systemd/udev/udev-builtin-path_id.c

/*
 * compose persistent device path
 *
 * Copyright (C) 2009-2011 Kay Sievers <kay.sievers@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 || strcmp(subsystem, subsys) != 0)
			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 (strncmp(udev_device_get_sysname(transportdev), "session", 7) == 0)
			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 */
	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 (strncmp(dent->d_name, "host", 4) != 0)
			continue;
		i = strtoul(&dent->d_name[4], &rest, 10);
		if (rest[0] != '\0')
			continue;
		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(struct udev_device *parent, char **path)
{
	const char *devtype;
	const char *name;
	const char *id;

	devtype = udev_device_get_devtype(parent);
	if (devtype == NULL || strcmp(devtype, "scsi_device") != 0)
		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;
	}

	/* lousy 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;
	}

	parent = handle_scsi_default(parent, path);
out:
	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 (strncmp(name, "nst", 3) == 0 && strchr("lma", name[3]) != NULL)
		path_prepend(path, "nst%c", name[3]);
	else if (strncmp(name, "st", 2) == 0 && 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 (strcmp(devtype, "usb_interface") != 0 && strcmp(devtype, "usb_device") != 0)
		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_cciss(struct udev_device *parent, char **path)
{
	return NULL;
}

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, const char *command, bool test)
{
	struct udev_device *parent;
	char *path = NULL;

	/* 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 (strcmp(subsys, "scsi_tape") == 0) {
			handle_scsi_tape(parent, &path);
		} else if (strcmp(subsys, "scsi") == 0) {
			parent = handle_scsi(parent, &path);
		} else if (strcmp(subsys, "cciss") == 0) {
			handle_cciss(parent, &path);
		} else if (strcmp(subsys, "usb") == 0) {
			parent = handle_usb(parent, &path);
		} else if (strcmp(subsys, "serio") == 0) {
			path_prepend(&path, "serio-%s", udev_device_get_sysnum(parent));
			parent = skip_subsystem(parent, "serio");
		} else if (strcmp(subsys, "pci") == 0) {
			path_prepend(&path, "pci-%s", udev_device_get_sysname(parent));
			parent = skip_subsystem(parent, "pci");
		} else if (strcmp(subsys, "platform") == 0) {
			path_prepend(&path, "platform-%s", udev_device_get_sysname(parent));
			parent = skip_subsystem(parent, "platform");
		} else if (strcmp(subsys, "acpi") == 0) {
			path_prepend(&path, "acpi-%s", udev_device_get_sysname(parent));
			parent = skip_subsystem(parent, "acpi");
		} else if (strcmp(subsys, "xen") == 0) {
			path_prepend(&path, "xen-%s", udev_device_get_sysname(parent));
			parent = skip_subsystem(parent, "xen");
		} else if (strcmp(subsys, "virtio") == 0) {
			path_prepend(&path, "virtio-pci-%s", udev_device_get_sysname(parent));
			parent = skip_subsystem(parent, "virtio");
		}

		parent = udev_device_get_parent(parent);
	}
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,
};