tombstone.c revision d7760c1688f8276a05e33345d81639f8cb5e7c3f 
1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stddef.h>
18#include <stdbool.h>
19#include <stdlib.h>
20#include <signal.h>
21#include <string.h>
22#include <stdio.h>
23#include <fcntl.h>
24#include <errno.h>
25#include <dirent.h>
26#include <time.h>
27#include <sys/ptrace.h>
28#include <sys/stat.h>
29
30#include <private/android_filesystem_config.h>
31
32#include <cutils/logger.h>
33#include <cutils/properties.h>
34
35#include <corkscrew/demangle.h>
36#include <corkscrew/backtrace.h>
37
38#ifdef HAVE_SELINUX
39#include <selinux/android.h>
40#endif
41
42#include "machine.h"
43#include "tombstone.h"
44#include "utility.h"
45
46#define STACK_DEPTH 32
47#define STACK_WORDS 16
48
49#define MAX_TOMBSTONES  10
50#define TOMBSTONE_DIR   "/data/tombstones"
51
52#define typecheck(x,y) {    \
53    typeof(x) __dummy1;     \
54    typeof(y) __dummy2;     \
55    (void)(&__dummy1 == &__dummy2); }
56
57
58static bool signal_has_address(int sig) {
59    switch (sig) {
60        case SIGILL:
61        case SIGFPE:
62        case SIGSEGV:
63        case SIGBUS:
64            return true;
65        default:
66            return false;
67    }
68}
69
70static const char *get_signame(int sig)
71{
72    switch(sig) {
73    case SIGILL:     return "SIGILL";
74    case SIGABRT:    return "SIGABRT";
75    case SIGBUS:     return "SIGBUS";
76    case SIGFPE:     return "SIGFPE";
77    case SIGSEGV:    return "SIGSEGV";
78    case SIGPIPE:    return "SIGPIPE";
79#ifdef SIGSTKFLT
80    case SIGSTKFLT:  return "SIGSTKFLT";
81#endif
82    case SIGSTOP:    return "SIGSTOP";
83    default:         return "?";
84    }
85}
86
87static const char *get_sigcode(int signo, int code)
88{
89    switch (signo) {
90    case SIGILL:
91        switch (code) {
92        case ILL_ILLOPC: return "ILL_ILLOPC";
93        case ILL_ILLOPN: return "ILL_ILLOPN";
94        case ILL_ILLADR: return "ILL_ILLADR";
95        case ILL_ILLTRP: return "ILL_ILLTRP";
96        case ILL_PRVOPC: return "ILL_PRVOPC";
97        case ILL_PRVREG: return "ILL_PRVREG";
98        case ILL_COPROC: return "ILL_COPROC";
99        case ILL_BADSTK: return "ILL_BADSTK";
100        }
101        break;
102    case SIGBUS:
103        switch (code) {
104        case BUS_ADRALN: return "BUS_ADRALN";
105        case BUS_ADRERR: return "BUS_ADRERR";
106        case BUS_OBJERR: return "BUS_OBJERR";
107        }
108        break;
109    case SIGFPE:
110        switch (code) {
111        case FPE_INTDIV: return "FPE_INTDIV";
112        case FPE_INTOVF: return "FPE_INTOVF";
113        case FPE_FLTDIV: return "FPE_FLTDIV";
114        case FPE_FLTOVF: return "FPE_FLTOVF";
115        case FPE_FLTUND: return "FPE_FLTUND";
116        case FPE_FLTRES: return "FPE_FLTRES";
117        case FPE_FLTINV: return "FPE_FLTINV";
118        case FPE_FLTSUB: return "FPE_FLTSUB";
119        }
120        break;
121    case SIGSEGV:
122        switch (code) {
123        case SEGV_MAPERR: return "SEGV_MAPERR";
124        case SEGV_ACCERR: return "SEGV_ACCERR";
125        }
126        break;
127    }
128    return "?";
129}
130
131static void dump_revision_info(log_t* log)
132{
133    char revision[PROPERTY_VALUE_MAX];
134
135    property_get("ro.revision", revision, "unknown");
136
137    _LOG(log, false, "Revision: '%s'\n", revision);
138}
139
140static void dump_build_info(log_t* log)
141{
142    char fingerprint[PROPERTY_VALUE_MAX];
143
144    property_get("ro.build.fingerprint", fingerprint, "unknown");
145
146    _LOG(log, false, "Build fingerprint: '%s'\n", fingerprint);
147}
148
149static void dump_fault_addr(log_t* log, pid_t tid, int sig)
150{
151    siginfo_t si;
152
153    memset(&si, 0, sizeof(si));
154    if(ptrace(PTRACE_GETSIGINFO, tid, 0, &si)){
155        _LOG(log, false, "cannot get siginfo: %s\n", strerror(errno));
156    } else if (signal_has_address(sig)) {
157        _LOG(log, false, "signal %d (%s), code %d (%s), fault addr %08x\n",
