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dad3b556 | 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 | #include "config.h" | |
28 | ||
29 | #if !defined(HAVE_SNPRINTF) || !defined(HAVE_VSNPRINTF) | |
30 | ||
31 | #include <sys/param.h> | |
32 | #include <sys/types.h> | |
33 | #include <sys/mman.h> | |
34 | #include <signal.h> | |
35 | #include <stdio.h> | |
36 | #include <unistd.h> | |
37 | #include <string.h> | |
38 | #if __STDC__ | |
39 | #include <stdarg.h> | |
40 | #include <stdlib.h> | |
41 | #else | |
42 | #include <varargs.h> | |
43 | #endif | |
44 | #include <setjmp.h> | |
45 | ||
46 | #ifndef roundup | |
47 | #define roundup (x, y) ((((x)+((y)-1))/(y))*(y)) | |
48 | #endif | |
49 | ||
50 | static int pgsize; | |
51 | static char *curobj; | |
52 | static int caught; | |
53 | static sigjmp_buf bail; | |
54 | ||
55 | #define EXTRABYTES 2 /* XXX: why 2? you don't want to know */ | |
56 | ||
57 | static char * | |
58 | msetup(str, n) | |
59 | char *str; | |
60 | size_t n; | |
61 | { | |
62 | char *e; | |
63 | ||
64 | if (n == 0) | |
65 | return NULL; | |
66 | if (pgsize == 0) | |
67 | pgsize = getpagesize(); | |
68 | curobj = (char *)malloc(n + EXTRABYTES + pgsize * 2); | |
69 | if (curobj == NULL) | |
70 | return NULL; | |
71 | e = curobj + n + EXTRABYTES; | |
72 | e = (char *)roundup((unsigned long)e, pgsize); | |
73 | if (mprotect(e, pgsize, PROT_NONE) == -1) { | |
74 | free(curobj); | |
75 | curobj = NULL; | |
76 | return NULL; | |
77 | } | |
78 | e = e - n - EXTRABYTES; | |
79 | *e = '\0'; | |
80 | return (e); | |
81 | } | |
82 | ||
83 | static void | |
84 | mcatch() | |
85 | { | |
86 | siglongjmp(bail, 1); | |
87 | } | |
88 | ||
89 | static void | |
90 | mcleanup(str, n, p) | |
91 | char *str; | |
92 | size_t n; | |
93 | char *p; | |
94 | { | |
95 | strncpy(str, p, n-1); | |
96 | str[n-1] = '\0'; | |
97 | if (mprotect((caddr_t)(p + n + EXTRABYTES), pgsize, | |
98 | PROT_READ|PROT_WRITE|PROT_EXEC) == -1) | |
99 | mprotect((caddr_t)(p + n + EXTRABYTES), pgsize, | |
100 | PROT_READ|PROT_WRITE); | |
101 | free(curobj); | |
102 | } | |
103 | ||
104 | #if !defined(HAVE_SNPRINTF) | |
105 | int | |
106 | #if __STDC__ | |
107 | snprintf(char *str, size_t n, char const *fmt, ...) | |
108 | #else | |
109 | snprintf(str, n, fmt, va_alist) | |
110 | char *str; | |
111 | size_t n; | |
112 | char *fmt; | |
113 | va_dcl | |
114 | #endif | |
115 | { | |
116 | va_list ap; | |
117 | #if __STDC__ | |
118 | va_start(ap, fmt); | |
119 | #else | |
120 | va_start(ap); | |
121 | #endif | |
122 | ||
123 | return (vsnprintf(str, n, fmt, ap)); | |
124 | va_end(ap); | |
125 | } | |
126 | #endif /* !defined(HAVE_SNPRINTF) */ | |
127 | ||
128 | #if !defined(HAVE_VSNPRINTF) | |
129 | int | |
130 | vsnprintf(str, n, fmt, ap) | |
131 | char *str; | |
132 | size_t n; | |
133 | char *fmt; | |
134 | char *ap; | |
135 | { | |
136 | struct sigaction osa, nsa; | |
137 | char *p; | |
138 | int ret = n + 1; /* if we bail, indicated we overflowed */ | |
139 | ||
140 | memset(&nsa, 0, sizeof nsa); | |
141 | nsa.sa_handler = mcatch; | |
142 | sigemptyset(&nsa.sa_mask); | |
143 | ||
144 | p = msetup(str, n); | |
145 | if (p == NULL) { | |
146 | *str = '\0'; | |
147 | return 0; | |
148 | } | |
149 | if (sigsetjmp(bail, 1) == 0) { | |
150 | if (sigaction(SIGSEGV, &nsa, &osa) == -1) { | |
151 | mcleanup(str, n, p); | |
152 | return (0); | |
153 | } | |
154 | ret = vsprintf(p, fmt, ap); | |
155 | } | |
156 | mcleanup(str, n, p); | |
157 | (void) sigaction(SIGSEGV, &osa, NULL); | |
158 | return (ret); | |
159 | } | |
160 | #endif /* !defined(HAVE_VSNPRINTF) */ | |
161 | ||
162 | #endif /* !defined(HAVE_SNPRINTF) || !defined(HAVE_VSNPRINTF) */ |