libzonecfg/common/scratchops.c

108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj/*
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * CDDL HEADER START
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * The contents of this file are subject to the terms of the
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * Common Development and Distribution License (the "License").
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * You may not use this file except in compliance with the License.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * or http://www.opensolaris.org/os/licensing.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * See the License for the specific language governing permissions
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * and limitations under the License.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * When distributing Covered Code, include this CDDL HEADER in each
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * If applicable, add the following below this CDDL HEADER, with the
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * fields enclosed by brackets "[]" replaced with your own identifying
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * information: Portions Copyright [yyyy] [name of copyright owner]
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * CDDL HEADER END
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj */
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj/*
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * Use is subject to license terms.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj */
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#pragma ident   "%Z%%M% %I% %E% SMI"
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj/*
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * This module contains functions used for reading and writing the scratch zone
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * translation files.  These files are used by Live Upgrade to keep track of
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * mappings between actual kernel zone names and the zones in an alternate boot
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * environment.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * The functions are MT-safe.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * The file format looks like this:
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  <zonename>  <kernel-zonename>   <alt-root>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj * The expected usage model is:
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  fp = zonecfg_open_scratch("", B_TRUE);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  zonecfg_lock_scratch(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  if (zonecfg_find_scratch(fp, zonename, altroot, NULL, 0) == 0) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *      handle error; zone already mounted
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  mount zone here
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  zonecfg_add_scratch(fp, zonename, kernname, altroot);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  zonecfg_close_scratch(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  fp = zonecfg_open_scratch(zoneroot, B_TRUE);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  ftruncate(fileno(fp), 0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  zonecfg_add_scratch(fp, zonename, kernname, "/");
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj *  zonecfg_close_scratch(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj */
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <stdio.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <unistd.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <fcntl.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <errno.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <string.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <sys/types.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <sys/stat.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <sys/param.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#include <libzonecfg.h>
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj#define PATH_MAPFILE    "tmp/.alt.lu-zone-map"
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjstatic int
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjlock_op(int fd, int type)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    struct flock lock;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    lock.l_type = type;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    lock.l_whence = SEEK_SET;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    lock.l_start = 0;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    lock.l_len = 0;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (fcntl(fd, F_SETLKW, &lock));
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjFILE *
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_open_scratch(const char *rootpath, boolean_t createfile)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    mode_t oldmask = umask(0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    struct stat lbuf, fbuf;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    int fd, flags;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    FILE *fp;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char mapfile[MAXPATHLEN];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    (void) snprintf(mapfile, sizeof (mapfile), "%s/" PATH_MAPFILE,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        rootpath);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    flags = O_RDWR | O_NOFOLLOW | O_NOLINKS;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if (createfile)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        flags |= O_EXCL | O_CREAT;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if ((fd = open(mapfile, flags, 0644)) == -1) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (!createfile) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            errno = ENOENT;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            goto failure;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (lstat(mapfile, &lbuf) == -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            goto failure;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (!S_ISREG(lbuf.st_mode) || lbuf.st_nlink != 1 ||
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            lbuf.st_uid != 0) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            errno = EINVAL;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            goto failure;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        fd = open(mapfile, O_RDWR);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (fd == -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            goto failure;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (fstat(fd, &fbuf) == -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            goto failure;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (lbuf.st_ino != fbuf.st_ino || lbuf.st_dev != fbuf.st_dev) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            errno = EINVAL;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            goto failure;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if (lock_op(fd, F_RDLCK) == -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        goto failure;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    (void) umask(oldmask);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if ((fp = fdopen(fd, "r+")) == NULL)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        (void) close(fd);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjfailure:
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if (fd != -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        (void) close(fd);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    (void) umask(oldmask);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (NULL);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjint
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_lock_scratch(FILE *fp)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if (fflush(fp) != 0)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (lock_op(fileno(fp), F_WRLCK));
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjvoid
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_close_scratch(FILE *fp)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    (void) fclose(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjint
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_get_scratch(FILE *fp, char *zonename, size_t namelen, char *kernname,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    size_t kernlen, char *altroot, size_t altlen)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char line[2 * ZONENAME_MAX + MAXPATHLEN + 2];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char *cp, *cp2;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    /* We always hold at least a read lock on the file */
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    for (;;) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (fgets(line, sizeof (line), fp) == NULL)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if ((cp = strchr(line, '\n')) == NULL)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        *cp = '\0';
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if ((cp = strchr(line, ' ')) == NULL)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            cp = line + strlen(line);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        else
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            *cp++ = '\0';
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (zonename != NULL &&
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            strlcpy(zonename, line, namelen) >= namelen)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            continue;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if ((cp2 = strchr(cp, ' ')) == NULL)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            cp2 = cp + strlen(cp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        else
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            *cp2++ = '\0';
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (kernname != NULL &&
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            strlcpy(kernname, cp, kernlen) >= kernlen)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            continue;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (altroot != NULL && strlcpy(altroot, cp2, altlen) >= altlen)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            continue;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        break;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjint
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_find_scratch(FILE *fp, const char *zonename, const char *altroot,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char *kernzone, size_t kernlen)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char zone[ZONENAME_MAX];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char aroot[MAXPATHLEN];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    rewind(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    while (zonecfg_get_scratch(fp, zone, sizeof (zone), kernzone, kernlen,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        aroot, sizeof (aroot)) == 0) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (strcmp(zone, zonename) == 0 && strcmp(altroot, aroot) == 0)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            return (0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjint
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_reverse_scratch(FILE *fp, const char *kernzone, char *zonename,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    size_t namelen, char *altroot, size_t altlen)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char kzone[ZONENAME_MAX];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    rewind(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    while (zonecfg_get_scratch(fp, zonename, namelen, kzone,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        sizeof (kzone), altroot, altlen) == 0) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (strcmp(kzone, kernzone) == 0)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            return (0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjint
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_add_scratch(FILE *fp, const char *zonename, const char *kernzone,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    const char *altroot)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if (fseek(fp, 0, SEEK_END) == -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if (fprintf(fp, "%s %s %s\n", zonename, kernzone, altroot) == EOF)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    if (fflush(fp) != 0)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjint
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_delete_scratch(FILE *fp, const char *kernzone)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char zone[ZONENAME_MAX];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char kzone[ZONENAME_MAX];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    char aroot[MAXPATHLEN];
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    long roffs, woffs;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    /*
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj     * The implementation here is intentionally quite simple.  We could
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj     * allocate a buffer that's big enough to hold the data up to
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj     * stat.st_size and then write back out the part we need to, but there
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj     * seems to be little point.
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj     */
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    rewind(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    roffs = 0;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    do {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        woffs = roffs;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (zonecfg_get_scratch(fp, NULL, 0, kzone, sizeof (kzone),
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            NULL, 0) != 0)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            return (-1);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        roffs = ftell(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    } while (strcmp(kzone, kernzone) != 0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    while (zonecfg_get_scratch(fp, zone, sizeof (zone), kzone,
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        sizeof (kzone), aroot, sizeof aroot) == 0) {
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        roffs = ftell(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (fseek(fp, woffs, SEEK_SET) == -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            break;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (fprintf(fp, "%s %s %s\n", zone, kzone, aroot) == EOF)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            break;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        woffs = ftell(fp);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj        if (fseek(fp, roffs, SEEK_SET) == -1)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj            break;
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    }
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    (void) ftruncate(fileno(fp), woffs);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjboolean_t
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonjzonecfg_is_scratch(const char *kernzone)
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj{
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj    return (strncmp(kernzone, "SUNWlu", 6) == 0);
108322fb1c3ed341aba9c80c9774df0ed9e35768carlsonj}