| 1 | /////////////////////////////////////////////////////////////////////////////// |
| 2 | // Name: src/unix/snglinst.cpp |
| 3 | // Purpose: implements wxSingleInstanceChecker class for Unix using |
| 4 | // lock files with fcntl(2) or flock(2) |
| 5 | // Author: Vadim Zeitlin |
| 6 | // Modified by: |
| 7 | // Created: 09.06.01 |
| 8 | // RCS-ID: $Id$ |
| 9 | // Copyright: (c) 2001 Vadim Zeitlin <zeitlin@dptmaths.ens-cachan.fr> |
| 10 | // Licence: wxWindows licence |
| 11 | /////////////////////////////////////////////////////////////////////////////// |
| 12 | |
| 13 | // ============================================================================ |
| 14 | // declarations |
| 15 | // ============================================================================ |
| 16 | |
| 17 | // ---------------------------------------------------------------------------- |
| 18 | // headers |
| 19 | // ---------------------------------------------------------------------------- |
| 20 | |
| 21 | // For compilers that support precompilation, includes "wx.h". |
| 22 | #include "wx/wxprec.h" |
| 23 | |
| 24 | #ifdef __BORLANDC__ |
| 25 | #pragma hdrstop |
| 26 | #endif |
| 27 | |
| 28 | #if wxUSE_SNGLINST_CHECKER |
| 29 | |
| 30 | #ifndef WX_PRECOMP |
| 31 | #include "wx/string.h" |
| 32 | #include "wx/log.h" |
| 33 | #include "wx/intl.h" |
| 34 | #include "wx/utils.h" // wxGetHomeDir() |
| 35 | #endif //WX_PRECOMP |
| 36 | |
| 37 | #include "wx/file.h" |
| 38 | |
| 39 | #include "wx/snglinst.h" |
| 40 | |
| 41 | #include <unistd.h> |
| 42 | #include <sys/types.h> |
| 43 | #include <sys/stat.h> // for S_I[RW]USR |
| 44 | #include <signal.h> // for kill() |
| 45 | #include <errno.h> |
| 46 | |
| 47 | #ifdef HAVE_FCNTL |
| 48 | #include <fcntl.h> |
| 49 | #elif defined(HAVE_FLOCK) |
| 50 | #include <sys/file.h> |
| 51 | #else |
| 52 | // normally, wxUSE_SNGLINST_CHECKER must have been reset by configure |
| 53 | #error "wxSingleInstanceChecker can't be compiled on this platform" |
| 54 | #endif // fcntl()/flock() |
| 55 | |
| 56 | // ---------------------------------------------------------------------------- |
| 57 | // constants |
| 58 | // ---------------------------------------------------------------------------- |
| 59 | |
| 60 | // argument of wxLockFile() |
| 61 | enum LockOperation |
| 62 | { |
| 63 | LOCK, |
| 64 | UNLOCK |
| 65 | }; |
| 66 | |
| 67 | // return value of CreateLockFile() |
| 68 | enum LockResult |
| 69 | { |
| 70 | LOCK_ERROR = -1, |
| 71 | LOCK_EXISTS, |
| 72 | LOCK_CREATED |
| 73 | }; |
| 74 | |
| 75 | // ---------------------------------------------------------------------------- |
| 76 | // private functions: (exclusively) lock/unlock the file |
| 77 | // ---------------------------------------------------------------------------- |
| 78 | |
| 79 | #ifdef HAVE_FCNTL |
| 80 | |
| 81 | static int wxLockFile(int fd, LockOperation lock) |
| 82 | { |
| 83 | // init the flock parameter struct |
| 84 | struct flock fl; |
| 85 | fl.l_type = lock == LOCK ? F_WRLCK : F_UNLCK; |
| 86 | |
| 87 | // lock the entire file |
| 88 | fl.l_start = |
| 89 | fl.l_len = |
| 90 | fl.l_whence = 0; |
| 91 | |
| 92 | // is this needed? |
| 93 | fl.l_pid = getpid(); |
| 94 | |
| 95 | return fcntl(fd, F_SETLK, &fl); |
| 96 | } |
| 97 | |
| 98 | #else // HAVE_FLOCK |
| 99 | |
| 100 | static int wxLockFile(int fd, LockOperation lock) |
| 101 | { |
| 102 | return flock(fd, lock == LOCK ? LOCK_EX | LOCK_NB : LOCK_UN); |
| 103 | } |
| 104 | |
| 105 | #endif // fcntl()/flock() |
| 106 | |
| 107 | // ---------------------------------------------------------------------------- |
| 108 | // wxSingleInstanceCheckerImpl: the real implementation class |
| 109 | // ---------------------------------------------------------------------------- |
| 110 | |
| 111 | class wxSingleInstanceCheckerImpl |
| 112 | { |
| 113 | public: |
| 114 | wxSingleInstanceCheckerImpl() |
| 115 | { |
| 116 | m_fdLock = -1; |
| 117 | m_pidLocker = 0; |
| 118 | } |
| 119 | |
| 120 | bool Create(const wxString& name); |
| 121 | |
| 122 | pid_t GetLockerPID() const { return m_pidLocker; } |
| 123 | |
| 124 | ~wxSingleInstanceCheckerImpl() { Unlock(); } |
| 125 | |
| 126 | private: |
| 127 | // try to create and lock the file |
