debuggerd.c revision 6b657472331ddb2cf5286167ff2460047a321be7 
1/* system/debuggerd/debuggerd.c
2**
3** Copyright 2006, The Android Open Source Project
4**
5** Licensed under the Apache License, Version 2.0 (the "License");
6** you may not use this file except in compliance with the License.
7** You may obtain a copy of the License at
8**
9**     http://www.apache.org/licenses/LICENSE-2.0
10**
11** Unless required by applicable law or agreed to in writing, software
12** distributed under the License is distributed on an "AS IS" BASIS,
13** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14** See the License for the specific language governing permissions and
15** limitations under the License.
16*/
17
18#include <stdio.h>
19#include <stdlib.h>
20#include <unistd.h>
21#include <errno.h>
22#include <signal.h>
23#include <pthread.h>
24#include <stdarg.h>
25#include <fcntl.h>
26#include <sys/types.h>
27#include <dirent.h>
28
29#include <sys/ptrace.h>
30#include <sys/wait.h>
31#include <sys/exec_elf.h>
32#include <sys/stat.h>
33
34#include <cutils/sockets.h>
35#include <cutils/logd.h>
36#include <cutils/sockets.h>
37#include <cutils/properties.h>
38
39#include <linux/input.h>
40
41#include <private/android_filesystem_config.h>
42
43#include "utility.h"
44
45#ifdef WITH_VFP
46#ifdef WITH_VFP_D32
47#define NUM_VFP_REGS 32
48#else
49#define NUM_VFP_REGS 16
50#endif
51#endif
52
53/* Main entry point to get the backtrace from the crashing process */
54extern int unwind_backtrace_with_ptrace(int tfd, pid_t pid, mapinfo *map,
55                                        unsigned int sp_list[],
56                                        int *frame0_pc_sane,
57                                        bool at_fault);
58
59static int logsocket = -1;
60
61#define ANDROID_LOG_INFO 4
62
63/* Log information onto the tombstone */
64void _LOG(int tfd, bool in_tombstone_only, const char *fmt, ...)
65{
66    char buf[128];
67
68    va_list ap;
69    va_start(ap, fmt);
70
71    if (tfd >= 0) {
72        int len;
73        vsnprintf(buf, sizeof(buf), fmt, ap);
74        len = strlen(buf);
75        if(tfd >= 0) write(tfd, buf, len);
76    }
77
78    if (!in_tombstone_only)
79        __android_log_vprint(ANDROID_LOG_INFO, "DEBUG", fmt, ap);
80}
81
82#define LOG(fmt...) _LOG(-1, 0, fmt)
83#if 0
84#define XLOG(fmt...) _LOG(-1, 0, fmt)
85#else
86#define XLOG(fmt...) do {} while(0)
87#endif
88
89// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so
90// 012345678901234567890123456789012345678901234567890123456789
91// 0         1         2         3         4         5
92
93mapinfo *parse_maps_line(char *line)
94{
95    mapinfo *mi;
96    int len = strlen(line);
97
98    if(len < 1) return 0;
99    line[--len] = 0;
100
101    if(len < 50) return 0;
102    if(line[20] != 'x') return 0;
103
104    mi = malloc(sizeof(mapinfo) + (len - 47));
105    if(mi == 0) return 0;
106
107    mi->start = strtoul(line, 0, 16);
108    mi->end = strtoul(line + 9, 0, 16);
109    /* To be filled in parse_exidx_info if the mapped section starts with
110     * elf_header
111     */
112    mi->exidx_start = mi->exidx_end = 0;
113    mi->next = 0;
114    strcpy(mi->name, line + 49);
115
116    return mi;
117}
118
119void dump_build_info(int tfd)
120{
121    char fingerprint[PROPERTY_VALUE_MAX];
122
