setproctitle.c revision 309275 
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 309275 2016-11-29 01:08:09Z emaste $");
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
58void
59setproctitle(const char *fmt, ...)
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	va_list ap;
71	size_t len;
72	unsigned long ul_ps_strings;
73	int oid[4];
74
75	if (buf == NULL) {
76		buf = malloc(SPT_BUFSIZE);
77		if (buf == NULL)
78			return;
79		nargv[0] = buf;
80	}
81
82	if (obuf == NULL ) {
83		obuf = malloc(SPT_BUFSIZE);
84		if (obuf == NULL)
85			return;
86		*obuf = '\0';
87	}
88
89	va_start(ap, fmt);
90
91	if (fmt) {
92		buf[SPT_BUFSIZE - 1] = '\0';
93
94		if (fmt[0] == '-') {
95			/* skip program name prefix */
96			fmt++;
97			len = 0;
98		} else {
99			/* print program name heading for grep */
100			(void)snprintf(buf, SPT_BUFSIZE, "%s: ", _getprogname());
101			len = strlen(buf);
102		}
103
104		/* print the argument string */
105		(void) vsnprintf(buf + len, SPT_BUFSIZE - len, fmt, ap);
106
107		nargvp = nargv;
108		nargc = 1;
109		kbuf = buf;
110	} else if (*obuf != '\0') {
111  		/* Idea from NetBSD - reset the title on fmt == NULL */
112		nargvp = oargv;
113		nargc = oargc;
114		kbuf = obuf;
115	} else
116		/* Nothing to restore */
117		return;
118
119	va_end(ap);
120
121	/* Set the title into the kernel cached command line */
122	oid[0] = CTL_KERN;
123	oid[1] = KERN_PROC;
124	oid[2] = KERN_PROC_ARGS;
125	oid[3] = getpid();
126	sysctl(oid, 4, 0, 0, kbuf, strlen(kbuf) + 1);
127
128	if (ps_strings == NULL) {
129		len = sizeof(ul_ps_strings);
130		if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
131		    0) == -1)
132			return;
133		ps_strings = (struct ps_strings *)ul_ps_strings;
134	}
135
136	/*
137	 * PS_STRINGS points to zeroed memory on a style #2 kernel.
138	 * Should not happen.
139	 */
140	if (ps_strings->ps_argvstr == NULL)
141		return;
142
143	/* style #3 */
144	if (oargc == -1) {
145		/* Record our original args */
146		oargc = ps_strings->ps_nargvstr;
147		oargv = ps_strings->ps_argvstr;
148		for (i = len = 0; i < oargc; i++) {
149			/*
150			 * The program may have scribbled into its
151			 * argv array, e.g., to remove some arguments.
152			 * If that has happened, break out before
153			 * trying to call strlen on a NULL pointer.
154			 */
155			if (oargv[i] == NULL) {
156				oargc = i;
157				break;
158			}
159			snprintf(obuf + len, SPT_BUFSIZE - len, "%s%s",
160			    len != 0 ? " " : "", oargv[i]);
161			if (len != 0)
162				len++;
163			len += strlen(oargv[i]);
164			if (len >= SPT_BUFSIZE)
165				break;
166		}
167	}
168	ps_strings->ps_nargvstr = nargc;
169	ps_strings->ps_argvstr = nargvp;
170}
171