debuggerd.c revision 83c6b052918178033875e7ea54ca746cf7303f87 
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
321const char *get_sigcode(int signo, int code)
322{
323    switch (signo) {
324    case SIGILL:
325        switch (code) {
326        case ILL_ILLOPC: return "ILL_ILLOPC";
327        case ILL_ILLOPN: return "ILL_ILLOPN";
328        case ILL_ILLADR: return "ILL_ILLADR";
329        case ILL_ILLTRP: return "ILL_ILLTRP";
330        case ILL_PRVOPC: return "ILL_PRVOPC";
331        case ILL_PRVREG: return "ILL_PRVREG";
332        case ILL_COPROC: return "ILL_COPROC";
333        case ILL_BADSTK: return "ILL_BADSTK";
334        }
335        break;
336    case SIGBUS:
337        switch (code) {
338        case BUS_ADRALN: return "BUS_ADRALN";
339        case BUS_ADRERR: return "BUS_ADRERR";
340        case BUS_OBJERR: return "BUS_OBJERR";
341        }
342        break;
343    case SIGFPE:
344        switch (code) {
345        case FPE_INTDIV: return "FPE_INTDIV";
346        case FPE_INTOVF: return "FPE_INTOVF";
347        case FPE_FLTDIV: return "FPE_FLTDIV";
348        case FPE_FLTOVF: return "FPE_FLTOVF";
349        case FPE_FLTUND: return "FPE_FLTUND";
350        case FPE_FLTRES: return "FPE_FLTRES";
351        case FPE_FLTINV: return "FPE_FLTINV";
352        case FPE_FLTSUB: return "FPE_FLTSUB";
353        }
354        break;
355    case SIGSEGV:
356        switch (code) {
357        case SEGV_MAPERR: return "SEGV_MAPERR";
358        case SEGV_ACCERR: return "SEGV_ACCERR";
359        }
360        break;
361    }
362    return "?";
363}
364
365void dump_fault_addr(int tfd, int pid, int sig)
366{
367    siginfo_t si;
368
369    memset(&si, 0, sizeof(si));
370    if(ptrace(PTRACE_GETSIGINFO, pid, 0, &si)){
371        _LOG(tfd, false, "cannot get siginfo: %s\n", strerror(errno));
372    } else {
373        _LOG(tfd, false, "signal %d (%s), code %d (%s), fault addr %08x\n",
374             sig, get_signame(sig),
375             si.si_code, get_sigcode(sig, si.si_code),
376             si.si_addr);
377    }
378}
379
380void dump_crash_banner(int tfd, unsigned pid, unsigned tid, int sig)
381{
382    char data[1024];
383    char *x = 0;
384    FILE *fp;
385
386    sprintf(data, "/proc/%d/cmdline", pid);
387    fp = fopen(data, "r");
388    if(fp) {
389        x = fgets(data, 1024, fp);
390        fclose(fp);
391    }
392
393    _LOG(tfd, false,
394         "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
395    dump_build_info(tfd);
396    _LOG(tfd, false, "pid: %d, tid: %d  >>> %s <<<\n",
397         pid, tid, x ? x : "UNKNOWN");
398
399    if(sig) dump_fault_addr(tfd, tid, sig);
400}
401
402static void parse_exidx_info(mapinfo *milist, pid_t pid)
403{
404    mapinfo *mi;
405    for (mi = milist; mi != NULL; mi = mi->next) {
406        Elf32_Ehdr ehdr;
407
408        memset(&ehdr, 0, sizeof(Elf32_Ehdr));
409        /* Read in sizeof(Elf32_Ehdr) worth of data from the beginning of
410         * mapped section.
