debuggerd.c revision 7fdcc435b67ddc82e4bfb68067b8bb96f34ebf77 
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[512];
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_elf_info if the mapped section starts with
110     * elf_header
111     */
112    mi->exidx_start = mi->exidx_end = 0;
113    mi->symbols = 0;
114    mi->next = 0;
115    strcpy(mi->name, line + 49);
116
117    return mi;
118}
119
120void dump_build_info(int tfd)
121{
122    char fingerprint[PROPERTY_VALUE_MAX];
123
124    property_get("ro.build.fingerprint", fingerprint, "unknown");
125
126    _LOG(tfd, false, "Build fingerprint: '%s'\n", fingerprint);
127}
128
129
130void dump_stack_and_code(int tfd, int pid, mapinfo *map,
131                         int unwind_depth, unsigned int sp_list[],
132                         bool at_fault)
133{
134    unsigned int sp, pc, p, end, data;
135    struct pt_regs r;
136    int sp_depth;
137    bool only_in_tombstone = !at_fault;
138    char code_buffer[80];
139
140    if(ptrace(PTRACE_GETREGS, pid, 0, &r)) return;
141    sp = r.ARM_sp;
142    pc = r.ARM_pc;
143
144    _LOG(tfd, only_in_tombstone, "\ncode around pc:\n");
145
146    end = p = pc & ~3;
147    p -= 32;
148    end += 32;
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 ((unsigned) r.ARM_lr != pc) {
168        _LOG(tfd, only_in_tombstone, "\ncode around lr:\n");
169
170        end = p = r.ARM_lr & ~3;
171        p -= 32;
172        end += 32;
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#ifdef WITH_VFP
291    struct user_vfp vfp_regs;
292    int i;
293
294    if(ptrace(PTRACE_GETVFPREGS, pid, 0, &vfp_regs)) {
295        _LOG(tfd, only_in_tombstone,
296             "cannot get registers: %s\n", strerror(errno));
297        return;
298    }
299
300    for (i = 0; i < NUM_VFP_REGS; i += 2) {
301        _LOG(tfd, only_in_tombstone,
302             " d%-2d %016llx  d%-2d %016llx\n",
303              i, vfp_regs.fpregs[i], i+1, vfp_regs.fpregs[i+1]);
304    }
305    _LOG(tfd, only_in_tombstone, " scr %08lx\n\n", vfp_regs.fpscr);
306#endif
307}
308
309const char *get_signame(int sig)
310{
311    switch(sig) {
312    case SIGILL:     return "SIGILL";
313    case SIGABRT:    return "SIGABRT";
314    case SIGBUS:     return "SIGBUS";
315    case SIGFPE:     return "SIGFPE";
316    case SIGSEGV:    return "SIGSEGV";
317    case SIGSTKFLT:  return "SIGSTKFLT";
318    default:         return "?";
319    }
320}
321
322void dump_fault_addr(int tfd, int pid, int sig)
323{
324    siginfo_t si;
325
326    memset(&si, 0, sizeof(si));
327    if(ptrace(PTRACE_GETSIGINFO, pid, 0, &si)){
328        _LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
329    } else {
330        _LOG(tfd, false, "signal %d (%s), fault addr %08x\n",
331            sig, get_signame(sig), si.si_addr);
332    }
333}
334
335void dump_crash_banner(int tfd, unsigned pid, unsigned tid, int sig)
336{
337    char data[1024];
338    char *x = 0;
339    FILE *fp;
340
341    sprintf(data, "/proc/%d/cmdline", pid);
342    fp = fopen(data, "r");
343    if(fp) {
344        x = fgets(data, 1024, fp);
345        fclose(fp);
346    }
347
348    _LOG(tfd, false,
349         "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
350    dump_build_info(tfd);
351    _LOG(tfd, false, "pid: %d, tid: %d  >>> %s <<<\n",
352         pid, tid, x ? x : "UNKNOWN");
353
354    if(sig) dump_fault_addr(tfd, tid, sig);
355}
356
357static void parse_elf_info(mapinfo *milist, pid_t pid)
358{
359    mapinfo *mi;
360    for (mi = milist; mi != NULL; mi = mi->next) {
361        Elf32_Ehdr ehdr;
362
363        memset(&ehdr, 0, sizeof(Elf32_Ehdr));
364        /* Read in sizeof(Elf32_Ehdr) worth of data from the beginning of
365         * mapped section.
