gen/common/exportent.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 1995 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

/*
 * Exported file system table manager. Reads/writes "/etc/xtab".
 */

#include <stdio.h>
#include <exportent.h>
#include <sys/file.h>
#include <ctype.h>

extern char *strtok();
extern char *strcpy();

#define LINESIZE 4096

static char *TMPFILE = "/tmp/xtabXXXXXX";

static char *skipwhite(char *);
static char *skipnonwhite(char *);

FILE *
setexportent(void)
{
    FILE *f;
    int fd;

    /*
     * Create the tab file if it does not exist already
     */
    if (access(TABFILE, F_OK) < 0) {
        fd = open(TABFILE, O_CREAT, 0644);
        close(fd);
    }
    if (access(TABFILE, W_OK) == 0) {
        f = fopen(TABFILE, "r+");
    } else {
        f = fopen(TABFILE, "r");
    }
    if (f == NULL) {
        return (NULL);
    }
    if (flock(fileno(f), LOCK_EX) < 0) {
        (void)fclose(f);
        return (NULL);
    }
    return (f);
}


void
endexportent(FILE *f)
{
    (void) fclose(f);
}


struct exportent *
getexportent(FILE *f)
{
    static char *line = NULL;
    static struct exportent xent;
    int len;
    char *p;

    if (line == NULL) {
        line = (char *)malloc(LINESIZE + 1);
    }
    if (fgets(line, LINESIZE, f) == NULL) {
        return (NULL);
    }
    len = strlen(line);
    if (line[len-1] == '\n') {
        line[len-1] = 0;
    }
    xent.xent_dirname = line;
    xent.xent_options = NULL;
    p = skipnonwhite(line);
    if (*p == 0) {
        return (&xent);
    }
    *p++ = 0;
    p = skipwhite(p);
    if (*p == 0) {
        return (&xent);
    }
    if (*p == '-') {
        p++;
    }
    xent.xent_options = p;
    return (&xent);
}

int
remexportent(FILE *f, char *dirname)
{
    char buf[LINESIZE];
    FILE *f2;
    int len;
    char *fname;
    int fd;
    long pos;
    long rempos;
    int remlen;
    int res;

    fname = (char *) malloc(strlen(TMPFILE) + 1);
    pos = ftell(f);
    rempos = 0;
    remlen = 0;
    (void)strcpy(fname, TMPFILE);
    fd = mkstemp(fname);
    if (fd < 0) {
        return (-1);
    }
    if (unlink(fname) < 0) {
        (void)close(fd);
        return (-1);
    }
    f2 = fdopen(fd, "r+");
    if (f2 == NULL) {
        (void)close(fd);
        return (-1);
    }
    len = strlen(dirname);
    rewind(f);
    while (fgets(buf, sizeof(buf), f)) {
        if (strncmp(buf, dirname,
            len) != 0 || ! isspace((unsigned char)buf[len])) {
            if (fputs(buf, f2) <= 0) {
                (void)fclose(f2);
                return (-1);
            }
        } else {
            remlen = strlen(buf);
            rempos = ftell(f) - remlen;
        }
    }
    rewind(f);
    if (ftruncate(fileno(f), 0L) < 0) {
        (void)fclose(f2);
        return (-1);
    }
    rewind(f2);
    while (fgets(buf, sizeof(buf), f2)) {
        if (fputs(buf, f) <= 0) {
            (void)fclose(f2);
            return (-1);
        }
    }
    (void)fclose(f2);
    if (remlen == 0) {
        /* nothing removed */
        (void) fseek(f, pos, L_SET);
        res = -1;
    } else if (pos <= rempos) {
        res = fseek(f, pos, L_SET);
    } else if (pos > rempos + remlen) {
        res = fseek(f, pos - remlen, L_SET);
    } else {
        res = fseek(f, rempos, L_SET);
    }
    return (res < 0 ? -1 : 0);
}

int
addexportent(FILE *f, char *dirname, char *options)
{
    long pos;

    pos = ftell(f);
    if (fseek(f, 0L, L_XTND) >= 0 &&
        fprintf(f, "%s", dirname) > 0 &&
        (options == NULL || fprintf(f, " -%s", options) > 0) &&
        fprintf(f, "\n") > 0 &&
        fseek(f, pos, L_SET) >= 0) {
        return (0);
    }
    return (-1);
}


char *
getexportopt(struct exportent *xent, char *opt)
{
    static char *tokenbuf = NULL;
    char *lp;
    char *tok;
    int len;

    if (tokenbuf == NULL) {
        tokenbuf = (char *)malloc(LINESIZE);
    }
    if (xent->xent_options == NULL) {
        return (NULL);
    }
    (void)strcpy(tokenbuf, xent->xent_options);
    lp = tokenbuf;
    len = strlen(opt);
    while ((tok = strtok(lp, ",")) != NULL) {
        lp = NULL;
        if (strncmp(opt, tok, len) == 0) {
            if (tok[len] == '=') {
                return (&tok[len + 1]);
            } else if (tok[len] == 0) {
                return ("");
            }
        }
    }
    return (NULL);
}


#define iswhite(c)  ((c) == ' ' || c == '\t')

static char *
skipwhite(char *str)
{
    while (*str && iswhite(*str)) {
        str++;
    }
    return (str);
}

static char *
skipnonwhite(char *str)
{
    while (*str && ! iswhite(*str)) {
        str++;
    }
    return (str);
}