src/udev/udev-builtin-path_id.c

   1 /* SPDX-License-Identifier: GPL-2.0+ */
   2 /*
   3  * compose persistent device path
   4  *
   5  * Copyright (C) 2009-2011 Kay Sievers <kay@vrfy.org>
   6  *
   7  * Logic based on Hannes Reinecke's shell script.
   8  *
   9  * This program is free software: you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation, either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  21  */
  22
  23 #include <ctype.h>
  24 #include <errno.h>
  25 #include <fcntl.h>
  26 #include <getopt.h>
  27 #include <stdarg.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32
  33 #include "alloc-util.h"
  34 #include "dirent-util.h"
  35 #include "fd-util.h"
  36 #include "string-util.h"
  37 #include "sysexits.h"
  38 #include "udev.h"
  39 #include "udev-util.h"
  40
  41 _printf_(2,3)
  42 static void path_prepend(char **path, const char *fmt, ...) {
  43         va_list va;
  44         _cleanup_free_ char *pre = NULL;
  45         int r;
  46
  47         va_start(va, fmt);
  48         r = vasprintf(&pre, fmt, va);
  49         va_end(va);
  50         if (r < 0) {
  51                 log_oom();
  52                 exit(EX_OSERR);
  53         }
  54
  55         if (*path) {
  56                 char *new;
  57
  58                 new = strjoin(pre, "-", *path);
  59                 if (!new) {
  60                         log_oom();
  61                         exit(EX_OSERR);
  62                 }
  63
  64                 free_and_replace(*path, new);
  65         } else {
  66                 *path = pre;
  67                 pre = NULL;
  68         }
  69 }
  70
  71 /*
  72 ** Linux only supports 32 bit luns.
  73 ** See drivers/scsi/scsi_scan.c::scsilun_to_int() for more details.
  74 */
  75 static void format_lun_number(struct udev_device *dev, char **path) {
  76         unsigned long lun = strtoul(udev_device_get_sysnum(dev), NULL, 10);
  77
  78         if (lun < 256)
  79                 /* address method 0, peripheral device addressing with bus id of zero */
  80                 path_prepend(path, "lun-%lu", lun);
  81         else
  82                 /* handle all other lun addressing methods by using a variant of the original lun format */
  83                 path_prepend(path, "lun-0x%04lx%04lx00000000", lun & 0xffff, (lun >> 16) & 0xffff);
  84 }
  85
  86 static struct udev_device *skip_subsystem(struct udev_device *dev, const char *subsys) {
  87         struct udev_device *parent = dev;
  88
  89         assert(dev);
  90         assert(subsys);
  91
  92         while (parent) {
  93                 const char *subsystem;
  94
  95                 subsystem = udev_device_get_subsystem(parent);
  96                 if (!streq_ptr(subsystem, subsys))
  97                         break;
  98
  99                 dev = parent;
 100                 parent = udev_device_get_parent(parent);
 101         }
 102
 103         return dev;
 104 }
 105
 106 static struct udev_device *handle_scsi_fibre_channel(struct udev_device *parent, char **path) {
 107         struct udev *udev;
 108         struct udev_device *targetdev;
 109         _cleanup_udev_device_unref_ struct udev_device *fcdev = NULL;
 110         const char *port;
 111         _cleanup_free_ char *lun = NULL;
 112
 113         assert(parent);
 114         assert(path);
 115
 116         udev = udev_device_get_udev(parent);
 117
 118         targetdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_target");
 119         if (!targetdev)
 120                 return NULL;
 121
 122         fcdev = udev_device_new_from_subsystem_sysname(udev, "fc_transport", udev_device_get_sysname(targetdev));
 123         if (!fcdev)
 124                 return NULL;
 125
 126         port = udev_device_get_sysattr_value(fcdev, "port_name");
 127         if (!port)
 128                 return NULL;
 129
 130         format_lun_number(parent, &lun);
 131         path_prepend(path, "fc-%s-%s", port, lun);
 132         return parent;
 133 }
 134
 135 static struct udev_device *handle_scsi_sas_wide_port(struct udev_device *parent, char **path) {
 136         struct udev *udev;
 137         struct udev_device *targetdev, *target_parent;
 138         _cleanup_udev_device_unref_ struct udev_device *sasdev = NULL;
 139         const char *sas_address;
 140         _cleanup_free_ char *lun = NULL;
 141
 142         assert(parent);
 143         assert(path);
 144
 145         udev = udev_device_get_udev(parent);
 146
