1 /* @(#)avoffset.c 1.39 21/04/28 Copyright 1987, 1995-2021 J. Schilling */
2 #include <schily/mconfig.h>
3 #ifndef lint
4 static UConst char sccsid[] =
5 "@(#)avoffset.c 1.39 21/04/28 Copyright 1987, 1995-2021 J. Schilling";
6 #endif
7 /*
8 * This program is a tool to generate the file "avoffset.h".
9 * It is used by functions that trace the stack to get to the top of the stack.
10 *
11 * It generates two defines:
12 * AV_OFFSET - offset of argv relative to the main() frame pointer
13 * FP_INDIR - number of stack frames above main()
14 * before encountering a NULL pointer.
15 *
16 * Copyright (c) 1987, 1995-2021 J. Schilling
17 */
18 /*
19 * The contents of this file are subject to the terms of the
20 * Common Development and Distribution License, Version 1.0 only
21 * (the "License"). You may not use this file except in compliance
22 * with the License.
23 *
24 * See the file CDDL.Schily.txt in this distribution for details.
25 * A copy of the CDDL is also available via the Internet at
26 * http://www.opensource.org/licenses/cddl1.txt
27 *
28 * When distributing Covered Code, include this CDDL HEADER in each
29 * file and include the License file CDDL.Schily.txt from this distribution.
30 */
31
32 #include <schily/stdio.h>
33 #include <schily/standard.h>
34 #include <schily/schily.h>
35 #include <schily/stdlib.h>
36 #include <schily/signal.h>
37
38 #ifdef HAVE_SCANSTACK
39 # include <schily/stkframe.h>
40 #endif
41
42 LOCAL RETSIGTYPE handler __PR((int signo));
43 EXPORT int main __PR((int ac, char **av));
44 LOCAL int stack_direction __PR((long *lp));
45
46 LOCAL RETSIGTYPE
handler(signo)47 handler(signo)
48 int signo;
49 {
50 fprintf(stderr, "Warning: Cannot scan stack on this environment.\n");
51 fprintf(stderr, "This is not an error, we just disable stack scannig.\n");
52
53 printf("\n#endif /* __AVOFFSET_H */\n");
54 fflush(stdout);
55 exit(0);
56 }
57
58
59 int
main(ac,av)60 main(ac, av)
61 int ac;
62 char **av;
63 {
64 int stdir;
65 #ifdef HAVE_SCANSTACK
66 volatile struct frame *fp;
67 register int i = 0;
68 register int o = 0;
69
70 /*
71 * As the SCO OpenServer C-Compiler has a bug that may cause
72 * the first function call to getfp() been done before the
73 * new stack frame is created, we call getfp() twice.
74 */
75 (void) getfp();
76 fp = (struct frame *)getfp();
77 #endif
78
79 #ifdef SIGBUS
80 signal(SIGBUS, handler);
81 #endif
82 signal(SIGSEGV, handler);
83 #ifdef SIGILL
84 signal(SIGILL, handler); /* For gcc -m64/sparc on FreeBSD */
85 #endif
86
87 printf("/*\n");
88 printf(" * This file has been generated automatically\n");
89 printf(" * by %s\n", sccsid);
90 printf(" * do not edit by hand.\n");
91 printf(" *\n");
92 printf(" * This file includes definitions for AV_OFFSET and FP_INDIR.\n");
93 printf(" * FP_INDIR is the number of fp chain elements above 'main'.\n");
94 printf(" * AV_OFFSET is the offset of &av[0] relative to the frame pointer in 'main'.\n");
95 printf(" *\n");
96 printf(" * If getav0() does not work on a specific architecture\n");
97 printf(" * the program which generated this include file may dump core.\n");
98 printf(" * In this case, the generated include file does not include\n");
99 printf(" * definitions for AV_OFFSET and FP_INDIR but ends after this comment.\n");
100 printf(" * If AV_OFFSET or FP_INDIR are missing in this file, all programs\n");
101 printf(" * which use the definitions are automatically disabled.\n");
102 printf(" */\n");
103 printf("#ifndef __AVOFFSET_H\n");
104 printf("#define __AVOFFSET_H\n\n");
105
106 stdir = stack_direction(0);
107 printf("#define STACK_DIRECTION %d\n", stdir);
108 fflush(stdout);
109
110 #ifdef HAVE_SCANSTACK
111 /*
112 * Note: Scanning the stack to look for argc/argv
113 * works only in the main thread.
114 *
115 * llvm-gcc-4.2 has a bug and creates an endless loop if we call:
116 * while (fp->fr_savfp) {
117 * We now try to limit this to 1000 loops in hope that the bug
118 * does not affect the new code extended as well.
119 */
120 while (i <= 1000 && fp->fr_savfp) {
121 /*
122 * Workaround for the still buggy clang...
123 * clang version 4.0.0 on ARM64 FreeBSD has become worse.
124 * If we do not have the strange write() call, this loop
125 * becomes an endless loop and the last line in the loop
126 * is never touched.
127 */
128 write(-1, "", 0);
129 if (fp->fr_savpc == 0)
130 break;
131
132 fp = (struct frame *)fp->fr_savfp;
133
134 i++;
135 }
136 /*
137 * Do not add any printf()'s before this line to allow avoffset
138 * to abort without printing more than the comment above.
139 */
140 fp = (struct frame *)getfp();
141 o = ((char *)av) - ((char *)fp);
142 if ((o % sizeof (char *)) != 0) {
143 fprintf(stderr, "AV_OFFSET value (%d) not a multiple of pointer size.\n", o);
144 fprintf(stderr, "Disabling scanning the stack.\n");
145
146 printf("\n#endif /* __AVOFFSET_H */\n");
147 exit(0);
148 }
149 if (o < -1000 || o > 1000) {
150 fprintf(stderr, "AV_OFFSET value (%d) does not look reasonable.\n", o);
151 fprintf(stderr, "Disabling scanning the stack.\n");
152
153 printf("\n#endif /* __AVOFFSET_H */\n");
154 exit(0);
155 }
156 if (i > 1000) {
157 fprintf(stderr, "FP_INDIR value (%d) does not look reasonable.\n", i);
158 fprintf(stderr, "Disabling scanning the stack.\n");
159
160 printf("\n#endif /* __AVOFFSET_H */\n");
161 exit(0);
162 }
163 printf("#define AV_OFFSET %d\n", o);
164 printf("#define FP_INDIR %d\n", i);
165 #endif
166 printf("\n#endif /* __AVOFFSET_H */\n");
167 fflush(stdout);
168 exit(0);
169 return (0); /* keep lint happy */
170 }
171
172 #ifndef __NO_INL__
173 #if __clang__ || (__GNUC__ > 3 || __GNUC__ == 3 && __GNUC_MINOR__ >= 2)
174 #define __NO_INL__ __attribute__((noinline))
175 #else
176 #define __NO_INL__
177 #endif
178 #endif
179
180 LOCAL __NO_INL__ int
stack_direction(lp)181 stack_direction(lp)
182 long *lp;
183 {
184 auto long *dummy[4];
185 int i;
186
187 for (i = 0; i < 4; i++)
188 dummy[i] = lp;
189
190 if (lp == 0) {
191 return (stack_direction((long *)dummy));
192 } else {
193 if ((long *)dummy == lp)
194 return (0);
195 return (((long *)dummy > lp) ? 1 : -1);
196 }
197 }
198
199 #ifdef HAVE_SCANSTACK
200 #define IS_AVOFFSET
201 #include "getfp.c"
202 #endif
203