os/assumes.c

   1 /*
   2  * Copyright (c) 2011, 2012 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #include <TargetConditionals.h>
  25 #include <dispatch/dispatch.h>
  26 #include <uuid/uuid.h>
  27 #include <sys/types.h>
  28 #include <sys/sysctl.h>
  29 #include <mach-o/loader.h>
  30 #include <mach-o/fat.h>
  31 #include <mach-o/arch.h>
  32 #include <mach-o/getsect.h>
  33 #include <pthread.h>
  34 #include <sys/types.h>
  35 #include <execinfo.h>
  36 #include <stdio.h>
  37 #include <dlfcn.h>
  38 #include <_simple.h>
  39 #include <errno.h>
  40 #include <pthread.h>
  41 #include <string.h>
  42 #include "os/assumes.h"
  43 #include "gen/assumes.h"
  44 #include <os/debug_private.h>
  45
  46 #define OSX_ASSUMES_LOG_REDIRECT_SECT_NAME "__osx_log_func"
  47 #define os_atomic_cmpxchg(p, o, n) __sync_bool_compare_and_swap((p), (o), (n))
  48
  49 static bool _os_should_abort_on_assumes = false;
  50
  51 static const char *
  52 _os_basename(const char *p)
  53 {
  54         return ((strrchr(p, '/') ? : p - 1) + 1);
  55 }
  56
  57 static void
  58 _os_get_build(char *build, size_t sz)
  59 {
  60         /* Get the build every time. We used to cache it, but if PID 1 experiences
  61          * an assumes() failure before the build has been set, that would mean that
  62          * all future failures would get bad build info. So we fetch it every time.
  63          * Since assumes() failures are on the slow path anyway, not a huge deal.
  64          */
  65         int mib[] = { CTL_KERN, KERN_OSVERSION };
  66
  67         size_t oldsz = sz;
  68         int r = sysctl(mib, 2, build, &sz, NULL, 0);
  69         if (r == 0 && sz == 1) {
  70                 (void)strlcpy(build, "99Z999", oldsz);
  71         }
  72 #if TARGET_IPHONE_SIMULATOR
  73         char *simVersion = getenv("SIMULATOR_RUNTIME_BUILD_VERSION");
  74         if (simVersion) {
  75             strlcat(build, " ", oldsz);
  76             strlcat(build, simVersion, oldsz);
  77         }
  78 #endif
  79 }
  80
  81 static void
  82 _os_get_image_uuid(void *hdr, uuid_t uuid)
  83 {
  84 #if __LP64__
  85         struct mach_header_64 *hdr32or64 = (struct mach_header_64 *)hdr;
  86 #else
  87         struct mach_header *hdr32or64 = (struct mach_header *)hdr;
  88 #endif /* __LP64__ */
  89
  90         size_t i = 0;
  91         size_t next = sizeof(*hdr32or64);
  92         struct load_command *cur = NULL;
  93         for (i = 0; i < hdr32or64->ncmds; i++) {
  94                 cur = (struct load_command *)((uintptr_t)hdr32or64 + next);
  95                 if (cur->cmd == LC_UUID) {
  96                         struct uuid_command *cmd = (struct uuid_command *)cur;
  97                         uuid_copy(uuid, cmd->uuid);
  98                         break;
  99                 }
 100
 101                 next += cur->cmdsize;
 102         }
 103
 104         if (i == hdr32or64->ncmds) {
 105                 uuid_clear(uuid);
 106         }
 107 }
 108
 109 static void
 110 _os_abort_on_assumes_once(void)
 111 {
 112         /* Embedded boot-args can get pretty long. Let's just hope this is big
 113          * enough.