123    property_get("ro.build.fingerprint", fingerprint, "unknown");
124
125    _LOG(tfd, false, "Build fingerprint: '%s'\n", fingerprint);
126}
127
128
129void dump_stack_and_code(int tfd, int pid, mapinfo *map,
130                         int unwind_depth, unsigned int sp_list[],
131                         bool at_fault)
132{
133    unsigned int sp, pc, p, end, data;
134    struct pt_regs r;
135    int sp_depth;
136    bool only_in_tombstone = !at_fault;
137    char code_buffer[80];
138
139    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) return;
140    sp = r.ARM_sp;
141    pc = r.ARM_pc;
142
143    _LOG(tfd, only_in_tombstone, "\ncode around pc:\n");
144
145    end = p = pc & ~3;
146    p -= 32;
147    end += 32;
148
149    /* Dump the code around PC as:
150     *  addr       contents
151     *  00008d34   fffffcd0 4c0eb530 b0934a0e 1c05447c
152     *  00008d44   f7ff18a0 490ced94 68035860 d0012b00
153     */
154    while (p <= end) {
155        int i;
156
157        sprintf(code_buffer, "%08x ", p);
158        for (i = 0; i < 4; i++) {
159            data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
160            sprintf(code_buffer + strlen(code_buffer), "%08x ", data);
161            p += 4;
162        }
163        _LOG(tfd, only_in_tombstone, "%s\n", code_buffer);
164    }
165
166    if ((unsigned) r.ARM_lr != pc) {
167        _LOG(tfd, only_in_tombstone, "\ncode around lr:\n");
168
169        end = p = r.ARM_lr & ~3;
170        p -= 32;
171        end += 32;
172
173        /* Dump the code around LR as:
174         *  addr       contents
175         *  00008d34   fffffcd0 4c0eb530 b0934a0e 1c05447c
176         *  00008d44   f7ff18a0 490ced94 68035860 d0012b00
177         */
178        while (p <= end) {
179            int i;
180
181            sprintf(code_buffer, "%08x ", p);
182            for (i = 0; i < 4; i++) {
183                data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
184                sprintf(code_buffer + strlen(code_buffer), "%08x ", data);
185                p += 4;
186            }
187            _LOG(tfd, only_in_tombstone, "%s\n", code_buffer);
188        }
189    }
190
191    p = sp - 64;
192    p &= ~3;
193    if (unwind_depth != 0) {
194        if (unwind_depth < STACK_CONTENT_DEPTH) {
195            end = sp_list[unwind_depth-1];
196        }
197        else {
198            end = sp_list[STACK_CONTENT_DEPTH-1];
199        }
200    }
201    else {
202        end = sp | 0x000000ff;
203        end += 0xff;
204    }
205
206    _LOG(tfd, only_in_tombstone, "\nstack:\n");
207
208    /* If the crash is due to PC == 0, there will be two frames that
209     * have identical SP value.
210     */
211    if (sp_list[0] == sp_list[1]) {
212        sp_depth = 1;
213    }
214    else {
215        sp_depth = 0;
216    }
217
218    while (p <= end) {
219         char *prompt;
220         char level[16];
221         data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
222         if (p == sp_list[sp_depth]) {
223             sprintf(level, "#%02d", sp_depth++);
224             prompt = level;
225         }
226         else {
227             prompt = "   ";
228         }
229
230         /* Print the stack content in the log for the first 3 frames. For the
231          * rest only print them in the tombstone file.
