svc/svcadm/synch.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * synchronous svcadm logic
 */

#include <locale.h>
#include <libintl.h>
#include <libscf.h>
#include <libscf_priv.h>
#include <libuutil.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>
#include <sys/stat.h>


/*
 * Definitions from svcadm.c.
 */
extern scf_handle_t *h;
extern ssize_t max_scf_fmri_sz;

extern void do_scfdie(int) __NORETURN;
extern int inst_get_state(scf_instance_t *, char *, const char *,
    scf_propertygroup_t **);
extern ssize_t get_astring_prop(const scf_propertygroup_t *, const char *,
    scf_property_t *, scf_value_t *, char *, size_t);
extern int get_bool_prop(scf_propertygroup_t *, const char *, uint8_t *);

#define scfdie()    do_scfdie(__LINE__)

int has_potential(scf_instance_t *, int);

/*
 * Determines if the specified instance is enabled, composing the
 * general and general_ovr property groups.  For simplicity, we map
 * most errors to "not enabled".
 */
int
is_enabled(scf_instance_t *inst)
{
    scf_propertygroup_t *pg;
    uint8_t bp;

    if ((pg = scf_pg_create(h)) == NULL)
        scfdie();

    if (scf_instance_get_pg(inst, SCF_PG_GENERAL_OVR, pg) == 0 &&
        get_bool_prop(pg, SCF_PROPERTY_ENABLED, &bp) == 0) {
        scf_pg_destroy(pg);
        return (bp);
    }

    if (scf_instance_get_pg(inst, SCF_PG_GENERAL, pg) == 0 &&
        get_bool_prop(pg, SCF_PROPERTY_ENABLED, &bp) == 0) {
        scf_pg_destroy(pg);
        return (bp);
    }

    scf_pg_destroy(pg);
    return (B_FALSE);
}

/*
 * Reads an astring property from a property group.  If the named
 * property doesn't exist, returns NULL.  The result of a successful
 * call should be freed.
 */
static char *
read_astring_prop(scf_propertygroup_t *pg, scf_value_t *val,
    scf_property_t *prop, const char *name)
{
    char *value;
    size_t value_sz;

    if (scf_pg_get_property(pg, name, prop) == -1) {
        switch (scf_error()) {
        case SCF_ERROR_NOT_FOUND:
        case SCF_ERROR_DELETED:
            return (NULL);
        default:
            scfdie();
        }
    }

    if (scf_property_get_value(prop, val) != 0) {
        switch (scf_error()) {
        case SCF_ERROR_DELETED:
        case SCF_ERROR_NOT_FOUND:
        case SCF_ERROR_CONSTRAINT_VIOLATED:
            return (NULL);
        default:
            scfdie();
        }
    }

    value_sz = scf_limit(SCF_LIMIT_MAX_VALUE_LENGTH);
    if ((value = malloc(value_sz)) == NULL)
        scfdie();

    if (scf_value_get_astring(val, value, value_sz) <= 0) {
        free(value);
        return (NULL);
    }

    return (value);
}

/*
 * Creates and returns an scf_iter for the values of the named
 * multi-value property.  Returns NULL on failure.
 */
static scf_iter_t *
prop_walk_init(scf_propertygroup_t *pg, const char *name)
{
    scf_iter_t *iter;
    scf_property_t *prop;

    if ((iter = scf_iter_create(h)) == NULL ||
        (prop = scf_property_create(h)) == NULL)
        scfdie();

    if (scf_pg_get_property(pg, name, prop) != 0) {
        switch (scf_error()) {
        case SCF_ERROR_NOT_FOUND:
        case SCF_ERROR_DELETED:
            goto error;
        default:
            scfdie();
        }
    }

    if (scf_iter_property_values(iter, prop) != 0) {
        if (scf_error() != SCF_ERROR_DELETED)
            scfdie();
        goto error;
    }

    scf_property_destroy(prop);
    return (iter);
error:
    scf_property_destroy(prop);
    scf_iter_destroy(iter);
    return (NULL);
}

