1 /*
2 * Revision 12: http://theos.com/~deraadt/snprintf.c
3 *
4 * Copyright (c) 1997 Theo de Raadt
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, 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 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #ifndef __VMS
28 # include <sys/param.h>
29 #endif
30 #include <sys/types.h>
31 #include <sys/mman.h>
32 #include <signal.h>
33 #include <stdio.h>
34 #if __STDC__
35 #include <stdarg.h>
36 #include <stdlib.h>
37 #else
38 #include <varargs.h>
39 #endif
40 #include <setjmp.h>
41 #include <unistd.h>
42 #include <string.h>
43
44 #ifndef roundup
45 #define roundup(x, y) ((((x)+((y)-1))/(y))*(y))
46 #endif
47
48 #ifdef __sgi
49 #define size_t ssize_t
50 #endif
51
52 static int pgsize;
53 static char *curobj;
54 static int caught;
55 static sigjmp_buf bail;
56
57 #define EXTRABYTES 2 /* XXX: why 2? you don't want to know */
58
59 static char *
msetup(str,n)60 msetup(str, n)
61 char *str;
62 size_t n;
63 {
64 char *e;
65
66 if (n == 0)
67 return NULL;
68 if (pgsize == 0)
69 pgsize = getpagesize();
70 curobj = (char *)malloc(n + EXTRABYTES + pgsize * 2);
71 if (curobj == NULL)
72 return NULL;
73 e = curobj + n + EXTRABYTES;
74 e = (char *)roundup((unsigned long)e, pgsize);
75 if (mprotect(e, pgsize, PROT_NONE) == -1) {
76 free(curobj);
77 curobj = NULL;
78 return NULL;
79 }
80 e = e - n - EXTRABYTES;
81 *e = '\0';
82 return (e);
83 }
84
85 static void
mcatch(int a)86 mcatch( int a )
87 {
88 siglongjmp(bail, 1);
89 }
90
91 static void
mcleanup(str,n,p)92 mcleanup(str, n, p)
93 char *str;
94 size_t n;
95 char *p;
96 {
97 strncpy(str, p, n-1);
98 str[n-1] = '\0';
99 if (mprotect((caddr_t)(p + n + EXTRABYTES), pgsize,
100 PROT_READ|PROT_WRITE|PROT_EXEC) == -1)
101 mprotect((caddr_t)(p + n + EXTRABYTES), pgsize,
102 PROT_READ|PROT_WRITE);
103 free(curobj);
104 }
105
106 int
107 #if __STDC__
vsnprintf(char * str,size_t n,char const * fmt,va_list ap)108 vsnprintf(char *str, size_t n, char const *fmt, va_list ap)
109 #else
110 vsnprintf(str, n, fmt, ap)
111 char *str;
112 size_t n;
113 char *fmt;
114 char *ap;
115 #endif
116 {
117 struct sigaction osa, nsa;
118 char *p;
119 int ret = n + 1; /* if we bail, indicated we overflowed */
120
121 memset(&nsa, 0, sizeof nsa);
122 nsa.sa_handler = mcatch;
123 sigemptyset(&nsa.sa_mask);
124
125 p = msetup(str, n);
126 if (p == NULL) {
127 *str = '\0';
128 return 0;
129 }
130 if (sigsetjmp(bail, 1) == 0) {
131 if (sigaction(SIGSEGV, &nsa, &osa) == -1) {
132 mcleanup(str, n, p);
133 return (0);
134 }
135 ret = vsprintf(p, fmt, ap);
136 }
137 mcleanup(str, n, p);
138 (void) sigaction(SIGSEGV, &osa, NULL);
139 return (ret);
140 }
141
142 int
143 #if __STDC__
snprintf(char * str,size_t n,char const * fmt,...)144 snprintf(char *str, size_t n, char const *fmt, ...)
145 #else
146 snprintf(str, n, fmt, va_alist)
147 char *str;
148 size_t n;
149 char *fmt;
150 va_dcl
151 #endif
152 {
153 va_list ap;
154 #if __STDC__
155 va_start(ap, fmt);
156 #else
157 va_start(ap);
158 #endif
159
160 return (vsnprintf(str, n, fmt, ap));
161 va_end(ap);
162 }
163
164
165
166