366         */
367        get_remote_struct(pid, (void *) (mi->start), &ehdr,
368                          sizeof(Elf32_Ehdr));
369        /* Check if it has the matching magic words */
370        if (IS_ELF(ehdr)) {
371            Elf32_Phdr phdr;
372            Elf32_Phdr *ptr;
373            int i;
374
375            ptr = (Elf32_Phdr *) (mi->start + ehdr.e_phoff);
376            for (i = 0; i < ehdr.e_phnum; i++) {
377                /* Parse the program header */
378                get_remote_struct(pid, (char *) (ptr+i), &phdr,
379                                  sizeof(Elf32_Phdr));
380                /* Found a EXIDX segment? */
381                if (phdr.p_type == PT_ARM_EXIDX) {
382                    mi->exidx_start = mi->start + phdr.p_offset;
383                    mi->exidx_end = mi->exidx_start + phdr.p_filesz;
384                    break;
385                }
386            }
387
388            /* Try to load symbols from this file */
389            mi->symbols = symbol_table_create(mi->name);
390        }
391    }
392}
393
394void dump_crash_report(int tfd, unsigned pid, unsigned tid, bool at_fault)
395{
396    char data[1024];
397    FILE *fp;
398    mapinfo *milist = 0;
399    unsigned int sp_list[STACK_CONTENT_DEPTH];
400    int stack_depth;
401    int frame0_pc_sane = 1;
402
403    if (!at_fault) {
404        _LOG(tfd, true,
405         "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
406        _LOG(tfd, true, "pid: %d, tid: %d\n", pid, tid);
407    }
408
409    dump_registers(tfd, tid, at_fault);
410
411    /* Clear stack pointer records */
412    memset(sp_list, 0, sizeof(sp_list));
413
414    sprintf(data, "/proc/%d/maps", pid);
415    fp = fopen(data, "r");
416    if(fp) {
417        while(fgets(data, 1024, fp)) {
418            mapinfo *mi = parse_maps_line(data);
419            if(mi) {
420                mi->next = milist;
421                milist = mi;
422            }
423        }
424        fclose(fp);
425    }
426
427    parse_elf_info(milist, tid);
428
429    /* If stack unwinder fails, use the default solution to dump the stack
430     * content.
431     */
432    stack_depth = unwind_backtrace_with_ptrace(tfd, tid, milist, sp_list,
433                                               &frame0_pc_sane, at_fault);
434
435    /* The stack unwinder should at least unwind two levels of stack. If less
436     * level is seen we make sure at lease pc and lr are dumped.
437     */
438    if (stack_depth < 2) {
439        dump_pc_and_lr(tfd, tid, milist, stack_depth, at_fault);
440    }
441
442    dump_stack_and_code(tfd, tid, milist, stack_depth, sp_list, at_fault);
443
444    while(milist) {
445        mapinfo *next = milist->next;
446        symbol_table_free(milist->symbols);
447        free(milist);
448        milist = next;
449    }
450}
451
452#define MAX_TOMBSTONES	10
453
454#define typecheck(x,y) {    \
455    typeof(x) __dummy1;     \
456    typeof(y) __dummy2;     \
457    (void)(&__dummy1 == &__dummy2); }
458
459#define TOMBSTONE_DIR	"/data/tombstones"
460
461/*
462 * find_and_open_tombstone - find an available tombstone slot, if any, of the
463 * form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
464 * file is available, we reuse the least-recently-modified file.
465 */
466static int find_and_open_tombstone(void)
467{
468    unsigned long mtime = ULONG_MAX;
469    struct stat sb;
470    char path[128];
471    int fd, i, oldest = 0;
472
473    /*
474     * XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
475     * to, our logic breaks. This check will generate a warning if that happens.
