1 /*
2 * Example program for unwinding core dumps.
3 *
4 * Compile a-la:
5 * gcc -Os -Wall \
6 * -Wl,--start-group \
7 * -lunwind -lunwind-x86 -lunwind-coredump \
8 * example-core-unwind.c \
9 * -Wl,--end-group \
10 * -oexample-core-unwind
11 *
12 * Run:
13 * eu-unstrip -n --core COREDUMP
14 * figure out which virtual addresses in COREDUMP correspond to which mapped executable files
15 * (binary and libraries), then supply them like this:
16 * ./example-core-unwind COREDUMP 0x400000:/bin/crashed_program 0x3458600000:/lib/libc.so.6 [...]
17 *
18 * Note: Program eu-unstrip is part of elfutils, virtual addresses of shared
19 * libraries can be determined by ldd (at least on linux).
20 */
21
22 #include "compiler.h"
23
24 #undef _GNU_SOURCE
25 #define _GNU_SOURCE 1
26 #undef __USE_GNU
27 #define __USE_GNU 1
28
29 #include <assert.h>
30 #include <ctype.h>
31 #include <dirent.h>
32 #include <errno.h>
33 #include <fcntl.h>
34 #include <inttypes.h>
35 #include <setjmp.h>
36 #include <signal.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <stdarg.h>
40 #include <stddef.h>
41 #include <string.h>
42 #include <syslog.h>
43 #include <sys/poll.h>
44 #include <sys/mman.h>
45 #include <sys/socket.h>
46 #include <sys/stat.h>
47 #include <sys/time.h>
48 #include <sys/types.h>
49 #include <sys/wait.h>
50 #include <sys/param.h>
51 #include <termios.h>
52 #include <time.h>
53 #include <unistd.h>
54 #include <stdbool.h>
55 #include <limits.h>
56 #include <pwd.h>
57 #include <grp.h>
58
59 /* For SIGSEGV handler code */
60 #include <execinfo.h>
61 #include <sys/ucontext.h>
62
63 #include <libunwind-coredump.h>
64
65
66 /* Utility logging functions */
67
68 enum {
69 LOGMODE_NONE = 0,
70 LOGMODE_STDIO = (1 << 0),
71 LOGMODE_SYSLOG = (1 << 1),
72 LOGMODE_BOTH = LOGMODE_SYSLOG + LOGMODE_STDIO,
73 };
74 const char *msg_prefix = "";
75 const char *msg_eol = "\n";
76 int logmode = LOGMODE_STDIO;
77 int xfunc_error_retval = EXIT_FAILURE;
78
xfunc_die(void)79 void xfunc_die(void)
80 {
81 exit(xfunc_error_retval);
82 }
83
verror_msg_helper(const char * s,va_list p,const char * strerr,int flags)84 static void verror_msg_helper(const char *s,
85 va_list p,
86 const char* strerr,
87 int flags)
88 {
89 char *msg;
90 int prefix_len, strerr_len, msgeol_len, used;
91
92 if (!logmode)
93 return;
94
95 used = vasprintf(&msg, s, p);
96 if (used < 0)
97 return;
98
99 /* This is ugly and costs +60 bytes compared to multiple
100 * fprintf's, but is guaranteed to do a single write.
101 * This is needed for e.g. when multiple children
102 * can produce log messages simultaneously. */
103
104 prefix_len = msg_prefix[0] ? strlen(msg_prefix) + 2 : 0;
105 strerr_len = strerr ? strlen(strerr) : 0;
106 msgeol_len = strlen(msg_eol);
107 /* +3 is for ": " before strerr and for terminating NUL */
108 char *msg1 = (char*) realloc(msg, prefix_len + used + strerr_len + msgeol_len + 3);
109 if (!msg1)
110 {
111 free(msg);
112 return;
113 }
114 msg = msg1;
115 /* TODO: maybe use writev instead of memmoving? Need full_writev? */
116 if (prefix_len)
117 {
118 char *p;
119 memmove(msg + prefix_len, msg, used);
120 used += prefix_len;
121 p = stpcpy(msg, msg_prefix);
122 p[0] = ':';
123 p[1] = ' ';
124 }
125 if (strerr)
126 {
127 if (s[0])
128 {
129 msg[used++] = ':';
130 msg[used++] = ' ';
131 }
132 strcpy(&msg[used], strerr);
133 used += strerr_len;
134 }
135 strcpy(&msg[used], msg_eol);
136
137 if (flags & LOGMODE_STDIO)
138 {
139 fflush(stdout);
140 used += write(STDERR_FILENO, msg, used + msgeol_len);
141 }
142 msg[used] = '\0'; /* remove msg_eol (usually "\n") */
143 if (flags & LOGMODE_SYSLOG)
144 {
145 syslog(LOG_ERR, "%s", msg + prefix_len);
146 }
147 free(msg);
148 }
149
log_msg(const char * s,...)150 void log_msg(const char *s, ...)