158             sig, get_signame(sig),
159             si.si_code, get_sigcode(sig, si.si_code),
160             (uintptr_t) si.si_addr);
161    } else {
162        _LOG(log, false, "signal %d (%s), code %d (%s), fault addr --------\n",
163             sig, get_signame(sig), si.si_code, get_sigcode(sig, si.si_code));
164    }
165}
166
167static void dump_thread_info(log_t* log, pid_t pid, pid_t tid, bool at_fault) {
168    char path[64];
169    char threadnamebuf[1024];
170    char* threadname = NULL;
171    FILE *fp;
172
173    snprintf(path, sizeof(path), "/proc/%d/comm", tid);
174    if ((fp = fopen(path, "r"))) {
175        threadname = fgets(threadnamebuf, sizeof(threadnamebuf), fp);
176        fclose(fp);
177        if (threadname) {
178            size_t len = strlen(threadname);
179            if (len && threadname[len - 1] == '\n') {
180                threadname[len - 1] = '\0';
181            }
182        }
183    }
184
185    if (at_fault) {
186        char procnamebuf[1024];
187        char* procname = NULL;
188
189        snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
190        if ((fp = fopen(path, "r"))) {
191            procname = fgets(procnamebuf, sizeof(procnamebuf), fp);
192            fclose(fp);
193        }
194
195        _LOG(log, false, "pid: %d, tid: %d, name: %s  >>> %s <<<\n", pid, tid,
196                threadname ? threadname : "UNKNOWN",
197                procname ? procname : "UNKNOWN");
198    } else {
199        _LOG(log, true, "pid: %d, tid: %d, name: %s\n", pid, tid,
200                threadname ? threadname : "UNKNOWN");
201    }
202}
203
204static void dump_backtrace(const ptrace_context_t* context __attribute((unused)),
205        log_t* log, pid_t tid __attribute((unused)), bool at_fault,
206        const backtrace_frame_t* backtrace, size_t frames) {
207    _LOG(log, !at_fault, "\nbacktrace:\n");
208
209    backtrace_symbol_t backtrace_symbols[STACK_DEPTH];
210    get_backtrace_symbols_ptrace(context, backtrace, frames, backtrace_symbols);
211    for (size_t i = 0; i < frames; i++) {
212        char line[MAX_BACKTRACE_LINE_LENGTH];
213        format_backtrace_line(i, &backtrace[i], &backtrace_symbols[i],
214                line, MAX_BACKTRACE_LINE_LENGTH);
215        _LOG(log, !at_fault, "    %s\n", line);
216    }
217    free_backtrace_symbols(backtrace_symbols, frames);
218}
219
220static void dump_stack_segment(const ptrace_context_t* context, log_t* log, pid_t tid,
221        bool only_in_tombstone, uintptr_t* sp, size_t words, int label) {
222    for (size_t i = 0; i < words; i++) {
223        uint32_t stack_content;
224        if (!try_get_word_ptrace(tid, *sp, &stack_content)) {
225            break;
226        }
227
228        const map_info_t* mi;
229        const symbol_t* symbol;
230        find_symbol_ptrace(context, stack_content, &mi, &symbol);
231
232        if (symbol) {
233            char* demangled_name = demangle_symbol_name(symbol->name);
234            const char* symbol_name = demangled_name ? demangled_name : symbol->name;
235            uint32_t offset = stack_content - (mi->start + symbol->start);
236            if (!i && label >= 0) {
237                if (offset) {
238                    _LOG(log, only_in_tombstone, "    #%02d  %08x  %08x  %s (%s+%u)\n",
239                            label, *sp, stack_content, mi ? mi->name : "", symbol_name, offset);
240                } else {
241                    _LOG(log, only_in_tombstone, "    #%02d  %08x  %08x  %s (%s)\n",
242                            label, *sp, stack_content, mi ? mi->name : "", symbol_name);
243                }
244            } else {
245                if (offset) {
246                    _LOG(log, only_in_tombstone, "         %08x  %08x  %s (%s+%u)\n",
247                            *sp, stack_content, mi ? mi->name : "", symbol_name, offset);
248                } else {
249                    _LOG(log, only_in_tombstone, "         %08x  %08x  %s (%s)\n",
