diff options
Diffstat (limited to 'lib/dir_lock.cpp')
| -rw-r--r-- | lib/dir_lock.cpp | 685 |
1 files changed, 0 insertions, 685 deletions
diff --git a/lib/dir_lock.cpp b/lib/dir_lock.cpp deleted file mode 100644 index fb016e1e..00000000 --- a/lib/dir_lock.cpp +++ /dev/null @@ -1,685 +0,0 @@ -// ************************************************************************** -// * This file is part of the FreeFileSync project. It is distributed under * -// * GNU General Public License: http://www.gnu.org/licenses/gpl.html * -// * Copyright (C) Zenju (zenju AT gmx DOT de) - All Rights Reserved * -// ************************************************************************** -#include "dir_lock.h" -#include <utility> -#include <wx/log.h> -#include <memory> -#include <zen/sys_error.h> -#include <zen/thread.h> //includes <boost/thread.hpp> -#include <zen/scope_guard.h> -#include <zen/guid.h> -#include <zen/tick_count.h> -#include <zen/assert_static.h> -#include <zen/int64.h> -#include <zen/file_handling.h> -#include <zen/serialize.h> -#include <zen/optional.h> - -#ifdef ZEN_WIN -#include <tlhelp32.h> -#include <zen/win.h> //includes "windows.h" -#include <zen/long_path_prefix.h> -#include <Sddl.h> //login sid -#include <Lmcons.h> //UNLEN - -#elif defined ZEN_LINUX || defined ZEN_MAC -#include <fcntl.h> //open() -#include <sys/stat.h> // -#include <unistd.h> //getsid() -#include <signal.h> //kill() -#include <pwd.h> //getpwuid_r() -#endif - -using namespace zen; -using namespace std::rel_ops; - - -namespace -{ -const int EMIT_LIFE_SIGN_INTERVAL = 5; //show life sign; unit: [s] -const int POLL_LIFE_SIGN_INTERVAL = 4; //poll for life sign; unit: [s] -const int DETECT_ABANDONED_INTERVAL = 30; //assume abandoned lock; unit: [s] - -const char LOCK_FORMAT_DESCR[] = "FreeFileSync"; -const int LOCK_FORMAT_VER = 2; //lock file format version -} - -//worker thread -class LifeSigns -{ -public: - LifeSigns(const Zstring& lockfilename) : //throw()!!! siehe SharedDirLock() - lockfilename_(lockfilename) {} //thread safety: make deep copy! - - void operator()() const //thread entry - { - try - { - while (true) - { - boost::this_thread::sleep(boost::posix_time::seconds(EMIT_LIFE_SIGN_INTERVAL)); //interruption point! - - //actual work - emitLifeSign(); //throw () - } - } - catch (const std::exception& e) //exceptions must be catched per thread - { - wxSafeShowMessage(L"FreeFileSync - " + _("An exception occurred"), utfCvrtTo<wxString>(e.what()) + L" (Dirlock)"); //simple wxMessageBox won't do for threads - } - } - - void emitLifeSign() const //try to append one byte...; throw() - { - const char buffer[1] = {' '}; -#ifdef ZEN_WIN - //ATTENTION: setting file pointer IS required! => use CreateFile/GENERIC_WRITE + SetFilePointerEx! - //although CreateFile/FILE_APPEND_DATA without SetFilePointerEx works locally, it MAY NOT work on some network shares creating a 4 gig file!!! - - const HANDLE fileHandle = ::CreateFile(applyLongPathPrefix(lockfilename_).c_str(), - GENERIC_READ | GENERIC_WRITE, //use both when writing over network, see comment in file_io.cpp - FILE_SHARE_READ, - nullptr, - OPEN_EXISTING, - FILE_ATTRIBUTE_NORMAL, - nullptr); - if (fileHandle == INVALID_HANDLE_VALUE) - return; - ZEN_ON_SCOPE_EXIT(::CloseHandle(fileHandle)); - - const LARGE_INTEGER moveDist = {}; - if (!::SetFilePointerEx(fileHandle, //__in HANDLE hFile, - moveDist, //__in LARGE_INTEGER liDistanceToMove, - nullptr, //__out_opt PLARGE_INTEGER lpNewFilePointer, - FILE_END)) //__in DWORD dwMoveMethod - return; - - DWORD bytesWritten = 0; //this parameter is NOT optional: http://blogs.msdn.com/b/oldnewthing/archive/2013/04/04/10407417.aspx - if (!::WriteFile(fileHandle, //_In_ HANDLE hFile, - buffer, //_In_ LPCVOID lpBuffer, - 1, //_In_ DWORD nNumberOfBytesToWrite, - &bytesWritten, //_Out_opt_ LPDWORD lpNumberOfBytesWritten, - nullptr)) //_Inout_opt_ LPOVERLAPPED lpOverlapped - return; - -#elif defined ZEN_LINUX || defined ZEN_MAC - const int fileHandle = ::open(lockfilename_.c_str(), O_WRONLY | O_APPEND); - if (fileHandle == -1) - return; - ZEN_ON_SCOPE_EXIT(::close(fileHandle)); - - const ssize_t bytesWritten = ::write(fileHandle, buffer, 1); - (void)bytesWritten; -#endif - } - -private: - const Zstring lockfilename_; //thread local! atomic ref-count => binary value-type semantics! -}; - - -namespace -{ -UInt64 getLockFileSize(const Zstring& filename) //throw FileError -{ -#ifdef ZEN_WIN - WIN32_FIND_DATA fileInfo = {}; - const HANDLE searchHandle = ::FindFirstFile(applyLongPathPrefix(filename).c_str(), &fileInfo); - if (searchHandle != INVALID_HANDLE_VALUE) - { - ::FindClose(searchHandle); - return UInt64(fileInfo.nFileSizeLow, fileInfo.nFileSizeHigh); - } - const wchar_t functionName[] = L"FindFirstFile"; -#elif defined ZEN_LINUX || defined ZEN_MAC - struct ::stat fileInfo = {}; - if (::stat(filename.c_str(), &fileInfo) == 0) //follow symbolic links - return UInt64(fileInfo.st_size); - const wchar_t functionName[] = L"stat"; -#endif - - const ErrorCode lastError = getLastError(); - const std::wstring errorMsg = replaceCpy(_("Cannot read file attributes of %x."), L"%x", fmtFileName(filename)); - const std::wstring errorDescr = formatSystemError(functionName, lastError); - throw FileError(errorMsg, errorDescr); -} - - -Zstring deleteAbandonedLockName(const Zstring& lockfilename) //make sure to NOT change file ending! -{ - const size_t pos = lockfilename.rfind(FILE_NAME_SEPARATOR); //search from end - return pos == Zstring::npos ? Zstr("Del.") + lockfilename : - Zstring(lockfilename.c_str(), pos + 1) + //include path separator - Zstr("Del.") + - afterLast(lockfilename, FILE_NAME_SEPARATOR); //returns the whole string if ch not found -} - - -#ifdef ZEN_WIN -Zstring getLoginSid() //throw FileError -{ - HANDLE hToken = 0; - if (!::OpenProcessToken(::GetCurrentProcess(), //__in HANDLE ProcessHandle, - TOKEN_ALL_ACCESS, //__in DWORD DesiredAccess, - &hToken)) //__out PHANDLE TokenHandle - throw FileError(_("Cannot get process information."), formatSystemError(L"OpenProcessToken", getLastError())); - ZEN_ON_SCOPE_EXIT(::CloseHandle(hToken)); - - DWORD bufferSize = 0; - ::GetTokenInformation(hToken, TokenGroups, nullptr, 0, &bufferSize); - - std::vector<char> buffer(bufferSize); - if (!::GetTokenInformation(hToken, //__in HANDLE TokenHandle, - TokenGroups, //__in TOKEN_INFORMATION_CLASS TokenInformationClass, - &buffer[0], //__out_opt LPVOID TokenInformation, - bufferSize, //__in DWORD TokenInformationLength, - &bufferSize)) //__out PDWORD ReturnLength - throw FileError(_("Cannot get process information."), formatSystemError(L"GetTokenInformation", getLastError())); - - auto groups = reinterpret_cast<const TOKEN_GROUPS*>(&buffer[0]); - - for (DWORD i = 0; i < groups->GroupCount; ++i) - if ((groups->Groups[i].Attributes & SE_GROUP_LOGON_ID) != 0) - { - LPTSTR sidStr = nullptr; - if (!::ConvertSidToStringSid(groups->Groups[i].Sid, //__in PSID Sid, - &sidStr)) //__out LPTSTR *StringSid - throw FileError(_("Cannot get process information."), formatSystemError(L"ConvertSidToStringSid", getLastError())); - ZEN_ON_SCOPE_EXIT(::LocalFree(sidStr)); - return sidStr; - } - throw FileError(_("Cannot get process information."), L"no login found"); //shouldn't happen -} -#endif - - -#ifdef ZEN_WIN -typedef DWORD ProcessId; -typedef DWORD SessionId; -#elif defined ZEN_LINUX || defined