setproctitle.c revision 93399 
1/*
2 * Copyright (c) 1995 Peter Wemm <peter@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, is permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice immediately at the beginning of the file, without modification,
10 *    this list of conditions, and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Absolutely no warranty of function or purpose is made by the author
15 *    Peter Wemm.
16 */
17
18#include <sys/cdefs.h>
19__FBSDID("$FreeBSD: head/lib/libc/gen/setproctitle.c 93399 2002-03-29 22:43:43Z markm $");
20
21#include "namespace.h"
22#include <sys/types.h>
23#include <sys/param.h>
24#include <sys/exec.h>
25#include <sys/sysctl.h>
26
27#include <vm/vm.h>
28#include <vm/vm_param.h>
29#include <vm/pmap.h>
30
31#include <stdio.h>
32#include <string.h>
33#include <stdlib.h>
34#include <unistd.h>
35#include "un-namespace.h"
36
37#include "libc_private.h"
38
39/*
40 * Older FreeBSD 2.0, 2.1 and 2.2 had different ps_strings structures and
41 * in different locations.
42 * 1: old_ps_strings at the very top of the stack.
43 * 2: old_ps_strings at SPARE_USRSPACE below the top of the stack.
44 * 3: ps_strings at the very top of the stack.
45 * This attempts to support a kernel built in the #2 and #3 era.
46 */
47
48struct old_ps_strings {
49	char	*old_ps_argvstr;
50	int	old_ps_nargvstr;
51	char	*old_ps_envstr;
52	int	old_ps_nenvstr;
53};
54#define	OLD_PS_STRINGS ((struct old_ps_strings *) \
55	(USRSTACK - SPARE_USRSPACE - sizeof(struct old_ps_strings)))
56
57#include <stdarg.h>
58
59#define SPT_BUFSIZE 2048	/* from other parts of sendmail */
60
61void
62setproctitle(const char *fmt, ...)
63{
64	static struct ps_strings *ps_strings;
65	static char buf[SPT_BUFSIZE];
66	static char obuf[SPT_BUFSIZE];
67	static char **oargv, *kbuf;
68	static int oargc = -1;
69	static char *nargv[2] = { buf, NULL };
70	char **nargvp;
71	int nargc;
72	int i;
73	va_list ap;
74	size_t len;
75	unsigned long ul_ps_strings;
76	int oid[4];
77
78	va_start(ap, fmt);
79
80	if (fmt) {
81		buf[sizeof(buf) - 1] = '\0';
82
83		if (fmt[0] == '-') {
84			/* skip program name prefix */
85			fmt++;
86			len = 0;
87		} else {
88			/* print program name heading for grep */
89			(void)snprintf(buf, sizeof(buf), "%s: ", _getprogname());
90			len = strlen(buf);
91		}
92
93		/* print the argument string */
94		(void) vsnprintf(buf + len, sizeof(buf) - len, fmt, ap);
95
96		nargvp = nargv;
97		nargc = 1;
98		kbuf = buf;
99	} else if (*obuf != '\0') {
100  		/* Idea from NetBSD - reset the title on fmt == NULL */
101		nargvp = oargv;
102		nargc = oargc;
103		kbuf = obuf;
104	} else
105		/* Nothing to restore */
106		return;
107
108	va_end(ap);
109
110	/* Set the title into the kernel cached command line */
111	oid[0] = CTL_KERN;
112	oid[1] = KERN_PROC;
113	oid[2] = KERN_PROC_ARGS;
114	oid[3] = getpid();
115	sysctl(oid, 4, 0, 0, kbuf, strlen(kbuf) + 1);
116
117	if (ps_strings == NULL) {
118		len = sizeof(ul_ps_strings);
119		if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
120		    0) == -1)
121			ul_ps_strings = PS_STRINGS;
122		ps_strings = (struct ps_strings *)ul_ps_strings;
123	}
124
125	/* PS_STRINGS points to zeroed memory on a style #2 kernel */
126	if (ps_strings->ps_argvstr) {
127		/* style #3 */
128		if (oargc == -1) {
129			/* Record our original args */
130			oargc = ps_strings->ps_nargvstr;
131			oargv = ps_strings->ps_argvstr;
132			for (i = len = 0; i < oargc; i++) {
133				/*
134				 * The program may have scribbled into its
135				 * argv array, e.g., to remove some arguments.
136				 * If that has happened, break out before
137				 * trying to call strlen on a NULL pointer.
138				 */
139				if (oargv[i] == NULL) {
140					oargc = i;
141					break;
142				}
143				snprintf(obuf + len, sizeof(obuf) - len, "%s%s",
144				    len ? " " : "", oargv[i]);
145				if (len)
146					len++;
147				len += strlen(oargv[i]);
148				if (len >= sizeof(obuf))
149					break;
150			}
151		}
152		ps_strings->ps_nargvstr = nargc;
153		ps_strings->ps_argvstr = nargvp;
154	} else {
155		/* style #2 - we can only restore our first arg :-( */
156		if (*obuf == '\0')
157			strncpy(obuf, OLD_PS_STRINGS->old_ps_argvstr,
158			    sizeof(obuf) - 1);
159		OLD_PS_STRINGS->old_ps_nargvstr = 1;
160		OLD_PS_STRINGS->old_ps_argvstr = nargvp[0];
161	}
162}
163