250                            *sp, stack_content, mi ? mi->name : "", symbol_name);
251                }
252            }
253            free(demangled_name);
254        } else {
255            if (!i && label >= 0) {
256                _LOG(log, only_in_tombstone, "    #%02d  %08x  %08x  %s\n",
257                        label, *sp, stack_content, mi ? mi->name : "");
258            } else {
259                _LOG(log, only_in_tombstone, "         %08x  %08x  %s\n",
260                        *sp, stack_content, mi ? mi->name : "");
261            }
262        }
263
264        *sp += sizeof(uint32_t);
265    }
266}
267
268static void dump_stack(const ptrace_context_t* context, log_t* log, pid_t tid, bool at_fault,
269        const backtrace_frame_t* backtrace, size_t frames) {
270    bool have_first = false;
271    size_t first, last;
272    for (size_t i = 0; i < frames; i++) {
273        if (backtrace[i].stack_top) {
274            if (!have_first) {
275                have_first = true;
276                first = i;
277            }
278            last = i;
279        }
280    }
281    if (!have_first) {
282        return;
283    }
284
285    _LOG(log, !at_fault, "\nstack:\n");
286
287    // Dump a few words before the first frame.
288    bool only_in_tombstone = !at_fault;
289    uintptr_t sp = backtrace[first].stack_top - STACK_WORDS * sizeof(uint32_t);
290    dump_stack_segment(context, log, tid, only_in_tombstone, &sp, STACK_WORDS, -1);
291
292    // Dump a few words from all successive frames.
293    // Only log the first 3 frames, put the rest in the tombstone.
294    for (size_t i = first; i <= last; i++) {
295        const backtrace_frame_t* frame = &backtrace[i];
296        if (sp != frame->stack_top) {
297            _LOG(log, only_in_tombstone, "         ........  ........\n");
298            sp = frame->stack_top;
299        }
300        if (i - first == 3) {
301            only_in_tombstone = true;
302        }
303        if (i == last) {
304            dump_stack_segment(context, log, tid, only_in_tombstone, &sp, STACK_WORDS, i);
305            if (sp < frame->stack_top + frame->stack_size) {
306                _LOG(log, only_in_tombstone, "         ........  ........\n");
307            }
308        } else {
309            size_t words = frame->stack_size / sizeof(uint32_t);
310            if (words == 0) {
311                words = 1;
312            } else if (words > STACK_WORDS) {
313                words = STACK_WORDS;
314            }
315            dump_stack_segment(context, log, tid, only_in_tombstone, &sp, words, i);
316        }
317    }
318}
319
320static void dump_backtrace_and_stack(const ptrace_context_t* context, log_t* log, pid_t tid,
321        bool at_fault) {
322    backtrace_frame_t backtrace[STACK_DEPTH];
323    ssize_t frames = unwind_backtrace_ptrace(tid, context, backtrace, 0, STACK_DEPTH);
324    if (frames > 0) {
325        dump_backtrace(context, log, tid, at_fault, backtrace, frames);
326        dump_stack(context, log, tid, at_fault, backtrace, frames);
327    }
328}
329
330static void dump_nearby_maps(const ptrace_context_t* context, log_t* log, pid_t tid) {
331    siginfo_t si;
332    memset(&si, 0, sizeof(si));
333    if (ptrace(PTRACE_GETSIGINFO, tid, 0, &si)) {
334        _LOG(log, false, "cannot get siginfo for %d: %s\n",
335                tid, strerror(errno));
336        return;
337    }
338    if (!signal_has_address(si.si_signo)) {
339        return;
340    }
341
342    uintptr_t addr = (uintptr_t) si.si_addr;
343    addr &= ~0xfff;     /* round to 4K page boundary */
344    if (addr == 0) {    /* null-pointer deref */
345        return;
346    }
347
348    _LOG(log, false, "\nmemory map around fault addr %08x:\n", (int)si.si_addr);
349
350    /*
351     * Search for a match, or for a hole where the match would be.  The list
352     * is backward from the file content, so it starts at high addresses.
