debuggerd.c revision ae7b91b68008ab09635a97a18e7d07a35e8404aa 
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/* Main entry point to get the backtrace from the crashing process */
46extern int unwind_backtrace_with_ptrace(int tfd, pid_t pid, mapinfo *map,
47                                        unsigned int sp_list[],
48                                        int *frame0_pc_sane,
49                                        bool at_fault);
50
51static int logsocket = -1;
52
53#define ANDROID_LOG_INFO 4
54
55/* Log information onto the tombstone */
56void _LOG(int tfd, bool in_tombstone_only, const char *fmt, ...)
57{
58    char buf[512];
59
60    va_list ap;
61    va_start(ap, fmt);
62
63    if (tfd >= 0) {
64        int len;
65        vsnprintf(buf, sizeof(buf), fmt, ap);
66        len = strlen(buf);
67        if(tfd >= 0) write(tfd, buf, len);
68    }
69
70    if (!in_tombstone_only)
71        __android_log_vprint(ANDROID_LOG_INFO, "DEBUG", fmt, ap);
72}
73
74#define LOG(fmt...) _LOG(-1, 0, fmt)
75#if 0
76#define XLOG(fmt...) _LOG(-1, 0, fmt)
77#else
78#define XLOG(fmt...) do {} while(0)
79#endif
80
81// 6f000000-6f01e000 rwxp 00000000 00:0c 16389419   /system/lib/libcomposer.so
82// 012345678901234567890123456789012345678901234567890123456789
83// 0         1         2         3         4         5
84
85mapinfo *parse_maps_line(char *line)
86{
87    mapinfo *mi;
88    int len = strlen(line);
89
90    if(len < 1) return 0;
91    line[--len] = 0;
92
93    if(len < 50) return 0;
94    if(line[20] != 'x') return 0;
95
96    mi = malloc(sizeof(mapinfo) + (len - 47));
97    if(mi == 0) return 0;
98
99    mi->start = strtoul(line, 0, 16);
100    mi->end = strtoul(line + 9, 0, 16);
101    /* To be filled in parse_elf_info if the mapped section starts with
102     * elf_header
103     */
104    mi->exidx_start = mi->exidx_end = 0;
105    mi->symbols = 0;
106    mi->next = 0;
107    strcpy(mi->name, line + 49);
108
109    return mi;
110}
111
112void dump_build_info(int tfd)
113{
114    char fingerprint[PROPERTY_VALUE_MAX];
115
116    property_get("ro.build.fingerprint", fingerprint, "unknown");
117
118    _LOG(tfd, false, "Build fingerprint: '%s'\n", fingerprint);
119}
120
121
122void dump_stack_and_code(int tfd, int pid, mapinfo *map,
123                         int unwind_depth, unsigned int sp_list[],
124                         int frame0_pc_sane, bool at_fault)
125{
126    unsigned int sp, pc, p, end, data;
127    struct pt_regs r;
128    int sp_depth;
129    bool only_in_tombstone = !at_fault;
130    char code_buffer[80];
131
132    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) return;
133    sp = r.ARM_sp;
134    pc = r.ARM_pc;
135
136    /* Died because calling the weeds - dump
137     * the code around the PC in the next frame instead.