 147         targetdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_target");
 148         if (!targetdev)
 149                 return NULL;
 150
 151         target_parent = udev_device_get_parent(targetdev);
 152         if (!target_parent)
 153                 return NULL;
 154
 155         sasdev = udev_device_new_from_subsystem_sysname(udev, "sas_device",
 156                                                         udev_device_get_sysname(target_parent));
 157         if (!sasdev)
 158                 return NULL;
 159
 160         sas_address = udev_device_get_sysattr_value(sasdev, "sas_address");
 161         if (!sas_address)
 162                 return NULL;
 163
 164         format_lun_number(parent, &lun);
 165         path_prepend(path, "sas-%s-%s", sas_address, lun);
 166         return parent;
 167 }
 168
 169 static struct udev_device *handle_scsi_sas(struct udev_device *parent, char **path)
 170 {
 171         struct udev *udev;
 172         struct udev_device *targetdev, *target_parent, *port, *expander;
 173         _cleanup_udev_device_unref_ struct udev_device
 174                 *target_sasdev = NULL, *expander_sasdev = NULL, *port_sasdev = NULL;
 175         const char *sas_address = NULL;
 176         const char *phy_id;
 177         const char *phy_count;
 178         _cleanup_free_ char *lun = NULL;
 179
 180         assert(parent);
 181         assert(path);
 182
 183         udev = udev_device_get_udev(parent);
 184
 185         targetdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_target");
 186         if (!targetdev)
 187                 return NULL;
 188
 189         target_parent = udev_device_get_parent(targetdev);
 190         if (!target_parent)
 191                 return NULL;
 192
 193         /* Get sas device */
 194         target_sasdev = udev_device_new_from_subsystem_sysname(
 195                         udev, "sas_device", udev_device_get_sysname(target_parent));
 196         if (!target_sasdev)
 197                 return NULL;
 198
 199         /* The next parent is sas port */
 200         port = udev_device_get_parent(target_parent);
 201         if (!port)
 202                 return NULL;
 203
 204         /* Get port device */
 205         port_sasdev = udev_device_new_from_subsystem_sysname(
 206                 udev, "sas_port", udev_device_get_sysname(port));
 207
 208         phy_count = udev_device_get_sysattr_value(port_sasdev, "num_phys");
 209         if (!phy_count)
 210                 return NULL;
 211
 212         /* Check if we are simple disk */
 213         if (strncmp(phy_count, "1", 2) != 0)
 214                 return handle_scsi_sas_wide_port(parent, path);
 215
 216         /* Get connected phy */
 217         phy_id = udev_device_get_sysattr_value(target_sasdev, "phy_identifier");
 218         if (!phy_id)
 219                 return NULL;
 220
 221         /* The port's parent is either hba or expander */
 222         expander = udev_device_get_parent(port);
 223         if (!expander)
 224                 return NULL;
 225
 226         /* Get expander device */
 227         expander_sasdev = udev_device_new_from_subsystem_sysname(
 228                         udev, "sas_device", udev_device_get_sysname(expander));
 229         if (expander_sasdev) {
 230                  /* Get expander's address */
 231                  sas_address = udev_device_get_sysattr_value(expander_sasdev,
 232                                                     "sas_address");
 233                  if (!sas_address)
 234                          return NULL;
 235         }
 236
 237         format_lun_number(parent, &lun);
 238         if (sas_address)
 239                  path_prepend(path, "sas-exp%s-phy%s-%s", sas_address, phy_id, lun);
 240         else
 241                  path_prepend(path, "sas-phy%s-%s", phy_id, lun);
 242
 243         return parent;
 244 }
 245
 246 static struct udev_device *handle_scsi_iscsi(struct udev_device *parent, char **path) {
 247         struct udev *udev;
 248         struct udev_device *transportdev;
 249         _cleanup_udev_device_unref_ struct udev_device
 250                 *sessiondev = NULL, *conndev = NULL;
 251         const char *target, *connname, *addr, *port;
 252         _cleanup_free_ char *lun = NULL;
 253
 254         assert(parent);
 255         assert(path);
 256
 257         udev = udev_device_get_udev(parent);
 258
 259         /* find iscsi session */
 260         transportdev = parent;
 261         for (;;) {
 262                 transportdev = udev_device_get_parent(transportdev);