353     */
354    map_info_t* map = context->map_info_list;
355    map_info_t *next = NULL;
356    map_info_t *prev = NULL;
357    while (map != NULL) {
358        if (addr >= map->start && addr < map->end) {
359            next = map->next;
360            break;
361        } else if (addr >= map->end) {
362            /* map would be between "prev" and this entry */
363            next = map;
364            map = NULL;
365            break;
366        }
367
368        prev = map;
369        map = map->next;
370    }
371
372    /*
373     * Show "next" then "match" then "prev" so that the addresses appear in
374     * ascending order (like /proc/pid/maps).
375     */
376    if (next != NULL) {
377        _LOG(log, false, "    %08x-%08x %s\n", next->start, next->end, next->name);
378    } else {
379        _LOG(log, false, "    (no map below)\n");
380    }
381    if (map != NULL) {
382        _LOG(log, false, "    %08x-%08x %s\n", map->start, map->end, map->name);
383    } else {
384        _LOG(log, false, "    (no map for address)\n");
385    }
386    if (prev != NULL) {
387        _LOG(log, false, "    %08x-%08x %s\n", prev->start, prev->end, prev->name);
388    } else {
389        _LOG(log, false, "    (no map above)\n");
390    }
391}
392
393static void dump_thread(const ptrace_context_t* context, log_t* log, pid_t tid, bool at_fault,
394        int* total_sleep_time_usec) {
395    wait_for_stop(tid, total_sleep_time_usec);
396
397    dump_registers(context, log, tid, at_fault);
398    dump_backtrace_and_stack(context, log, tid, at_fault);
399    if (at_fault) {
400        dump_memory_and_code(context, log, tid, at_fault);
401        dump_nearby_maps(context, log, tid);
402    }
403}
404
405/* Return true if some thread is not detached cleanly */
406static bool dump_sibling_thread_report(const ptrace_context_t* context,
407        log_t* log, pid_t pid, pid_t tid, int* total_sleep_time_usec) {
408    char task_path[64];
409    snprintf(task_path, sizeof(task_path), "/proc/%d/task", pid);
410
411    DIR* d = opendir(task_path);
412    /* Bail early if cannot open the task directory */
413    if (d == NULL) {
414        XLOG("Cannot open /proc/%d/task\n", pid);
415        return false;
416    }
417
418    bool detach_failed = false;
419    struct dirent debuf;
420    struct dirent *de;
421    while (!readdir_r(d, &debuf, &de) && de) {
422        /* Ignore "." and ".." */
423        if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, "..")) {
424            continue;
425        }
426
427        /* The main thread at fault has been handled individually */
428        char* end;
429        pid_t new_tid = strtoul(de->d_name, &end, 10);
430        if (*end || new_tid == tid) {
431            continue;
432        }
433
434        /* Skip this thread if cannot ptrace it */
435        if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0) {
436            continue;
437        }
438
439        _LOG(log, true, "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
440        dump_thread_info(log, pid, new_tid, false);
441        dump_thread(context, log, new_tid, false, total_sleep_time_usec);
442
443        if (ptrace(PTRACE_DETACH, new_tid, 0, 0) != 0) {
444            LOG("ptrace detach from %d failed: %s\n", new_tid, strerror(errno));
445            detach_failed = true;
446        }
447    }
448
449    closedir(d);
450    return detach_failed;
451}
452
453/*
454 * Reads the contents of the specified log device, filters out the entries
455 * that don't match the specified pid, and writes them to the tombstone file.
456 *
457 * If "tailOnly" is set, we only print the last few lines.
