setproctitle.c revision 108163 
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 108163 2002-12-21 22:04:50Z bbraun $");
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 = NULL;
66	static char *obuf = NULL;
67	static char **oargv, *kbuf;
68	static int oargc = -1;
69	static char *nargv[2] = { NULL, 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	if (buf == NULL) {
79		buf = malloc(SPT_BUFSIZE);
80		if (buf == NULL)
81			return;
82		nargv[0] = buf;
83	}
84
85	if (obuf == NULL ) {
86		obuf = malloc(SPT_BUFSIZE);
87		if (obuf == NULL)
88			return;
89	}
90
91	va_start(ap, fmt);
92
93	if (fmt) {
94		buf[SPT_BUFSIZE - 1] = '\0';
95
96		if (fmt[0] == '-') {
97			/* skip program name prefix */
98			fmt++;
99			len = 0;
100		} else {
101			/* print program name heading for grep */
102			(void)snprintf(buf, SPT_BUFSIZE, "%s: ", _getprogname());
103			len = strlen(buf);
104		}
105
106		/* print the argument string */
107		(void) vsnprintf(buf + len, SPT_BUFSIZE - len, fmt, ap);
108
109		nargvp = nargv;
110		nargc = 1;
111		kbuf = buf;
112	} else if (*obuf != '\0') {
113  		/* Idea from NetBSD - reset the title on fmt == NULL */
114		nargvp = oargv;
115		nargc = oargc;
116		kbuf = obuf;
117	} else
118		/* Nothing to restore */
119		return;
120
121	va_end(ap);
122
123	/* Set the title into the kernel cached command line */
124	oid[0] = CTL_KERN;
125	oid[1] = KERN_PROC;
126	oid[2] = KERN_PROC_ARGS;
127	oid[3] = getpid();
128	sysctl(oid, 4, 0, 0, kbuf, strlen(kbuf) + 1);
129
130	if (ps_strings == NULL) {
131		len = sizeof(ul_ps_strings);
132		if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
133		    0) == -1)
134			ul_ps_strings = PS_STRINGS;
135		ps_strings = (struct ps_strings *)ul_ps_strings;
136	}
137
138	/* PS_STRINGS points to zeroed memory on a style #2 kernel */
139	if (ps_strings->ps_argvstr) {
140		/* style #3 */
141		if (oargc == -1) {
142			/* Record our original args */
143			oargc = ps_strings->ps_nargvstr;
144			oargv = ps_strings->ps_argvstr;
145			for (i = len = 0; i < oargc; i++) {
146				/*
147				 * The program may have scribbled into its
148				 * argv array, e.g., to remove some arguments.
149				 * If that has happened, break out before
150				 * trying to call strlen on a NULL pointer.
151				 */
152				if (oargv[i] == NULL) {
153					oargc = i;
154					break;
155				}
156				snprintf(obuf + len, SPT_BUFSIZE - len, "%s%s",
157				    len ? " " : "", oargv[i]);
158				if (len)
159					len++;
160				len += strlen(oargv[i]);
161				if (len >= SPT_BUFSIZE)
162					break;
163			}
164		}
165		ps_strings->ps_nargvstr = nargc;
166		ps_strings->ps_argvstr = nargvp;
167	} else {
168		/* style #2 - we can only restore our first arg :-( */
169		if (*obuf == '\0')
170			strncpy(obuf, OLD_PS_STRINGS->old_ps_argvstr,
171			    SPT_BUFSIZE - 1);
172		OLD_PS_STRINGS->old_ps_nargvstr = 1;
173		OLD_PS_STRINGS->old_ps_argvstr = nargvp[0];
174	}
175}
176