 263                 if (!transportdev)
 264                         return NULL;
 265                 if (startswith(udev_device_get_sysname(transportdev), "session"))
 266                         break;
 267         }
 268
 269         /* find iscsi session device */
 270         sessiondev = udev_device_new_from_subsystem_sysname(udev, "iscsi_session", udev_device_get_sysname(transportdev));
 271         if (!sessiondev)
 272                 return NULL;
 273
 274         target = udev_device_get_sysattr_value(sessiondev, "targetname");
 275         if (!target)
 276                 return NULL;
 277
 278         connname = strjoina("connection", udev_device_get_sysnum(transportdev), ":0");
 279         conndev = udev_device_new_from_subsystem_sysname(udev, "iscsi_connection", connname);
 280         if (!conndev)
 281                 return NULL;
 282
 283         addr = udev_device_get_sysattr_value(conndev, "persistent_address");
 284         port = udev_device_get_sysattr_value(conndev, "persistent_port");
 285         if (!addr || !port)
 286                 return NULL;
 287
 288         format_lun_number(parent, &lun);
 289         path_prepend(path, "ip-%s:%s-iscsi-%s-%s", addr, port, target, lun);
 290         return parent;
 291 }
 292
 293 static struct udev_device *handle_scsi_ata(struct udev_device *parent, char **path) {
 294         struct udev *udev;
 295         struct udev_device *targetdev, *target_parent;
 296         _cleanup_udev_device_unref_ struct udev_device *atadev = NULL;
 297         const char *port_no;
 298
 299         assert(parent);
 300         assert(path);
 301
 302         udev = udev_device_get_udev(parent);
 303
 304         targetdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_host");
 305         if (!targetdev)
 306                 return NULL;
 307
 308         target_parent = udev_device_get_parent(targetdev);
 309         if (!target_parent)
 310                 return NULL;
 311
 312         atadev = udev_device_new_from_subsystem_sysname(udev, "ata_port", udev_device_get_sysname(target_parent));
 313         if (!atadev)
 314                 return NULL;
 315
 316         port_no = udev_device_get_sysattr_value(atadev, "port_no");
 317         if (!port_no)
 318                 return NULL;
 319
 320         path_prepend(path, "ata-%s", port_no);
 321         return parent;
 322 }
 323
 324 static struct udev_device *handle_scsi_default(struct udev_device *parent, char **path) {
 325         struct udev_device *hostdev;
 326         int host, bus, target, lun;
 327         const char *name, *base, *pos;
 328         _cleanup_closedir_ DIR *dir = NULL;
 329         struct dirent *dent;
 330         int basenum = -1;
 331
 332         assert(parent);
 333         assert(path);
 334
 335         hostdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_host");
 336         if (!hostdev)
 337                 return NULL;
 338
 339         name = udev_device_get_sysname(parent);
 340         if (sscanf(name, "%d:%d:%d:%d", &host, &bus, &target, &lun) != 4)
 341                 return NULL;
 342
 343         /*
 344          * Rebase host offset to get the local relative number
 345          *
 346          * Note: This is by definition racy, unreliable and too simple.
 347          * Please do not copy this model anywhere. It's just a left-over
 348          * from the time we had no idea how things should look like in
 349          * the end.
 350          *
 351          * Making assumptions about a global in-kernel counter and use
 352          * that to calculate a local offset is a very broken concept. It
 353          * can only work as long as things are in strict order.
 354          *
 355          * The kernel needs to export the instance/port number of a
 356          * controller directly, without the need for rebase magic like
 357          * this. Manual driver unbind/bind, parallel hotplug/unplug will
 358          * get into the way of this "I hope it works" logic.
 359          */
 360
 361         base = udev_device_get_syspath(hostdev);
 362         pos = strrchr(base, '/');
 363         if (!pos)
 364                 return NULL;
 365
 366         base = strndupa(base, pos - base);
 367         dir = opendir(base);
 368         if (!dir)
 369                 return NULL;
 370
 371         FOREACH_DIRENT_ALL(dent, dir, break) {
 372                 char *rest;
 373                 int i;
 374
 375                 if (dent->d_name[0] == '.')