232          */
233         _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
234              "%s %08x  %08x  %s\n", prompt, p, data,
235              map_to_name(map, data, ""));
236         p += 4;
237    }
238    /* print another 64-byte of stack data after the last frame */
239
240    end = p+64;
241    while (p <= end) {
242         data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
243         _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
244              "    %08x  %08x  %s\n", p, data,
245              map_to_name(map, data, ""));
246         p += 4;
247    }
248}
249
250void dump_pc_and_lr(int tfd, int pid, mapinfo *map, int unwound_level,
251                    bool at_fault)
252{
253    struct pt_regs r;
254
255    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
256        _LOG(tfd, !at_fault, "tid %d not responding!\n", pid);
257        return;
258    }
259
260    if (unwound_level == 0) {
261        _LOG(tfd, !at_fault, "         #%02d  pc %08x  %s\n", 0, r.ARM_pc,
262             map_to_name(map, r.ARM_pc, "<unknown>"));
263    }
264    _LOG(tfd, !at_fault, "         #%02d  lr %08x  %s\n", 1, r.ARM_lr,
265            map_to_name(map, r.ARM_lr, "<unknown>"));
266}
267
268void dump_registers(int tfd, int pid, bool at_fault)
269{
270    struct pt_regs r;
271    bool only_in_tombstone = !at_fault;
272
273    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
274        _LOG(tfd, only_in_tombstone,
275             "cannot get registers: %s\n", strerror(errno));
276        return;
277    }
278
279    _LOG(tfd, only_in_tombstone, " r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
280         r.ARM_r0, r.ARM_r1, r.ARM_r2, r.ARM_r3);
281    _LOG(tfd, only_in_tombstone, " r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
282         r.ARM_r4, r.ARM_r5, r.ARM_r6, r.ARM_r7);
283    _LOG(tfd, only_in_tombstone, " r8 %08x  r9 %08x  10 %08x  fp %08x\n",
284         r.ARM_r8, r.ARM_r9, r.ARM_r10, r.ARM_fp);
285    _LOG(tfd, only_in_tombstone,
286         " ip %08x  sp %08x  lr %08x  pc %08x  cpsr %08x\n",
287         r.ARM_ip, r.ARM_sp, r.ARM_lr, r.ARM_pc, r.ARM_cpsr);
288
289#ifdef WITH_VFP
290    struct user_vfp vfp_regs;
291    int i;
292
293    if(ptrace(PTRACE_GETVFPREGS, pid, 0, &vfp_regs)) {
294        _LOG(tfd, only_in_tombstone,
295             "cannot get registers: %s\n", strerror(errno));
296        return;
297    }
298
299    for (i = 0; i < NUM_VFP_REGS; i += 2) {
300        _LOG(tfd, only_in_tombstone,
301             " d%-2d %016llx  d%-2d %016llx\n",
302              i, vfp_regs.fpregs[i], i+1, vfp_regs.fpregs[i+1]);
303    }
304    _LOG(tfd, only_in_tombstone, " scr %08lx\n\n", vfp_regs.fpscr);
305#endif
306}
307
308const char *get_signame(int sig)
309{
310    switch(sig) {
311    case SIGILL:     return "SIGILL";
312    case SIGABRT:    return "SIGABRT";
313    case SIGBUS:     return "SIGBUS";
314    case SIGFPE:     return "SIGFPE";
315    case SIGSEGV:    return "SIGSEGV";
316    case SIGSTKFLT:  return "SIGSTKFLT";
317    default:         return "?";
318    }
319}
320
321void dump_fault_addr(int tfd, int pid, int sig)
322{
323    siginfo_t si;
324
325    memset(&si, 0, sizeof(si));
326    if(ptrace(PTRACE_GETSIGINFO, pid, 0, &si)){
327        _LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
328    } else {
329        _LOG(tfd, false, "signal %d (%s), fault addr %08x\n",
330            sig, get_signame(sig), si.si_addr);
331    }
332}
333
334void dump_crash_banner(int tfd, unsigned pid, unsigned tid, int sig)
335{
336    char data[1024];
337    char *x = 0;
338    FILE *fp;
339
340    sprintf(data, "/proc/%d/cmdline", pid);
341    fp = fopen(data, "r");
342    if(fp) {
343        x = fgets(data, 1024, fp);
344        fclose(fp);
345    }
346
347    _LOG(tfd, false,
348         "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
349    dump_build_info(tfd);
350    _LOG(tfd, false, "pid: %d, tid: %d  >>> %s <<<\n",
351         pid, tid, x ? x : "UNKNOWN");
352
353    if(sig) dump_fault_addr(tfd, tid, sig);
354}
355
356static void parse_exidx_info(mapinfo *milist, pid_t pid)
357{
358    mapinfo *mi;
359    for (mi = milist; mi != NULL; mi = mi->next) {
360        Elf32_Ehdr ehdr;
361
362        memset(&ehdr, 0, sizeof(Elf32_Ehdr));
363        /* Read in sizeof(Elf32_Ehdr) worth of data from the beginning of
364         * mapped section.
