xref: /freebsd/lib/libc/gen/setproctitle.c (revision 69c9999d0ca45b210e75706ab4952ad5a33ce6ec)
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("$FreeBSD$");
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 
48 struct 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 
61 void
62 setproctitle(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