path_prepend(path, "lun-%d", lun);
        /* handle all other lun addressing methods by using a variant of the original lun format */
        return path_prepend(path, "lun-0x%04x%04x00000000", (lun & 0xffff), (lun >> 16) & 0xffff);
}

static struct udev_device *skip_subsystem(struct udev_device *dev, const char *subsys)
{
        struct udev_device *parent = dev;

        while (parent != NULL) {
                const char *subsystem;

                subsystem = udev_device_get_subsystem(parent);
                if (subsystem == NULL || !streq(subsystem, subsys))
                        break;
                dev = parent;
                parent = udev_device_get_parent(parent);
        }
        return dev;
}

static struct udev_device *handle_scsi_fibre_channel(struct udev_device *parent, char **path)
{
        struct udev *udev  = udev_device_get_udev(parent);
        struct udev_device *targetdev;
        struct udev_device *fcdev = NULL;
        const char *port;
        char *lun = NULL;

        targetdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_target");
        if (targetdev == NULL)
                return NULL;

        fcdev = udev_device_new_from_subsystem_sysname(udev, "fc_transport", udev_device_get_sysname(targetdev));
        if (fcdev == NULL)
                return NULL;
        port = udev_device_get_sysattr_value(fcdev, "port_name");
        if (port == NULL) {
                parent = NULL;
                goto out;
        }

        format_lun_number(parent, &lun);
        path_prepend(path, "fc-%s-%s", port, lun);
        if (lun)
                free(lun);
out:
        udev_device_unref(fcdev);
        return parent;
}

static struct udev_device *handle_scsi_sas(struct udev_device *parent, char **path)
{
        struct udev *udev  = udev_device_get_udev(parent);
        struct udev_device *targetdev;
        struct udev_device *target_parent;
        struct udev_device *sasdev;
        const char *sas_address;
        char *lun = NULL;

        targetdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_target");
        if (targetdev == NULL)
                return NULL;

        target_parent = udev_device_get_parent(targetdev);
        if (target_parent == NULL)
                return NULL;

        sasdev = udev_device_new_from_subsystem_sysname(udev, "sas_device",
                                udev_device_get_sysname(target_parent));
        if (sasdev == NULL)
                return NULL;

        sas_address = udev_device_get_sysattr_value(sasdev, "sas_address");
        if (sas_address == NULL) {
                parent = NULL;
                goto out;
        }

        format_lun_number(parent, &lun);
        path_prepend(path, "sas-%s-%s", sas_address, lun);
        if (lun)
                free(lun);
out:
        udev_device_unref(sasdev);
        return parent;
}

static struct udev_device *handle_scsi_iscsi(struct udev_device *parent, char **path)
{
        struct udev *udev  = udev_device_get_udev(parent);
        struct udev_device *transportdev;
        struct udev_device *sessiondev = NULL;
        const char *target;
        char *connname;
        struct udev_device *conndev = NULL;
        const char *addr;
        const char *port;
        char *lun = NULL;

        /* find iscsi session */
        transportdev = parent;
        for (;;) {
                transportdev = udev_device_get_parent(transportdev);
                if (transportdev == NULL)
                        return NULL;
                if (startswith(udev_device_get_sysname(transportdev), "session"))
                        break;
        }

        /* find iscsi session device */
        sessiondev = udev_device_new_from_subsystem_sysname(udev, "iscsi_session", udev_device_get_sysname(transportdev));
        if (sessiondev == NULL)
                return NULL;
        target = udev_device_get_sysattr_value(sessiondev, "targetname");
        if (target == NULL) {
                parent = NULL;
                goto out;
        }

        if (asprintf(&connname, "connection%s:0", udev_device_get_sysnum(transportdev)) < 0) {
                parent = NULL;
                goto out;
        }
        conndev = udev_device_new_from_subsystem_sysname(udev, "iscsi_connection", connname);
        free(connname);
        if (conndev == NULL) {
                parent = NULL;
                goto out;
        }
        addr = udev_device_get_sysattr_value(conndev, "persistent_address");
        port = udev_device_get_sysattr_value(conndev, "persistent_port");
        if (addr == NULL || port == NULL) {
                parent = NULL;
                goto out;
        }