 114          */
 115         char bootargs[2048];
 116         size_t len = sizeof(bootargs) - 1;
 117
 118         if (sysctlbyname("kern.bootargs", bootargs, &len, NULL, 0) == 0) {
 119                 if (strnstr(bootargs, "-os_assumes_fatal", len)) {
 120                         _os_should_abort_on_assumes = true;
 121                 }
 122         }
 123 }
 124
 125 static bool
 126 _os_abort_on_assumes(void)
 127 {
 128         static pthread_once_t once = PTHREAD_ONCE_INIT;
 129         bool result = false;
 130
 131         if (getpid() != 1) {
 132                 if (getenv("OS_ASSUMES_FATAL")) {
 133                         result = true;
 134                 } else {
 135                         pthread_once(&once, _os_abort_on_assumes_once);
 136                         result = _os_should_abort_on_assumes;
 137                 }
 138         } else {
 139                 if (getenv("OS_ASSUMES_FATAL_PID1")) {
 140                         result = true;
 141                 }
 142         }
 143
 144         return result;
 145 }
 146
 147 #if __LP64__
 148 typedef struct mach_header_64 os_mach_header;
 149 #else
 150 typedef struct mach_header os_mach_header;
 151 #endif
 152
 153 static os_redirect_t
 154 _os_find_log_redirect_func(os_mach_header *hdr)
 155 {
 156         os_redirect_t result = NULL;
 157
 158         char name[128];
 159         unsigned long size = 0;
 160         uint8_t *data = getsectiondata(hdr, OS_ASSUMES_REDIRECT_SEG, OS_ASSUMES_REDIRECT_SECT, &size);
 161         if (!data) {
 162                 data = getsectiondata(hdr, "__TEXT", OSX_ASSUMES_LOG_REDIRECT_SECT_NAME, &size);
 163
 164                 if (data && size < sizeof(name) - 2) {
 165                         (void)strlcpy(name, (const char *)data, size + 1);
 166                         result = dlsym(RTLD_DEFAULT, name);
 167                 }
 168         } else if (size == sizeof(struct _os_redirect_assumes_s)) {
 169                 struct _os_redirect_assumes_s *redirect = (struct _os_redirect_assumes_s *)data;
 170                 result = redirect->redirect;
 171         }
 172
 173         return result;
 174 }
 175
 176 static bool
 177 _os_log_redirect(void *hdr, const char *msg)
 178 {
 179         bool result = false;
 180
 181         os_redirect_t redirect_func = _os_find_log_redirect_func(hdr);
 182         if (redirect_func) {
 183                 result = redirect_func(msg);
 184         }
 185
 186         return result;
 187 }
 188
 189 __attribute__((always_inline))
 190 static void
 191 _os_construct_message(uint64_t code, _SIMPLE_STRING asl_message, Dl_info *info, char *buff, size_t sz)
 192 {
 193         const char *image_name = NULL;
 194         uintptr_t offset = 0;
 195         uuid_string_t uuid_str;
 196
 197         void *ret = __builtin_return_address(0);
 198         if (dladdr(ret, info)) {
 199                 uuid_t uuid;
 200                 _os_get_image_uuid(info->dli_fbase, uuid);
 201
 202                 uuid_unparse(uuid, uuid_str);
 203                 image_name = _os_basename(info->dli_fname);
 204
 205                 offset = ret - info->dli_fbase;
 206         }
 207
 208         char sig[64];
 209         (void)snprintf(sig, sizeof(sig), "%s:%lu", uuid_str, offset);
 210
 211         char result[24];
 212         (void)snprintf(result, sizeof(result), "0x%llx", code);
 213
 214         char build[32];
 215         size_t bsz = sizeof(build);
 216         _os_get_build(build, bsz);
 217
 218         (void)snprintf(buff, sz, "assertion failed: %s: %s + %lu [%s]: %s", build, image_name, offset, uuid_str, result);
 219
 220         _simple_asl_msg_set(asl_message, "com.apple.message.domain", "com.apple.assumes.failure");
 221         _simple_asl_msg_set(asl_message, "com.apple.message.signature", sig);
 222         _simple_asl_msg_set(asl_message, "com.apple.message.signature2", result);
 223         _simple_asl_msg_set(asl_message, "com.apple.message.signature3", image_name);
 224         _simple_asl_msg_set(asl_message, "com.apple.message.summarize", "YES");
 225 }
 226
 227 #pragma mark Internal Implementations
 228 __attribute__((always_inline))
 229 static inline void
 230 _os_assumes_log_impl(uint64_t code)
 231 {
 232         _SIMPLE_STRING asl_message = _simple_asl_msg_new();
 233         if (asl_message) {
 234                 Dl_info info;
 235                 char message[256];
 236                 _os_construct_message(code, asl_message, &info, message, sizeof(message));
 237                 if (!_os_log_redirect(info.dli_fbase, message)) {
 238                         _os_debug_log_error_str(message);
 239                         _simple_asl_msg_set(asl_message, "Level", "Error");
 240                         _simple_asl_msg_set(asl_message, "Message", "");
 241                         _simple_asl_send(asl_message);
 242                 }
 243
 244                 _simple_sfree(asl_message);
 245         }
 246
 247         if (_os_abort_on_assumes()) {
 248                 __builtin_trap();
 249         }
 250 }
 251
 252 __attribute__((always_inline))
 253 static inline char *
 254 _os_assert_log_impl(uint64_t code)
 255 {
 256         char *result = NULL;
 257
 258         _SIMPLE_STRING asl_message = _simple_asl_msg_new();
 259         if (asl_message) {
 260                 Dl_info info;
 261                 char message[256];
 262                 _os_construct_message(code, asl_message, &info, message, sizeof(message));
 263                 if (!_os_log_redirect(info.dli_fbase, message)) {
 264                         _os_debug_log_error_str(message);
 265                         _simple_asl_msg_set(asl_message, "Level", "Error");
 266                         _simple_asl_msg_set(asl_message, "Message", "");
 267                         _simple_asl_send(asl_message);
 268                 }
 269
 270                 _simple_sfree(asl_message);
 271                 result = strdup(message);
 272         }
 273
 274 #if LIBC_NO_LIBCRASHREPORTERCLIENT
 275         /* There is no crash report information facility on embedded, which is
 276          * really regrettable. Fortunately, all we need to capture is the value
 277          * which tripped up the assertion. We can just stuff that into the thread's
 278          * name.