411         */
412        get_remote_struct(pid, (void *) (mi->start), &ehdr,
413                          sizeof(Elf32_Ehdr));
414        /* Check if it has the matching magic words */
415        if (IS_ELF(ehdr)) {
416            Elf32_Phdr phdr;
417            Elf32_Phdr *ptr;
418            int i;
419
420            ptr = (Elf32_Phdr *) (mi->start + ehdr.e_phoff);
421            for (i = 0; i < ehdr.e_phnum; i++) {
422                /* Parse the program header */
423                get_remote_struct(pid, (char *) (ptr+i), &phdr,
424                                  sizeof(Elf32_Phdr));
425                /* Found a EXIDX segment? */
426                if (phdr.p_type == PT_ARM_EXIDX) {
427                    mi->exidx_start = mi->start + phdr.p_offset;
428                    mi->exidx_end = mi->exidx_start + phdr.p_filesz;
429                    break;
430                }
431            }
432        }
433    }
434}
435
436void dump_crash_report(int tfd, unsigned pid, unsigned tid, bool at_fault)
437{
438    char data[1024];
439    FILE *fp;
440    mapinfo *milist = 0;
441    unsigned int sp_list[STACK_CONTENT_DEPTH];
442    int stack_depth;
443    int frame0_pc_sane = 1;
444
445    if (!at_fault) {
446        _LOG(tfd, true,
447         "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
448        _LOG(tfd, true, "pid: %d, tid: %d\n", pid, tid);
449    }
450
451    dump_registers(tfd, tid, at_fault);
452
453    /* Clear stack pointer records */
454    memset(sp_list, 0, sizeof(sp_list));
455
456    sprintf(data, "/proc/%d/maps", pid);
457    fp = fopen(data, "r");
458    if(fp) {
459        while(fgets(data, 1024, fp)) {
460            mapinfo *mi = parse_maps_line(data);
461            if(mi) {
462                mi->next = milist;
463                milist = mi;
464            }
465        }
466        fclose(fp);
467    }
468
469    parse_exidx_info(milist, tid);
470
471    /* If stack unwinder fails, use the default solution to dump the stack
472     * content.
473     */
474    stack_depth = unwind_backtrace_with_ptrace(tfd, tid, milist, sp_list,
475                                               &frame0_pc_sane, at_fault);
476
477    /* The stack unwinder should at least unwind two levels of stack. If less
478     * level is seen we make sure at lease pc and lr are dumped.
479     */
480    if (stack_depth < 2) {
481        dump_pc_and_lr(tfd, tid, milist, stack_depth, at_fault);
482    }
483
484    dump_stack_and_code(tfd, tid, milist, stack_depth, sp_list, at_fault);
485
486    while(milist) {
487        mapinfo *next = milist->next;
488        free(milist);
489        milist = next;
490    }
491}
492
493#define MAX_TOMBSTONES	10
494
495#define typecheck(x,y) {    \
496    typeof(x) __dummy1;     \
497    typeof(y) __dummy2;     \
498    (void)(&__dummy1 == &__dummy2); }
499
500#define TOMBSTONE_DIR	"/data/tombstones"
501
502/*
503 * find_and_open_tombstone - find an available tombstone slot, if any, of the
504 * form tombstone_XX where XX is 00 to MAX_TOMBSTONES-1, inclusive. If no
505 * file is available, we reuse the least-recently-modified file.
506 */
507static int find_and_open_tombstone(void)
508{
509    unsigned long mtime = ULONG_MAX;
510    struct stat sb;
511    char path[128];
512    int fd, i, oldest = 0;
513
514    /*
515     * XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought
516     * to, our logic breaks. This check will generate a warning if that happens.
517     */
518    typecheck(mtime, sb.st_mtime);
519
520    /*
521     * In a single wolf-like pass, find an available slot and, in case none
522     * exist, find and record the least-recently-modified file.