365         */
366        get_remote_struct(pid, (void *) (mi->start), &ehdr,
367                          sizeof(Elf32_Ehdr));
368        /* Check if it has the matching magic words */
369        if (IS_ELF(ehdr)) {
370            Elf32_Phdr phdr;
371            Elf32_Phdr *ptr;
372            int i;
373
374            ptr = (Elf32_Phdr *) (mi->start + ehdr.e_phoff);
375            for (i = 0; i < ehdr.e_phnum; i++) {
376                /* Parse the program header */
377                get_remote_struct(pid, (char *) (ptr+i), &phdr,
378                                  sizeof(Elf32_Phdr));
379                /* Found a EXIDX segment? */
380                if (phdr.p_type == PT_ARM_EXIDX) {
381                    mi->exidx_start = mi->start + phdr.p_offset;
382                    mi->exidx_end = mi->exidx_start + phdr.p_filesz;
383                    break;
384                }
385            }
386        }
387    }
388}
389
390void dump_crash_report(int tfd, unsigned pid, unsigned tid, bool at_fault)
391{
392    char data[1024];
393    FILE *fp;
394    mapinfo *milist = 0;
395    unsigned int sp_list[STACK_CONTENT_DEPTH];
396    int stack_depth;
397    int frame0_pc_sane = 1;
398
399    if (!at_fault) {
400        _LOG(tfd, true,
401         "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
402        _LOG(tfd, true, "pid: %d, tid: %d\n", pid, tid);
403    }
404
405    dump_registers(tfd, tid, at_fault);
406
407    /* Clear stack pointer records */
408    memset(sp_list, 0, sizeof(sp_list));
409
410    sprintf(data, "/proc/%d/maps", pid);
411    fp = fopen(data, "r");
412    if(fp) {
413        while(fgets(data, 1024, fp)) {
414            mapinfo *mi = parse_maps_line(data);
415            if(mi) {
416                mi->next = milist;
417                milist = mi;
418            }
419        }
420        fclose(fp);
421    }
422
423    parse_exidx_info(milist, tid);
424
425    /* If stack unwinder fails, use the default solution to dump the stack
426     * content.
427     */
428    stack_depth = unwind_backtrace_with_ptrace(tfd, tid, milist, sp_list,
429                                               &frame0_pc_sane, at_fault);
430
431    /* The stack unwinder should at least unwind two levels of stack. If less
432     * level is seen we make sure at lease pc and lr are dumped.
433     */
434    if (stack_depth < 2) {
435        dump_pc_and_lr(tfd, tid, milist, stack_depth, at_fault);
436    }
437
438    dump_stack_and_code(tfd, tid, milist, stack_depth, sp_list, at_fault);
439
440    while(milist) {
441        mapinfo *next = milist->next;
442        free(milist);
443        milist = next;
444    }
445}
446
447#define MAX_TOMBSTONES	10
448
449#define typecheck(x,y) {    \
450    typeof(x) __dummy1;     \
451    typeof(y) __dummy2;     \
452    (void)(&__dummy1 == &__dummy2); }
453
454#define TOMBSTONE_DIR	"/data/tombstones"
455
456/*
457 * find_and_open_tombstone - find an available tombstone slot, if any, of the
458 * form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
459 * file is available, we reuse the least-recently-modified file.
460 */
461static int find_and_open_tombstone(void)
462{
463    unsigned long mtime = ULONG_MAX;
464    struct stat sb;
465    char path[128];
466    int fd, i, oldest = 0;
467
468    /*
469     * XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
470     * to, our logic breaks. This check will generate a warning if that happens.
