/*
 * Copyright (c) 1995 Peter Wemm <peter@freebsd.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice immediately at the beginning of the file, without modification,
 *    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.
 * 3. Absolutely no warranty of function or purpose is made by the author
 *    Peter Wemm.
 *
 * $FreeBSD: src/lib/libc/gen/setproctitle.c,v 1.18 2003/07/01 09:45:35 alfred Exp $
 */

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

#include <vm/pmap.h>
#include <vm/vm.h>
#include <vm/vm_param.h>

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

#include "libc_private.h"
#include "../upmap/upmap.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.
 * This attempts to support a kernel built in the #2 and #3 era.
 */

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 */

void
setproctitle(const char *fmt, ...)
{
        static struct ps_strings *ps_strings;
        static char *buf = NULL;
        static char *obuf = NULL;
        static char **oargv, *kbuf;
        static int oargc = -1;
        static char *nargv[2] = { NULL, NULL };
        char **nargvp;
        int nargc;
        int i;
        va_list ap;
        size_t len;
        unsigned long ul_ps_strings;
        int oid[4];

        va_start(ap, fmt);

        if (__ukp_spt(fmt, ap) == 0) {
                va_end(ap);
                return;
        }

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

        if (obuf == NULL ) {
                obuf = malloc(SPT_BUFSIZE);
                if (obuf == NULL) {
                        va_end(ap);
                        return;
                }
                *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 */
                        snprintf(buf, SPT_BUFSIZE, "%s: ", _getprogname());
                        len = strlen(buf);
                }

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

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

        va_end(ap);

        /* Set the title into the kernel cached command line */
        oid[0] = CTL_KERN;
        oid[1] = KERN_PROC;
        oid[2] = KERN_PROC_ARGS;
        oid[3] = getpid();
        sysctl(oid, 4, 0, 0, kbuf, strlen(kbuf) + 1);

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

        /* PS_STRINGS points to zeroed memory on a style #2 kernel */
        if (ps_strings->ps_argvstr) {
                /* 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 ? " " : "", oargv[i]);
                                if (len)
                                        len++;
                                len += strlen(oargv[i]);
                                if (len >= SPT_BUFSIZE)
                                        break;
                        }
                }
                ps_strings->ps_nargvstr = nargc;
                ps_strings->ps_argvstr = nargvp;
        } else {
                /* style #2 - we can only restore our first arg :-( */
                if (*obuf == '\0')
                        strncpy(obuf, OLD_PS_STRINGS->old_ps_argvstr,
                            SPT_BUFSIZE - 1);
                OLD_PS_STRINGS->old_ps_nargvstr = 1;
                OLD_PS_STRINGS->old_ps_argvstr = nargvp[0];
        }
}