path: root/policy.c

/*
 * mdadm - manage Linux "md" devices aka RAID arrays.
 *
 * Copyright (C) 2001-2009 Neil Brown <neilb@suse.de>
 *
 *
 *    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, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *    Author: Neil Brown
 *    Email: <neilb@suse.de>
 */

#include "mdadm.h"
#include <dirent.h>
#include <fnmatch.h>
#include <ctype.h>
#include "dlink.h"
/*
 * Policy module for mdadm.
 * A policy statement about a device lists a set of values for each
 * of a set of names.  Each value can have a metadata type as context.
 *
 * names include:
 *   action - the actions that can be taken on hot-plug
 *   domain - the domain(s) that the device is part of
 *
 * Policy information is extracted from various sources, but
 * particularly from a set of policy rules in mdadm.conf
 */

void pol_new(struct dev_policy **pol, char *name, char *val, char *metadata)
{
	struct dev_policy *n = malloc(sizeof(*n));
	const char *real_metadata = NULL;
	int i;

	n->name = name;
	n->value = val;

	/* We need to normalise the metadata name */
	if (metadata) {
		for (i = 0; superlist[i] ; i++)
			if (strcmp(metadata, superlist[i]->name) == 0) {
				real_metadata = superlist[i]->name;
				break;
			}
		if (!real_metadata) {
			if (strcmp(metadata, "1") == 0 ||
			    strcmp(metadata, "1.0") == 0 ||
			    strcmp(metadata, "1.1") == 0 ||
			    strcmp(metadata, "1.2") == 0)
				real_metadata = super1.name;
		}
		if (!real_metadata) {
			static char *prev = NULL;
			if (prev != metadata) {
				fprintf(stderr, Name ": metadata=%s unrecognised - ignoring rule\n",
					metadata);
				prev = metadata;
			}
			real_metadata = "unknown";
		}
	}

	n->metadata = real_metadata;
	n->next = *pol;
	*pol = n;
}

static int pol_lesseq(struct dev_policy *a, struct dev_policy *b)
{
	int cmp;

	if (a->name < b->name)
		return 1;
	if (a->name > b->name)
		return 0;

	cmp = strcmp(a->value, b->value);
	if (cmp < 0)
		return 1;
	if (cmp > 0)
		return 0;

	return (a->metadata <= b->metadata);
}

static void pol_sort(struct dev_policy **pol)
{
	/* sort policy list in *pol by name/metadata/value
	 * using merge sort
	 */

	struct dev_policy *pl[2];
	pl[0] = *pol;
	pl[1] = NULL;

	do {
		struct dev_policy **plp[2], *p[2];
		int curr = 0;
		struct dev_policy nul = { NULL, NULL, NULL, NULL };
		struct dev_policy *prev = &nul;
		int next = 0;

		/* p[] are the two lists that we are merging.
		 * plp[] are the ends of the two lists we create
		 * from the merge.
		 * 'curr' is which of plp[] that we are currently
		 *   adding items to.
		 * 'next' is which if p[] we will take the next
		 *   item from.
		 * 'prev' is that last value, which was placed in
		 * plp[curr].
		 */
		plp[0] = &pl[0];
		plp[1] = &pl[1];
		p[0] = pl[0];
		p[1] = pl[1];

		/* take least of p[0] and p[1]
		 * if it is larger than prev, add to
		 * plp[curr], else swap curr then add
		 */
		while (p[0] || p[1]) {
			if (p[next] == NULL ||
			    (p[1-next] != NULL &&
			     !(pol_lesseq(prev, p[1-next])
			       ^pol_lesseq(p[1-next], p[next])
			       ^pol_lesseq(p[next], prev)))
				)
				next = 1 - next;

			if (!pol_lesseq(prev, p[next]))
				curr = 1 - curr;

