subr_hints.c

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/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2000,2001 Peter Wemm <peter@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include <sys/param.h>
#include <sys/lock.h>
#include <sys/kenv.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/bus.h>
 
#define FBACK_MDENV     0       /* MD env (e.g. loader.conf) */
#define FBACK_STENV     1       /* Static env */
#define FBACK_STATIC    2       /* static_hints */
 
/*
 * We'll use hintenv_merged to indicate that the dynamic environment has been
 * properly prepared for hint usage.  This implies that the dynamic environment
 * has already been setup (dynamic_kenv) and that we have added any supplied
 * static_hints to the dynamic environment.
 */
static bool     hintenv_merged;
/* Static environment and static hints cannot change, so we'll skip known bad */
static bool     stenv_skip;
static bool     sthints_skip;
/*
 * Access functions for device resources.
 */
 
static void
static_hints_to_env(void *data __unused)
{
        const char *cp;
        char *line, *eq;
        int eqidx, i;
 
        cp = static_hints;
        while (cp && *cp != '\0') {
                eq = strchr(cp, '=');
                if (eq == NULL)
                        /* Bad hint value */
                        continue;
                eqidx = eq - cp;
 
                i = strlen(cp);
                line = malloc(i + 1, M_TEMP, M_WAITOK);
                strcpy(line, cp);
                line[eqidx] = line[i] = '\0';
                /*
                 * Before adding a hint to the dynamic environment, check if
                 * another value for said hint has already been added.  This is
                 * needed because static environment overrides static hints and
                 * dynamic environment overrides all.
                 */
                if (testenv(line) == 0)
                        kern_setenv(line, line + eqidx + 1);
                free(line, M_TEMP);
                cp += i + 1;
        }
        hintenv_merged = true;
}
 
/* Any time after dynamic env is setup */
SYSINIT(hintenv, SI_SUB_KMEM + 1, SI_ORDER_SECOND, static_hints_to_env, NULL);
 
/*
 * Checks the environment to see if we even have any hints.  If it has no hints,
 * then res_find can take the hint that there's no point in searching it and
 * either move on to the next environment or fail early.
 */
static bool
_res_checkenv(char *envp)
{
        char *cp;
 
        cp = envp;
        while (cp) {
                if (strncmp(cp, "hint.", 5) == 0)
                        return (true);
                while (*cp != '\0')
                        cp++;
                cp++;
                if (*cp == '\0')
                        break;
        }
        return (false);
}
 
/*
 * Evil wildcarding resource string lookup.
 * This walks the supplied env string table and returns a match.
 * The start point can be remembered for incremental searches.
 */
static int
res_find(char **hintp_cookie, int *line, int *startln,
    const char *name, int *unit, const char *resname, const char *value,
    const char **ret_name, int *ret_namelen, int *ret_unit,
    const char **ret_resname, int *ret_resnamelen, const char **ret_value)
{
        int fbacklvl = FBACK_MDENV, i = 0, n = 0, namelen;
        char r_name[32];
        int r_unit;
        char r_resname[32];
        char r_value[128];
        const char *s, *cp;
        char *hintp, *p;
        bool dyn_used = false;
 
        /*
         * We are expecting that the caller will pass us a hintp_cookie that
         * they are tracking.  Upon entry, if *hintp_cookie is *not* set, this
         * indicates to us that we should be figuring out based on the current
         * environment where to search.  This keeps us sane throughout the
         * entirety of a single search.
         */
        if (*hintp_cookie == NULL) {
                hintp = NULL;
                if (hintenv_merged) {
                        /*
                         * static_hints, if it was previously used, has
                         * already been folded in to the environment
                         * by this point.
                         */
                        mtx_lock(&kenv_lock);
                        cp = kenvp[0];
                        for (i = 0; cp != NULL; cp = kenvp[++i]) {
                                if (!strncmp(cp, "hint.", 5)) {
                                        hintp = kenvp[0];
                                        break;
                                }
                        }
                        mtx_unlock(&kenv_lock);
                        dyn_used = true;
                } else {
                        /*
                         * We'll have a chance to keep coming back here until
                         * we've actually exhausted all of our possibilities.
                         * We might have chosen the MD/Static env because it
                         * had some kind of hints, but perhaps it didn't have
                         * the hint we are looking for.  We don't provide any
                         * fallback when searching the dynamic environment.
                         */
fallback:
                        if (dyn_used || fbacklvl >= FBACK_STATIC)
                                return (ENOENT);
 
                        switch (fbacklvl) {
                        case FBACK_MDENV:
                                fbacklvl++;
                                if (_res_checkenv(md_envp)) {
                                        hintp = md_envp;
                                        break;
                                }
 
