1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/base/nsDumpUtils.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,493 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +
1.10 +#include "nsDumpUtils.h"
1.11 +#include "nsDirectoryServiceDefs.h"
1.12 +#include "nsDirectoryServiceUtils.h"
1.13 +#include "prenv.h"
1.14 +#include <errno.h>
1.15 +#include "mozilla/Services.h"
1.16 +#include "nsIObserverService.h"
1.17 +#include "mozilla/ClearOnShutdown.h"
1.18 +
1.19 +#ifdef XP_UNIX // {
1.20 +#include "mozilla/Preferences.h"
1.21 +#include <fcntl.h>
1.22 +#include <unistd.h>
1.23 +#include <sys/types.h>
1.24 +#include <sys/stat.h>
1.25 +
1.26 +using namespace mozilla;
1.27 +
1.28 +/*
1.29 + * The following code supports triggering a registered callback upon
1.30 + * receiving a specific signal.
1.31 + *
1.32 + * Take about:memory for example, we register
1.33 + * 1. doGCCCDump for doMemoryReport
1.34 + * 2. doMemoryReport for sDumpAboutMemorySignum(SIGRTMIN)
1.35 + * and sDumpAboutMemoryAfterMMUSignum(SIGRTMIN+1).
1.36 + *
1.37 + * When we receive one of these signals, we write the signal number to a pipe.
1.38 + * The IO thread then notices that the pipe has been written to, and kicks off
1.39 + * the appropriate task on the main thread.
1.40 + *
1.41 + * This scheme is similar to using signalfd(), except it's portable and it
1.42 + * doesn't require the use of sigprocmask, which is problematic because it
1.43 + * masks signals received by child processes.
1.44 + *
1.45 + * In theory, we could use Chromium's MessageLoopForIO::CatchSignal() for this.
1.46 + * But that uses libevent, which does not handle the realtime signals (bug
1.47 + * 794074).
1.48 + */
1.49 +
1.50 +// This is the write-end of a pipe that we use to notice when a
1.51 +// specific signal occurs.
1.52 +static Atomic<int> sDumpPipeWriteFd(-1);
1.53 +
1.54 +const char* const FifoWatcher::kPrefName =
1.55 + "memory_info_dumper.watch_fifo.enabled";
1.56 +
1.57 +static void
1.58 +DumpSignalHandler(int aSignum)
1.59 +{
1.60 + // This is a signal handler, so everything in here needs to be
1.61 + // async-signal-safe. Be careful!
1.62 +
1.63 + if (sDumpPipeWriteFd != -1) {
1.64 + uint8_t signum = static_cast<int>(aSignum);
1.65 + write(sDumpPipeWriteFd, &signum, sizeof(signum));
1.66 + }
1.67 +}
1.68 +
1.69 +NS_IMPL_ISUPPORTS(FdWatcher, nsIObserver);
1.70 +
1.71 +void FdWatcher::Init()
1.72 +{
1.73 + MOZ_ASSERT(NS_IsMainThread());
1.74 +
1.75 + nsCOMPtr<nsIObserverService> os = services::GetObserverService();
1.76 + os->AddObserver(this, "xpcom-shutdown", /* ownsWeak = */ false);
1.77 +
1.78 + XRE_GetIOMessageLoop()->PostTask(
1.79 + FROM_HERE,
1.80 + NewRunnableMethod(this, &FdWatcher::StartWatching));
1.81 +}
1.82 +
1.83 +// Implementations may call this function multiple times if they ensure that
1.84 +// it's safe to call OpenFd() multiple times and they call StopWatching()
1.85 +// first.
1.86 +void FdWatcher::StartWatching()
1.87 +{
1.88 + MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
1.89 + MOZ_ASSERT(mFd == -1);
1.90 +
1.91 + mFd = OpenFd();
1.92 + if (mFd == -1) {
1.93 + LOG("FdWatcher: OpenFd failed.");
1.94 + return;
1.95 + }
1.96 +
1.97 + MessageLoopForIO::current()->WatchFileDescriptor(
1.98 + mFd, /* persistent = */ true,
1.99 + MessageLoopForIO::WATCH_READ,
1.100 + &mReadWatcher, this);
1.101 +}
1.102 +
1.103 +// Since implementations can call StartWatching() multiple times, they can of
1.104 +// course call StopWatching() multiple times.