/*
 * Reads the next value from the multi-value property using the
 * scf_iter obtained by prop_walk_init, and places it in the buffer
 * pointed to by fmri.  Returns -1 on failure, 0 when done, and non-0
 * when returning a value.
 */
static int
prop_walk_step(scf_iter_t *iter, char *fmri, size_t len)
{
    int r;
    scf_value_t *val;

    if ((val = scf_value_create(h)) == NULL)
        scfdie();

    r = scf_iter_next_value(iter, val);
    if (r == 0)
        goto out;
    if (r == -1) {
        if (scf_error() != SCF_ERROR_DELETED)
            scfdie();
        goto out;
    }
    if (scf_value_get_astring(val, fmri, len) <= 0) {
        r = -1;
        goto out;
    }

out:
    scf_value_destroy(val);
    return (r);
}

/*
 * Determines if a file dependency is satisfied, taking into account
 * whether it is an exclusion dependency or not.  If we can't access
 * the file, we err on the side of caution and assume the dependency
 * isn't satisfied.
 */
static int
file_has_potential(char *fmri, int exclude)
{
    const char *path;
    struct stat st;

    int good = exclude ? B_FALSE : B_TRUE;

    if (scf_parse_file_fmri(fmri, NULL, &path) != 0)
        return (good);

    if (stat(path, &st) == 0)
        return (good);

    if (errno == EACCES) {
        uu_warn(gettext("Unable to access \"%s\".\n"), path);
        return (B_FALSE);
    }

    return (!good);
}

/*
 * Determines if a dependency on a service instance is satisfiable.
 * Returns 0 if not, 1 if it is, or 2 if it is an optional or exclude
 * dependency and the service only "weakly" satisfies (i.e. is disabled
 * or is in maintenance state).
 */
static int
inst_has_potential(scf_instance_t *inst, int enabled, int optional, int exclude)
{
    char state[MAX_SCF_STATE_STRING_SZ];

    if (!enabled)
        return ((optional || exclude) ? 2 : 0);

    /*
     * Normally we would return a positive value on failure;
     * relying on startd to place the service in maintenance.  But
     * if we can't read a service's state, we have to assume it is
     * out to lunch.
     */
    if (inst_get_state(inst, state, NULL, NULL) != 0)
        return (0);

    /*
     * Optional dependencies which are offline always have a possibility of
     * coming online.
     */
    if (optional && strcmp(state, SCF_STATE_STRING_OFFLINE) == 0)
        return (2);

    if (strcmp(state, SCF_STATE_STRING_MAINT) == 0) {
        /*
         * Enabled services in maintenance state satisfy
         * optional-all dependencies.
         */
        return ((optional || exclude) ? 2 : 0);
    }

    /*
     * We're enabled and not in maintenance.
     */
    if (exclude)
        return (0);

    if (strcmp(state, SCF_STATE_STRING_ONLINE) == 0 ||
        strcmp(state, SCF_STATE_STRING_DEGRADED) == 0)
        return (1);

    return (has_potential(inst, B_FALSE));
}

/*
 * Determines if a dependency on an fmri is satisfiable, handling the
 * separate cases for file, service, and instance fmris.  Returns false
 * if not, or true if it is.  Takes into account if the dependency is
 * an optional or exclusive one.
 */
static int
fmri_has_potential(char *fmri, int isfile, int optional, int exclude,
    int restarter)
{
    scf_instance_t *inst;
    scf_service_t *svc;
    scf_iter_t *iter;
    int good = exclude ? B_FALSE : B_TRUE;
    int enabled;
    int r, result;
    int optbad;

    assert(!optional || !exclude);

    if (isfile)
        return (file_has_potential(fmri, exclude));

    if ((inst = scf_instance_create(h)) == NULL ||
        (svc = scf_service_create(h)) == NULL ||
        (iter = scf_iter_create(h)) == NULL)
        scfdie();

    if (scf_handle_decode_fmri(h, fmri, NULL, NULL, inst, NULL, NULL,
        SCF_DECODE_FMRI_EXACT) == 0) {
        enabled = is_enabled(inst);
        result =
            (inst_has_potential(inst, enabled, optional, exclude) != 0);
        goto out;
    }

