/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1995 Peter Wemm
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "namespace.h"
#include <sys/param.h>
#include <sys/elf_common.h>
#include <sys/exec.h>
#include <sys/sysctl.h>

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include "un-namespace.h"

#include "libc_private.h"

/*
 * Older FreeBSD 2.0, 2.1 and 2.2 had different ps_strings structures and
 * in different locations.
 * 1: old_ps_strings at the very top of the stack.
 * 2: old_ps_strings at SPARE_USRSPACE below the top of the stack.
 * 3: ps_strings at the very top of the stack.
 * We only support a kernel providing #3 style ps_strings.
 *
 * For historical purposes, a definition of the old ps_strings structure
 * and location is preserved below:
struct old_ps_strings {
        char    *old_ps_argvstr;
        int     old_ps_nargvstr;
        char    *old_ps_envstr;
        int     old_ps_nenvstr;
};
#define OLD_PS_STRINGS ((struct old_ps_strings *) \
        (USRSTACK - SPARE_USRSPACE - sizeof(struct old_ps_strings)))
 */

#include <stdarg.h>

#define SPT_BUFSIZE 2048        /* from other parts of sendmail */

static char *
setproctitle_internal(const char *fmt, va_list ap)
{
        static struct ps_strings *ps_strings;
        static char *buf = NULL;
        static char *obuf = NULL;
        static char **oargv;
        static int oargc = -1;
        static char *nargv[2] = { NULL, NULL };
        char **nargvp;
        int nargc;
        int i;
        size_t len;
        unsigned long ul_ps_strings;

        if (buf == NULL) {
                buf = malloc(SPT_BUFSIZE);
                if (buf == NULL)
                        return (NULL);
                nargv[0] = buf;
        }

        if (obuf == NULL ) {
                obuf = malloc(SPT_BUFSIZE);
                if (obuf == NULL)
                        return (NULL);
                *obuf = '\0';
        }

        if (fmt) {
                buf[SPT_BUFSIZE - 1] = '\0';

                if (fmt[0] == '-') {
                        /* skip program name prefix */
                        fmt++;
                        len = 0;
                } else {
                        /* print program name heading for grep */
                        (void)snprintf(buf, SPT_BUFSIZE, "%s: ", _getprogname());
                        len = strlen(buf);
                }

                /* print the argument string */
                (void)vsnprintf(buf + len, SPT_BUFSIZE - len, fmt, ap);

                nargvp = nargv;
                nargc = 1;
        } else if (*obuf != '\0') {
                /* Idea from NetBSD - reset the title on fmt == NULL */
                nargvp = oargv;
                nargc = oargc;
        } else
                /* Nothing to restore */
                return (NULL);

        if (ps_strings == NULL)
                (void)_elf_aux_info(AT_PS_STRINGS, &ps_strings,
                    sizeof(ps_strings));

        if (ps_strings == NULL) {
                len = sizeof(ul_ps_strings);
                if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
                    0) == -1)
                        return (NULL);
                ps_strings = (struct ps_strings *)ul_ps_strings;
        }

        if (ps_strings == NULL)
                return (NULL);

        /*
         * PS_STRINGS points to zeroed memory on a style #2 kernel.
         * Should not happen.
         */
        if (ps_strings->ps_argvstr == NULL)
                return (NULL);

        /* style #3 */
        if (oargc == -1) {
                /* Record our original args */
                oargc = ps_strings->ps_nargvstr;
                oargv = ps_strings->ps_argvstr;
                for (i = len = 0; i < oargc; i++) {
                        /*
                         * The program may have scribbled into its
                         * argv array, e.g., to remove some arguments.
                         * If that has happened, break out before
                         * trying to call strlen on a NULL pointer.
                         */
                        if (oargv[i] == NULL) {
                                oargc = i;
                                break;
                        }
                        snprintf(obuf + len, SPT_BUFSIZE - len, "%s%s",
                            len != 0 ? " " : "", oargv[i]);
                        if (len != 0)
                                len++;
                        len += strlen(oargv[i]);
                        if (len >= SPT_BUFSIZE)
                                break;
                }
        }
        ps_strings->ps_nargvstr = nargc;
        ps_strings->ps_argvstr = nargvp;

        return (nargvp[0]);
}

static int fast_update = 0;

void
setproctitle_fast(const char *fmt, ...)
{
        va_list ap;
        char *buf;
        int oid[4];

        va_start(ap, fmt);
        buf = setproctitle_internal(fmt, ap);
        va_end(ap);

        if (buf && !fast_update) {
                /* Tell the kernel to start looking in user-space */
                oid[0] = CTL_KERN;
                oid[1] = KERN_PROC;
                oid[2] = KERN_PROC_ARGS;
                oid[3] = -1;
                sysctl(oid, 4, 0, 0, "", 0);
                fast_update = 1;
        }
}

void
setproctitle(const char *fmt, ...)
{
        va_list ap;
        char *buf;
        int oid[4];

        va_start(ap, fmt);
        buf = setproctitle_internal(fmt, ap);
        va_end(ap);

        if (buf != NULL) {
                /* Set the title into the kernel cached command line */
                oid[0] = CTL_KERN;
                oid[1] = KERN_PROC;
                oid[2] = KERN_PROC_ARGS;
                oid[3] = -1;
                sysctl(oid, 4, 0, 0, buf, strlen(buf) + 1);
                fast_update = 0;
        }
}