libzfs/common/libzfs_util.c

	libzfs_util.c revision ea8dc4b6d2251b437950c0056bc626b311c73c27
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

/*
 * Internal utility routines for the ZFS library.
 */

#include <errno.h>
#include <fcntl.h>
#include <libintl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <sys/mnttab.h>

#include <libzfs.h>

#include "libzfs_impl.h"

static int zfs_fd = -1;
static FILE *mnttab_file;
static FILE *sharetab_file;
static int sharetab_opened;

void (*error_func)(const char *, va_list);

/*
 * All error handling is kept within libzfs where we have the most information
 * immediately available.  While this may not be suitable for a general purpose
 * library, it greatly simplifies our commands.  This command name is used to
 * prefix all error messages appropriately.
 */
void
zfs_error(const char *fmt, ...)
{
    va_list ap;

    va_start(ap, fmt);

    if (error_func != NULL) {
        error_func(fmt, ap);
    } else {
        (void) vfprintf(stderr, fmt, ap);
        (void) fprintf(stderr, "\n");
    }

    va_end(ap);
}

/*
 * An internal error is something that we cannot recover from, and should never
 * happen (such as running out of memory).  It should only be used in
 * exceptional circumstances.
 */
void
zfs_fatal(const char *fmt, ...)
{
    va_list ap;

    va_start(ap, fmt);

    if (error_func != NULL) {
        error_func(fmt, ap);
    } else {
        (void) vfprintf(stderr, fmt, ap);
        (void) fprintf(stderr, "\n");
    }

    va_end(ap);

    exit(1);
}

/*
 * Consumers (such as the JNI interface) that need to capture error output can
 * override the default error handler using this function.
 */
void
zfs_set_error_handler(void (*func)(const char *, va_list))
{
    error_func = func;
}

/*
 * Display an out of memory error message and abort the current program.
 */
void
no_memory(void)
{
    assert(errno == ENOMEM);
    zfs_fatal(dgettext(TEXT_DOMAIN, "internal error: out of memory\n"));
}

/*
 * A safe form of malloc() which will die if the allocation fails.
 */
void *
zfs_malloc(size_t size)
{
    void *data;

    if ((data = calloc(1, size)) == NULL)
        no_memory();

    return (data);
}

/*
 * A safe form of strdup() which will die if the allocation fails.
 */
char *
zfs_strdup(const char *str)
{
    char *ret;

    if ((ret = strdup(str)) == NULL)
        no_memory();

    return (ret);
}

/*
 * Utility functions around common used files - /dev/zfs, /etc/mnttab, and
 * /etc/dfs/sharetab.
 */
int
zfs_ioctl(int cmd, zfs_cmd_t *zc)
{
    if (zfs_fd == -1 &&
        (zfs_fd = open(ZFS_DEV, O_RDWR)) < 0)
        zfs_fatal(dgettext(TEXT_DOMAIN, "internal error: unable to "
            "open ZFS device\n"), MNTTAB);

    return (ioctl(zfs_fd, cmd, zc));
}

FILE *
zfs_mnttab(void)
{
    if (mnttab_file == NULL &&
        (mnttab_file = fopen(MNTTAB, "r")) == NULL)
        zfs_fatal(dgettext(TEXT_DOMAIN, "internal error: unable to "
            "open %s\n"), MNTTAB);

    return (mnttab_file);
}

FILE *
zfs_sharetab(void)
{
    if (sharetab_opened)
        return (sharetab_file);

    sharetab_opened = TRUE;
    return (sharetab_file = fopen("/etc/dfs/sharetab", "r"));
}

/*
 * Cleanup function for library.  Close any file descriptors that were
 * opened as part of the above functions.
 */
#pragma fini(zfs_fini)
void
zfs_fini(void)
{
    if (zfs_fd != -1)
        (void) close(zfs_fd);
    if (sharetab_file)
        (void) fclose(sharetab_file);
    if (mnttab_file)
        (void) fclose(mnttab_file);
}

/*
 * Convert a number to an appropriately human-readable output.
 */
void
zfs_nicenum(uint64_t num, char *buf, size_t buflen)
{
    uint64_t n = num;
    int index = 0;
    char u;

    while (n >= 1024) {
        n /= 1024;
        index++;
    }

    u = " KMGTPE"[index];

    if (index == 0) {
        (void) snprintf(buf, buflen, "%llu", n);
    } else if ((num & ((1ULL << 10 * index) - 1)) == 0) {
        /*
         * If this is an even multiple of the base, always display
         * without any decimal precision.
         */
        (void) snprintf(buf, buflen, "%llu%c", n, u);
    } else {
        /*
         * We want to choose a precision that reflects the best choice
         * for fitting in 5 characters.  This can get rather tricky when
         * we have numbers that are very close to an order of magnitude.
         * For example, when displaying 10239 (which is really 9.999K),
         * we want only a single place of precision for 10.0K.  We could
         * develop some complex heuristics for this, but it's much
         * easier just to try each combination in turn.
         */
        int i;
        for (i = 2; i >= 0; i--) {
            (void) snprintf(buf, buflen, "%.*f%c", i,
                (double)num / (1ULL << 10 * index), u);
            if (strlen(buf) <= 5)
                break;
        }
    }
}