setproctitle.c revision 302408 
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 298226 2016-04-18 21:05:15Z avos $");
20
21#include "namespace.h"
22#include <sys/param.h>
23#include <sys/exec.h>
24#include <sys/sysctl.h>
25
26#include <vm/vm.h>
27#include <vm/vm_param.h>
28#include <vm/pmap.h>
29
30#include <stdio.h>
31#include <string.h>
32#include <stdlib.h>
33#include <unistd.h>
34#include "un-namespace.h"
35
36#include "libc_private.h"
37
38/*
39 * Older FreeBSD 2.0, 2.1 and 2.2 had different ps_strings structures and
40 * in different locations.
41 * 1: old_ps_strings at the very top of the stack.
42 * 2: old_ps_strings at SPARE_USRSPACE below the top of the stack.
43 * 3: ps_strings at the very top of the stack.
44 * We only support a kernel providing #3 style ps_strings.
45 *
46 * For historical purposes, a definition of the old ps_strings structure
47 * and location is preserved below:
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
58#include <stdarg.h>
59
60#define SPT_BUFSIZE 2048	/* from other parts of sendmail */
61
62void
63setproctitle(const char *fmt, ...)
64{
65	static struct ps_strings *ps_strings;
66	static char *buf = NULL;
67	static char *obuf = NULL;
68	static char **oargv, *kbuf;
69	static int oargc = -1;
70	static char *nargv[2] = { NULL, NULL };
71	char **nargvp;
72	int nargc;
73	int i;
74	va_list ap;
75	size_t len;
76	unsigned long ul_ps_strings;
77	int oid[4];
78
79	if (buf == NULL) {
80		buf = malloc(SPT_BUFSIZE);
81		if (buf == NULL)
82			return;
83		nargv[0] = buf;
84	}
85
86	if (obuf == NULL ) {
87		obuf = malloc(SPT_BUFSIZE);
88		if (obuf == NULL)
89			return;
90		*obuf = '\0';
91	}
92
93	va_start(ap, fmt);
94
95	if (fmt) {
96		buf[SPT_BUFSIZE - 1] = '\0';
97
98		if (fmt[0] == '-') {
99			/* skip program name prefix */
100			fmt++;
101			len = 0;
102		} else {
103			/* print program name heading for grep */
104			(void)snprintf(buf, SPT_BUFSIZE, "%s: ", _getprogname());
105			len = strlen(buf);
106		}
107
108		/* print the argument string */
109		(void) vsnprintf(buf + len, SPT_BUFSIZE - len, fmt, ap);
110
111		nargvp = nargv;
112		nargc = 1;
113		kbuf = buf;
114	} else if (*obuf != '\0') {
115  		/* Idea from NetBSD - reset the title on fmt == NULL */
116		nargvp = oargv;
117		nargc = oargc;
118		kbuf = obuf;
119	} else
120		/* Nothing to restore */
121		return;
122
123	va_end(ap);
124
125	/* Set the title into the kernel cached command line */
126	oid[0] = CTL_KERN;
127	oid[1] = KERN_PROC;
128	oid[2] = KERN_PROC_ARGS;
129	oid[3] = getpid();
130	sysctl(oid, 4, 0, 0, kbuf, strlen(kbuf) + 1);
131
132	if (ps_strings == NULL) {
133		len = sizeof(ul_ps_strings);
134		if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
135		    0) == -1)
136			return;
137		ps_strings = (struct ps_strings *)ul_ps_strings;
138	}
139
140	/*
141	 * PS_STRINGS points to zeroed memory on a style #2 kernel.
142	 * Should not happen.
143	 */
144	if (ps_strings->ps_argvstr == NULL)
145		return;
146
147	/* style #3 */
148	if (oargc == -1) {
149		/* Record our original args */
150		oargc = ps_strings->ps_nargvstr;
151		oargv = ps_strings->ps_argvstr;
152		for (i = len = 0; i < oargc; i++) {
153			/*
154			 * The program may have scribbled into its
155			 * argv array, e.g., to remove some arguments.
156			 * If that has happened, break out before
157			 * trying to call strlen on a NULL pointer.
158			 */
159			if (oargv[i] == NULL) {
160				oargc = i;
161				break;
162			}
163			snprintf(obuf + len, SPT_BUFSIZE - len, "%s%s",
164			    len != 0 ? " " : "", oargv[i]);
165			if (len != 0)
166				len++;
167			len += strlen(oargv[i]);
168			if (len >= SPT_BUFSIZE)
169				break;
170		}
171	}
172	ps_strings->ps_nargvstr = nargc;
173	ps_strings->ps_argvstr = nargvp;
174}
175