			*plp[curr] = prev = p[next];
			plp[curr] = &p[next]->next;
			p[next] = p[next]->next;
		}
		*plp[0] = NULL;
		*plp[1] = NULL;
	} while (pl[0] && pl[1]);
	if (pl[0])
		*pol = pl[0];
	else
		*pol = pl[1];
}

static void pol_dedup(struct dev_policy *pol)
{
	/* This is a sorted list - remove duplicates. */
	while (pol && pol->next) {
		if (pol_lesseq(pol->next, pol)) {
			struct dev_policy *tmp = pol->next;
			pol->next = tmp->next;
			free(tmp);
		} else
			pol = pol->next;
	}
}

/*
 * pol_find finds the first entry in the policy
 * list to match name.
 * If it returns non-NULL there is at least one
 * value, but how many can only be found by
 * iterating through the list.
 */
struct dev_policy *pol_find(struct dev_policy *pol, char *name)
{
	while (pol && pol->name < name)
		pol = pol->next;

	if (!pol || pol->name != name)
		return NULL;
	return pol;
}

static char *disk_path(struct mdinfo *disk)
{
	struct stat stb;
	int prefix_len;
	DIR *by_path;
	char symlink[PATH_MAX] = "/dev/disk/by-path/";
	struct dirent *ent;

	by_path = opendir(symlink);
	if (!by_path)
		return NULL;
	prefix_len = strlen(symlink);

	while ((ent = readdir(by_path)) != NULL) {
		if (ent->d_type != DT_LNK)
			continue;
		strncpy(symlink + prefix_len,
			ent->d_name,
			sizeof(symlink) - prefix_len);
		if (stat(symlink, &stb) < 0)
			continue;
		if ((stb.st_mode & S_IFMT) != S_IFBLK)
			continue;
		if (stb.st_rdev != makedev(disk->disk.major, disk->disk.minor))
			continue;
		closedir(by_path);
		return strdup(ent->d_name);
	}
	closedir(by_path);
	return NULL;
}

char type_part[] = "part";
char type_disk[] = "disk";
static char *disk_type(struct mdinfo *disk)
{
	char buf[30+20+20];
	struct stat stb;
	sprintf(buf, "/sys/dev/block/%d:%d/partition",
		disk->disk.major, disk->disk.minor);
	if (stat(buf, &stb) == 0)
		return type_part;
	else
		return type_disk;
}

static int pol_match(struct rule *rule, char *path, char *type)
{
	/* check if this rule matches on path and type */
	int pathok = 0; /* 0 == no path, 1 == match, -1 == no match yet */
	int typeok = 0;

	while (rule) {
		if (rule->name == rule_path) {
			if (pathok == 0)
				pathok = -1;
			if (fnmatch(rule->value, path, 0) == 0)
				pathok = 1;
		}
		if (rule->name == rule_type) {
			if (typeok == 0)
				typeok = -1;
			if (strcmp(rule->value, type) == 0)
				typeok = 1;
		}
		rule = rule->next;
	}
	return pathok >= 0 && typeok >= 0;
}

static void pol_merge(struct dev_policy **pol, struct rule *rule)
{
	/* copy any name assignments from rule into pol */
	struct rule *r;
	char *metadata = NULL;
	for (r = rule; r ; r = r->next)
		if (r->name == pol_metadata)
			metadata = r->value;

	for (r = rule; r ; r = r->next)
		if (r->name == pol_act ||
		    r->name == pol_domain)
			pol_new(pol, r->name, r->value, metadata);
}

static int path_has_part(char *path, char **part)
{
	/* check if path ends with "-partNN" and
	 * if it does, place a pointer to "-pathNN"
	 * in 'part'.
	 */
	int l = strlen(path);
	while (l > 1 && isdigit(path[l-1]))
		l--;
	if (l < 5 || strncmp(path+l-5, "-part", 5) != 0)
		return 0;
	*part = path+l-4;
	return 1;
}

static void pol_merge_part(struct dev_policy **pol, struct rule *rule, char *part)
{
	/* copy any name assignments from rule into pol, appending
	 * -part to any domain.  The string with -part appended is
	 * stored with the rule so it has a lifetime to match
	 * the rule.
	 */
	struct rule *r;
	char *metadata = NULL;
	for (r = rule; r ; r = r->next)
		if (r->name == pol_metadata)
			metadata = r->value;