        format_lun_number(parent, &lun);
        path_prepend(path, "ip-%s:%s-iscsi-%s-%s", addr, port, target, lun);
        if (lun)
                free(lun);
out:
        udev_device_unref(sessiondev);
        udev_device_unref(conndev);
        return parent;
}

static struct udev_device *handle_scsi_default(struct udev_device *parent, char **path)
{
        struct udev_device *hostdev;
        int host, bus, target, lun;
        const char *name;
        char *base;
        char *pos;
        DIR *dir;
        struct dirent *dent;
        int basenum;

        hostdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_host");
        if (hostdev == NULL)
                return NULL;

        name = udev_device_get_sysname(parent);
        if (sscanf(name, "%d:%d:%d:%d", &host, &bus, &target, &lun) != 4)
                return NULL;

        /*
         * Rebase host offset to get the local relative number
         *
         * Note: This is by definition racy, unreliable and too simple.
         * Please do not copy this model anywhere. It's just a left-over
         * from the time we had no idea how things should look like in
         * the end.
         *
         * Making assumptions about a global in-kernel counter and use
         * that to calculate a local offset is a very broken concept. It
         * can only work as long as things are in strict order.
         *
         * The kernel needs to export the instance/port number of a
         * controller directly, without the need for rebase magic like
         * this. Manual driver unbind/bind, parallel hotplug/unplug will
         * get into the way of this "I hope it works" logic.
         */
        basenum = -1;
        base = strdup(udev_device_get_syspath(hostdev));
        if (base == NULL)
                return NULL;
        pos = strrchr(base, '/');
        if (pos == NULL) {
                parent = NULL;
                goto out;
        }
        pos[0] = '\0';
        dir = opendir(base);
        if (dir == NULL) {
                parent = NULL;
                goto out;
        }
        for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
                char *rest;
                int i;

                if (dent->d_name[0] == '.')
                        continue;
                if (dent->d_type != DT_DIR && dent->d_type != DT_LNK)
                        continue;
                if (!startswith(dent->d_name, "host"))
                        continue;
                i = strtoul(&dent->d_name[4], &rest, 10);
                if (rest[0] != '\0')
                        continue;
                /*
                 * find the smallest number; the host really needs to export its
                 * own instance number per parent device; relying on the global host
                 * enumeration and plainly rebasing the numbers sounds unreliable
                 */
                if (basenum == -1 || i < basenum)
                        basenum = i;
        }
        closedir(dir);
        if (basenum == -1) {
                parent = NULL;
                goto out;
        }
        host -= basenum;

        path_prepend(path, "scsi-%u:%u:%u:%u", host, bus, target, lun);
out:
        free(base);
        return hostdev;
}

static struct udev_device *handle_scsi_hyperv(struct udev_device *parent, char **path) {
        struct udev_device *hostdev;
        struct udev_device *vmbusdev;
        const char *guid_str;
        char *lun = NULL;
        char guid[38];
        size_t i, k;

        hostdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_host");
        if (!hostdev)
                return NULL;

        vmbusdev = udev_device_get_parent(hostdev);
        if (!vmbusdev)
                return NULL;

        guid_str = udev_device_get_sysattr_value(vmbusdev, "device_id");
        if (!guid_str)
                return NULL;

        if (strlen(guid_str) < 37 || guid_str[0] != '{' || guid_str[36] != '}')
                return NULL;

        for (i = 1, k = 0; i < 36; i++) {
                if (guid_str[i] == '-')
                        continue;
                guid[k++] = guid_str[i];
        }
        guid[k] = '\0';

        format_lun_number(parent, &lun);
        path_prepend(path, "vmbus-%s-%s", guid, lun);
        free(lun);
        return parent;
}

static struct udev_device *handle_scsi(struct udev_device *parent, char **path)
{
        const char *devtype;
        const char *name;
        const char *id;

        devtype = udev_device_get_devtype(parent);
        if (devtype == NULL || !streq(devtype, "scsi_device"))
                return parent;