476     */
477    typecheck(mtime, sb.st_mtime);
478
479    /*
480     * In a single wolf-like pass, find an available slot and, in case none
481     * exist, find and record the least-recently-modified file.
482     */
483    for (i = 0; i < MAX_TOMBSTONES; i++) {
484        snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
485
486        if (!stat(path, &sb)) {
487            if (sb.st_mtime < mtime) {
488                oldest = i;
489                mtime = sb.st_mtime;
490            }
491            continue;
492        }
493        if (errno != ENOENT)
494            continue;
495
496        fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
497        if (fd < 0)
498            continue;	/* raced ? */
499
500        fchown(fd, AID_SYSTEM, AID_SYSTEM);
501        return fd;
502    }
503
504    /* we didn't find an available file, so we clobber the oldest one */
505    snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
506    fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
507    fchown(fd, AID_SYSTEM, AID_SYSTEM);
508
509    return fd;
510}
511
512/* Return true if some thread is not detached cleanly */
513static bool dump_sibling_thread_report(int tfd, unsigned pid, unsigned tid)
514{
515    char task_path[1024];
516
517    sprintf(task_path, "/proc/%d/task", pid);
518    DIR *d;
519    struct dirent *de;
520    int need_cleanup = 0;
521
522    d = opendir(task_path);
523    /* Bail early if cannot open the task directory */
524    if (d == NULL) {
525        XLOG("Cannot open /proc/%d/task\n", pid);
526        return false;
527    }
528    while ((de = readdir(d)) != NULL) {
529        unsigned new_tid;
530        /* Ignore "." and ".." */
531        if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
532            continue;
533        new_tid = atoi(de->d_name);
534        /* The main thread at fault has been handled individually */
535        if (new_tid == tid)
536            continue;
537
538        /* Skip this thread if cannot ptrace it */
539        if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0)
540            continue;
541
542        dump_crash_report(tfd, pid, new_tid, false);
543        need_cleanup |= ptrace(PTRACE_DETACH, new_tid, 0, 0);
544    }
545    closedir(d);
546    return need_cleanup != 0;
547}
548
549/* Return true if some thread is not detached cleanly */
550static bool engrave_tombstone(unsigned pid, unsigned tid, int debug_uid,
551                              int signal)
552{
553    int fd;
554    bool need_cleanup = false;
555
556    mkdir(TOMBSTONE_DIR, 0755);
557    chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
558
559    fd = find_and_open_tombstone();
560    if (fd < 0)
561        return need_cleanup;
562
563    dump_crash_banner(fd, pid, tid, signal);
564    dump_crash_report(fd, pid, tid, true);
565    /*
566     * If the user has requested to attach gdb, don't collect the per-thread
567     * information as it increases the chance to lose track of the process.