471     */
472    typecheck(mtime, sb.st_mtime);
473
474    /*
475     * In a single wolf-like pass, find an available slot and, in case none
476     * exist, find and record the least-recently-modified file.
477     */
478    for (i = 0; i < MAX_TOMBSTONES; i++) {
479        snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
480
481        if (!stat(path, &sb)) {
482            if (sb.st_mtime < mtime) {
483                oldest = i;
484                mtime = sb.st_mtime;
485            }
486            continue;
487        }
488        if (errno != ENOENT)
489            continue;
490
491        fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
492        if (fd < 0)
493            continue;	/* raced ? */
494
495        fchown(fd, AID_SYSTEM, AID_SYSTEM);
496        return fd;
497    }
498
499    /* we didn't find an available file, so we clobber the oldest one */
500    snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
501    fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
502    fchown(fd, AID_SYSTEM, AID_SYSTEM);
503
504    return fd;
505}
506
507/* Return true if some thread is not detached cleanly */
508static bool dump_sibling_thread_report(int tfd, unsigned pid, unsigned tid)
509{
510    char task_path[1024];
511
512    sprintf(task_path, "/proc/%d/task", pid);
513    DIR *d;
514    struct dirent *de;
515    int need_cleanup = 0;
516
517    d = opendir(task_path);
518    /* Bail early if cannot open the task directory */
519    if (d == NULL) {
520        XLOG("Cannot open /proc/%d/task\n", pid);
521        return false;
522    }
523    while ((de = readdir(d)) != NULL) {
524        unsigned new_tid;
525        /* Ignore "." and ".." */
526        if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
527            continue;
528        new_tid = atoi(de->d_name);
529        /* The main thread at fault has been handled individually */
530        if (new_tid == tid)
531            continue;
532
533        /* Skip this thread if cannot ptrace it */
534        if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0)
535            continue;
536
537        dump_crash_report(tfd, pid, new_tid, false);
538        need_cleanup |= ptrace(PTRACE_DETACH, new_tid, 0, 0);
539    }
540    closedir(d);
541    return need_cleanup != 0;
542}
543
544/* Return true if some thread is not detached cleanly */
545static bool engrave_tombstone(unsigned pid, unsigned tid, int debug_uid,
546                              int signal)
547{
548    int fd;
549    bool need_cleanup = false;
550
551    mkdir(TOMBSTONE_DIR, 0755);
552    chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
553
554    fd = find_and_open_tombstone();
555    if (fd < 0)
556        return need_cleanup;
557
558    dump_crash_banner(fd, pid, tid, signal);
559    dump_crash_report(fd, pid, tid, true);
560    /*
561     * If the user has requested to attach gdb, don't collect the per-thread
562     * information as it increases the chance to lose track of the process.
563     */
564    if ((signed)pid > debug_uid) {
565        need_cleanup = dump_sibling_thread_report(fd, pid, tid);
566    }
567
568    close(fd);
569    return need_cleanup;
570}
571
572static int
573write_string(const char* file, const char* string)
574{
575    int len;
576    int fd;
577    ssize_t amt;
578    fd = open(file, O_RDWR);
579    len = strlen(string);
580    if (fd < 0)
581        return -errno;
582    amt = write(fd, string, len);
583    close(fd);
584    return amt >= 0 ? 0 : -errno;
585}
586
587static
588void init_debug_led(void)
589{
590    // trout leds
591    write_string("/sys/class/leds/red/brightness", "0");
592    write_string("/sys/class/leds/green/brightness", "0");
593    write_string("/sys/class/leds/blue/brightness", "0");
594    write_string("/sys/class/leds/red/device/blink", "0");
595    // sardine leds
596    write_string("/sys/class/leds/left/cadence", "0,0");
597}
598
599static
600void enable_debug_led(void)