138     */
139    if (frame0_pc_sane == 0) {
140        pc = r.ARM_lr;
141    }
142
143    _LOG(tfd, only_in_tombstone,
144         "\ncode around %s:\n", frame0_pc_sane ? "pc" : "lr");
145
146    end = p = pc & ~3;
147    p -= 16;
148    end += 16;
149
150    /* Dump the code around PC as:
151     *  addr       contents
152     *  00008d34   fffffcd0 4c0eb530 b0934a0e 1c05447c
153     *  00008d44   f7ff18a0 490ced94 68035860 d0012b00
154     */
155    while (p <= end) {
156        int i;
157
158        sprintf(code_buffer, "%08x ", p);
159        for (i = 0; i < 4; i++) {
160            data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
161            sprintf(code_buffer + strlen(code_buffer), "%08x ", data);
162            p += 4;
163        }
164        _LOG(tfd, only_in_tombstone, "%s\n", code_buffer);
165    }
166
167    if (frame0_pc_sane) {
168        _LOG(tfd, only_in_tombstone, "\ncode around lr:\n");
169
170        end = p = r.ARM_lr & ~3;
171        p -= 16;
172        end += 16;
173
174        /* Dump the code around LR as:
175         *  addr       contents
176         *  00008d34   fffffcd0 4c0eb530 b0934a0e 1c05447c
177         *  00008d44   f7ff18a0 490ced94 68035860 d0012b00
178         */
179        while (p <= end) {
180            int i;
181
182            sprintf(code_buffer, "%08x ", p);
183            for (i = 0; i < 4; i++) {
184                data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
185                sprintf(code_buffer + strlen(code_buffer), "%08x ", data);
186                p += 4;
187            }
188            _LOG(tfd, only_in_tombstone, "%s\n", code_buffer);
189        }
190    }
191
192    p = sp - 64;
193    p &= ~3;
194    if (unwind_depth != 0) {
195        if (unwind_depth < STACK_CONTENT_DEPTH) {
196            end = sp_list[unwind_depth-1];
197        }
198        else {
199            end = sp_list[STACK_CONTENT_DEPTH-1];
200        }
201    }
202    else {
203        end = sp | 0x000000ff;
204        end += 0xff;
205    }
206
207    _LOG(tfd, only_in_tombstone, "\nstack:\n");
208
209    /* If the crash is due to PC == 0, there will be two frames that
210     * have identical SP value.
211     */
212    if (sp_list[0] == sp_list[1]) {
213        sp_depth = 1;
214    }
215    else {
216        sp_depth = 0;
217    }
218
219    while (p <= end) {
220         char *prompt;
221         char level[16];
222         data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
223         if (p == sp_list[sp_depth]) {
224             sprintf(level, "#%02d", sp_depth++);
225             prompt = level;
226         }
227         else {
228             prompt = "   ";
229         }
230
231         /* Print the stack content in the log for the first 3 frames. For the
232          * rest only print them in the tombstone file.
233          */
234         _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
235              "%s %08x  %08x  %s\n", prompt, p, data,
236              map_to_name(map, data, ""));
237         p += 4;
238    }
239    /* print another 64-byte of stack data after the last frame */
240
241    end = p+64;
242    while (p <= end) {
243         data = ptrace(PTRACE_PEEKTEXT, pid, (void*)p, NULL);
244         _LOG(tfd, (sp_depth > 2) || only_in_tombstone,
245              "    %08x  %08x  %s\n", p, data,
246              map_to_name(map, data, ""));
247         p += 4;
248    }
249}
250
251void dump_pc_and_lr(int tfd, int pid, mapinfo *map, int unwound_level,
252                    bool at_fault)
253{
254    struct pt_regs r;
255
256    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
257        _LOG(tfd, !at_fault, "tid %d not responding!\n", pid);
258        return;
259    }
260
261    if (unwound_level == 0) {
262        _LOG(tfd, !at_fault, "         #%02d  pc %08x  %s\n", 0, r.ARM_pc,
263             map_to_name(map, r.ARM_pc, "<unknown>"));
264    }
265    _LOG(tfd, !at_fault, "         #%02d  lr %08x  %s\n", 1, r.ARM_lr,
266            map_to_name(map, r.ARM_lr, "<unknown>"));
267}
268
269void dump_registers(int tfd, int pid, bool at_fault)
270{
271    struct pt_regs r;
272    bool only_in_tombstone = !at_fault;
273
274    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) {
275        _LOG(tfd, only_in_tombstone,
276             "cannot get registers: %s\n", strerror(errno));
277        return;
278    }
279
280    _LOG(tfd, only_in_tombstone, " r0 %08x  r1 %08x  r2 %08x  r3 %08x\n",
281         r.ARM_r0, r.ARM_r1, r.ARM_r2, r.ARM_r3);