523     */
524    for (i = 0; i < MAX_TOMBSTONES; i++) {
525        snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", i);
526
527        if (!stat(path, &sb)) {
528            if (sb.st_mtime < mtime) {
529                oldest = i;
530                mtime = sb.st_mtime;
531            }
532            continue;
533        }
534        if (errno != ENOENT)
535            continue;
536
537        fd = open(path, O_CREAT | O_EXCL | O_WRONLY, 0600);
538        if (fd < 0)
539            continue;	/* raced ? */
540
541        fchown(fd, AID_SYSTEM, AID_SYSTEM);
542        return fd;
543    }
544
545    /* we didn't find an available file, so we clobber the oldest one */
546    snprintf(path, sizeof(path), TOMBSTONE_DIR"/tombstone_%02d", oldest);
547    fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);
548    fchown(fd, AID_SYSTEM, AID_SYSTEM);
549
550    return fd;
551}
552
553/* Return true if some thread is not detached cleanly */
554static bool dump_sibling_thread_report(int tfd, unsigned pid, unsigned tid)
555{
556    char task_path[1024];
557
558    sprintf(task_path, "/proc/%d/task", pid);
559    DIR *d;
560    struct dirent *de;
561    int need_cleanup = 0;
562
563    d = opendir(task_path);
564    /* Bail early if cannot open the task directory */
565    if (d == NULL) {
566        XLOG("Cannot open /proc/%d/task\n", pid);
567        return false;
568    }
569    while ((de = readdir(d)) != NULL) {
570        unsigned new_tid;
571        /* Ignore "." and ".." */
572        if (!strcmp(de->d_name, ".") || !strcmp(de->d_name, ".."))
573            continue;
574        new_tid = atoi(de->d_name);
575        /* The main thread at fault has been handled individually */
576        if (new_tid == tid)
577            continue;
578
579        /* Skip this thread if cannot ptrace it */
580        if (ptrace(PTRACE_ATTACH, new_tid, 0, 0) < 0)
581            continue;
582
583        dump_crash_report(tfd, pid, new_tid, false);
584        need_cleanup |= ptrace(PTRACE_DETACH, new_tid, 0, 0);
585    }
586    closedir(d);
587    return need_cleanup != 0;
588}
589
590/* Return true if some thread is not detached cleanly */
591static bool engrave_tombstone(unsigned pid, unsigned tid, int debug_uid,
592                              int signal)
593{
594    int fd;
595    bool need_cleanup = false;
596
597    mkdir(TOMBSTONE_DIR, 0755);
598    chown(TOMBSTONE_DIR, AID_SYSTEM, AID_SYSTEM);
599
600    fd = find_and_open_tombstone();
601    if (fd < 0)
602        return need_cleanup;
603
604    dump_crash_banner(fd, pid, tid, signal);
605    dump_crash_report(fd, pid, tid, true);
606    /*
607     * If the user has requested to attach gdb, don't collect the per-thread
608     * information as it increases the chance to lose track of the process.
609     */
610    if ((signed)pid > debug_uid) {
611        need_cleanup = dump_sibling_thread_report(fd, pid, tid);
612    }
613
614    close(fd);
615    return need_cleanup;
616}
617
618static int
619write_string(const char* file, const char* string)
620{
621    int len;
622    int fd;
623    ssize_t amt;
624    fd = open(file, O_RDWR);
625    len = strlen(string);
626    if (fd < 0)
627        return -errno;
628    amt = write(fd, string, len);
629    close(fd);
630    return amt >= 0 ? 0 : -errno;
631}
632
633static
634void init_debug_led(void)
635{
636    // trout leds
637    write_string("/sys/class/leds/red/brightness", "0");
638    write_string("/sys/class/leds/green/brightness", "0");
639    write_string("/sys/class/leds/blue/brightness", "0");
640    write_string("/sys/class/leds/red/device/blink", "0");
641    // sardine leds
642    write_string("/sys/class/leds/left/cadence", "0,0");
643}
644
645static
646void enable_debug_led(void)
647{
648    // trout leds
649    write_string("/sys/class/leds/red/brightness", "255");
650    // sardine leds