601{
602    // trout leds
603    write_string("/sys/class/leds/red/brightness", "255");
604    // sardine leds
605    write_string("/sys/class/leds/left/cadence", "1,0");
606}
607
608static
609void disable_debug_led(void)
610{
611    // trout leds
612    write_string("/sys/class/leds/red/brightness", "0");
613    // sardine leds
614    write_string("/sys/class/leds/left/cadence", "0,0");
615}
616
617extern int init_getevent();
618extern void uninit_getevent();
619extern int get_event(struct input_event* event, int timeout);
620
621static void wait_for_user_action(unsigned tid, struct ucred* cr)
622{
623    (void)tid;
624    /* First log a helpful message */
625    LOG(    "********************************************************\n"
626            "* Process %d has been suspended while crashing.  To\n"
627            "* attach gdbserver for a gdb connection on port 5039:\n"
628            "*\n"
629            "*     adb shell gdbserver :5039 --attach %d &\n"
630            "*\n"
631            "* Press HOME key to let the process continue crashing.\n"
632            "********************************************************\n",
633            cr->pid, cr->pid);
634
635    /* wait for HOME key (TODO: something useful for devices w/o HOME key) */
636    if (init_getevent() == 0) {
637        int ms = 1200 / 10;
638        int dit = 1;
639        int dah = 3*dit;
640        int _       = -dit;
641        int ___     = 3*_;
642        int _______ = 7*_;
643        const signed char codes[] = {
644           dit,_,dit,_,dit,___,dah,_,dah,_,dah,___,dit,_,dit,_,dit,_______
645        };
646        size_t s = 0;
647        struct input_event e;
648        int home = 0;
649        init_debug_led();
650        enable_debug_led();
651        do {
652            int timeout = abs((int)(codes[s])) * ms;
653            int res = get_event(&e, timeout);
654            if (res == 0) {
655                if (e.type==EV_KEY && e.code==KEY_HOME && e.value==0)
656                    home = 1;
657            } else if (res == 1) {
658                if (++s >= sizeof(codes)/sizeof(*codes))
659                    s = 0;
660                if (codes[s] > 0) {
661                    enable_debug_led();
662                } else {
663                    disable_debug_led();
664                }
665            }
666        } while (!home);
667        uninit_getevent();
668    }
669
670    /* don't forget to turn debug led off */
671    disable_debug_led();
672
673    /* close filedescriptor */
674    LOG("debuggerd resuming process %d", cr->pid);
675 }
676
677static void handle_crashing_process(int fd)
678{
679    char buf[64];
680    struct stat s;
681    unsigned tid;
682    struct ucred cr;
683    int n, len, status;
684    int tid_attach_status = -1;
685    unsigned retry = 30;
686    bool need_cleanup = false;
687
688    char value[PROPERTY_VALUE_MAX];
689    property_get("debug.db.uid", value, "-1");
690    int debug_uid = atoi(value);
691
692    XLOG("handle_crashing_process(%d)\n", fd);
693
694    len = sizeof(cr);
695    n = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
696    if(n != 0) {
697        LOG("cannot get credentials\n");
698        goto done;
699    }
700
701    XLOG("reading tid\n");
702    fcntl(fd, F_SETFL, O_NONBLOCK);
703    while((n = read(fd, &tid, sizeof(unsigned))) != sizeof(unsigned)) {
704        if(errno == EINTR) continue;
705        if(errno == EWOULDBLOCK) {
706            if(retry-- > 0) {
707                usleep(100 * 1000);
708                continue;
709            }
710            LOG("timed out reading tid\n");
711            goto done;
712        }
713        LOG("read failure? %s\n", strerror(errno));
714        goto done;
715    }
716
717    sprintf(buf,"/proc/%d/task/%d", cr.pid, tid);
718    if(stat(buf, &s)) {
719        LOG("tid %d does not exist in pid %d. ignoring debug request\n",
720            tid, cr.pid);
721        close(fd);
722        return;