151 {
152 va_list p;
153 va_start(p, s);
154 verror_msg_helper(s, p, NULL, logmode);
155 va_end(p);
156 }
157 /* It's a macro, not function, since it collides with log() from math.h */
158 #undef log
159 #define log(...) log_msg(__VA_ARGS__)
160
error_msg(const char * s,...)161 void error_msg(const char *s, ...)
162 {
163 va_list p;
164 va_start(p, s);
165 verror_msg_helper(s, p, NULL, logmode);
166 va_end(p);
167 }
168
error_msg_and_die(const char * s,...)169 void error_msg_and_die(const char *s, ...)
170 {
171 va_list p;
172 va_start(p, s);
173 verror_msg_helper(s, p, NULL, logmode);
174 va_end(p);
175 xfunc_die();
176 }
177
perror_msg(const char * s,...)178 void perror_msg(const char *s, ...)
179 {
180 va_list p;
181 va_start(p, s);
182 /* Guard against "<error message>: Success" */
183 verror_msg_helper(s, p, errno ? strerror(errno) : NULL, logmode);
184 va_end(p);
185 }
186
perror_msg_and_die(const char * s,...)187 void perror_msg_and_die(const char *s, ...)
188 {
189 va_list p;
190 va_start(p, s);
191 /* Guard against "<error message>: Success" */
192 verror_msg_helper(s, p, errno ? strerror(errno) : NULL, logmode);
193 va_end(p);
194 xfunc_die();
195 }
196
die_out_of_memory(void)197 void die_out_of_memory(void)
198 {
199 error_msg_and_die("Out of memory, exiting");
200 }
201
202 /* End of utility logging functions */
203
204
205
206 static
handle_sigsegv(int sig,siginfo_t * info,void * ucontext)207 void handle_sigsegv(int sig, siginfo_t *info, void *ucontext)
208 {
209 long ip = 0;
210 ucontext_t *uc UNUSED;
211
212 uc = ucontext;
213 #if defined(__linux__)
214 #ifdef UNW_TARGET_X86
215 ip = uc->uc_mcontext.gregs[REG_EIP];
216 #elif defined(UNW_TARGET_X86_64)
217 ip = uc->uc_mcontext.gregs[REG_RIP];
218 #elif defined(UNW_TARGET_ARM)
219 ip = uc->uc_mcontext.arm_pc;
220 #endif
221 #elif defined(__FreeBSD__)
222 #ifdef __i386__
223 ip = uc->uc_mcontext.mc_eip;
224 #elif defined(__amd64__)
225 ip = uc->uc_mcontext.mc_rip;
226 #else
227 #error Port me
228 #endif
229 #else
230 #error Port me
231 #endif
232 dprintf(2, "signal:%d address:0x%lx ip:0x%lx\n",
233 sig,
234 /* this is void*, but using %p would print "(null)"
235 * even for ptrs which are not exactly 0, but, say, 0x123:
236 */
237 (long)info->si_addr,
238 ip);
239
240 {
241 /* glibc extension */
242 void *array[50];
243 int size;
244 size = backtrace(array, 50);
245 #ifdef __linux__
246 backtrace_symbols_fd(array, size, 2);
247 #endif
248 }
249
250 _exit(1);
251 }
252
install_sigsegv_handler(void)253 static void install_sigsegv_handler(void)
254 {
255 struct sigaction sa;
256 memset(&sa, 0, sizeof(sa));
257 sa.sa_sigaction = handle_sigsegv;
258 sa.sa_flags = SA_SIGINFO;
259 sigaction(SIGSEGV, &sa, NULL);
260 sigaction(SIGILL, &sa, NULL);
261 sigaction(SIGFPE, &sa, NULL);
262 sigaction(SIGBUS, &sa, NULL);
263 }
264
265 int
main(int argc UNUSED,char ** argv)266 main(int argc UNUSED, char **argv)
267 {
268 unw_addr_space_t as;
269 struct UCD_info *ui;
270 unw_cursor_t c;
271 int ret;
272
273 #define TEST_FRAMES 4
274 #define TEST_NAME_LEN 32