        /* firewire */
        id = udev_device_get_sysattr_value(parent, "ieee1394_id");
        if (id != NULL) {
                parent = skip_subsystem(parent, "scsi");
                path_prepend(path, "ieee1394-0x%s", id);
                goto out;
        }

        /* scsi sysfs does not have a "subsystem" for the transport */
        name = udev_device_get_syspath(parent);

        if (strstr(name, "/rport-") != NULL) {
                parent = handle_scsi_fibre_channel(parent, path);
                goto out;
        }

        if (strstr(name, "/end_device-") != NULL) {
                parent = handle_scsi_sas(parent, path);
                goto out;
        }

        if (strstr(name, "/session") != NULL) {
                parent = handle_scsi_iscsi(parent, path);
                goto out;
        }

        /*
         * We do not support the ATA transport class, it uses global counters
         * to name the ata devices which numbers spread across multiple
         * controllers.
         *
         * The real link numbers are not exported. Also, possible chains of ports
         * behind port multipliers cannot be composed that way.
         *
         * Until all that is solved at the kernel level, there are no by-path/
         * links for ATA devices.
         */
        if (strstr(name, "/ata") != NULL) {
                parent = NULL;
                goto out;
        }

        if (strstr(name, "/vmbus_") != NULL) {
                parent = handle_scsi_hyperv(parent, path);
                goto out;
        }

        parent = handle_scsi_default(parent, path);
out:
        return parent;
}

static struct udev_device *handle_cciss(struct udev_device *parent, char **path)
{
        const char *str;
        unsigned int controller, disk;

        str = udev_device_get_sysname(parent);
        if (sscanf(str, "c%ud%u%*s", &controller, &disk) != 2)
                return NULL;

        path_prepend(path, "cciss-disk%u", disk);
        parent = skip_subsystem(parent, "cciss");
        return parent;
}

static void handle_scsi_tape(struct udev_device *dev, char **path)
{
        const char *name;

        /* must be the last device in the syspath */
        if (*path != NULL)
                return;

        name = udev_device_get_sysname(dev);
        if (startswith(name, "nst") && strchr("lma", name[3]) != NULL)
                path_prepend(path, "nst%c", name[3]);
        else if (startswith(name, "st") && strchr("lma", name[2]) != NULL)
                path_prepend(path, "st%c", name[2]);
}

static struct udev_device *handle_usb(struct udev_device *parent, char **path)
{
        const char *devtype;
        const char *str;
        const char *port;

        devtype = udev_device_get_devtype(parent);
        if (devtype == NULL)
                return parent;
        if (!streq(devtype, "usb_interface") && !streq(devtype, "usb_device"))
                return parent;

        str = udev_device_get_sysname(parent);
        port = strchr(str, '-');
        if (port == NULL)
                return parent;
        port++;

        parent = skip_subsystem(parent, "usb");
        path_prepend(path, "usb-0:%s", port);
        return parent;
}

static struct udev_device *handle_ccw(struct udev_device *parent, struct udev_device *dev, char **path)
{
        struct udev_device *scsi_dev;

        scsi_dev = udev_device_get_parent_with_subsystem_devtype(dev, "scsi", "scsi_device");
        if (scsi_dev != NULL) {
                const char *wwpn;
                const char *lun;
                const char *hba_id;

                hba_id = udev_device_get_sysattr_value(scsi_dev, "hba_id");
                wwpn = udev_device_get_sysattr_value(scsi_dev, "wwpn");
                lun = udev_device_get_sysattr_value(scsi_dev, "fcp_lun");
                if (hba_id != NULL && lun != NULL && wwpn != NULL) {
                        path_prepend(path, "ccw-%s-zfcp-%s:%s", hba_id, wwpn, lun);
                        goto out;
                }
        }

        path_prepend(path, "ccw-%s", udev_device_get_sysname(parent));
out:
        parent = skip_subsystem(parent, "ccw");
        return parent;
}

static int builtin_path_id(struct udev_device *dev, int argc, char *argv[], bool test)
{
        struct udev_device *parent;
        char *path = NULL;
        bool some_transport = false;