568     */
569    if ((signed)pid > debug_uid) {
570        need_cleanup = dump_sibling_thread_report(fd, pid, tid);
571    }
572
573    close(fd);
574    return need_cleanup;
575}
576
577static int
578write_string(const char* file, const char* string)
579{
580    int len;
581    int fd;
582    ssize_t amt;
583    fd = open(file, O_RDWR);
584    len = strlen(string);
585    if (fd < 0)
586        return -errno;
587    amt = write(fd, string, len);
588    close(fd);
589    return amt >= 0 ? 0 : -errno;
590}
591
592static
593void init_debug_led(void)
594{
595    // trout leds
596    write_string("/sys/class/leds/red/brightness", "0");
597    write_string("/sys/class/leds/green/brightness", "0");
598    write_string("/sys/class/leds/blue/brightness", "0");
599    write_string("/sys/class/leds/red/device/blink", "0");
600    // sardine leds
601    write_string("/sys/class/leds/left/cadence", "0,0");
602}
603
604static
605void enable_debug_led(void)
606{
607    // trout leds
608    write_string("/sys/class/leds/red/brightness", "255");
609    // sardine leds
610    write_string("/sys/class/leds/left/cadence", "1,0");
611}
612
613static
614void disable_debug_led(void)
615{
616    // trout leds
617    write_string("/sys/class/leds/red/brightness", "0");
618    // sardine leds
619    write_string("/sys/class/leds/left/cadence", "0,0");
620}
621
622extern int init_getevent();
623extern void uninit_getevent();
624extern int get_event(struct input_event* event, int timeout);
625
626static void wait_for_user_action(unsigned tid, struct ucred* cr)
627{
628    (void)tid;
629    /* First log a helpful message */
630    LOG(    "********************************************************\n"
631            "* Process %d has been suspended while crashing.  To\n"
632            "* attach gdbserver for a gdb connection on port 5039:\n"
633            "*\n"
634            "*     adb shell gdbserver :5039 --attach %d &\n"
635            "*\n"
636            "* Press HOME key to let the process continue crashing.\n"
637            "********************************************************\n",
638            cr->pid, cr->pid);
639
640    /* wait for HOME key (TODO: something useful for devices w/o HOME key) */
641    if (init_getevent() == 0) {
642        int ms = 1200 / 10;
643        int dit = 1;
644        int dah = 3*dit;
645        int _       = -dit;
646        int ___     = 3*_;
647        int _______ = 7*_;
648        const signed char codes[] = {
649           dit,_,dit,_,dit,___,dah,_,dah,_,dah,___,dit,_,dit,_,dit,_______
650        };
651        size_t s = 0;
652        struct input_event e;
653        int home = 0;
654        init_debug_led();
655        enable_debug_led();
656        do {
657            int timeout = abs((int)(codes[s])) * ms;
658            int res = get_event(&e, timeout);
659            if (res == 0) {
660                if (e.type==EV_KEY && e.code==KEY_HOME && e.value==0)
661                    home = 1;
662            } else if (res == 1) {
663                if (++s >= sizeof(codes)/sizeof(*codes))
664                    s = 0;
665                if (codes[s] > 0) {
666                    enable_debug_led();
667                } else {
668                    disable_debug_led();
669                }
670            }
671        } while (!home);
672        uninit_getevent();
673    }
674
675    /* don't forget to turn debug led off */
676    disable_debug_led();
677
678    /* close filedescriptor */
679    LOG("debuggerd resuming process %d", cr->pid);
680 }
681
682static void handle_crashing_process(int fd)
683{
684    char buf[64];
685    struct stat s;
686    unsigned tid;
687    struct ucred cr;
688    int n, len, status;
689    int tid_attach_status = -1;
690    unsigned retry = 30;
691    bool need_cleanup = false;
692
693    char value[PROPERTY_VALUE_MAX];
694    property_get("debug.db.uid", value, "-1");
695    int debug_uid = atoi(value);
696
697    XLOG("handle_crashing_process(%d)\n", fd);
698
699    len = sizeof(cr);
700    n = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
701    if(n != 0) {
702        LOG("cannot get credentials\n");
703        goto done;
704    }
705
706    XLOG("reading tid\n");
707    fcntl(fd, F_SETFL, O_NONBLOCK);
708    while((n = read(fd, &tid, sizeof(unsigned))) != sizeof(unsigned)) {
709        if(errno == EINTR) continue;
710        if(errno == EWOULDBLOCK) {
711            if(retry-- > 0) {