723    }
724
725    XLOG("BOOM: pid=%d uid=%d gid=%d tid=%d\n", cr.pid, cr.uid, cr.gid, tid);
726
727    tid_attach_status = ptrace(PTRACE_ATTACH, tid, 0, 0);
728    if(tid_attach_status < 0) {
729        LOG("ptrace attach failed: %s\n", strerror(errno));
730        goto done;
731    }
732
733    close(fd);
734    fd = -1;
735
736    for(;;) {
737        n = waitpid(tid, &status, __WALL);
738
739        if(n < 0) {
740            if(errno == EAGAIN) continue;
741            LOG("waitpid failed: %s\n", strerror(errno));
742            goto done;
743        }
744
745        XLOG("waitpid: n=%d status=%08x\n", n, status);
746
747        if(WIFSTOPPED(status)){
748            n = WSTOPSIG(status);
749            switch(n) {
750            case SIGSTOP:
751                XLOG("stopped -- continuing\n");
752                n = ptrace(PTRACE_CONT, tid, 0, 0);
753                if(n) {
754                    LOG("ptrace failed: %s\n", strerror(errno));
755                    goto done;
756                }
757                continue;
758
759            case SIGILL:
760            case SIGABRT:
761            case SIGBUS:
762            case SIGFPE:
763            case SIGSEGV:
764            case SIGSTKFLT: {
765                XLOG("stopped -- fatal signal\n");
766                need_cleanup = engrave_tombstone(cr.pid, tid, debug_uid, n);
767                kill(tid, SIGSTOP);
768                goto done;
769            }
770
771            default:
772                XLOG("stopped -- unexpected signal\n");
773                goto done;
774            }
775        } else {
776            XLOG("unexpected waitpid response\n");
777            goto done;
778        }
779    }
780
781done:
782    XLOG("detaching\n");
783
784    /* stop the process so we can debug */
785    kill(cr.pid, SIGSTOP);
786
787    /*
788     * If a thread has been attached by ptrace, make sure it is detached
789     * successfully otherwise we will get a zombie.
790     */
791    if (tid_attach_status == 0) {
792        int detach_status;
793        /* detach so we can attach gdbserver */
794        detach_status = ptrace(PTRACE_DETACH, tid, 0, 0);
795        need_cleanup |= (detach_status != 0);
796    }
797
798    /*
799     * if debug.db.uid is set, its value indicates if we should wait
800     * for user action for the crashing process.
801     * in this case, we log a message and turn the debug LED on
802     * waiting for a gdb connection (for instance)
803     */
804
805    if ((signed)cr.uid <= debug_uid) {
806        wait_for_user_action(tid, &cr);
807    }
808
809    /* resume stopped process (so it can crash in peace) */
810    kill(cr.pid, SIGCONT);
811
812    if (need_cleanup) {
813        LOG("debuggerd committing suicide to free the zombie!\n");
814        kill(getpid(), SIGKILL);
815    }
816
817    if(fd != -1) close(fd);
818}
819
820int main()
821{
822    int s;
823    struct sigaction act;
824
825    logsocket = socket_local_client("logd",
826            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
827    if(logsocket < 0) {
828        logsocket = -1;
829    } else {
830        fcntl(logsocket, F_SETFD, FD_CLOEXEC);
831    }
832
833    act.sa_handler = SIG_DFL;
834    sigemptyset(&act.sa_mask);
835    sigaddset(&act.sa_mask,SIGCHLD);
836    act.sa_flags = SA_NOCLDWAIT;
837    sigaction(SIGCHLD, &act, 0);
838
839    s = socket_local_server("android:debuggerd",
840            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
841    if(s < 0) return -1;
842    fcntl(s, F_SETFD, FD_CLOEXEC);
843
844    LOG("debuggerd: " __DATE__ " " __TIME__ "\n");
845
846    for(;;) {
847        struct sockaddr addr;
848        socklen_t alen;
849        int fd;
850
851        alen = sizeof(addr);
852        fd = accept(s, &addr, &alen);
853        if(fd < 0) continue;
854
855        fcntl(fd, F_SETFD, FD_CLOEXEC);
856
857        handle_crashing_process(fd);
858    }
859    return 0;
860}
861