 376                         continue;
 377                 if (!IN_SET(dent->d_type, DT_DIR, DT_LNK))
 378                         continue;
 379                 if (!startswith(dent->d_name, "host"))
 380                         continue;
 381                 i = strtoul(&dent->d_name[4], &rest, 10);
 382                 if (rest[0] != '\0')
 383                         continue;
 384                 /*
 385                  * find the smallest number; the host really needs to export its
 386                  * own instance number per parent device; relying on the global host
 387                  * enumeration and plainly rebasing the numbers sounds unreliable
 388                  */
 389                 if (basenum == -1 || i < basenum)
 390                         basenum = i;
 391         }
 392         if (basenum == -1)
 393                 return hostdev;
 394         host -= basenum;
 395
 396         path_prepend(path, "scsi-%u:%u:%u:%u", host, bus, target, lun);
 397         return hostdev;
 398 }
 399
 400 static struct udev_device *handle_scsi_hyperv(struct udev_device *parent, char **path) {
 401         struct udev_device *hostdev;
 402         struct udev_device *vmbusdev;
 403         const char *guid_str;
 404         _cleanup_free_ char *lun = NULL;
 405         char guid[38];
 406         size_t i, k;
 407
 408         assert(parent);
 409         assert(path);
 410
 411         hostdev = udev_device_get_parent_with_subsystem_devtype(parent, "scsi", "scsi_host");
 412         if (!hostdev)
 413                 return NULL;
 414
 415         vmbusdev = udev_device_get_parent(hostdev);
 416         if (!vmbusdev)
 417                 return NULL;
 418
 419         guid_str = udev_device_get_sysattr_value(vmbusdev, "device_id");
 420         if (!guid_str)
 421                 return NULL;
 422
 423         if (strlen(guid_str) < 37 || guid_str[0] != '{' || guid_str[36] != '}')
 424                 return NULL;
 425
 426         for (i = 1, k = 0; i < 36; i++) {
 427                 if (guid_str[i] == '-')
 428                         continue;
 429                 guid[k++] = guid_str[i];
 430         }
 431         guid[k] = '\0';
 432
 433         format_lun_number(parent, &lun);
 434         path_prepend(path, "vmbus-%s-%s", guid, lun);
 435         return parent;
 436 }
 437
 438 static struct udev_device *handle_scsi(struct udev_device *parent, char **path, bool *supported_parent) {
 439         const char *devtype, *id, *name;
 440
 441         devtype = udev_device_get_devtype(parent);
 442         if (!streq_ptr(devtype, "scsi_device"))
 443                 return parent;
 444
 445         /* firewire */
 446         id = udev_device_get_sysattr_value(parent, "ieee1394_id");
 447         if (id) {
 448                 path_prepend(path, "ieee1394-0x%s", id);
 449                 *supported_parent = true;
 450                 return skip_subsystem(parent, "scsi");
 451         }
 452
 453         /* scsi sysfs does not have a "subsystem" for the transport */
 454         name = udev_device_get_syspath(parent);
 455
 456         if (strstr(name, "/rport-")) {
 457                 *supported_parent = true;
 458                 return handle_scsi_fibre_channel(parent, path);
 459         }
 460
 461         if (strstr(name, "/end_device-")) {
 462                 *supported_parent = true;
 463                 return handle_scsi_sas(parent, path);
 464         }
 465
 466         if (strstr(name, "/session")) {
 467                 *supported_parent = true;
 468                 return handle_scsi_iscsi(parent, path);
 469         }
 470
 471         if (strstr(name, "/ata"))
 472                 return handle_scsi_ata(parent, path);
 473
 474         if (strstr(name, "/vmbus_"))
 475                 return handle_scsi_hyperv(parent, path);
 476
 477         return handle_scsi_default(parent, path);
 478 }
 479
 480 static struct udev_device *handle_cciss(struct udev_device *parent, char **path) {
 481         const char *str;
 482         unsigned int controller, disk;
 483
 484         str = udev_device_get_sysname(parent);
 485         if (sscanf(str, "c%ud%u%*s", &controller, &disk) != 2)
 486                 return NULL;
 487
 488         path_prepend(path, "cciss-disk%u", disk);
 489         return skip_subsystem(parent, "cciss");
 490 }
 491
 492 static void handle_scsi_tape(struct udev_device *dev, char **path) {
 493         const char *name;
 494
 495         /* must be the last device in the syspath */
 496         if (*path)
 497                 return;
 498
 499         name = udev_device_get_sysname(dev);
 500         if (startswith(name, "nst") && strchr("lma", name[3]))
 501                 path_prepend(path, "nst%c", name[3]);