458 */
459static void dump_log_file(log_t* log, pid_t pid, const char* filename,
460    bool tailOnly)
461{
462    bool first = true;
463
464    /* circular buffer, for "tailOnly" mode */
465    const int kShortLogMaxLines = 5;
466    const int kShortLogLineLen = 256;
467    char shortLog[kShortLogMaxLines][kShortLogLineLen];
468    int shortLogCount = 0;
469    int shortLogNext = 0;
470
471    int logfd = open(filename, O_RDONLY | O_NONBLOCK);
472    if (logfd < 0) {
473        XLOG("Unable to open %s: %s\n", filename, strerror(errno));
474        return;
475    }
476
477    union {
478        unsigned char buf[LOGGER_ENTRY_MAX_LEN + 1];
479        struct logger_entry entry;
480    } log_entry;
481
482    while (true) {
483        ssize_t actual = read(logfd, log_entry.buf, LOGGER_ENTRY_MAX_LEN);
484        if (actual < 0) {
485            if (errno == EINTR) {
486                /* interrupted by signal, retry */
487                continue;
488            } else if (errno == EAGAIN) {
489                /* non-blocking EOF; we're done */
490                break;
491            } else {
492                _LOG(log, true, "Error while reading log: %s\n",
493                    strerror(errno));
494                break;
495            }
496        } else if (actual == 0) {
497            _LOG(log, true, "Got zero bytes while reading log: %s\n",
498                strerror(errno));
499            break;
500        }
501
502        /*
503         * NOTE: if you XLOG something here, this will spin forever,
504         * because you will be writing as fast as you're reading.  Any
505         * high-frequency debug diagnostics should just be written to
506         * the tombstone file.
507         */
508
509        struct logger_entry* entry = &log_entry.entry;
510
511        if (entry->pid != (int32_t) pid) {
512            /* wrong pid, ignore */
513            continue;
514        }
515
516        if (first) {
517            _LOG(log, true, "--------- %slog %s\n",
518                tailOnly ? "tail end of " : "", filename);
519            first = false;
520        }
521
522        /*
523         * Msg format is: <priority:1><tag:N>\0<message:N>\0
524         *
525         * We want to display it in the same format as "logcat -v threadtime"
526         * (although in this case the pid is redundant).
527         *
528         * TODO: scan for line breaks ('\n') and display each text line
529         * on a separate line, prefixed with the header, like logcat does.
530         */
531        static const char* kPrioChars = "!.VDIWEFS";
532        unsigned char prio = entry->msg[0];
533        char* tag = entry->msg + 1;
534        char* msg = tag + strlen(tag) + 1;
535
536        /* consume any trailing newlines */
537        char* eatnl = msg + strlen(msg) - 1;
538        while (eatnl >= msg && *eatnl == '\n') {
539            *eatnl-- = '\0';
540        }
541
542        char prioChar = (prio < strlen(kPrioChars) ? kPrioChars[prio] : '?');
543
544        char timeBuf[32];
545        time_t sec = (time_t) entry->sec;
546        struct tm tmBuf;
547        struct tm* ptm;
548        ptm = localtime_r(&sec, &tmBuf);
549        strftime(timeBuf, sizeof(timeBuf), "%m-%d %H:%M:%S", ptm);
550
551        if (tailOnly) {
552            snprintf(shortLog[shortLogNext], kShortLogLineLen,
553                "%s.%03d %5d %5d %c %-8s: %s",
554                timeBuf, entry->nsec / 1000000, entry->pid, entry->tid,
555                prioChar, tag, msg);
556            shortLogNext = (shortLogNext + 1) % kShortLogMaxLines;
557            shortLogCount++;
558        } else {
559            _LOG(log, true, "%s.%03d %5d %5d %c %-8s: %s\n",
560                timeBuf, entry->nsec / 1000000, entry->pid, entry->tid,
561                prioChar, tag, msg);
562        }
563    }
564
565    if (tailOnly) {
566        int i;
567
568        /*
569         * If we filled the buffer, we want to start at "next", which has
570         * the oldest entry.  If we didn't, we want to start at zero.
571         */
572        if (shortLogCount < kShortLogMaxLines) {
573            shortLogNext = 0;
574        } else {
575            shortLogCount = kShortLogMaxLines;  /* cap at window size */
576        }
577
578        for (i = 0; i < shortLogCount; i++) {
579            _LOG(log, true, "%s\n", shortLog[shortLogNext]);
580            shortLogNext = (shortLogNext + 1) % kShortLogMaxLines;
581        }
582    }
583
584    close(logfd);
585}
586
587/*
588 * Dumps the logs generated by the specified pid to the tombstone, from both
589 * "system" and "main" log devices.  Ideally we'd interleave the output.