                                /* FALLTHROUGH */
                        case FBACK_STENV:
                                fbacklvl++;
                                if (!stenv_skip && _res_checkenv(kern_envp)) {
                                        hintp = kern_envp;
                                        break;
                                } else
                                        stenv_skip = true;
 
                                /* FALLTHROUGH */
                        case FBACK_STATIC:
                                fbacklvl++;
                                /* We'll fallback to static_hints if needed/can */
                                if (!sthints_skip &&
                                    _res_checkenv(static_hints))
                                        hintp = static_hints;
                                else
                                        sthints_skip = true;
 
                                break;
                        default:
                                return (ENOENT);
                        }
                }
 
                if (hintp == NULL)
                        return (ENOENT);
                *hintp_cookie = hintp;
        } else {
                hintp = *hintp_cookie;
                if (hintenv_merged && hintp == kenvp[0])
                        dyn_used = true;
                else
                        /*
                         * If we aren't using the dynamic environment, we need
                         * to run through the proper fallback procedure again.
                         * This is so that we do continuations right if we're
                         * working with *line and *startln.
                         */
                        goto fallback;
        }
 
        if (dyn_used) {
                mtx_lock(&kenv_lock);
                i = 0;
        }
 
        if (name)
                namelen = strlen(name);
        cp = hintp;
        while (cp) {
                (*line)++;
                if (strncmp(cp, "hint.", 5) != 0)
                        goto nexthint;
                if (name && strncmp(cp + 5, name, namelen) != 0)
                        goto nexthint;
                n = sscanf(cp + 5, "%32[^.].%d.%32[^=]=%127s", r_name, &r_unit,
                    r_resname, r_value);
                if (n != 4) {
                        printf("CONFIG: invalid hint '%s'\n", cp);
                        p = strchr(cp, 'h');
                        *p = 'H';
                        goto nexthint;
                }
                if (startln && *startln >= 0 && *line < *startln)
                        goto nexthint;
                if (name && strcmp(name, r_name) != 0)
                        goto nexthint;
                if (unit && *unit != r_unit)
                        goto nexthint;
                if (resname && strcmp(resname, r_resname) != 0)
                        goto nexthint;
                if (value && strcmp(value, r_value) != 0)
                        goto nexthint;
                /* Successfully found a hint matching all criteria */
                break;
nexthint:
                if (dyn_used) {
                        cp = kenvp[++i];
                        if (cp == NULL)
                                break;
                } else {
                        while (*cp != '\0')
                                cp++;
                        cp++;
                        if (*cp == '\0') {
                                cp = NULL;
                                break;
                        }
                }
        }
        if (dyn_used)
                mtx_unlock(&kenv_lock);
        if (cp == NULL)
                goto fallback;
 
        s = cp;
        /* This is a bit of a hack, but at least is reentrant */
        /* Note that it returns some !unterminated! strings. */
        s = strchr(s, '.') + 1;         /* start of device */
        if (ret_name)
                *ret_name = s;
        s = strchr(s, '.') + 1;         /* start of unit */
        if (ret_namelen && ret_name)
                *ret_namelen = s - *ret_name - 1; /* device length */
        if (ret_unit)
                *ret_unit = r_unit;
        s = strchr(s, '.') + 1;         /* start of resname */
        if (ret_resname)
                *ret_resname = s;
        s = strchr(s, '=') + 1;         /* start of value */
        if (ret_resnamelen && ret_resname)
                *ret_resnamelen = s - *ret_resname - 1; /* value len */
        if (ret_value)
                *ret_value = s;
        if (startln)                    /* line number for anchor */
                *startln = *line + 1;
        return 0;
}
 
/*
 * Search all the data sources for matches to our query.  We look for
 * dynamic hints first as overrides for static or fallback hints.
 */
static int
resource_find(int *line, int *startln,
    const char *name, int *unit, const char *resname, const char *value,
    const char **ret_name, int *ret_namelen, int *ret_unit,
    const char **ret_resname, int *ret_resnamelen, const char **ret_value)
{
        int i;
        int un;
        char *hintp;
 
        *line = 0;
        hintp = NULL;
 