 502         else if (startswith(name, "st") && strchr("lma", name[2]))
 503                 path_prepend(path, "st%c", name[2]);
 504 }
 505
 506 static struct udev_device *handle_usb(struct udev_device *parent, char **path) {
 507         const char *devtype, *str, *port;
 508
 509         devtype = udev_device_get_devtype(parent);
 510         if (!devtype)
 511                 return parent;
 512         if (!STR_IN_SET(devtype, "usb_interface", "usb_device"))
 513                 return parent;
 514
 515         str = udev_device_get_sysname(parent);
 516         port = strchr(str, '-');
 517         if (!port)
 518                 return parent;
 519         port++;
 520
 521         path_prepend(path, "usb-0:%s", port);
 522         return skip_subsystem(parent, "usb");
 523 }
 524
 525 static struct udev_device *handle_bcma(struct udev_device *parent, char **path) {
 526         const char *sysname;
 527         unsigned int core;
 528
 529         sysname = udev_device_get_sysname(parent);
 530         if (sscanf(sysname, "bcma%*u:%u", &core) != 1)
 531                 return NULL;
 532
 533         path_prepend(path, "bcma-%u", core);
 534         return parent;
 535 }
 536
 537 /* Handle devices of AP bus in System z platform. */
 538 static struct udev_device *handle_ap(struct udev_device *parent, char **path) {
 539         const char *type, *func;
 540
 541         assert(parent);
 542         assert(path);
 543
 544         type = udev_device_get_sysattr_value(parent, "type");
 545         func = udev_device_get_sysattr_value(parent, "ap_functions");
 546
 547         if (type && func)
 548                 path_prepend(path, "ap-%s-%s", type, func);
 549         else
 550                 path_prepend(path, "ap-%s", udev_device_get_sysname(parent));
 551
 552         return skip_subsystem(parent, "ap");
 553 }
 554
 555 static int builtin_path_id(struct udev_device *dev, int argc, char *argv[], bool test) {
 556         struct udev_device *parent;
 557         _cleanup_free_ char *path = NULL;
 558         bool supported_transport = false;
 559         bool supported_parent = false;
 560
 561         assert(dev);
 562
 563         /* walk up the chain of devices and compose path */
 564         parent = dev;
 565         while (parent) {
 566                 const char *subsys;
 567
 568                 subsys = udev_device_get_subsystem(parent);
 569                 if (!subsys) {
 570                         ;
 571                 } else if (streq(subsys, "scsi_tape")) {
 572                         handle_scsi_tape(parent, &path);
 573                 } else if (streq(subsys, "scsi")) {
 574                         parent = handle_scsi(parent, &path, &supported_parent);
 575                         supported_transport = true;
 576                 } else if (streq(subsys, "cciss")) {
 577                         parent = handle_cciss(parent, &path);
 578                         supported_transport = true;
 579                 } else if (streq(subsys, "usb")) {
 580                         parent = handle_usb(parent, &path);
 581                         supported_transport = true;
 582                 } else if (streq(subsys, "bcma")) {
 583                         parent = handle_bcma(parent, &path);
 584                         supported_transport = true;
 585                 } else if (streq(subsys, "serio")) {
 586                         path_prepend(&path, "serio-%s", udev_device_get_sysnum(parent));
 587                         parent = skip_subsystem(parent, "serio");
 588                 } else if (streq(subsys, "pci")) {
 589                         path_prepend(&path, "pci-%s", udev_device_get_sysname(parent));
 590                         parent = skip_subsystem(parent, "pci");
 591                         supported_parent = true;
 592                 } else if (streq(subsys, "platform")) {
 593                         path_prepend(&path, "platform-%s", udev_device_get_sysname(parent));
 594                         parent = skip_subsystem(parent, "platform");
 595                         supported_transport = true;
 596                         supported_parent = true;
 597                 } else if (streq(subsys, "acpi")) {
 598                         path_prepend(&path, "acpi-%s", udev_device_get_sysname(parent));
 599                         parent = skip_subsystem(parent, "acpi");
 600                         supported_parent = true;
 601                 } else if (streq(subsys, "xen")) {
 602                         path_prepend(&path, "xen-%s", udev_device_get_sysname(parent));
 603                         parent = skip_subsystem(parent, "xen");
 604                         supported_parent = true;