	for (r = rule; r ; r = r->next) {
		if (r->name == pol_act)
			pol_new(pol, r->name, r->value, metadata);
		else if (r->name == pol_domain) {
			char *dom;
			int len;
			if (r->dups == NULL)
				r->dups = dl_head();
			len = strlen(r->value);
			for (dom = dl_next(r->dups); dom != r->dups;
			     dom = dl_next(dom))
				if (strcmp(dom+len+1, part)== 0)
					break;
			if (dom == r->dups) {
				char *newdom = dl_strndup(
					r->value, len + 1 + strlen(part));
				strcat(strcat(newdom, "-"), part);
				dl_add(r->dups, newdom);
				dom = newdom;
			}
			pol_new(pol, r->name, dom, metadata);
		}
	}
}

static struct pol_rule *config_rules = NULL;
static struct pol_rule **config_rules_end = NULL;
static int config_rules_has_path = 0;

/*
 * most policy comes from a set policy rules that are
 * read from the config file.
 * disk_policy() gathers policy information for the
 * disk described in the given mdinfo (disk.{major,minor}).
 */
struct dev_policy *disk_policy(struct mdinfo *disk)
{
	char *path = NULL;
	char *type = disk_type(disk);
	struct pol_rule *rules;
	struct dev_policy *pol = NULL;

	if (!type)
		return NULL;
	if (config_rules_has_path) {
		path = disk_path(disk);
		if (!path)
			return NULL;
	}

	rules = config_rules;

	while (rules) {
		char *part;
		if (rules->type == rule_policy)
			if (pol_match(rules->rule, path, type))
				pol_merge(&pol, rules->rule);
		if (rules->type == rule_part && strcmp(type, type_part) == 0)
			if (path_has_part(path, &part)) {
				*part = 0;
				if (pol_match(rules->rule, path, type_disk))
					pol_merge_part(&pol, rules->rule, part+1);
				*part = '-';
			}
		rules = rules->next;
	}
	pol_sort(&pol);
	pol_dedup(pol);
	free(path);
	return pol;
}

/*
 * process policy rules read from config file.
 */

char rule_path[] = "path";
char rule_type[] = "type";

char rule_policy[] = "policy";
char rule_part[] = "part-policy";

char pol_metadata[] = "metadata";
char pol_act[] = "action";
char pol_domain[] = "domain";

static int try_rule(char *w, char *name, struct rule **rp)
{
	struct rule *r;
	int len = strlen(name);
	if (strncmp(w, name, len) != 0 ||
	    w[len] != '=')
		return 0;
	r = malloc(sizeof(*r));
	r->next = *rp;
	r->name = name;
	r->value = strdup(w+len+1);
	r->dups = NULL;
	*rp = r;
	return 1;
}

void policyline(char *line, char *type)
{
	struct pol_rule *pr;
	char *w;

	if (config_rules_end == NULL)
		config_rules_end = &config_rules;

	pr = malloc(sizeof(*pr));
	pr->type = type;
	pr->rule = NULL;
	for (w = dl_next(line); w != line ; w = dl_next(w)) {
		if (try_rule(w, rule_path, &pr->rule))
			config_rules_has_path = 1;
		else if (! try_rule(w, rule_type, &pr->rule) &&
			 ! try_rule(w, pol_metadata, &pr->rule) &&
			 ! try_rule(w, pol_act, &pr->rule) &&
			 ! try_rule(w, pol_domain, &pr->rule))
			fprintf(stderr, Name ": policy rule %s unrecognised and ignored\n",
				w);
	}
	pr->next = config_rules;
	config_rules = pr;
}

void policy_free(void)
{
	while (config_rules) {
		struct pol_rule *pr = config_rules;
		struct rule *r;

		config_rules = config_rules->next;

		for (r = pr->rule; r; ) {
			struct rule *next = r->next;
			free(r->value);
			if (r->dups)
				free_line(r->dups);
			free(r);
			r = next;
		}
		free(pr);
	}
	config_rules_end = NULL;
	config_rules_has_path = 0;
}

void dev_policy_free(struct dev_policy *p)
{
	struct dev_policy *t;
	while (p) {
		t = p;
		p = p->next;
		free(t);
	}
}