651    write_string("/sys/class/leds/left/cadence", "1,0");
652}
653
654static
655void disable_debug_led(void)
656{
657    // trout leds
658    write_string("/sys/class/leds/red/brightness", "0");
659    // sardine leds
660    write_string("/sys/class/leds/left/cadence", "0,0");
661}
662
663extern int init_getevent();
664extern void uninit_getevent();
665extern int get_event(struct input_event* event, int timeout);
666
667static void wait_for_user_action(unsigned tid, struct ucred* cr)
668{
669    (void)tid;
670    /* First log a helpful message */
671    LOG(    "********************************************************\n"
672            "* Process %d has been suspended while crashing.  To\n"
673            "* attach gdbserver for a gdb connection on port 5039:\n"
674            "*\n"
675            "*     adb shell gdbserver :5039 --attach %d &\n"
676            "*\n"
677            "* Press HOME key to let the process continue crashing.\n"
678            "********************************************************\n",
679            cr->pid, cr->pid);
680
681    /* wait for HOME key (TODO: something useful for devices w/o HOME key) */
682    if (init_getevent() == 0) {
683        int ms = 1200 / 10;
684        int dit = 1;
685        int dah = 3*dit;
686        int _       = -dit;
687        int ___     = 3*_;
688        int _______ = 7*_;
689        const signed char codes[] = {
690           dit,_,dit,_,dit,___,dah,_,dah,_,dah,___,dit,_,dit,_,dit,_______
691        };
692        size_t s = 0;
693        struct input_event e;
694        int home = 0;
695        init_debug_led();
696        enable_debug_led();
697        do {
698            int timeout = abs((int)(codes[s])) * ms;
699            int res = get_event(&e, timeout);
700            if (res == 0) {
701                if (e.type==EV_KEY && e.code==KEY_HOME && e.value==0)
702                    home = 1;
703            } else if (res == 1) {
704                if (++s >= sizeof(codes)/sizeof(*codes))
705                    s = 0;
706                if (codes[s] > 0) {
707                    enable_debug_led();
708                } else {
709                    disable_debug_led();
710                }
711            }
712        } while (!home);
713        uninit_getevent();
714    }
715
716    /* don't forget to turn debug led off */
717    disable_debug_led();
718
719    /* close filedescriptor */
720    LOG("debuggerd resuming process %d", cr->pid);
721 }
722
723static void handle_crashing_process(int fd)
724{
725    char buf[64];
726    struct stat s;
727    unsigned tid;
728    struct ucred cr;
729    int n, len, status;
730    int tid_attach_status = -1;
731    unsigned retry = 30;
732    bool need_cleanup = false;
733
734    char value[PROPERTY_VALUE_MAX];
735    property_get("debug.db.uid", value, "-1");
736    int debug_uid = atoi(value);
737
738    XLOG("handle_crashing_process(%d)\n", fd);
739
740    len = sizeof(cr);
741    n = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
742    if(n != 0) {
743        LOG("cannot get credentials\n");
744        goto done;
745    }
746
747    XLOG("reading tid\n");
748    fcntl(fd, F_SETFL, O_NONBLOCK);
749    while((n = read(fd, &tid, sizeof(unsigned))) != sizeof(unsigned)) {
750        if(errno == EINTR) continue;
751        if(errno == EWOULDBLOCK) {
752            if(retry-- > 0) {
753                usleep(100 * 1000);
754                continue;
755            }
756            LOG("timed out reading tid\n");
757            goto done;
758        }
759        LOG("read failure? %s\n", strerror(errno));
760        goto done;
761    }
762
763    sprintf(buf,"/proc/%d/task/%d", cr.pid, tid);
764    if(stat(buf, &s)) {
765        LOG("tid %d does not exist in pid %d. ignoring debug request\n",
766            tid, cr.pid);
767        close(fd);
768        return;
769    }
770
771    XLOG("BOOM: pid=%d uid=%d gid=%d tid=%d\n", cr.pid, cr.uid, cr.gid, tid);
