Systemd/src/basic/proc-cmdline.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <stdbool.h>
#include <stddef.h>
#include <string.h>

#include "alloc-util.h"
#include "extract-word.h"
#include "fileio.h"
#include "macro.h"
#include "parse-util.h"
#include "proc-cmdline.h"
#include "process-util.h"
#include "special.h"
#include "string-util.h"
#include "util.h"
#include "virt.h"

int proc_cmdline(char **ret) {
        const char *e;
        assert(ret);

        /* For testing purposes it is sometimes useful to be able to override what we consider /proc/cmdline to be */
        e = secure_getenv("SYSTEMD_PROC_CMDLINE");
        if (e) {
                char *m;

                m = strdup(e);
                if (!m)
                        return -ENOMEM;

                *ret = m;
                return 0;
        }

        if (detect_container() > 0)
                return get_process_cmdline(1, 0, false, ret);
        else
                return read_one_line_file("/proc/cmdline", ret);
}

int proc_cmdline_parse(proc_cmdline_parse_t parse_item, void *data, unsigned flags) {

        _cleanup_free_ char *line = NULL;
        const char *p;
        int r;

        assert(parse_item);

        r = proc_cmdline(&line);
        if (r < 0)
                return r;

        p = line;
        for (;;) {
                _cleanup_free_ char *word = NULL;
                char *value, *key, *q;

                r = extract_first_word(&p, &word, NULL, EXTRACT_QUOTES|EXTRACT_RELAX);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;

                key = word;

                /* Filter out arguments that are intended only for the initrd */
                q = startswith(word, "rd.");
                if (q) {
                        if (!in_initrd())
                                continue;

                        if (flags & PROC_CMDLINE_STRIP_RD_PREFIX)
                                key = q;
                }

                value = strchr(key, '=');
                if (value)
                        *(value++) = 0;

                r = parse_item(key, value, data);
                if (r < 0)
                        return r;
        }

        return 0;
}

static bool relaxed_equal_char(char a, char b) {

        return a == b ||
                (a == '_' && b == '-') ||
                (a == '-' && b == '_');
}

char *proc_cmdline_key_startswith(const char *s, const char *prefix) {

        assert(s);
        assert(prefix);

        /* Much like startswith(), but considers "-" and "_" the same */

        for (; *prefix != 0; s++, prefix++)
                if (!relaxed_equal_char(*s, *prefix))
                        return NULL;

        return (char*) s;
}

bool proc_cmdline_key_streq(const char *x, const char *y) {
        assert(x);
        assert(y);

        /* Much like streq(), but considers "-" and "_" the same */

        for (; *x != 0 || *y != 0; x++, y++)
                if (!relaxed_equal_char(*x, *y))
                        return false;

        return true;
}

int proc_cmdline_get_key(const char *key, unsigned flags, char **value) {
        _cleanup_free_ char *line = NULL, *ret = NULL;
        bool found = false;
        const char *p;
        int r;

        /* Looks for a specific key on the kernel command line. Supports two modes:
         *
         * a) The "value" parameter is used. In this case a parameter beginning with the "key" string followed by "="
         *    is searched, and the value following this is returned in "value".
         *
         * b) as above, but the PROC_CMDLINE_VALUE_OPTIONAL flag is set. In this case if the key is found as a
         *    separate word (i.e. not followed by "=" but instead by whitespace or the end of the command line), then
         *    this is also accepted, and "value" is returned as NULL.
         *
         * c) The "value" parameter is NULL. In this case a search for the exact "key" parameter is performed.
         *
         * In all three cases, > 0 is returned if the key is found, 0 if not. */

        if (isempty(key))
                return -EINVAL;

        if ((flags & PROC_CMDLINE_VALUE_OPTIONAL) && !value)
                return -EINVAL;

        r = proc_cmdline(&line);
        if (r < 0)
                return r;

        p = line;
        for (;;) {
                _cleanup_free_ char *word = NULL;
                const char *e;

                r = extract_first_word(&p, &word, NULL, EXTRACT_QUOTES|EXTRACT_RELAX);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;

                /* Automatically filter out arguments that are intended only for the initrd, if we are not in the
                 * initrd. */
                if (!in_initrd() && startswith(word, "rd."))
                        continue;

                if (value) {
                        e = proc_cmdline_key_startswith(word, key);
                        if (!e)
                                continue;

                        if (*e == '=') {
                                r = free_and_strdup(&ret, e+1);
                                if (r < 0)
                                        return r;

                                found = true;

                        } else if (*e == 0 && (flags & PROC_CMDLINE_VALUE_OPTIONAL))
                                found = true;

                } else {
                        if (streq(word, key))
                                found = true;
                }
        }

        if (value)
                *value = TAKE_PTR(ret);

        return found;
}

int proc_cmdline_get_bool(const char *key, bool *ret) {
        _cleanup_free_ char *v = NULL;
        int r;

        assert(ret);

        r = proc_cmdline_get_key(key, PROC_CMDLINE_VALUE_OPTIONAL, &v);
        if (r < 0)
                return r;
        if (r == 0) {
                *ret = false;
                return 0;
        }

        if (v) { /* parameter passed */
                r = parse_boolean(v);
                if (r < 0)
                        return r;
                *ret = r;
        } else /* no parameter passed */
                *ret = true;

        return 1;
}

int shall_restore_state(void) {
        bool ret;
        int r;

        r = proc_cmdline_get_bool("systemd.restore_state", &ret);
        if (r < 0)
                return r;

        return r > 0 ? ret : true;
}

static const char * const rlmap[] = {
        "emergency", SPECIAL_EMERGENCY_TARGET,
        "-b",        SPECIAL_EMERGENCY_TARGET,
        "rescue",    SPECIAL_RESCUE_TARGET,
        "single",    SPECIAL_RESCUE_TARGET,
        "-s",        SPECIAL_RESCUE_TARGET,
        "s",         SPECIAL_RESCUE_TARGET,
        "S",         SPECIAL_RESCUE_TARGET,
        "1",         SPECIAL_RESCUE_TARGET,
        "2",         SPECIAL_MULTI_USER_TARGET,
        "3",         SPECIAL_MULTI_USER_TARGET,
        "4",         SPECIAL_MULTI_USER_TARGET,
        "5",         SPECIAL_GRAPHICAL_TARGET,
        NULL
};

static const char * const rlmap_initrd[] = {
        "emergency", SPECIAL_EMERGENCY_TARGET,
        "rescue",    SPECIAL_RESCUE_TARGET,
        NULL
};

const char* runlevel_to_target(const char *word) {
        const char * const *rlmap_ptr;
        size_t i;

        if (!word)
                return NULL;

        if (in_initrd()) {
                word = startswith(word, "rd.");
                if (!word)
                        return NULL;
        }

        rlmap_ptr = in_initrd() ? rlmap_initrd : rlmap;

        for (i = 0; rlmap_ptr[i]; i += 2)
                if (streq(word, rlmap_ptr[i]))
                        return rlmap_ptr[i+1];

        return NULL;
}