 279          */
 280         char name[64];
 281         (void)pthread_getname_np(pthread_self(), name, sizeof(name));
 282
 283         char newname[64];
 284         if (strlen(name) == 0) {
 285                 (void)snprintf(newname, sizeof(newname), "[Fatal bug: 0x%llx]", code);
 286         } else {
 287                 (void)snprintf(newname, sizeof(newname), "%s [Fatal bug: 0x%llx]", name, code);
 288         }
 289
 290         (void)pthread_setname_np(newname);
 291 #endif
 292
 293         return result;
 294 }
 295
 296 __attribute__((always_inline))
 297 static inline void
 298 _os_assumes_log_ctx_impl(os_log_callout_t callout, void *ctx, uint64_t code)
 299 {
 300         _SIMPLE_STRING asl_message = _simple_asl_msg_new();
 301         if (asl_message) {
 302                 Dl_info info;
 303                 char message[256];
 304                 _os_construct_message(code, asl_message, &info, message, sizeof(message));
 305
 306                 (void)callout(asl_message, ctx, message);
 307                 _simple_sfree(asl_message);
 308         }
 309
 310         if (_os_abort_on_assumes()) {
 311                 __builtin_trap();
 312         }
 313 }
 314
 315 __attribute__((always_inline))
 316 static inline char *
 317 _os_assert_log_ctx_impl(os_log_callout_t callout, void *ctx, uint64_t code)
 318 {
 319         char *result = NULL;
 320
 321         _SIMPLE_STRING asl_message = _simple_asl_msg_new();
 322         if (asl_message) {
 323                 Dl_info info;
 324                 char message[256];
 325                 _os_construct_message(code, asl_message, &info, message, sizeof(message));
 326
 327                 (void)callout(asl_message, ctx, message);
 328                 _simple_sfree(asl_message);
 329                 result = strdup(message);
 330         }
 331         return result;
 332 }
 333
 334 #pragma mark Public Interfaces
 335 void
 336 _os_assumes_log(uint64_t code)
 337 {
 338         _os_assumes_log_impl(code);
 339 }
 340
 341 char *
 342 _os_assert_log(uint64_t code)
 343 {
 344         return _os_assert_log_impl(code);
 345 }
 346
 347 void
 348 _os_assumes_log_ctx(os_log_callout_t callout, void *ctx, uint64_t code)
 349 {
 350         _os_assumes_log_ctx_impl(callout, ctx, code);
 351 }
 352
 353 char *
 354 _os_assert_log_ctx(os_log_callout_t callout, void *ctx, uint64_t code)
 355 {
 356         return _os_assert_log_ctx_impl(callout, ctx, code);
 357 }
 358
 359 void
 360 _os_avoid_tail_call(void)
 361 {
 362         // no-op
 363 }
 364
 365 #pragma mark Legacy
 366 void
 367 _osx_assumes_log(uint64_t code)
 368 {
 369         _os_assumes_log(code);
 370 }
 371
 372 char *
 373 _osx_assert_log(uint64_t code)
 374 {
 375         return _os_assert_log_impl(code);
 376 }
 377
 378 void
 379 _osx_assumes_log_ctx(osx_log_callout_t callout, void *ctx, uint64_t code)
 380 {
 381         _os_assumes_log_ctx_impl(callout, ctx, code);
 382 }
 383
 384 char *
 385 _osx_assert_log_ctx(osx_log_callout_t callout, void *ctx, uint64_t code)
 386 {
 387         return _os_assert_log_ctx_impl(callout, ctx, code);
 388 }
 389
 390 void
 391 _osx_avoid_tail_call(void)
 392 {
 393         _os_avoid_tail_call();
 394 }