source: MondoRescue/branches/2.2.9/mindi-busybox/procps/sysctl.c@ 3320

/* vi: set sw=4 ts=4: */
/*
 * Sysctl 1.01 - A utility to read and manipulate the sysctl parameters
 *
 * Copyright 1999 George Staikos
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * Changelog:
 * v1.01   - added -p <preload> to preload values from a file
 * v1.01.1 - busybox applet aware by <solar@gentoo.org>
 */

#include "libbb.h"

enum {
    FLAG_SHOW_KEYS       = 1 << 0,
    FLAG_SHOW_KEY_ERRORS = 1 << 1,
    FLAG_TABLE_FORMAT    = 1 << 2, /* not implemented */
    FLAG_SHOW_ALL        = 1 << 3,
    FLAG_PRELOAD_FILE    = 1 << 4,
    FLAG_WRITE           = 1 << 5,
};
#define OPTION_STR "neAapw"

static void sysctl_dots_to_slashes(char *name)
{
    char *cptr, *last_good, *end;

    /* Convert minimum number of '.' to '/' so that
     * we end up with existing file's name.
     *
     * Example from bug 3894:
     * net.ipv4.conf.eth0.100.mc_forwarding ->
     * net/ipv4/conf/eth0.100/mc_forwarding
     * NB: net/ipv4/conf/eth0/mc_forwarding *also exists*,
     * therefore we must start from the end, and if
     * we replaced even one . -> /, start over again,
     * but never replace dots before the position
     * where last replacement occurred.
     *
     * Another bug we later had is that
     * net.ipv4.conf.eth0.100
     * (without .mc_forwarding) was mishandled.
     *
     * To set up testing: modprobe 8021q; vconfig add eth0 100
     */
    end = name + strlen(name);
    last_good = name - 1;
    *end = '.'; /* trick the loop into trying full name too */

 again:
    cptr = end;
    while (cptr > last_good) {
        if (*cptr == '.') {
            *cptr = '\0';
            //bb_error_msg("trying:'%s'", name);
            if (access(name, F_OK) == 0) {
                *cptr = '/';
                //bb_error_msg("replaced:'%s'", name);
                last_good = cptr;
                goto again;
            }
            *cptr = '.';
        }
        cptr--;
    }
    *end = '\0';
}

static int sysctl_act_on_setting(char *setting)
{
    int fd, retval = EXIT_SUCCESS;
    char *cptr, *outname;
    char *value = value; /* for compiler */

    outname = xstrdup(setting);

    cptr = outname;
    while (*cptr) {
        if (*cptr == '/')
            *cptr = '.';
        cptr++;
    }

    if (option_mask32 & FLAG_WRITE) {
        cptr = strchr(setting, '=');
        if (cptr == NULL) {
            bb_error_msg("error: '%s' must be of the form name=value",
                outname);
            retval = EXIT_FAILURE;
            goto end;
        }
        value = cptr + 1;  /* point to the value in name=value */
        if (setting == cptr || !*value) {
            bb_error_msg("error: malformed setting '%s'", outname);
            retval = EXIT_FAILURE;
            goto end;
        }
        *cptr = '\0';
        outname[cptr - setting] = '\0';
        /* procps 3.2.7 actually uses these flags */
        fd = open(setting, O_WRONLY|O_CREAT|O_TRUNC, 0666);
    } else {
        fd = open(setting, O_RDONLY);
    }

    if (fd < 0) {
        switch (errno) {
        case ENOENT:
            if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
                bb_error_msg("error: '%s' is an unknown key", outname);
            break;
        default:
            bb_perror_msg("error %sing key '%s'",
                    option_mask32 & FLAG_WRITE ?
                        "sett" : "read",
                    outname);
            break;
        }
        retval = EXIT_FAILURE;
        goto end;
    }

    if (option_mask32 & FLAG_WRITE) {
//TODO: procps 3.2.7 writes "value\n", note trailing "\n"
        xwrite_str(fd, value);
        close(fd);
        if (option_mask32 & FLAG_SHOW_KEYS)
            printf("%s = ", outname);
        puts(value);
    } else {
        char c;

        value = cptr = xmalloc_read(fd, NULL);
        close(fd);
        if (value == NULL) {
            bb_perror_msg("error reading key '%s'", outname);
            goto end;
        }