        /* S390 ccw bus */
        parent = udev_device_get_parent_with_subsystem_devtype(dev, "ccw", NULL);
        if (parent != NULL) {
                handle_ccw(parent, dev, &path);
                goto out;
        }

        /* walk up the chain of devices and compose path */
        parent = dev;
        while (parent != NULL) {
                const char *subsys;

                subsys = udev_device_get_subsystem(parent);
                if (subsys == NULL) {
                        ;
                } else if (streq(subsys, "scsi_tape")) {
                        handle_scsi_tape(parent, &path);
                } else if (streq(subsys, "scsi")) {
                        parent = handle_scsi(parent, &path);
                        some_transport = true;
                } else if (streq(subsys, "cciss")) {
                        parent = handle_cciss(parent, &path);
                        some_transport = true;
                } else if (streq(subsys, "usb")) {
                        parent = handle_usb(parent, &path);
                        some_transport = true;
                } else if (streq(subsys, "serio")) {
                        path_prepend(&path, "serio-%s", udev_device_get_sysnum(parent));
                        parent = skip_subsystem(parent, "serio");
                } else if (streq(subsys, "pci")) {
                        path_prepend(&path, "pci-%s", udev_device_get_sysname(parent));
                        parent = skip_subsystem(parent, "pci");
                } else if (streq(subsys, "platform")) {
                        path_prepend(&path, "platform-%s", udev_device_get_sysname(parent));
                        parent = skip_subsystem(parent, "platform");
                        some_transport = true;
                } else if (streq(subsys, "acpi")) {
                        path_prepend(&path, "acpi-%s", udev_device_get_sysname(parent));
                        parent = skip_subsystem(parent, "acpi");
                } else if (streq(subsys, "xen")) {
                        path_prepend(&path, "xen-%s", udev_device_get_sysname(parent));
                        parent = skip_subsystem(parent, "xen");
                } else if (streq(subsys, "virtio")) {
                        path_prepend(&path, "virtio-pci-%s", udev_device_get_sysname(parent));
                        parent = skip_subsystem(parent, "virtio");
                } else if (streq(subsys, "scm")) {
                        path_prepend(&path, "scm-%s", udev_device_get_sysname(parent));
                        parent = skip_subsystem(parent, "scm");
                }

                parent = udev_device_get_parent(parent);
        }

        /*
         * Do not return a single-parent-device-only for block
         * devices, they might have entire buses behind it which
         * do not get unique IDs only by using the parent device.
         */
        if (!some_transport && streq(udev_device_get_subsystem(dev), "block")) {
                free(path);
                path = NULL;
        }

out:
        if (path != NULL) {
                char tag[UTIL_NAME_SIZE];
                size_t i;
                const char *p;

                /* compose valid udev tag name */
                for (p = path, i = 0; *p; p++) {
                        if ((*p >= '0' && *p <= '9') ||
                            (*p >= 'A' && *p <= 'Z') ||
                            (*p >= 'a' && *p <= 'z') ||
                            *p == '-') {
                                tag[i++] = *p;
                                continue;
                        }

                        /* skip all leading '_' */
                        if (i == 0)
                                continue;

                        /* avoid second '_' */
                        if (tag[i-1] == '_')
                                continue;

                        tag[i++] = '_';
                }
                /* strip trailing '_' */
                while (i > 0 && tag[i-1] == '_')
                        i--;
                tag[i] = '\0';

                udev_builtin_add_property(dev, test, "ID_PATH", path);
                udev_builtin_add_property(dev, test, "ID_PATH_TAG", tag);
                free(path);
                return EXIT_SUCCESS;
        }
        return EXIT_FAILURE;
}

const struct udev_builtin udev_builtin_path_id = {
        .name = "path_id",
        .cmd = builtin_path_id,
        .help = "compose persistent device path",
        .run_once = true,
};