1.105 +void FdWatcher::StopWatching()
1.106 +{
1.107 + MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
1.108 +
1.109 + mReadWatcher.StopWatchingFileDescriptor();
1.110 + if (mFd != -1) {
1.111 + close(mFd);
1.112 + mFd = -1;
1.113 + }
1.114 +}
1.115 +
1.116 +StaticRefPtr<SignalPipeWatcher> SignalPipeWatcher::sSingleton;
1.117 +
1.118 +/* static */ SignalPipeWatcher*
1.119 +SignalPipeWatcher::GetSingleton()
1.120 +{
1.121 + if (!sSingleton) {
1.122 + sSingleton = new SignalPipeWatcher();
1.123 + sSingleton->Init();
1.124 + ClearOnShutdown(&sSingleton);
1.125 + }
1.126 + return sSingleton;
1.127 +}
1.128 +
1.129 +void
1.130 +SignalPipeWatcher::RegisterCallback(uint8_t aSignal,
1.131 + PipeCallback aCallback)
1.132 +{
1.133 + MutexAutoLock lock(mSignalInfoLock);
1.134 +
1.135 + for (SignalInfoArray::index_type i = 0; i < mSignalInfo.Length(); i++)
1.136 + {
1.137 + if (mSignalInfo[i].mSignal == aSignal) {
1.138 + LOG("Register Signal(%d) callback failed! (DUPLICATE)", aSignal);
1.139 + return;
1.140 + }
1.141 + }
1.142 + SignalInfo signalInfo = { aSignal, aCallback };
1.143 + mSignalInfo.AppendElement(signalInfo);
1.144 + RegisterSignalHandler(signalInfo.mSignal);
1.145 +}
1.146 +
1.147 +void
1.148 +SignalPipeWatcher::RegisterSignalHandler(uint8_t aSignal)
1.149 +{
1.150 + struct sigaction action;
1.151 + memset(&action, 0, sizeof(action));
1.152 + sigemptyset(&action.sa_mask);
1.153 + action.sa_handler = DumpSignalHandler;
1.154 +
1.155 + if (aSignal) {
1.156 + if (sigaction(aSignal, &action, nullptr)) {
1.157 + LOG("SignalPipeWatcher failed to register sig %d.", aSignal);
1.158 + }
1.159 + } else {
1.160 + MutexAutoLock lock(mSignalInfoLock);
1.161 + for (SignalInfoArray::index_type i = 0; i < mSignalInfo.Length(); i++) {
1.162 + if (sigaction(mSignalInfo[i].mSignal, &action, nullptr)) {
1.163 + LOG("SignalPipeWatcher failed to register signal(%d) "
1.164 + "dump signal handler.", mSignalInfo[i].mSignal);
1.165 + }
1.166 + }
1.167 + }
1.168 +}
1.169 +
1.170 +SignalPipeWatcher::~SignalPipeWatcher()
1.171 +{
1.172 + if (sDumpPipeWriteFd != -1) {
1.173 + StopWatching();
1.174 + }
1.175 +}
1.176 +
1.177 +int SignalPipeWatcher::OpenFd()
1.178 +{
1.179 + MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
1.180 +
1.181 + // Create a pipe. When we receive a signal in our signal handler, we'll
1.182 + // write the signum to the write-end of this pipe.
1.183 + int pipeFds[2];
1.184 + if (pipe(pipeFds)) {
1.185 + LOG("SignalPipeWatcher failed to create pipe.");
1.186 + return -1;
1.187 + }
1.188 +
1.189 + // Close this pipe on calls to exec().
1.190 + fcntl(pipeFds[0], F_SETFD, FD_CLOEXEC);
1.191 + fcntl(pipeFds[1], F_SETFD, FD_CLOEXEC);
1.192 +
1.193 + int readFd = pipeFds[0];
1.194 + sDumpPipeWriteFd = pipeFds[1];
1.195 +
1.196 + RegisterSignalHandler();
1.197 + return readFd;
1.198 +}
1.199 +
1.200 +void SignalPipeWatcher::StopWatching()
1.201 +{
1.202 + MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
1.203 +
1.204 + // Close sDumpPipeWriteFd /after/ setting the fd to -1.
