setproctitle.c revision 336449 
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: stable/11/lib/libc/gen/setproctitle.c 336449 2018-07-18 09:54:32Z kib $");
20
21#include "namespace.h"
22#include <sys/param.h>
23#include <sys/exec.h>
24#include <sys/sysctl.h>
25
26#include <stdio.h>
27#include <string.h>
28#include <stdlib.h>
29#include <unistd.h>
30#include "un-namespace.h"
31
32#include "libc_private.h"
33
34/*
35 * Older FreeBSD 2.0, 2.1 and 2.2 had different ps_strings structures and
36 * in different locations.
37 * 1: old_ps_strings at the very top of the stack.
38 * 2: old_ps_strings at SPARE_USRSPACE below the top of the stack.
39 * 3: ps_strings at the very top of the stack.
40 * We only support a kernel providing #3 style ps_strings.
41 *
42 * For historical purposes, a definition of the old ps_strings structure
43 * and location is preserved below:
44struct old_ps_strings {
45	char	*old_ps_argvstr;
46	int	old_ps_nargvstr;
47	char	*old_ps_envstr;
48	int	old_ps_nenvstr;
49};
50#define	OLD_PS_STRINGS ((struct old_ps_strings *) \
51	(USRSTACK - SPARE_USRSPACE - sizeof(struct old_ps_strings)))
52 */
53
54#include <stdarg.h>
55
56#define SPT_BUFSIZE 2048	/* from other parts of sendmail */
57
58static char *
59setproctitle_internal(const char *fmt, va_list ap)
60{
61	static struct ps_strings *ps_strings;
62	static char *buf = NULL;
63	static char *obuf = NULL;
64	static char **oargv, *kbuf;
65	static int oargc = -1;
66	static char *nargv[2] = { NULL, NULL };
67	char **nargvp;
68	int nargc;
69	int i;
70	size_t len;
71	unsigned long ul_ps_strings;
72
73	if (buf == NULL) {
74		buf = malloc(SPT_BUFSIZE);
75		if (buf == NULL)
76			return (NULL);
77		nargv[0] = buf;
78	}
79
80	if (obuf == NULL ) {
81		obuf = malloc(SPT_BUFSIZE);
82		if (obuf == NULL)
83			return (NULL);
84		*obuf = '\0';
85	}
86
87	if (fmt) {
88		buf[SPT_BUFSIZE - 1] = '\0';
89
90		if (fmt[0] == '-') {
91			/* skip program name prefix */
92			fmt++;
93			len = 0;
94		} else {
95			/* print program name heading for grep */
96			(void)snprintf(buf, SPT_BUFSIZE, "%s: ", _getprogname());
97			len = strlen(buf);
98		}
99
100		/* print the argument string */
101		(void) vsnprintf(buf + len, SPT_BUFSIZE - len, fmt, ap);
102
103		nargvp = nargv;
104		nargc = 1;
105		kbuf = buf;
106	} else if (*obuf != '\0') {
107  		/* Idea from NetBSD - reset the title on fmt == NULL */
108		nargvp = oargv;
109		nargc = oargc;
110		kbuf = obuf;
111	} else
112		/* Nothing to restore */
113		return (NULL);
114
115	if (ps_strings == NULL) {
116		len = sizeof(ul_ps_strings);
117		if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
118		    0) == -1)
119			return (NULL);
120		ps_strings = (struct ps_strings *)ul_ps_strings;
121	}
122
123	/*
124	 * PS_STRINGS points to zeroed memory on a style #2 kernel.
125	 * Should not happen.
126	 */
127	if (ps_strings->ps_argvstr == NULL)
128		return (NULL);
129
130	/* style #3 */
131	if (oargc == -1) {
132		/* Record our original args */
133		oargc = ps_strings->ps_nargvstr;
134		oargv = ps_strings->ps_argvstr;
135		for (i = len = 0; i < oargc; i++) {
136			/*
137			 * The program may have scribbled into its
138			 * argv array, e.g., to remove some arguments.
139			 * If that has happened, break out before
140			 * trying to call strlen on a NULL pointer.
141			 */
142			if (oargv[i] == NULL) {
143				oargc = i;
144				break;
145			}
146			snprintf(obuf + len, SPT_BUFSIZE - len, "%s%s",
147			    len != 0 ? " " : "", oargv[i]);
148			if (len != 0)
149				len++;
150			len += strlen(oargv[i]);
151			if (len >= SPT_BUFSIZE)
152				break;
153		}
154	}
155	ps_strings->ps_nargvstr = nargc;
156	ps_strings->ps_argvstr = nargvp;
157
158	return (nargvp[0]);
159}
160
161static int fast_update = 0;
162
163void
164setproctitle_fast(const char *fmt, ...)
165{
166	va_list ap;
167	char *buf;
168	int oid[4];
169
170	va_start(ap, fmt);
171	buf = setproctitle_internal(fmt, ap);
172	va_end(ap);
173
174	if (buf && !fast_update) {
175		/* Tell the kernel to start looking in user-space */
176		oid[0] = CTL_KERN;
177		oid[1] = KERN_PROC;
178		oid[2] = KERN_PROC_ARGS;
179		oid[3] = getpid();
180		sysctl(oid, 4, 0, 0, "", 0);
181		fast_update = 1;
182	}
183}
184
185void
186setproctitle(const char *fmt, ...)
187{
188	va_list ap;
189	char *buf;
190	int oid[4];
191
192	va_start(ap, fmt);
193	buf = setproctitle_internal(fmt, ap);
194	va_end(ap);
195
196	if (buf != NULL) {
197		/* Set the title into the kernel cached command line */
198		oid[0] = CTL_KERN;
199		oid[1] = KERN_PROC;
200		oid[2] = KERN_PROC_ARGS;
201		oid[3] = getpid();
202		sysctl(oid, 4, 0, 0, buf, strlen(buf) + 1);
203		fast_update = 0;
204	}
205}
206