    if (scf_handle_decode_fmri(h, fmri, NULL, svc, NULL, NULL, NULL,
        SCF_DECODE_FMRI_EXACT) != 0) {
        /*
         * If we are checking a restarter dependency, a bad
         * or nonexistent service will never be noticed.
         */
        result = restarter ? B_FALSE : good;
        goto out;
    }

    if (scf_iter_service_instances(iter, svc) != 0) {
        if (scf_error() != SCF_ERROR_DELETED)
            scfdie();
        result = good;
        goto out;
    }

    optbad = 0;
    for (;;) {
        r = scf_iter_next_instance(iter, inst);
        if (r == 0) {
            result = exclude || (optional && !optbad);
            goto out;
        }
        if (r == -1) {
            if (scf_error() != SCF_ERROR_DELETED)
                scfdie();
            result = good;
            goto out;
        }

        enabled = is_enabled(inst);
        r = inst_has_potential(inst, enabled, optional, exclude);

        /*
         * Exclusion dependencies over services map to
         * require-none for its instances.
         */
        if (exclude)
            r = (r == 0);

        if (r == 1) {
            /*
             * Remember, if this is an exclusion dependency
             * (which means we are here because there
             * exists an instance which wasn't satisfiable
             * in that regard), good means bad.
             */
            result = good;
            goto out;
        }

        if (optional && r == 0)
            optbad = 1;
    }

out:
    scf_instance_destroy(inst);
    scf_service_destroy(svc);
    scf_iter_destroy(iter);
    return (result);
}

static int
eval_require_any(scf_iter_t *iter, char *value, size_t value_sz, int isfile)
{
    int r, empty = B_TRUE;

    for (;;) {
        /*
         * For reasons unknown, an empty require_any dependency
         * group is considered by startd to be satisfied.
         * This insanity fortunately doesn't extend to
         * dependencies on services with no instances.
         */
        if ((r = prop_walk_step(iter, value, value_sz)) <= 0)
            return ((r == 0 && empty) ? B_TRUE : r);
        if (fmri_has_potential(value, isfile, B_FALSE, B_FALSE,
            B_FALSE))
            return (1);
        empty = B_FALSE;
    }
}

static int
eval_all(scf_iter_t *iter, char *value, size_t value_sz,
    int isfile, int optional, int exclude)
{
    int r;

    for (;;) {
        if ((r = prop_walk_step(iter, value, value_sz)) <= 0)
            return ((r == 0) ? 1 : r);
        if (!fmri_has_potential(value, isfile, optional, exclude,
            B_FALSE))
            return (0);
    }
}

static int
eval_require_all(scf_iter_t *iter, char *value, size_t value_sz, int isfile)
{
    return (eval_all(iter, value, value_sz, isfile, B_FALSE, B_FALSE));
}

static int
eval_optional_all(scf_iter_t *iter, char *value, size_t value_sz, int isfile)
{
    return (eval_all(iter, value, value_sz, isfile, B_TRUE, B_FALSE));
}

static int
eval_exclude_all(scf_iter_t *iter, char *value, size_t value_sz, int isfile)
{
    return (eval_all(iter, value, value_sz, isfile, B_FALSE, B_TRUE));
}

/*
 * Examines the state and health of an instance's restarter and
 * dependencies, and determines the impact of both on the instance's
 * ability to be brought on line.  A true return value indicates that
 * instance appears to be a likely candidate for the online club.
 * False indicates that there is no hope for the instance.
 */
int
has_potential(scf_instance_t *inst, int restarter_only)
{
    scf_snapshot_t *snap;
    scf_iter_t *iter, *viter = NULL;
    scf_propertygroup_t *pg;
    scf_property_t *prop;
    scf_value_t *val;
    char *type = NULL, *grouping = NULL;
    char *value;
    size_t value_sz;
    int result = B_TRUE, r;
    int isfile;

    value_sz = scf_limit(SCF_LIMIT_MAX_VALUE_LENGTH);
    if ((iter = scf_iter_create(h)) == NULL ||
        (snap = scf_snapshot_create(h)) == NULL ||
        (pg = scf_pg_create(h)) == NULL ||
        (val = scf_value_create(h)) == NULL ||
        (prop = scf_property_create(h)) == NULL ||
        (value = malloc(value_sz)) == NULL)
        scfdie();