        /* dev.cdrom.info and sunrpc.transports, for example,
         * are multi-line. Try "sysctl sunrpc.transports"
         */
        while ((c = *cptr) != '\0') {
            if (option_mask32 & FLAG_SHOW_KEYS)
                printf("%s = ", outname);
            while (1) {
                fputc(c, stdout);
                cptr++;
                if (c == '\n')
                    break;
                c = *cptr;
                if (c == '\0')
                    break;
            }
        }
        free(value);
    }
 end:
    free(outname);
    return retval;
}

static int sysctl_act_recursive(const char *path)
{
    DIR *dirp;
    struct stat buf;
    struct dirent *entry;
    char *next;
    int retval = 0;

    stat(path, &buf);
    if (S_ISDIR(buf.st_mode) && !(option_mask32 & FLAG_WRITE)) {
        dirp = opendir(path);
        if (dirp == NULL)
            return -1;
        while ((entry = readdir(dirp)) != NULL) {
            next = concat_subpath_file(path, entry->d_name);
            if (next == NULL)
                continue; /* d_name is "." or ".." */
            /* if path was ".", drop "./" prefix: */
            retval |= sysctl_act_recursive((next[0] == '.' && next[1] == '/') ?
                        next + 2 : next);
            free(next);
        }
        closedir(dirp);
    } else {
        char *name = xstrdup(path);
        retval |= sysctl_act_on_setting(name);
        free(name);
    }

    return retval;
}

/* Set sysctl's from a conf file. Format example:
 * # Controls IP packet forwarding
 * net.ipv4.ip_forward = 0
 */
static int sysctl_handle_preload_file(const char *filename)
{
    char *token[2];
    parser_t *parser;

    parser = config_open(filename);
    /* Must do it _after_ config_open(): */
    xchdir("/proc/sys");
    /* xchroot(".") - if you are paranoid */

//TODO: ';' is comment char too
//TODO: comment may be only at line start. "var=1 #abc" - "1 #abc" is the value
// (but _whitespace_ from ends should be trimmed first (and we do it right))
//TODO: "var==1" is mishandled (must use "=1" as a value, but uses "1")
// can it be fixed by removing PARSE_COLLAPSE bit?
    while (config_read(parser, token, 2, 2, "# \t=", PARSE_NORMAL)) {
        char *tp;
        sysctl_dots_to_slashes(token[0]);
        tp = xasprintf("%s=%s", token[0], token[1]);
        sysctl_act_recursive(tp);
        free(tp);
    }
    if (ENABLE_FEATURE_CLEAN_UP)
        config_close(parser);
    return 0;
}

int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sysctl_main(int argc UNUSED_PARAM, char **argv)
{
    int retval;
    int opt;

    opt = getopt32(argv, "+" OPTION_STR); /* '+' - stop on first non-option */
    argv += optind;
    opt ^= (FLAG_SHOW_KEYS | FLAG_SHOW_KEY_ERRORS);
    option_mask32 = opt;

    if (opt & FLAG_PRELOAD_FILE) {
        option_mask32 |= FLAG_WRITE;
        /* xchdir("/proc/sys") is inside */
        return sysctl_handle_preload_file(*argv ? *argv : "/etc/sysctl.conf");
    }
    xchdir("/proc/sys");
    /* xchroot(".") - if you are paranoid */
    if (opt & (FLAG_TABLE_FORMAT | FLAG_SHOW_ALL)) {
        return sysctl_act_recursive(".");
    }

    retval = 0;
    while (*argv) {
        sysctl_dots_to_slashes(*argv);
        retval |= sysctl_act_recursive(*argv);
        argv++;
    }

    return retval;
}