282    _LOG(tfd, only_in_tombstone, " r4 %08x  r5 %08x  r6 %08x  r7 %08x\n",
283         r.ARM_r4, r.ARM_r5, r.ARM_r6, r.ARM_r7);
284    _LOG(tfd, only_in_tombstone, " r8 %08x  r9 %08x  10 %08x  fp %08x\n",
285         r.ARM_r8, r.ARM_r9, r.ARM_r10, r.ARM_fp);
286    _LOG(tfd, only_in_tombstone,
287         " ip %08x  sp %08x  lr %08x  pc %08x  cpsr %08x\n",
288         r.ARM_ip, r.ARM_sp, r.ARM_lr, r.ARM_pc, r.ARM_cpsr);
289}
290
291const char *get_signame(int sig)
292{
293    switch(sig) {
294    case SIGILL:     return "SIGILL";
295    case SIGABRT:    return "SIGABRT";
296    case SIGBUS:     return "SIGBUS";
297    case SIGFPE:     return "SIGFPE";
298    case SIGSEGV:    return "SIGSEGV";
299    case SIGSTKFLT:  return "SIGSTKFLT";
300    default:         return "?";
301    }
302}
303
304void dump_fault_addr(int tfd, int pid, int sig)
305{
306    siginfo_t si;
307
308    memset(&si, 0, sizeof(si));
309    if(ptrace(PTRACE_GETSIGINFO, pid, 0, &si)){
310        _LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
311    } else {
312        _LOG(tfd, false, "signal %d (%s), fault addr %08x\n",
313            sig, get_signame(sig), si.si_addr);
314    }
315}
316
317void dump_crash_banner(int tfd, unsigned pid, unsigned tid, int sig)
318{
319    char data[1024];
320    char *x = 0;
321    FILE *fp;
322
323    sprintf(data, "/proc/%d/cmdline", pid);
324    fp = fopen(data, "r");
325    if(fp) {
326        x = fgets(data, 1024, fp);
327        fclose(fp);
328    }
329
330    _LOG(tfd, false,
331         "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
332    dump_build_info(tfd);
333    _LOG(tfd, false, "pid: %d, tid: %d  >>> %s <<<\n",
334         pid, tid, x ? x : "UNKNOWN");
335
336    if(sig) dump_fault_addr(tfd, tid, sig);
337}
338
339static void parse_elf_info(mapinfo *milist, pid_t pid)
340{
341    mapinfo *mi;
342    for (mi = milist; mi != NULL; mi = mi->next) {
343        Elf32_Ehdr ehdr;
344
345        memset(&ehdr, 0, sizeof(Elf32_Ehdr));
346        /* Read in sizeof(Elf32_Ehdr) worth of data from the beginning of
347         * mapped section.
348         */
349        get_remote_struct(pid, (void *) (mi->start), &ehdr,
350                          sizeof(Elf32_Ehdr));
351        /* Check if it has the matching magic words */
352        if (IS_ELF(ehdr)) {
353            Elf32_Phdr phdr;
354            Elf32_Phdr *ptr;
355            int i;
356
357            ptr = (Elf32_Phdr *) (mi->start + ehdr.e_phoff);
358            for (i = 0; i < ehdr.e_phnum; i++) {
359                /* Parse the program header */
360                get_remote_struct(pid, (char *) ptr+i, &phdr,
361                                  sizeof(Elf32_Phdr));
362                /* Found a EXIDX segment? */
363                if (phdr.p_type == PT_ARM_EXIDX) {
364                    mi->exidx_start = mi->start + phdr.p_offset;
365                    mi->exidx_end = mi->exidx_start + phdr.p_filesz;
366                    break;
367                }
368            }
369
370            /* Try to load symbols from this file */
371            mi->symbols = symbol_table_create(mi->name);
372        }
373    }
374}
375
376void dump_crash_report(int tfd, unsigned pid, unsigned tid, bool at_fault)
377{
378    char data[1024];
379    FILE *fp;
380    mapinfo *milist = 0;
381    unsigned int sp_list[STACK_CONTENT_DEPTH];
382    int stack_depth;
383    int frame0_pc_sane = 1;
384
385    if (!at_fault) {
386        _LOG(tfd, true,
387         "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
388        _LOG(tfd, true, "pid: %d, tid: %d\n", pid, tid);
389    }
390
391    dump_registers(tfd, tid, at_fault);
392
393    /* Clear stack pointer records */
394    memset(sp_list, 0, sizeof(sp_list));
395
396    sprintf(data, "/proc/%d/maps", pid);
397    fp = fopen(data, "r");
398    if(fp) {
399        while(fgets(data, 1024, fp)) {
400            mapinfo *mi = parse_maps_line(data);
401            if(mi) {
402                mi->next = milist;
403                milist = mi;
404            }
405        }
406        fclose(fp);
407    }
408
409    parse_elf_info(milist, tid);
410
411    /* If stack unwinder fails, use the default solution to dump the stack
412     * content.
413     */
414    stack_depth = unwind_backtrace_with_ptrace(tfd, tid, milist, sp_list,
415                                               &frame0_pc_sane, at_fault);
416
417    /* The stack unwinder should at least unwind two levels of stack. If less
418     * level is seen we make sure at lease pc and lr are dumped.