275 int testcase = 0;
276 int test_cur = 0;
277 long test_start_ips[TEST_FRAMES];
278 char test_names[TEST_FRAMES][TEST_NAME_LEN];
279
280 install_sigsegv_handler();
281
282 const char *progname = strrchr(argv[0], '/');
283 if (progname)
284 progname++;
285 else
286 progname = argv[0];
287
288 if (!argv[1])
289 error_msg_and_die("Usage: %s COREDUMP [VADDR:BINARY_FILE]...", progname);
290
291 msg_prefix = progname;
292
293 as = unw_create_addr_space(&_UCD_accessors, 0);
294 if (!as)
295 error_msg_and_die("unw_create_addr_space() failed");
296
297 ui = _UCD_create(argv[1]);
298 if (!ui)
299 error_msg_and_die("_UCD_create('%s') failed", argv[1]);
300 ret = unw_init_remote(&c, as, ui);
301 if (ret < 0)
302 error_msg_and_die("unw_init_remote() failed: ret=%d\n", ret);
303
304 argv += 2;
305
306 /* Enable checks for the crasher test program? */
307 if (*argv && !strcmp(*argv, "-testcase"))
308 {
309 testcase = 1;
310 logmode = LOGMODE_NONE;
311 argv++;
312 }
313
314 while (*argv)
315 {
316 char *colon;
317 long vaddr = strtol(*argv, &colon, 16);
318 if (*colon != ':')
319 error_msg_and_die("Bad format: '%s'", *argv);
320 if (_UCD_add_backing_file_at_vaddr(ui, vaddr, colon + 1) < 0)
321 error_msg_and_die("Can't add backing file '%s'", colon + 1);
322 argv++;
323 }
324
325 for (;;)
326 {
327 unw_word_t ip;
328 ret = unw_get_reg(&c, UNW_REG_IP, &ip);
329 if (ret < 0)
330 error_msg_and_die("unw_get_reg(UNW_REG_IP) failed: ret=%d\n", ret);
331
332 unw_proc_info_t pi;
333 ret = unw_get_proc_info(&c, &pi);
334 if (ret < 0)
335 error_msg_and_die("unw_get_proc_info(ip=0x%lx) failed: ret=%d\n", (long) ip, ret);
336
337 if (!testcase)
338 printf("\tip=0x%08lx proc=%08lx-%08lx handler=0x%08lx lsda=0x%08lx\n",
339 (long) ip,
340 (long) pi.start_ip, (long) pi.end_ip,
341 (long) pi.handler, (long) pi.lsda);
342
343 if (testcase && test_cur < TEST_FRAMES)
344 {
345 unw_word_t off;
346
347 test_start_ips[test_cur] = (long) pi.start_ip;
348 if (unw_get_proc_name(&c, test_names[test_cur], sizeof(test_names[0]), &off) != 0)
349 {
350 test_names[test_cur][0] = '\0';
351 }
352 test_cur++;
353 }
354
355 log("step");
356 ret = unw_step(&c);
357 log("step done:%d", ret);
358 if (ret < 0)
359 error_msg_and_die("FAILURE: unw_step() returned %d", ret);
360 if (ret == 0)
361 break;
362 }
363 log("stepping ended");
364
365 /* Check that the second and third frames are equal, but distinct of the
366 * others */
367 if (testcase &&
368 (test_cur != 4
369 || test_start_ips[1] != test_start_ips[2]
370 || test_start_ips[0] == test_start_ips[1]
371 || test_start_ips[2] == test_start_ips[3]
372 )
373 )
374 {
375 fprintf(stderr, "FAILURE: start IPs incorrect\n");
376 return -1;
377 }
378
379 if (testcase &&
380 ( strcmp(test_names[0], "a")
381 || strcmp(test_names[1], "b")
382 || strcmp(test_names[2], "b")
383 || strcmp(test_names[3], "main")
384 )
385 )
386 {
387 fprintf(stderr, "FAILURE: procedure names are missing/incorrect\n");
388 return -1;
389 }
390
391 _UCD_destroy(ui);
392 unw_destroy_addr_space(as);
393
394 return 0;
395 }
396