        /* Search for exact unit matches first */
        i = res_find(&hintp, line, startln, name, unit, resname, value,
            ret_name, ret_namelen, ret_unit, ret_resname, ret_resnamelen,
            ret_value);
        if (i == 0)
                return 0;
        if (unit == NULL)
                return ENOENT;
        /* If we are still here, search for wildcard matches */
        un = -1;
        i = res_find(&hintp, line, startln, name, &un, resname, value,
            ret_name, ret_namelen, ret_unit, ret_resname, ret_resnamelen,
            ret_value);
        if (i == 0)
                return 0;
        return ENOENT;
}
 
int
resource_int_value(const char *name, int unit, const char *resname, int *result)
{
        int error;
        const char *str;
        char *op;
        unsigned long val;
        int line;
 
        line = 0;
        error = resource_find(&line, NULL, name, &unit, resname, NULL,
            NULL, NULL, NULL, NULL, NULL, &str);
        if (error)
                return error;
        if (*str == '\0') 
                return EFTYPE;
        val = strtoul(str, &op, 0);
        if (*op != '\0') 
                return EFTYPE;
        *result = val;
        return 0;
}
 
int
resource_long_value(const char *name, int unit, const char *resname,
    long *result)
{
        int error;
        const char *str;
        char *op;
        unsigned long val;
        int line;
 
        line = 0;
        error = resource_find(&line, NULL, name, &unit, resname, NULL,
            NULL, NULL, NULL, NULL, NULL, &str);
        if (error)
                return error;
        if (*str == '\0') 
                return EFTYPE;
        val = strtoul(str, &op, 0);
        if (*op != '\0') 
                return EFTYPE;
        *result = val;
        return 0;
}
 
int
resource_string_value(const char *name, int unit, const char *resname,
    const char **result)
{
        int error;
        const char *str;
        int line;
 
        line = 0;
        error = resource_find(&line, NULL, name, &unit, resname, NULL,
            NULL, NULL, NULL, NULL, NULL, &str);
        if (error)
                return error;
        *result = str;
        return 0;
}
 
/*
 * This is a bit nasty, but allows us to not modify the env strings.
 */
static const char *
resource_string_copy(const char *s, int len)
{
        static char stringbuf[256];
        static int offset = 0;
        const char *ret;
 
        if (len == 0)
                len = strlen(s);
        if (len > 255)
                return NULL;
        if ((offset + len + 1) > 255)
                offset = 0;
        bcopy(s, &stringbuf[offset], len);
        stringbuf[offset + len] = '\0';
        ret = &stringbuf[offset];
        offset += len + 1;
        return ret;
}
 
/*
 * err = resource_find_match(&anchor, &name, &unit, resname, value)
 * Iteratively fetch a list of devices wired "at" something
 * res and value are restrictions.  eg: "at", "scbus0".
 * For practical purposes, res = required, value = optional.
 * *name and *unit are set.
 * set *anchor to zero before starting.
 */
int
resource_find_match(int *anchor, const char **name, int *unit,
    const char *resname, const char *value)
{
        const char *found_name;
        int found_namelen;
        int found_unit;
        int ret;
        int newln;
 
        newln = *anchor;
        ret = resource_find(anchor, &newln, NULL, NULL, resname, value,
            &found_name, &found_namelen, &found_unit, NULL, NULL, NULL);
        if (ret == 0) {
                *name = resource_string_copy(found_name, found_namelen);
                *unit = found_unit;
        }
        *anchor = newln;
        return ret;
}
 
/*
 * err = resource_find_dev(&anchor, name, &unit, res, value);
 * Iterate through a list of devices, returning their unit numbers.
 * res and value are optional restrictions.  eg: "at", "scbus0".
 * *unit is set to the value.
 * set *anchor to zero before starting.
 */
int
resource_find_dev(int *anchor, const char *name, int *unit,
    const char *resname, const char *value)
{
        int found_unit;
        int newln;
        int ret;
 
        newln = *anchor;
        ret = resource_find(anchor, &newln, name, NULL, resname, value,
            NULL, NULL, &found_unit, NULL, NULL, NULL);
        if (ret == 0) {
                *unit = found_unit;
        }
        *anchor = newln;
        return ret;
}
 
/*
 * Check to see if a device is disabled via a disabled hint.
 */
int
resource_disabled(const char *name, int unit)
{
        int error, value;
 
        error = resource_int_value(name, unit, "disabled", &value);
        if (error)
               return (0);
        return (value);
}
 
/*
 * Clear a value associated with a device by removing it from
 * the kernel environment.  This only removes a hint for an
 * exact unit.
 */
int
resource_unset_value(const char *name, int unit, const char *resname)
{
        char varname[128];
        const char *retname, *retvalue;
        int error, line;
        size_t len;
 
        line = 0;
        error = resource_find(&line, NULL, name, &unit, resname, NULL,
            &retname, NULL, NULL, NULL, NULL, &retvalue);
        if (error)
                return (error);
 
        retname -= strlen("hint.");
        len = retvalue - retname - 1;
        if (len > sizeof(varname) - 1)
                return (ENAMETOOLONG);
        memcpy(varname, retname, len);
        varname[len] = '\0';
        return (kern_unsetenv(varname));
}