419     */
420    if (stack_depth < 2) {
421        dump_pc_and_lr(tfd, tid, milist, stack_depth, at_fault);
422    }
423
424    dump_stack_and_code(tfd, tid, milist, stack_depth, sp_list, frame0_pc_sane,
425                        at_fault);
426
427    while(milist) {
428        mapinfo *next = milist->next;
429        symbol_table_free(milist->symbols);
430        free(milist);
431        milist = next;
432    }
433}
434
435#define MAX_TOMBSTONES	10
436
437#define typecheck(x,y) {    \
438    typeof(x) __dummy1;     \
439    typeof(y) __dummy2;     \
440    (void)(&__dummy1 == &__dummy2); }
441
442#define TOMBSTONE_DIR	"/data/tombstones"
443
444/*
445 * find_and_open_tombstone - find an available tombstone slot, if any, of the
446 * form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
447 * file is available, we reuse the least-recently-modified file.
448 */
449static int find_and_open_tombstone(void)
450{
451    unsigned long mtime = ULONG_MAX;
452    struct stat sb;
453    char path[128];
454    int fd, i, oldest = 0;
455
456    /*
457     * XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
458     * to, our logic breaks. This check will generate a warning if that happens.
459     */
460    typecheck(mtime, sb.st_mtime);
461
462    /*
463     * In a single wolf-like pass, find an available slot and, in case none
464     * exist, find and record the least-recently-modified file.
465     */
466    for (i = 0; i < MAX_TOMBSTONES; i++) {
467        snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
468
469        if (!stat(path, &sb)) {
470            if (sb.st_mtime < mtime) {
471                oldest = i;
472                mtime = sb.st_mtime;
473            }
474            continue;
475        }
476        if (errno != ENOENT)
477            continue;
478
479        fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
480        if (fd < 0)
481            continue;	/* raced ? */
482
483        fchown(fd, AID_SYSTEM, AID_SYSTEM);
484        return fd;
485    }
486
487    /* we didn't find an available file, so we clobber the oldest one */
488    snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
489    fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
490    fchown(fd, AID_SYSTEM, AID_SYSTEM);
491
492    return fd;
493}
494
495/* Return true if some thread is not detached cleanly */
496static bool dump_sibling_thread_report(int tfd, unsigned pid, unsigned tid)
497{
498    char task_path[1024];
499
500    sprintf(task_path, "/proc/%d/task", pid);
501    DIR *d;
502    struct dirent *de;
503    int need_cleanup = 0;
504
505    d = opendir(task_path);
506    /* Bail early if cannot open the task directory */
507    if (d == NULL) {
508        XLOG("Cannot open /proc/%d/task\n", pid);
509        return false;
510    }
511    while ((de = readdir(d)) != NULL) {
512        unsigned new_tid;
513        /* Ignore "." and ".." */
514        if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
515            continue;
516        new_tid = atoi(de->d_name);
517        /* The main thread at fault has been handled individually */
518        if (new_tid == tid)
519            continue;
520
521        /* Skip this thread if cannot ptrace it */
522        if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0)
523            continue;
524
525        dump_crash_report(tfd, pid, new_tid, false);
526        need_cleanup |= ptrace(PTRACE_DETACH, new_tid, 0, 0);
527    }
528    closedir(d);
529    return need_cleanup != 0;
530}
531
532/* Return true if some thread is not detached cleanly */
533static bool engrave_tombstone(unsigned pid, unsigned tid, int debug_uid,
534                              int signal)
535{
536    int fd;
537    bool need_cleanup = false;
538
539    mkdir(TOMBSTONE_DIR, 0755);
540    chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
541
542    fd = find_and_open_tombstone();
543    if (fd < 0)
544        return need_cleanup;
545
546    dump_crash_banner(fd, pid, tid, signal);
547    dump_crash_report(fd, pid, tid, true);
548    /*
549     * If the user has requested to attach gdb, don't collect the per-thread
550     * information as it increases the chance to lose track of the process.