ZEN_MAC -typedef pid_t ProcessId; -typedef pid_t SessionId; -#endif - -//return ppid on Windows, sid on Linux/Mac, "no value" if process corresponding to "processId" is not existing -Opt<SessionId> getSessionId(ProcessId processId) //throw FileError -{ -#ifdef ZEN_WIN - //note: ::OpenProcess() is no alternative as it may successfully return for crashed processes! -> remark: "WaitForSingleObject" may identify this case! - HANDLE snapshot = ::CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, //__in DWORD dwFlags, - 0); //__in DWORD th32ProcessID - if (snapshot == INVALID_HANDLE_VALUE) - throw FileError(_("Cannot get process information."), formatSystemError(L"CreateToolhelp32Snapshot", getLastError())); - ZEN_ON_SCOPE_EXIT(::CloseHandle(snapshot)); - - PROCESSENTRY32 processEntry = {}; - processEntry.dwSize = sizeof(processEntry); - - if (!::Process32First(snapshot, //__in HANDLE hSnapshot, - &processEntry)) //__inout LPPROCESSENTRY32 lppe - throw FileError(_("Cannot get process information."), formatSystemError(L"Process32First", getLastError())); //ERROR_NO_MORE_FILES not possible - do - { - if (processEntry.th32ProcessID == processId) //yes, MSDN says this is the way: http://msdn.microsoft.com/en-us/library/windows/desktop/ms684868(v=vs.85).aspx - return processEntry.th32ParentProcessID; //parent id is stable, even if parent process has already terminated! - } - while (::Process32Next(snapshot, &processEntry)); - if (::GetLastError() != ERROR_NO_MORE_FILES) //yes, they call it "files" - throw FileError(_("Cannot get process information."), formatSystemError(L"Process32Next", getLastError())); - - return NoValue(); - -#elif defined ZEN_LINUX || defined ZEN_MAC - if (::kill(processId, 0) != 0) //sig == 0: no signal sent, just existence check - return NoValue(); - - pid_t procSid = ::getsid(processId); //NOT to be confused with "login session", e.g. not stable on OS X!!! - if (procSid == -1) - throw FileError(_("Cannot get process information."), formatSystemError(L"getsid", getLastError())); - - return procSid; -#endif -} - - -class FromCurrentProcess {}; //tag - -struct LockInformation //throw FileError -{ - explicit LockInformation(FromCurrentProcess) : - lockId(zen::generateGUID()), - sessionId(), //dummy value -#ifdef ZEN_WIN - processId(::GetCurrentProcessId()) //never fails - { - DWORD bufferSize = 0; - ::GetComputerNameEx(ComputerNameDnsFullyQualified, nullptr, &bufferSize); //get required buffer size - - std::vector<wchar_t> buffer(bufferSize); - if (!::GetComputerNameEx(ComputerNameDnsFullyQualified, //__in COMPUTER_NAME_FORMAT NameType, - &buffer[0], //__out LPTSTR lpBuffer, - &bufferSize)) //__inout LPDWORD lpnSize - throw FileError(_("Cannot get process information."), formatSystemError(L"GetComputerNameEx", getLastError())); - - computerName = "Windows." + utfCvrtTo<std::string>(&buffer[0]); - - bufferSize = UNLEN + 1; - buffer.resize(bufferSize); - if (!::GetUserName(&buffer[0], //__out LPTSTR lpBuffer, - &bufferSize)) //__inout LPDWORD lpnSize - throw FileError(_("Cannot get process information."), formatSystemError(L"GetUserName", getLastError())); - userId = utfCvrtTo<std::string>(&buffer[0]); - -#elif defined ZEN_LINUX || defined ZEN_MAC - processId(::getpid()) //never fails - { - std::vector<char> buffer(10000); - - if (::gethostname(&buffer[0], buffer.size()) != 0) - throw FileError(_("Cannot get process information."), formatSystemError(L"gethostname", getLastError())); - computerName += "Linux."; //distinguish linux/windows lock files - computerName += &buffer[0]; - - if (::getdomainname(&buffer[0], buffer.size()) != 0) - throw FileError(_("Cannot get process