setproctitle.c revision 281763 
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 281763 2015-04-20 09:07:12Z kib $");
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 * We only support a kernel providing #3 style ps_strings.
46 *
47 * For historical purposes, a definition of the old ps_strings structure
48 * and location is preserved below:
49struct old_ps_strings {
50	char	*old_ps_argvstr;
51	int	old_ps_nargvstr;
52	char	*old_ps_envstr;
53	int	old_ps_nenvstr;
54};
55#define	OLD_PS_STRINGS ((struct old_ps_strings *) \
56	(USRSTACK - SPARE_USRSPACE - sizeof(struct old_ps_strings)))
57 */
58
59#include <stdarg.h>
60
61#define SPT_BUFSIZE 2048	/* from other parts of sendmail */
62
63void
64setproctitle(const char *fmt, ...)
65{
66	static struct ps_strings *ps_strings;
67	static char *buf = NULL;
68	static char *obuf = NULL;
69	static char **oargv, *kbuf;
70	static int oargc = -1;
71	static char *nargv[2] = { NULL, NULL };
72	char **nargvp;
73	int nargc;
74	int i;
75	va_list ap;
76	size_t len;
77	unsigned long ul_ps_strings;
78	int oid[4];
79
80	if (buf == NULL) {
81		buf = malloc(SPT_BUFSIZE);
82		if (buf == NULL)
83			return;
84		nargv[0] = buf;
85	}
86
87	if (obuf == NULL ) {
88		obuf = malloc(SPT_BUFSIZE);
89		if (obuf == NULL)
90			return;
91		*obuf = '\0';
92	}
93
94	va_start(ap, fmt);
95
96	if (fmt) {
97		buf[SPT_BUFSIZE - 1] = '\0';
98
99		if (fmt[0] == '-') {
100			/* skip program name prefix */
101			fmt++;
102			len = 0;
103		} else {
104			/* print program name heading for grep */
105			(void)snprintf(buf, SPT_BUFSIZE, "%s: ", _getprogname());
106			len = strlen(buf);
107		}
108
109		/* print the argument string */
110		(void) vsnprintf(buf + len, SPT_BUFSIZE - len, fmt, ap);
111
112		nargvp = nargv;
113		nargc = 1;
114		kbuf = buf;
115	} else if (*obuf != '\0') {
116  		/* Idea from NetBSD - reset the title on fmt == NULL */
117		nargvp = oargv;
118		nargc = oargc;
119		kbuf = obuf;
120	} else
121		/* Nothing to restore */
122		return;
123
124	va_end(ap);
125
126	/* Set the title into the kernel cached command line */
127	oid[0] = CTL_KERN;
128	oid[1] = KERN_PROC;
129	oid[2] = KERN_PROC_ARGS;
130	oid[3] = getpid();
131	sysctl(oid, 4, 0, 0, kbuf, strlen(kbuf) + 1);
132
133	if (ps_strings == NULL) {
134		len = sizeof(ul_ps_strings);
135		if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
136		    0) == -1)
137			ul_ps_strings = PS_STRINGS;
138		ps_strings = (struct ps_strings *)ul_ps_strings;
139	}
140
141	/*
142	 * PS_STRINGS points to zeroed memory on a style #2 kernel.
143	 * Should not happen.
144	 */
145	if (ps_strings->ps_argvstr == NULL)
146		return;
147
148	/* style #3 */
149	if (oargc == -1) {
150		/* Record our original args */
151		oargc = ps_strings->ps_nargvstr;
152		oargv = ps_strings->ps_argvstr;
153		for (i = len = 0; i < oargc; i++) {
154			/*
155			 * The program may have scribbled into its
156			 * argv array, e.g., to remove some arguments.
157			 * If that has happened, break out before
158			 * trying to call strlen on a NULL pointer.
159			 */
160			if (oargv[i] == NULL) {
161				oargc = i;
162				break;
163			}
164			snprintf(obuf + len, SPT_BUFSIZE - len, "%s%s",
165			    len != 0 ? " " : "", oargv[i]);
166			if (len != 0)
167				len++;
168			len += strlen(oargv[i]);
169			if (len >= SPT_BUFSIZE)
170				break;
171		}
172	}
173	ps_strings->ps_nargvstr = nargc;
174	ps_strings->ps_argvstr = nargvp;
175}
176