1.205 + // Otherwise we have the (admittedly far-fetched) race where we
1.206 + //
1.207 + // 1) close sDumpPipeWriteFd
1.208 + // 2) open a new fd with the same number as sDumpPipeWriteFd
1.209 + // had.
1.210 + // 3) receive a signal, then write to the fd.
1.211 + int pipeWriteFd = sDumpPipeWriteFd.exchange(-1);
1.212 + close(pipeWriteFd);
1.213 +
1.214 + FdWatcher::StopWatching();
1.215 +}
1.216 +
1.217 +void SignalPipeWatcher::OnFileCanReadWithoutBlocking(int aFd)
1.218 +{
1.219 + MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
1.220 +
1.221 + uint8_t signum;
1.222 + ssize_t numReceived = read(aFd, &signum, sizeof(signum));
1.223 + if (numReceived != sizeof(signum)) {
1.224 + LOG("Error reading from buffer in "
1.225 + "SignalPipeWatcher::OnFileCanReadWithoutBlocking.");
1.226 + return;
1.227 + }
1.228 +
1.229 + {
1.230 + MutexAutoLock lock(mSignalInfoLock);
1.231 + for (SignalInfoArray::index_type i = 0; i < mSignalInfo.Length(); i++) {
1.232 + if(signum == mSignalInfo[i].mSignal) {
1.233 + mSignalInfo[i].mCallback(signum);
1.234 + return;
1.235 + }
1.236 + }
1.237 + }
1.238 + LOG("SignalPipeWatcher got unexpected signum.");
1.239 +}
1.240 +
1.241 +StaticRefPtr<FifoWatcher> FifoWatcher::sSingleton;
1.242 +
1.243 +/* static */ FifoWatcher*
1.244 +FifoWatcher::GetSingleton()
1.245 +{
1.246 + if (!sSingleton) {
1.247 + nsAutoCString dirPath;
1.248 + Preferences::GetCString(
1.249 + "memory_info_dumper.watch_fifo.directory", &dirPath);
1.250 + sSingleton = new FifoWatcher(dirPath);
1.251 + sSingleton->Init();
1.252 + ClearOnShutdown(&sSingleton);
1.253 + }
1.254 + return sSingleton;
1.255 +}
1.256 +
1.257 +/* static */ bool
1.258 +FifoWatcher::MaybeCreate()
1.259 +{
1.260 + MOZ_ASSERT(NS_IsMainThread());
1.261 +
1.262 + if (XRE_GetProcessType() != GeckoProcessType_Default) {
1.263 + // We want this to be main-process only, since two processes can't listen
1.264 + // to the same fifo.
1.265 + return false;
1.266 + }
1.267 +
1.268 + if (!Preferences::GetBool(kPrefName, false)) {
1.269 + LOG("Fifo watcher disabled via pref.");
1.270 + return false;
1.271 + }
1.272 +
1.273 + // The FifoWatcher is held alive by the observer service.
1.274 + if (!sSingleton) {
1.275 + GetSingleton();
1.276 + }
1.277 + return true;
1.278 +}
1.279 +
1.280 +void
1.281 +FifoWatcher::RegisterCallback(const nsCString& aCommand, FifoCallback aCallback)
1.282 +{
1.283 + MutexAutoLock lock(mFifoInfoLock);
1.284 +
1.285 + for (FifoInfoArray::index_type i = 0; i < mFifoInfo.Length(); i++)
1.286 + {
1.287 + if (mFifoInfo[i].mCommand.Equals(aCommand)) {
1.288 + LOG("Register command(%s) callback failed! (DUPLICATE)", aCommand.get());
1.289 + return;
1.290 + }
1.291 + }
1.292 + FifoInfo aFifoInfo = { aCommand, aCallback };
1.293 + mFifoInfo.AppendElement(aFifoInfo);
1.294 +}
1.295 +
1.296 +FifoWatcher::~FifoWatcher()
1.297 +{
1.298 +}
1.299 +
1.300 +int FifoWatcher::OpenFd()
1.301 +{
1.302 + // If the memory_info_dumper.directory pref is specified, put the fifo
1.303 + // there. Otherwise, put it into the system's tmp directory.