772
773    tid_attach_status = ptrace(PTRACE_ATTACH, tid, 0, 0);
774    if(tid_attach_status < 0) {
775        LOG("ptrace attach failed: %s\n", strerror(errno));
776        goto done;
777    }
778
779    close(fd);
780    fd = -1;
781
782    for(;;) {
783        n = waitpid(tid, &status, __WALL);
784
785        if(n < 0) {
786            if(errno == EAGAIN) continue;
787            LOG("waitpid failed: %s\n", strerror(errno));
788            goto done;
789        }
790
791        XLOG("waitpid: n=%d status=%08x\n", n, status);
792
793        if(WIFSTOPPED(status)){
794            n = WSTOPSIG(status);
795            switch(n) {
796            case SIGSTOP:
797                XLOG("stopped -- continuing\n");
798                n = ptrace(PTRACE_CONT, tid, 0, 0);
799                if(n) {
800                    LOG("ptrace failed: %s\n", strerror(errno));
801                    goto done;
802                }
803                continue;
804
805            case SIGILL:
806            case SIGABRT:
807            case SIGBUS:
808            case SIGFPE:
809            case SIGSEGV:
810            case SIGSTKFLT: {
811                XLOG("stopped -- fatal signal\n");
812                need_cleanup = engrave_tombstone(cr.pid, tid, debug_uid, n);
813                kill(tid, SIGSTOP);
814                goto done;
815            }
816
817            default:
818                XLOG("stopped -- unexpected signal\n");
819                goto done;
820            }
821        } else {
822            XLOG("unexpected waitpid response\n");
823            goto done;
824        }
825    }
826
827done:
828    XLOG("detaching\n");
829
830    /* stop the process so we can debug */
831    kill(cr.pid, SIGSTOP);
832
833    /*
834     * If a thread has been attached by ptrace, make sure it is detached
835     * successfully otherwise we will get a zombie.
836     */
837    if (tid_attach_status == 0) {
838        int detach_status;
839        /* detach so we can attach gdbserver */
840        detach_status = ptrace(PTRACE_DETACH, tid, 0, 0);
841        need_cleanup |= (detach_status != 0);
842    }
843
844    /*
845     * if debug.db.uid is set, its value indicates if we should wait
846     * for user action for the crashing process.
847     * in this case, we log a message and turn the debug LED on
848     * waiting for a gdb connection (for instance)
849     */
850
851    if ((signed)cr.uid <= debug_uid) {
852        wait_for_user_action(tid, &cr);
853    }
854
855    /* resume stopped process (so it can crash in peace) */
856    kill(cr.pid, SIGCONT);
857
858    if (need_cleanup) {
859        LOG("debuggerd committing suicide to free the zombie!\n");
860        kill(getpid(), SIGKILL);
861    }
862
863    if(fd != -1) close(fd);
864}
865
866int main()
867{
868    int s;
869    struct sigaction act;
870
871    logsocket = socket_local_client("logd",
872            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_DGRAM);
873    if(logsocket < 0) {
874        logsocket = -1;
875    } else {
876        fcntl(logsocket, F_SETFD, FD_CLOEXEC);
877    }
878
879    act.sa_handler = SIG_DFL;
880    sigemptyset(&act.sa_mask);
881    sigaddset(&act.sa_mask,SIGCHLD);
882    act.sa_flags = SA_NOCLDWAIT;
883    sigaction(SIGCHLD, &act, 0);
884
885    s = socket_local_server("android:debuggerd",
886            ANDROID_SOCKET_NAMESPACE_ABSTRACT, SOCK_STREAM);
887    if(s < 0) return -1;
888    fcntl(s, F_SETFD, FD_CLOEXEC);
889
890    LOG("debuggerd: " __DATE__ " " __TIME__ "\n");
891
892    for(;;) {
893        struct sockaddr addr;
894        socklen_t alen;
895        int fd;
896
897        alen = sizeof(addr);
898        fd = accept(s, &addr, &alen);
899        if(fd < 0) continue;
900
901        fcntl(fd, F_SETFD, FD_CLOEXEC);
902
903        handle_crashing_process(fd);
904    }
905    return 0;
906}
907