551     */
552    if ((signed)pid > debug_uid) {
553        need_cleanup = dump_sibling_thread_report(fd, pid, tid);
554    }
555
556    close(fd);
557    return need_cleanup;
558}
559
560static int
561write_string(const char* file, const char* string)
562{
563    int len;
564    int fd;
565    ssize_t amt;
566    fd = open(file, O_RDWR);
567    len = strlen(string);
568    if (fd < 0)
569        return -errno;
570    amt = write(fd, string, len);
571    close(fd);
572    return amt >= 0 ? 0 : -errno;
573}
574
575static
576void init_debug_led(void)
577{
578    // trout leds
579    write_string("/sys/class/leds/red/brightness", "0");
580    write_string("/sys/class/leds/green/brightness", "0");
581    write_string("/sys/class/leds/blue/brightness", "0");
582    write_string("/sys/class/leds/red/device/blink", "0");
583    // sardine leds
584    write_string("/sys/class/leds/left/cadence", "0,0");
585}
586
587static
588void enable_debug_led(void)
589{
590    // trout leds
591    write_string("/sys/class/leds/red/brightness", "255");
592    // sardine leds
593    write_string("/sys/class/leds/left/cadence", "1,0");
594}
595
596static
597void disable_debug_led(void)
598{
599    // trout leds
600    write_string("/sys/class/leds/red/brightness", "0");
601    // sardine leds
602    write_string("/sys/class/leds/left/cadence", "0,0");
603}
604
605extern int init_getevent();
606extern void uninit_getevent();
607extern int get_event(struct input_event* event, int timeout);
608
609static void wait_for_user_action(unsigned tid, struct ucred* cr)
610{
611    (void)tid;
612    /* First log a helpful message */
613    LOG(    "********************************************************\n"
614            "* process %d crashed. debuggerd waiting for gdbserver   \n"
615            "*                                                       \n"
616            "*     adb shell gdbserver :port --attach %d &           \n"
617            "*                                                       \n"
618            "* and press the HOME key.                               \n"
619            "********************************************************\n",
620            cr->pid, cr->pid);
621
622    /* wait for HOME key */
623    if (init_getevent() == 0) {
624        int ms = 1200 / 10;
625        int dit = 1;
626        int dah = 3*dit;
627        int _       = -dit;
628        int ___     = 3*_;
629        int _______ = 7*_;
630        const signed char codes[] = {
631           dit,_,dit,_,dit,___,dah,_,dah,_,dah,___,dit,_,dit,_,dit,_______
632        };
633        size_t s = 0;
634        struct input_event e;
635        int home = 0;
636        init_debug_led();
637        enable_debug_led();
638        do {
639            int timeout = abs((int)(codes[s])) * ms;
640            int res = get_event(&e, timeout);
641            if (res == 0) {
642                if (e.type==EV_KEY && e.code==KEY_HOME && e.value==0)
643                    home = 1;
644            } else if (res == 1) {
645                if (++s >= sizeof(codes)/sizeof(*codes))
646                    s = 0;
647                if (codes[s] > 0) {
648                    enable_debug_led();
649                } else {
650                    disable_debug_led();
651                }
652            }
653        } while (!home);
654        uninit_getevent();
655    }
656
657    /* don't forget to turn debug led off */
658    disable_debug_led();
659
660    /* close filedescriptor */
661    LOG("debuggerd resuming process %d", cr->pid);
662 }
663
664static void handle_crashing_process(int fd)
665{
666    char buf[64];
667    struct stat s;
668    unsigned tid;
669    struct ucred cr;
670    int n, len, status;
671    int tid_attach_status = -1;
672    unsigned retry = 30;
673    bool need_cleanup = false;
674
675    char value[PROPERTY_VALUE_MAX];
676    property_get("debug.db.uid", value, "-1");
677    int debug_uid = atoi(value);
678
679    XLOG("handle_crashing_process(%d)\n", fd);
680
681    len = sizeof(cr);
682    n = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
683    if(n != 0) {
684        LOG("cannot get credentials\n");
685        goto done;
686    }
687
688    XLOG("reading tid\n");
689    fcntl(fd, F_SETFL, O_NONBLOCK);
690    while((n = read(fd, &tid, sizeof(unsigned))) != sizeof(unsigned)) {
691        if(errno == EINTR) continue;
692        if(errno == EWOULDBLOCK) {
693            if(retry-- > 0) {