    /*
     * First we check our restarter as an implicit dependency.
     */
    if (scf_instance_get_pg_composed(inst, NULL, SCF_PG_GENERAL, pg) != 0)
        scfdie();

    r = get_astring_prop(pg, SCF_PROPERTY_RESTARTER, prop, val, value,
        value_sz);
    if (r == -ENOENT) {
        (void) strlcpy(value, SCF_SERVICE_STARTD, value_sz);
    } else if (r < 0 || r > max_scf_fmri_sz) {
        /*
         * Normally we would return true and let the restarter
         * tell our caller there is a problem by changing the
         * instance's state, but that's not going to happen if
         * the restarter is invalid.
         */
        result = B_FALSE;
        goto out;
    }

    if (!fmri_has_potential(value, B_FALSE, B_FALSE, B_FALSE, B_TRUE)) {
        result = B_FALSE;
        goto out;
    }

    if (restarter_only)
        goto out;

    /*
     * Now we check explicit dependencies.
     */
    if (scf_instance_get_snapshot(inst, "running", snap) != 0) {
        if (scf_error() != SCF_ERROR_NOT_FOUND)
            scfdie();
        scf_snapshot_destroy(snap);
        snap = NULL;
    }

    if (scf_iter_instance_pgs_typed_composed(iter, inst, snap,
        SCF_GROUP_DEPENDENCY) != 0) {
        if (scf_error() != SCF_ERROR_DELETED)
            scfdie();
        goto out;
    }

    for (;;) {
        r = scf_iter_next_pg(iter, pg);
        if (r == 0)
            break;
        if (r == -1) {
            if (scf_error() != SCF_ERROR_DELETED)
                scfdie();
            goto out;
        }

        if ((grouping = read_astring_prop(pg, val, prop,
            SCF_PROPERTY_GROUPING)) == NULL)
            goto out;

        if ((type = read_astring_prop(pg, val, prop,
            SCF_PROPERTY_TYPE)) == NULL)
            goto out;

        if (strcmp(type, "path") == 0) {
            isfile = B_TRUE;
        } else if (strcmp(type, "service") == 0) {
            isfile = B_FALSE;
        } else {
            free(type);
            goto out;
        }
        free(type);

        if ((viter = prop_walk_init(pg, SCF_PROPERTY_ENTITIES)) == NULL)
            goto out;

        if (strcmp(grouping, SCF_DEP_REQUIRE_ALL) == 0) {
            r = eval_require_all(viter, value, value_sz, isfile);
        } else if (strcmp(grouping, SCF_DEP_REQUIRE_ANY) == 0) {
            r = eval_require_any(viter, value, value_sz, isfile);
        } else if (strcmp(grouping, SCF_DEP_EXCLUDE_ALL) == 0) {
            r = eval_exclude_all(viter, value, value_sz, isfile);
        } else if (strcmp(grouping, SCF_DEP_OPTIONAL_ALL) == 0) {
            r = eval_optional_all(viter, value, value_sz, isfile);
        } else {
            scf_iter_destroy(viter);
            free(grouping);
            grouping = NULL;
            goto out;
        }

        scf_iter_destroy(viter);
        free(grouping);
        grouping = NULL;

        if (r == 0) {
            result = B_FALSE;
            goto out;
        } else if (r == -1) {
            goto out;
        }
    }

out:
    free(value);
    scf_property_destroy(prop);
    scf_value_destroy(val);
    scf_pg_destroy(pg);
    if (snap != NULL)
        scf_snapshot_destroy(snap);
    if (grouping != NULL)
        free(grouping);
    scf_iter_destroy(iter);
    return (result);
}