1.304 +
1.305 + nsCOMPtr<nsIFile> file;
1.306 +
1.307 + nsresult rv;
1.308 + if (mDirPath.Length() > 0) {
1.309 + rv = XRE_GetFileFromPath(mDirPath.get(), getter_AddRefs(file));
1.310 + if (NS_FAILED(rv)) {
1.311 + LOG("FifoWatcher failed to open file \"%s\"", mDirPath.get());
1.312 + return -1;
1.313 + }
1.314 + } else {
1.315 + rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, getter_AddRefs(file));
1.316 + if (NS_WARN_IF(NS_FAILED(rv)))
1.317 + return -1;
1.318 + }
1.319 +
1.320 + rv = file->AppendNative(NS_LITERAL_CSTRING("debug_info_trigger"));
1.321 + if (NS_WARN_IF(NS_FAILED(rv)))
1.322 + return -1;
1.323 +
1.324 + nsAutoCString path;
1.325 + rv = file->GetNativePath(path);
1.326 + if (NS_WARN_IF(NS_FAILED(rv)))
1.327 + return -1;
1.328 +
1.329 + // unlink might fail because the file doesn't exist, or for other reasons.
1.330 + // But we don't care it fails; any problems will be detected later, when we
1.331 + // try to mkfifo or open the file.
1.332 + if (unlink(path.get())) {
1.333 + LOG("FifoWatcher::OpenFifo unlink failed; errno=%d. "
1.334 + "Continuing despite error.", errno);
1.335 + }
1.336 +
1.337 + if (mkfifo(path.get(), 0766)) {
1.338 + LOG("FifoWatcher::OpenFifo mkfifo failed; errno=%d", errno);
1.339 + return -1;
1.340 + }
1.341 +
1.342 +#ifdef ANDROID
1.343 + // Android runs with a umask, so we need to chmod our fifo to make it
1.344 + // world-writable.
1.345 + chmod(path.get(), 0666);
1.346 +#endif
1.347 +
1.348 + int fd;
1.349 + do {
1.350 + // The fifo will block until someone else has written to it. In
1.351 + // particular, open() will block until someone else has opened it for
1.352 + // writing! We want open() to succeed and read() to block, so we open
1.353 + // with NONBLOCK and then fcntl that away.
1.354 + fd = open(path.get(), O_RDONLY | O_NONBLOCK);
1.355 + } while (fd == -1 && errno == EINTR);
1.356 +
1.357 + if (fd == -1) {
1.358 + LOG("FifoWatcher::OpenFifo open failed; errno=%d", errno);
1.359 + return -1;
1.360 + }
1.361 +
1.362 + // Make fd blocking now that we've opened it.
1.363 + if (fcntl(fd, F_SETFL, 0)) {
1.364 + close(fd);
1.365 + return -1;
1.366 + }
1.367 +
1.368 + return fd;
1.369 +}
1.370 +
1.371 +void FifoWatcher::OnFileCanReadWithoutBlocking(int aFd)
1.372 +{
1.373 + MOZ_ASSERT(XRE_GetIOMessageLoop() == MessageLoopForIO::current());
1.374 +
1.375 + char buf[1024];
1.376 + int nread;
1.377 + do {
1.378 + // sizeof(buf) - 1 to leave space for the null-terminator.
1.379 + nread = read(aFd, buf, sizeof(buf));
1.380 + } while(nread == -1 && errno == EINTR);
1.381 +
1.382 + if (nread == -1) {
1.383 + // We want to avoid getting into a situation where
1.384 + // OnFileCanReadWithoutBlocking is called in an infinite loop, so when
1.385 + // something goes wrong, stop watching the fifo altogether.
1.386 + LOG("FifoWatcher hit an error (%d) and is quitting.", errno);
1.387 + StopWatching();
1.388 + return;
1.389 + }
1.390 +
1.391 + if (nread == 0) {
1.392 + // If we get EOF, that means that the other side closed the fifo. We need
1.393 + // to close and re-open the fifo; if we don't,
1.394 + // OnFileCanWriteWithoutBlocking will be called in an infinite loop.
1.395 +
1.396 + LOG("FifoWatcher closing and re-opening fifo.");
1.397 + StopWatching();
1.398 + StartWatching();
1.399 + return;
1.400 + }
1.401 +
1.402 + nsAutoCString inputStr;
1.403 + inputStr.Append(buf, nread);
1.404 +
1.405 + // Trimming whitespace is important because if you do
1.406 + // |echo "foo" >> debug_info_trigger|,
1.407 + // it'll actually write "foo\n" to the fifo.