 605                 } else if (streq(subsys, "virtio")) {
 606                         parent = skip_subsystem(parent, "virtio");
 607                         supported_transport = true;
 608                 } else if (streq(subsys, "scm")) {
 609                         path_prepend(&path, "scm-%s", udev_device_get_sysname(parent));
 610                         parent = skip_subsystem(parent, "scm");
 611                         supported_transport = true;
 612                         supported_parent = true;
 613                 } else if (streq(subsys, "ccw")) {
 614                         path_prepend(&path, "ccw-%s", udev_device_get_sysname(parent));
 615                         parent = skip_subsystem(parent, "ccw");
 616                         supported_transport = true;
 617                         supported_parent = true;
 618                 } else if (streq(subsys, "ccwgroup")) {
 619                         path_prepend(&path, "ccwgroup-%s", udev_device_get_sysname(parent));
 620                         parent = skip_subsystem(parent, "ccwgroup");
 621                         supported_transport = true;
 622                         supported_parent = true;
 623                 } else if (streq(subsys, "ap")) {
 624                         parent = handle_ap(parent, &path);
 625                         supported_transport = true;
 626                         supported_parent = true;
 627                 } else if (streq(subsys, "iucv")) {
 628                         path_prepend(&path, "iucv-%s", udev_device_get_sysname(parent));
 629                         parent = skip_subsystem(parent, "iucv");
 630                         supported_transport = true;
 631                         supported_parent = true;
 632                 } else if (streq(subsys, "nvme")) {
 633                         const char *nsid = udev_device_get_sysattr_value(dev, "nsid");
 634
 635                         if (nsid) {
 636                                 path_prepend(&path, "nvme-%s", nsid);
 637                                 parent = skip_subsystem(parent, "nvme");
 638                                 supported_parent = true;
 639                                 supported_transport = true;
 640                         }
 641                 }
 642
 643                 if (parent)
 644                         parent = udev_device_get_parent(parent);
 645         }
 646
 647         if (!path)
 648                 return EXIT_FAILURE;
 649
 650         /*
 651          * Do not return devices with an unknown parent device type. They
 652          * might produce conflicting IDs if the parent does not provide a
 653          * unique and predictable name.
 654          */
 655         if (!supported_parent)
 656                 return EXIT_FAILURE;
 657
 658         /*
 659          * Do not return block devices without a well-known transport. Some
 660          * devices do not expose their buses and do not provide a unique
 661          * and predictable name that way.
 662          */
 663         if (streq_ptr(udev_device_get_subsystem(dev), "block") && !supported_transport)
 664                 return EXIT_FAILURE;
 665
 666         {
 667                 char tag[UTIL_NAME_SIZE];
 668                 size_t i;
 669                 const char *p;
 670
 671                 /* compose valid udev tag name */
 672                 for (p = path, i = 0; *p; p++) {
 673                         if ((*p >= '0' && *p <= '9') ||
 674                             (*p >= 'A' && *p <= 'Z') ||
 675                             (*p >= 'a' && *p <= 'z') ||
 676                             *p == '-') {
 677                                 tag[i++] = *p;
 678                                 continue;
 679                         }
 680
 681                         /* skip all leading '_' */
 682                         if (i == 0)
 683                                 continue;
 684
 685                         /* avoid second '_' */
 686                         if (tag[i-1] == '_')
 687                                 continue;
 688
 689                         tag[i++] = '_';
 690                 }
 691                 /* strip trailing '_' */
 692                 while (i > 0 && tag[i-1] == '_')
 693                         i--;
 694                 tag[i] = '\0';
 695
 696                 udev_builtin_add_property(dev, test, "ID_PATH", path);
 697                 udev_builtin_add_property(dev, test, "ID_PATH_TAG", tag);
 698         }
 699
 700         return EXIT_SUCCESS;
 701 }
 702
 703 const struct udev_builtin udev_builtin_path_id = {
 704         .name = "path_id",
 705         .cmd = builtin_path_id,
 706         .help = "Compose persistent device path",
 707         .run_once = true,
 708 };