694                usleep(100 * 1000);
695                continue;
696            }
697            LOG("timed out reading tid\n");
698            goto done;
699        }
700        LOG("read failure? %s\n", strerror(errno));
701        goto done;
702    }
703
704    sprintf(buf,"/proc/%d/task/%d", cr.pid, tid);
705    if(stat(buf, &s)) {
706        LOG("tid %d does not exist in pid %d. ignorning debug request\n",
707            tid, cr.pid);
708        close(fd);
709        return;
710    }
711
712    XLOG("BOOM: pid=%d uid=%d gid=%d tid=%d\n", cr.pid, cr.uid, cr.gid, tid);
713
714    tid_attach_status = ptrace(PTRACE_ATTACH, tid, 0, 0);
715    if(tid_attach_status < 0) {
716        LOG("ptrace attach failed: %s\n", strerror(errno));
717        goto done;
718    }
719
720    close(fd);
721    fd = -1;
722
723    for(;;) {
724        n = waitpid(tid, &status, __WALL);
725
726        if(n < 0) {
727            if(errno == EAGAIN) continue;
728            LOG("waitpid failed: %s\n", strerror(errno));
729            goto done;
730        }
731
732        XLOG("waitpid: n=%d status=%08x\n", n, status);
733
734        if(WIFSTOPPED(status)){
735            n = WSTOPSIG(status);
736            switch(n) {
737            case SIGSTOP:
738                XLOG("stopped -- continuing\n");
739                n = ptrace(PTRACE_CONT, tid, 0, 0);
740                if(n) {
741                    LOG("ptrace failed: %s\n", strerror(errno));
742                    goto done;
743                }
744                continue;
745
746            case SIGILL:
747            case SIGABRT:
748            case SIGBUS:
749            case SIGFPE:
750            case SIGSEGV:
751            case SIGSTKFLT: {
752                XLOG("stopped -- fatal signal\n");
753                need_cleanup = engrave_tombstone(cr.pid, tid, debug_uid, n);
754                kill(tid, SIGSTOP);
755                goto done;
756            }
757
758            default:
759                XLOG("stopped -- unexpected signal\n");
760                goto done;
761            }
762        } else {
763            XLOG("unexpected waitpid response\n");
764            goto done;
765        }
766    }
767
768done:
769    XLOG("detaching\n");
770
771    /* stop the process so we can debug */
772    kill(cr.pid, SIGSTOP);
773
774    /*
775     * If a thread has been attached by ptrace, make sure it is detached
776     * successfully otherwise we will get a zombie.
777     */
778    if (tid_attach_status == 0) {
779        int detach_status;
780        /* detach so we can attach gdbserver */
781        detach_status = ptrace(PTRACE_DETACH, tid, 0, 0);
782        need_cleanup |= (detach_status != 0);
783    }
784
785    /*
786     * if debug.db.uid is set, its value indicates if we should wait
787     * for user action for the crashing process.
788     * in this case, we log a message and turn the debug LED on
789     * waiting for a gdb connection (for instance)
790     */
791
792    if ((signed)cr.uid <= debug_uid) {
793        wait_for_user_action(tid, &cr);
794    }
795
796    /* resume stopped process (so it can crash in peace) */
797    kill(cr.pid, SIGCONT);
798
799    if (need_cleanup) {
800        LOG("debuggerd committing suicide to free the zombie!\n");
801        kill(getpid(), SIGKILL);
802    }
803
804    if(fd != -1) close(fd);
805}
806
807int main()
808{
809    int s;
810    struct sigaction act;
811
812    logsocket = socket_local_client("logd",
813            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
814    if(logsocket < 0) {
815        logsocket = -1;
816    } else {
817        fcntl(logsocket, F_SETFD, FD_CLOEXEC);
818    }
819
820    act.sa_handler = SIG_DFL;
821    sigemptyset(&act.sa_mask);
822    sigaddset(&act.sa_mask,SIGCHLD);
823    act.sa_flags = SA_NOCLDWAIT;
824    sigaction(SIGCHLD, &act, 0);
825
826    s = socket_local_server("android:debuggerd",
827            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
828    if(s < 0) return -1;
829    fcntl(s, F_SETFD, FD_CLOEXEC);
830
831    LOG("debuggerd: " __DATE__ " " __TIME__ "\n");
832
833    for(;;) {
834        struct sockaddr addr;
835        socklen_t alen;
836        int fd;
837
838        alen = sizeof(addr);
839        fd = accept(s, &addr, &alen);
840        if(fd < 0) continue;
841
842        fcntl(fd, F_SETFD, FD_CLOEXEC);
843
844        handle_crashing_process(fd);
845    }
846    return 0;
847}
848