information."), formatSystemError(L"getdomainname", getLastError())); - computerName += "."; - computerName += &buffer[0]; - - const uid_t userIdNo = ::getuid(); //never fails - userId.assign(reinterpret_cast<const char*>(&userIdNo), sizeof(userIdNo)); - - //the id alone is not very distinctive, e.g. often 1000 on Ubuntu => add name - buffer.resize(std::max<long>(buffer.size(), ::sysconf(_SC_GETPW_R_SIZE_MAX))); //::sysconf may return long(-1) - struct passwd buffer2 = {}; - struct passwd* pwsEntry = nullptr; - if (::getpwuid_r(userIdNo, &buffer2, &buffer[0], buffer.size(), &pwsEntry) != 0) //getlogin() is deprecated and not working on Ubuntu at all!!! - throw FileError(_("Cannot get process information."), formatSystemError(L"getpwuid_r", getLastError())); - if (!pwsEntry) - throw FileError(_("Cannot get process information."), L"no login found"); //should not happen? - userId += pwsEntry->pw_name; -#endif - - Opt<SessionId> sessionIdTmp = getSessionId(processId); //throw FileError - if (!sessionIdTmp) - throw FileError(_("Cannot get process information."), L"no session id found"); //should not happen? - sessionId = *sessionIdTmp; - } - - explicit LockInformation(BinStreamIn& stream) //throw UnexpectedEndOfStreamError - { - char tmp[sizeof(LOCK_FORMAT_DESCR)] = {}; - readArray(stream, &tmp, sizeof(tmp)); //file format header - const int lockFileVersion = readNumber<boost::int32_t>(stream); // - - if (!std::equal(std::begin(tmp), std::end(tmp), std::begin(LOCK_FORMAT_DESCR)) || - lockFileVersion != LOCK_FORMAT_VER) - throw UnexpectedEndOfStreamError(); //well, not really...!? - - lockId = readContainer<std::string>(stream); // - computerName = readContainer<std::string>(stream); //UnexpectedEndOfStreamError - userId = readContainer<std::string>(stream); // - sessionId = static_cast<SessionId>(readNumber<std::uint64_t>(stream)); //[!] conversion - processId = static_cast<ProcessId>(readNumber<std::uint64_t>(stream)); //[!] conversion - } - - void toStream(BinStreamOut& stream) const //throw () - { - writeArray(stream, LOCK_FORMAT_DESCR, sizeof(LOCK_FORMAT_DESCR)); - writeNumber<boost::int32_t>(stream, LOCK_FORMAT_VER); - - assert_static(sizeof(processId) <= sizeof(std::uint64_t)); //ensure cross-platform compatibility! - assert_static(sizeof(sessionId) <= sizeof(std::uint64_t)); // - - writeContainer(stream, lockId); - writeContainer(stream, computerName); - writeContainer(stream, userId); - writeNumber<std::uint64_t>(stream, sessionId); - writeNumber<std::uint64_t>(stream, processId); - } - - std::string lockId; //16 byte GUID - a universal identifier for this lock (no matter what the path is, considering symlinks, distributed network, etc.) - - //identify local computer - std::string computerName; //format: HostName.DomainName - std::string userId; - - //identify running process - SessionId sessionId; //Windows: parent process id; Linux/OS X: session of the process, NOT the user - ProcessId processId; -}; - - -//wxGetFullHostName() is a performance killer for some users, so don't touch! - - -LockInformation retrieveLockInfo(const Zstring& lockfilename) //throw FileError -{ - BinStreamIn streamIn = loadBinStream<BinaryStream>(lockfilename); //throw FileError - try - { - return LockInformation(streamIn); //throw UnexpectedEndOfStreamError - } - catch (UnexpectedEndOfStreamError&) - { - throw FileError(replaceCpy(_("Cannot read file %x."), L"%x", fmtFileName(lockfilename)), L"unexpected end of stream"); - } -} - - -inline -std::string retrieveLockId(const Zstring& lockfilename) //throw FileError -{ - return retrieveLockInfo(lockfilename).lockId; //throw FileError -} - - -enum ProcessStatus -{ - PROC_STATUS_NOT_RUNNING, - PROC_STATUS_RUNNING, - PROC_STATUS_ITS_US, - PROC_STATUS_CANT_TELL -}; - -ProcessStatus getProcessStatus(const LockInformation& lockInfo) //throw FileError -{ - const LockInformation localInfo((FromCurrentProcess())); //throw FileError - - if (lockInfo.computerName != localInfo.computerName || - lockInfo.userId != localInfo.userId) //another user may run a session right now! - return PROC_STATUS_CANT_TELL; //lock owned by different computer in this network - - if (lockInfo.sessionId == localInfo.sessionId && - lockInfo.processId == localInfo.processId) //obscure, but possible: deletion failed or a lock file is "stolen" and put back while the program is running - return PROC_STATUS_ITS_US; - - if (Opt<SessionId> sessionId = getSessionId(lockInfo.processId)) //throw FileError - return *sessionId == lockInfo.sessionId ? PROC_STATUS_RUNNING : PROC_STATUS_NOT_RUNNING; - return PROC_STATUS_NOT_RUNNING; -} - - -const std::int64_t TICKS_PER_SEC = ticksPerSec(); //= 0 on error - - -void waitOnDirLock(const Zstring& lockfilename, DirLockCallback* callback) //throw FileError -{ - const std::wstring infoMsg = replaceCpy(_("Waiting while directory is locked (%x)..."), L"%x", fmtFileName(lockfilename)); - - if (callback) - callback->reportStatus(infoMsg); - //--------------------------------------------------------------- - try - { - //convenience optimization only: if we know the owning process crashed, we needn't wait DETECT_ABANDONED_INTERVAL sec - bool lockOwnderDead = false; - std::string originalLockId; //empty if it cannot be retrieved - try - { - const LockInformation& lockInfo = retrieveLockInfo(lockfilename); //throw FileError - originalLockId = lockInfo.lockId; - switch (getProcessStatus(lockInfo)) //throw FileError - { - case PROC_STATUS_ITS_US: //since we've already passed LockAdmin, the lock file seems abandoned ("stolen"?) although it's from this process - case PROC_STATUS_NOT_RUNNING: - lockOwnderDead = true; - break; - case PROC_STATUS_RUNNING: - case PROC_STATUS_CANT_TELL: - break; - } - } - catch (FileError&) {} //logfile may be only partly written -> this is no error! - - UInt64 fileSizeOld; - TickVal lastLifeSign = getTicks(); - - while (true) - { - const TickVal now = getTicks(); - const UInt64 fileSizeNew = ::getLockFileSize(lockfilename); //throw FileError - - if (TICKS_PER_SEC <= 0 || !lastLifeSign.isValid() || !now.isValid()) - throw FileError(L"System timer failed."); //no i18n: "should" never throw ;) - - if (fileSizeNew != fileSizeOld) //received life sign from lock - { - fileSizeOld = fileSizeNew; - lastLifeSign = now; - } - - if (lockOwnderDead || //no need to wait any longer... - dist(lastLifeSign, now) / TICKS_PER_SEC > DETECT_ABANDONED_INTERVAL) - { - DirLock dummy(deleteAbandonedLockName(lockfilename), callback); //throw FileError - - //now that the lock is in place check existence again: meanwhile another process may have deleted and created a new lock! - - if (!originalLockId.empty()) - if (retrieveLockId(lockfilename) != originalLockId) //throw FileError -> since originalLockId is filled, we are not expecting errors! - return; //another process has placed a new lock, leave scope: the wait for the old lock is technically over... - - if (::getLockFileSize(lockfilename) != fileSizeOld) //throw FileError - continue; //late life sign - - removeFile(lockfilename); //throw FileError - return; - } - - //wait some time... - assert_static(1000 * POLL_LIFE_SIGN_INTERVAL % GUI_CALLBACK_INTERVAL == 0); - for (size_t i = 0; i < 1000 * POLL_LIFE_SIGN_INTERVAL / GUI_CALLBACK_INTERVAL; ++i) - { - if (callback) callback->requestUiRefresh(); - boost::this_thread::sleep(boost::posix_time::milliseconds(GUI_CALLBACK_INTERVAL)); - - if (callback) - { - //one signal missed: it's likely this is an abandoned lock => show countdown - if (dist(lastLifeSign, now) / TICKS_PER_SEC > EMIT_LIFE_SIGN_INTERVAL) - { - const int remainingSeconds = std::max<int>(0, DETECT_ABANDONED_INTERVAL - dist(lastLifeSign, getTicks()) / TICKS_PER_SEC); - const std::wstring remSecMsg = replaceCpy(_P("1 sec", "%x sec", remainingSeconds), L"%x", numberTo<std::wstring>(remainingSeconds)); - callback->reportStatus(infoMsg + L" " + remSecMsg); - } - else - callback->reportStatus(infoMsg); //emit a message in any case (might clear other one) - } - } - } - } - catch (FileError&) - { - if (!somethingExists(lockfilename)) //a benign(?) race condition with FileError - return; //what we are waiting for... - throw; - } -} - - -void releaseLock(const Zstring& lockfilename) //throw () -{ - try - { - removeFile(lockfilename); //throw FileError - } - catch (FileError&) {} -} - - -bool tryLock(const Zstring& lockfilename) //throw FileError -{ -#ifdef ZEN_WIN - const HANDLE fileHandle = ::CreateFile(applyLongPathPrefix(lockfilename).c_str(), - GENERIC_READ | GENERIC_WRITE, //use both when writing over network, see comment in file_io.cpp - FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, - nullptr, - CREATE_NEW, - FILE_ATTRIBUTE_NORMAL, - nullptr); - if (fileHandle == INVALID_HANDLE_VALUE) - { - const DWORD lastError = ::GetLastError(); - if (lastError == ERROR_FILE_EXISTS || //confirmed to be used - lastError == ERROR_ALREADY_EXISTS) //comment on msdn claims, this one is used on Windows Mobile 6 - return false; - else - throw FileError(replaceCpy(_("Cannot write file %x."), L"%x", fmtFileName(lockfilename)), formatSystemError(L"CreateFile", getLastError())); - } - ScopeGuard guardLockFile = zen::makeGuard([&] { removeFile(lockfilename); }); - FileOutput fileOut(fileHandle, lockfilename); //pass handle ownership - - //be careful to avoid CreateFile() + CREATE_ALWAYS on a hidden file -> see file_io.cpp - //=> we don't need it that badly //::SetFileAttributes(applyLongPathPrefix(lockfilename).c_str(), FILE_ATTRIBUTE_HIDDEN); //(try to) hide it - -#elif defined ZEN_LINUX || defined ZEN_MAC - ::umask(0); //important! -> why? - //O_EXCL contains a race condition on NFS file systems: http://linux.die.net/man/2/open - const int fileHandle = ::open(lockfilename.c_str(), O_CREAT | O_WRONLY | O_EXCL, S_IRWXU | S_IRWXG | S_IRWXO); - if (fileHandle == -1) - { - if (errno == EEXIST) - return false; - else - throw FileError(replaceCpy(_("Cannot write file %x."), L"%x", fmtFileName(lockfilename)), formatSystemError(L"open", getLastError())); - } - ScopeGuard guardLockFile = zen::makeGuard([&] { removeFile(lockfilename); }); - FileOutputUnbuffered fileOut(fileHandle, lockfilename); //pass handle ownership -#endif - - //write housekeeping info: user, process info, lock GUID - BinaryStream binStream; - { - BinStreamOut streamOut; - LockInformation(FromCurrentProcess()).toStream(streamOut); - binStream = streamOut.get(); - } - if (!binStream.empty()) - fileOut.write(&*binStream.begin(), binStream.size()); //throw FileError - - guardLockFile.dismiss(); //lockfile created successfully - return true; -} -} - - -class DirLock::SharedDirLock -{ -public: - SharedDirLock(const Zstring& lockfilename, DirLockCallback* callback) : //throw FileError - lockfilename_(lockfilename) - { - while (!::tryLock(lockfilename)) //throw FileError - ::waitOnDirLock(lockfilename, callback); // - - threadObj = boost::thread(LifeSigns(lockfilename)); - } - - ~SharedDirLock() - { - threadObj.interrupt(); //thread lifetime is subset of this instances's life - threadObj.join(); //we assert precondition "threadObj.joinable()"!!! - - ::releaseLock(lockfilename_); //throw () - } - -private: - SharedDirLock(const DirLock&); - SharedDirLock& operator=(const DirLock&); - - const Zstring lockfilename_; - boost::thread threadObj; -}; - - -class DirLock::LockAdmin //administrate all locks held by this process to avoid deadlock by recursion -{ -public: - static LockAdmin& instance() - { - static LockAdmin inst; - return inst; - } - - //create or retrieve a SharedDirLock - std::shared_ptr<SharedDirLock> retrieve(const Zstring& lockfilename, DirLockCallback* callback) //throw FileError - { - tidyUp(); - - //optimization: check if we already own a lock for this path - auto iterGuid = fileToGuid.find(lockfilename); - if (iterGuid != fileToGuid.end()) - if (const std::shared_ptr<SharedDirLock>& activeLock = getActiveLock(iterGuid->second)) //returns null-lock if not found - return activeLock; //SharedDirLock is still active -> enlarge circle of shared ownership - - try //check based on lock GUID, deadlock prevention: "lockfilename" may be an alternative name for a lock already owned by this process - { - const std::string lockId = retrieveLockId(lockfilename); //throw FileError - if (const std::shared_ptr<SharedDirLock>& activeLock = getActiveLock(lockId)) //returns null-lock if not found - { - fileToGuid[lockfilename] = lockId; //found an alias for one of our active locks - return activeLock; - } - } - catch (FileError&) {} //catch everything, let SharedDirLock constructor deal with errors, e.g. 0-sized/corrupted lock files - - //lock not owned by us => create a new one - auto newLock = std::make_shared<SharedDirLock>(lockfilename, callback); //throw FileError - const std::string& newLockGuid = retrieveLockId(lockfilename); //throw FileError - - //update registry - fileToGuid[lockfilename] = newLockGuid; //throw() - guidToLock[newLockGuid] = newLock; // - - return newLock; - } - -private: - LockAdmin() {} - LockAdmin(const LockAdmin&); //=delete - LockAdmin& operator=(const LockAdmin&); //=delete - - typedef std::string UniqueId; - typedef std::map<Zstring, UniqueId, LessFilename> FileToGuidMap; //n:1 handle uppper/lower case correctly - typedef std::map<UniqueId, std::weak_ptr<SharedDirLock>> GuidToLockMap; //1:1 - - std::shared_ptr<SharedDirLock> getActiveLock(const UniqueId& lockId) //returns null if none found - { - auto iterLock = guidToLock.find(lockId); - return iterLock != guidToLock.end() ? iterLock->second.lock() : nullptr; //try to get shared_ptr; throw() - } - - void tidyUp() //remove obsolete lock entries - { - map_remove_if(guidToLock, [ ](const GuidToLockMap::value_type& v) { return !v.second.lock(); }); - map_remove_if(fileToGuid, [&](const FileToGuidMap::value_type& v) { return guidToLock.find(v.second) == guidToLock.end(); }); - } - - FileToGuidMap fileToGuid; //lockname |-> GUID; locks can be referenced by a lockfilename or alternatively a GUID - GuidToLockMap guidToLock; //GUID |-> "shared lock ownership" -}; - - -DirLock::DirLock(const Zstring& lockfilename, DirLockCallback* callback) //throw FileError -{ - if (callback) - callback->reportStatus(replaceCpy(_("Creating file %x"), L"%x", fmtFileName(lockfilename))); - -#ifdef ZEN_WIN - const DWORD bufferSize = 10000; - std::vector<wchar_t> volName(bufferSize); - if (::GetVolumePathName(lockfilename.c_str(), //__in LPCTSTR lpszFileName, - &volName[0], //__out LPTSTR lpszVolumePathName, - bufferSize)) //__in DWORD cchBufferLength - { - DWORD dt = ::GetDriveType(&volName[0]); - if (dt == DRIVE_CDROM) - return; //we don't need a lock for a CD ROM - } -#endif - - sharedLock = LockAdmin::instance().retrieve(lockfilename, callback); //throw FileError -} |