xref: /freebsd/lib/libc/gen/setproctitle.c (revision daf1cffce2e07931f27c6c6998652e90df6ba87e)
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  * $FreeBSD$
18  */
19 
20 #include <sys/types.h>
21 #include <sys/param.h>
22 #include <sys/exec.h>
23 #include <sys/sysctl.h>
24 
25 #include <vm/vm.h>
26 #include <vm/vm_param.h>
27 #include <vm/pmap.h>
28 
29 #include <stdio.h>
30 #include <string.h>
31 #include <stdlib.h>
32 #include <unistd.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  * This attempts to support a kernel built in the #2 and #3 era.
41  */
42 
43 struct old_ps_strings {
44 	char	*old_ps_argvstr;
45 	int	old_ps_nargvstr;
46 	char	*old_ps_envstr;
47 	int	old_ps_nenvstr;
48 };
49 #define	OLD_PS_STRINGS ((struct old_ps_strings *) \
50 	(USRSTACK - SPARE_USRSPACE - sizeof(struct old_ps_strings)))
51 
52 #if defined(__STDC__)		/* from other parts of sendmail */
53 #include <stdarg.h>
54 #else
55 #include <varargs.h>
56 #endif
57 
58 
59 #define SPT_BUFSIZE 2048	/* from other parts of sendmail */
60 extern char * __progname;	/* is this defined in a .h anywhere? */
61 
62 void
63 #if defined(__STDC__)
64 setproctitle(const char *fmt, ...)
65 #else
66 setproctitle(fmt, va_alist)
67 	const char *fmt;
68 	va_dcl
69 #endif
70 {
71 	static struct ps_strings *ps_strings;
72 	static char buf[SPT_BUFSIZE];
73 	static char obuf[SPT_BUFSIZE];
74 	static char **oargv, *kbuf;
75 	static int oargc = -1;
76 	static char *nargv[2] = { buf, NULL };
77 	char **nargvp;
78 	int nargc;
79 	va_list ap;
80 	size_t len;
81 	unsigned long ul_ps_strings;
82 	int oid[4];
83 
84 #if defined(__STDC__)
85 	va_start(ap, fmt);
86 #else
87 	va_start(ap);
88 #endif
89 
90 	if (fmt) {
91 		buf[sizeof(buf) - 1] = '\0';
92 
93 		/* print program name heading for grep */
94 		(void) snprintf(buf, sizeof(buf), "%s: ", __progname);
95 
96 		/*
97 		 * can't use return from sprintf, as that is the count of how
98 		 * much it wanted to write, not how much it actually did.
99 		 */
100 
101 		len = strlen(buf);
102 
103 		/* print the argument string */
104 		(void) vsnprintf(buf + len, sizeof(buf) - len, fmt, ap);
105 
106 		nargvp = nargv;
107 		nargc = 1;
108 		kbuf = buf;
109 	} else if (*obuf != '\0') {
110   		/* Idea from NetBSD - reset the title on fmt == NULL */
111 		nargvp = oargv;
112 		nargc = oargc;
113 		kbuf = obuf;
114 	} else
115 		/* Nothing to restore */
116 		return;
117 
118 	va_end(ap);
119 
120 	/* Set the title into the kernel cached command line */
121 	oid[0] = CTL_KERN;
122 	oid[1] = KERN_PROC;
123 	oid[2] = KERN_PROC_ARGS;
124 	oid[3] = getpid();
125 	sysctl(oid, 4, 0, 0, kbuf, strlen(kbuf) + 1);
126 
127 	if (ps_strings == NULL) {
128 		len = sizeof(ul_ps_strings);
129 		if (sysctlbyname("kern.ps_strings", &ul_ps_strings, &len, NULL,
130 		    0) == -1)
131 			ul_ps_strings = PS_STRINGS;
132 		ps_strings = (struct ps_strings *)ul_ps_strings;
133 	}
134 
135 	/* PS_STRINGS points to zeroed memory on a style #2 kernel */
136 	if (ps_strings->ps_argvstr) {
137 		/* style #3 */
138 		if (oargc == -1) {
139 			/* Record our original args */
140 			oargc = ps_strings->ps_nargvstr;
141 			oargv = ps_strings->ps_argvstr;
142 			for (nargc = len = 0; nargc < oargc; nargc++) {
143 				snprintf(obuf + len, sizeof(obuf) - len, "%s%s",
144 				    len ? " " : "", oargv[nargc]);
145 				if (len)
146 					len++;
147 				len += strlen(oargv[nargc]);
148 				if (len >= sizeof(obuf))
149 					break;
150 			}
151 		}
152 		ps_strings->ps_nargvstr = nargc;
153 		ps_strings->ps_argvstr = nargvp;
154 	} else {
155 		/* style #2 - we can only restore our first arg :-( */
156 		if (*obuf == '\0')
157 			strncpy(obuf, OLD_PS_STRINGS->old_ps_argvstr,
158 			    sizeof(obuf) - 1);
159 		OLD_PS_STRINGS->old_ps_nargvstr = 1;
160 		OLD_PS_STRINGS->old_ps_argvstr = nargvp[0];
161 	}
162 }
163