712                usleep(100 * 1000);
713                continue;
714            }
715            LOG("timed out reading tid\n");
716            goto done;
717        }
718        LOG("read failure? %s\n", strerror(errno));
719        goto done;
720    }
721
722    sprintf(buf,"/proc/%d/task/%d", cr.pid, tid);
723    if(stat(buf, &s)) {
724        LOG("tid %d does not exist in pid %d. ignoring debug request\n",
725            tid, cr.pid);
726        close(fd);
727        return;
728    }
729
730    XLOG("BOOM: pid=%d uid=%d gid=%d tid=%d\n", cr.pid, cr.uid, cr.gid, tid);
731
732    tid_attach_status = ptrace(PTRACE_ATTACH, tid, 0, 0);
733    if(tid_attach_status < 0) {
734        LOG("ptrace attach failed: %s\n", strerror(errno));
735        goto done;
736    }
737
738    close(fd);
739    fd = -1;
740
741    for(;;) {
742        n = waitpid(tid, &status, __WALL);
743
744        if(n < 0) {
745            if(errno == EAGAIN) continue;
746            LOG("waitpid failed: %s\n", strerror(errno));
747            goto done;
748        }
749
750        XLOG("waitpid: n=%d status=%08x\n", n, status);
751
752        if(WIFSTOPPED(status)){
753            n = WSTOPSIG(status);
754            switch(n) {
755            case SIGSTOP:
756                XLOG("stopped -- continuing\n");
757                n = ptrace(PTRACE_CONT, tid, 0, 0);
758                if(n) {
759                    LOG("ptrace failed: %s\n", strerror(errno));
760                    goto done;
761                }
762                continue;
763
764            case SIGILL:
765            case SIGABRT:
766            case SIGBUS:
767            case SIGFPE:
768            case SIGSEGV:
769            case SIGSTKFLT: {
770                XLOG("stopped -- fatal signal\n");
771                need_cleanup = engrave_tombstone(cr.pid, tid, debug_uid, n);
772                kill(tid, SIGSTOP);
773                goto done;
774            }
775
776            default:
777                XLOG("stopped -- unexpected signal\n");
778                goto done;
779            }
780        } else {
781            XLOG("unexpected waitpid response\n");
782            goto done;
783        }
784    }
785
786done:
787    XLOG("detaching\n");
788
789    /* stop the process so we can debug */
790    kill(cr.pid, SIGSTOP);
791
792    /*
793     * If a thread has been attached by ptrace, make sure it is detached
794     * successfully otherwise we will get a zombie.
795     */
796    if (tid_attach_status == 0) {
797        int detach_status;
798        /* detach so we can attach gdbserver */
799        detach_status = ptrace(PTRACE_DETACH, tid, 0, 0);
800        need_cleanup |= (detach_status != 0);
801    }
802
803    /*
804     * if debug.db.uid is set, its value indicates if we should wait
805     * for user action for the crashing process.
806     * in this case, we log a message and turn the debug LED on
807     * waiting for a gdb connection (for instance)
808     */
809
810    if ((signed)cr.uid <= debug_uid) {
811        wait_for_user_action(tid, &cr);
812    }
813
814    /* resume stopped process (so it can crash in peace) */
815    kill(cr.pid, SIGCONT);
816
817    if (need_cleanup) {
818        LOG("debuggerd committing suicide to free the zombie!\n");
819        kill(getpid(), SIGKILL);
820    }
821
822    if(fd != -1) close(fd);
823}
824
825int main()
826{
827    int s;
828    struct sigaction act;
829
830    logsocket = socket_local_client("logd",
831            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
832    if(logsocket < 0) {
833        logsocket = -1;
834    } else {
835        fcntl(logsocket, F_SETFD, FD_CLOEXEC);
836    }
837
838    act.sa_handler = SIG_DFL;
839    sigemptyset(&act.sa_mask);
840    sigaddset(&act.sa_mask,SIGCHLD);
841    act.sa_flags = SA_NOCLDWAIT;
842    sigaction(SIGCHLD, &act, 0);
843
844    s = socket_local_server("android:debuggerd",
845            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
846    if(s < 0) return -1;
847    fcntl(s, F_SETFD, FD_CLOEXEC);
848
849    LOG("debuggerd: " __DATE__ " " __TIME__ "\n");
850
851    for(;;) {
852        struct sockaddr addr;
853        socklen_t alen;
854        int fd;
855
856        alen = sizeof(addr);
857        fd = accept(s, &addr, &alen);
858        if(fd < 0) continue;
859
860        fcntl(fd, F_SETFD, FD_CLOEXEC);
861
862        handle_crashing_process(fd);
863    }
864    return 0;
865}
866