590 */
591static void dump_logs(log_t* log, pid_t pid, bool tailOnly)
592{
593    dump_log_file(log, pid, "/dev/log/system", tailOnly);
594    dump_log_file(log, pid, "/dev/log/main", tailOnly);
595}
596
597/*
598 * Dumps all information about the specified pid to the tombstone.
599 */
600static bool dump_crash(log_t* log, pid_t pid, pid_t tid, int signal,
601        bool dump_sibling_threads, int* total_sleep_time_usec)
602{
603    /* don't copy log messages to tombstone unless this is a dev device */
604    char value[PROPERTY_VALUE_MAX];
605    property_get("ro.debuggable", value, "0");
606    bool want_logs = (value[0] == '1');
607
608    _LOG(log, false,
609            "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
610    dump_build_info(log);
611    dump_revision_info(log);
612    dump_thread_info(log, pid, tid, true);
613    if(signal) {
614        dump_fault_addr(log, tid, signal);
615    }
616
617    ptrace_context_t* context = load_ptrace_context(tid);
618    dump_thread(context, log, tid, true, total_sleep_time_usec);
619
620    if (want_logs) {
621        dump_logs(log, pid, true);
622    }
623
624    bool detach_failed = false;
625    if (dump_sibling_threads) {
626        detach_failed = dump_sibling_thread_report(context, log, pid, tid, total_sleep_time_usec);
627    }
628
629    free_ptrace_context(context);
630
631    if (want_logs) {
632        dump_logs(log, pid, false);
633    }
634    return detach_failed;
635}
636
637/*
638 * find_and_open_tombstone - find an available tombstone slot, if any, of the
639 * form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
640 * file is available, we reuse the least-recently-modified file.
641 *
642 * Returns the path of the tombstone file, allocated using malloc().  Caller must free() it.
643 */
644static char* find_and_open_tombstone(int* fd)
645{
646    unsigned long mtime = ULONG_MAX;
647    struct stat sb;
648
649    /*
650     * XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
651     * to, our logic breaks. This check will generate a warning if that happens.
652     */
653    typecheck(mtime, sb.st_mtime);
654
655    /*
656     * In a single wolf-like pass, find an available slot and, in case none
657     * exist, find and record the least-recently-modified file.
658     */
659    char path[128];
660    int oldest = 0;
661    for (int i = 0; i < MAX_TOMBSTONES; i++) {
662        snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
663
664        if (!stat(path, &sb)) {
665            if (sb.st_mtime < mtime) {
666                oldest = i;
667                mtime = sb.st_mtime;
668            }
669            continue;
670        }
671        if (errno != ENOENT)
672            continue;
673
674        *fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
675        if (*fd < 0)
676            continue;   /* raced ? */
677
678        fchown(*fd, AID_SYSTEM, AID_SYSTEM);
679        return strdup(path);
680    }
681
682    /* we didn't find an available file, so we clobber the oldest one */
683    snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
684    *fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
685    if (*fd < 0) {
686        LOG("failed to open tombstone file '%s': %s\n", path, strerror(errno));
687        return NULL;
688    }
689    fchown(*fd, AID_SYSTEM, AID_SYSTEM);
690    return strdup(path);
691}
692
693char* engrave_tombstone(pid_t pid, pid_t tid, int signal,
694        bool dump_sibling_threads, bool quiet, bool* detach_failed,
695        int* total_sleep_time_usec) {
696    mkdir(TOMBSTONE_DIR, 0755);
697    chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
698
699#ifdef HAVE_SELINUX
700    if (selinux_android_restorecon(TOMBSTONE_DIR) == -1) {
701        *detach_failed = false;
702        return NULL;
703    }
704#endif
705
706    int fd;
707    char* path = find_and_open_tombstone(&fd);
708    if (!path) {
709        *detach_failed = false;
710        return NULL;
711    }
712
713    log_t log;
714    log.tfd = fd;
715    log.quiet = quiet;
716    *detach_failed = dump_crash(&log, pid, tid, signal, dump_sibling_threads,
717            total_sleep_time_usec);
718
719    close(fd);
720    return path;
721}
722