1.408 + inputStr.Trim("\b\t\r\n");
1.409 +
1.410 + {
1.411 + MutexAutoLock lock(mFifoInfoLock);
1.412 +
1.413 + for (FifoInfoArray::index_type i = 0; i < mFifoInfo.Length(); i++) {
1.414 + const nsCString commandStr = mFifoInfo[i].mCommand;
1.415 + if(inputStr == commandStr.get()) {
1.416 + mFifoInfo[i].mCallback(inputStr);
1.417 + return;
1.418 + }
1.419 + }
1.420 + }
1.421 + LOG("Got unexpected value from fifo; ignoring it.");
1.422 +}
1.423 +
1.424 +#endif // XP_UNIX }
1.425 +
1.426 +// In Android case, this function will open a file named aFilename under
1.427 +// /data/local/tmp/"aFoldername".
1.428 +// Otherwise, it will open a file named aFilename under "NS_OS_TEMP_DIR".
1.429 +/* static */ nsresult
1.430 +nsDumpUtils::OpenTempFile(const nsACString& aFilename, nsIFile** aFile,
1.431 + const nsACString& aFoldername)
1.432 +{
1.433 +#ifdef ANDROID
1.434 + // For Android, first try the downloads directory which is world-readable
1.435 + // rather than the temp directory which is not.
1.436 + if (!*aFile) {
1.437 + char *env = PR_GetEnv("DOWNLOADS_DIRECTORY");
1.438 + if (env) {
1.439 + NS_NewNativeLocalFile(nsCString(env), /* followLinks = */ true, aFile);
1.440 + }
1.441 + }
1.442 +#endif
1.443 + nsresult rv;
1.444 + if (!*aFile) {
1.445 + rv = NS_GetSpecialDirectory(NS_OS_TEMP_DIR, aFile);
1.446 + if (NS_WARN_IF(NS_FAILED(rv)))
1.447 + return rv;
1.448 + }
1.449 +
1.450 +#ifdef ANDROID
1.451 + // /data/local/tmp is a true tmp directory; anyone can create a file there,
1.452 + // but only the user which created the file can remove it. We want non-root
1.453 + // users to be able to remove these files, so we write them into a
1.454 + // subdirectory of the temp directory and chmod 777 that directory.
1.455 + if (aFoldername != EmptyCString()) {
1.456 + rv = (*aFile)->AppendNative(aFoldername);
1.457 + if (NS_WARN_IF(NS_FAILED(rv)))
1.458 + return rv;
1.459 +
1.460 + // It's OK if this fails; that probably just means that the directory already
1.461 + // exists.
1.462 + (*aFile)->Create(nsIFile::DIRECTORY_TYPE, 0777);
1.463 +
1.464 + nsAutoCString dirPath;
1.465 + rv = (*aFile)->GetNativePath(dirPath);
1.466 + if (NS_WARN_IF(NS_FAILED(rv)))
1.467 + return rv;
1.468 +
1.469 + while (chmod(dirPath.get(), 0777) == -1 && errno == EINTR) {}
1.470 + }
1.471 +#endif
1.472 +
1.473 + nsCOMPtr<nsIFile> file(*aFile);
1.474 +
1.475 + rv = file->AppendNative(aFilename);
1.476 + if (NS_WARN_IF(NS_FAILED(rv)))
1.477 + return rv;
1.478 +
1.479 + rv = file->CreateUnique(nsIFile::NORMAL_FILE_TYPE, 0666);
1.480 + if (NS_WARN_IF(NS_FAILED(rv)))
1.481 + return rv;
1.482 +
1.483 +#ifdef ANDROID
1.484 + // Make this file world-read/writable; the permissions passed to the
1.485 + // CreateUnique call above are not sufficient on Android, which runs with a
1.486 + // umask.
1.487 + nsAutoCString path;
1.488 + rv = file->GetNativePath(path);
1.489 + if (NS_WARN_IF(NS_FAILED(rv)))
1.490 + return rv;
1.491 +
1.492 + while (chmod(path.get(), 0666) == -1 && errno == EINTR) {}
1.493 +#endif
1.494 +
1.495 + return NS_OK;
1.496 +}