| 128 | LockResult CreateLockFile(); |
| 129 | |
| 130 | // unlock and remove the lock file |
| 131 | void Unlock(); |
| 132 | |
| 133 | // the descriptor of our lock file, -1 if none |
| 134 | int m_fdLock; |
| 135 | |
| 136 | // pid of the process owning the lock file |
| 137 | pid_t m_pidLocker; |
| 138 | |
| 139 | // the name of the lock file |
| 140 | wxString m_nameLock; |
| 141 | }; |
| 142 | |
| 143 | // ============================================================================ |
| 144 | // wxSingleInstanceCheckerImpl implementation |
| 145 | // ============================================================================ |
| 146 | |
| 147 | LockResult wxSingleInstanceCheckerImpl::CreateLockFile() |
| 148 | { |
| 149 | // try to open the file |
| 150 | m_fdLock = open(m_nameLock.fn_str(), |
| 151 | O_WRONLY | O_CREAT | O_EXCL, |
| 152 | S_IRUSR | S_IWUSR); |
| 153 | |
| 154 | if ( m_fdLock != -1 ) |
| 155 | { |
| 156 | // try to lock it |
| 157 | if ( wxLockFile(m_fdLock, LOCK) == 0 ) |
| 158 | { |
| 159 | // fine, we have the exclusive lock to the file, write our PID |
| 160 | // into it |
| 161 | m_pidLocker = getpid(); |
| 162 | |
| 163 | // use char here, not wxChar! |
| 164 | char buf[256]; // enough for any PID size |
| 165 | int len = sprintf(buf, "%d", (int)m_pidLocker) + 1; |
| 166 | |
| 167 | if ( write(m_fdLock, buf, len) != len ) |
| 168 | { |
| 169 | wxLogSysError(_("Failed to write to lock file '%s'"), |
| 170 | m_nameLock.c_str()); |
| 171 | |
| 172 | Unlock(); |
| 173 | |
| 174 | return LOCK_ERROR; |
| 175 | } |
| 176 | |
| 177 | fsync(m_fdLock); |
| 178 | |
| 179 | // change file's permission so that only this user can access it: |
| 180 | if ( chmod(m_nameLock.fn_str(), S_IRUSR | S_IWUSR) != 0 ) |
| 181 | { |
| 182 | wxLogSysError(_("Failed to set permissions on lock file '%s'"), |
| 183 | m_nameLock.c_str()); |
| 184 | |
| 185 | Unlock(); |
| 186 | |
| 187 | return LOCK_ERROR; |
| 188 | } |
| 189 | |
| 190 | return LOCK_CREATED; |
| 191 | } |
| 192 | else // failure: see what exactly happened |
| 193 | { |
| 194 | close(m_fdLock); |
| 195 | m_fdLock = -1; |
| 196 | |
| 197 | if ( errno != EACCES && errno != EAGAIN ) |
| 198 | { |
| 199 | wxLogSysError(_("Failed to lock the lock file '%s'"), |
| 200 | m_nameLock.c_str()); |
| 201 | |
| 202 | unlink(m_nameLock.fn_str()); |
| 203 | |
| 204 | return LOCK_ERROR; |
| 205 | } |
| 206 | //else: couldn't lock because the lock is held by another process: |
| 207 | // this might have happened because of a race condition: |
| 208 | // maybe another instance opened and locked the file between |
| 209 | // our calls to open() and flock(), so don't give an error |
| 210 | } |
| 211 | } |
| 212 | |
| 213 | // we didn't create and lock the file |
| 214 | return LOCK_EXISTS; |
| 215 | } |
| 216 | |
| 217 | bool wxSingleInstanceCheckerImpl::Create(const wxString& name) |
| 218 | { |
| 219 | m_nameLock = name; |
| 220 | |
| 221 | switch ( CreateLockFile() ) |
| 222 | { |
| 223 | case LOCK_EXISTS: |
| 224 | // there is a lock file, check below if it is still valid |
| 225 | break; |
| 226 | |
| 227 | case LOCK_CREATED: |
| 228 | // nothing more to do |
| 229 | return true; |
| 230 | |
| 231 | case LOCK_ERROR: |
| 232 | // oops... |
| 233 | return false; |
| 234 | } |
| 235 | |
| 236 | // Check if the file is owned by current user and has 0600 permissions. |
| 237 | // If it doesn't, it's a fake file, possibly meant as a DoS attack, and |
| 238 | // so we refuse to touch it: |
| 239 | wxStructStat stats; |
| 240 | if ( wxStat(name, &stats) != 0 ) |
| 241 | { |
| 242 | wxLogSysError(_("Failed to inspect the lock file '%s'"), name.c_str()); |
| 243 | return false; |
| 244 | } |
| 245 | if ( stats.st_uid != getuid() ) |
| 246 | { |
| 247 | wxLogError(_("Lock file '%s' has incorrect owner."), name.c_str()); |
| 248 | return false; |
| 249 | } |
| 250 | if ( stats.st_mode != (S_IFREG | S_IRUSR | S_IWUSR) ) |
| 251 | { |
| 252 | wxLogError(_("Lock file '%s' has incorrect permissions."), name.c_str()); |
| 253 | return false; |
| 254 | } |
| 255 | |
| 256 | // try to open the file for reading and get the PID of the process |
| 257 | // which has it |
| 258 | wxFile file(name, wxFile::read); |
| 259 | if ( !file.IsOpened() ) |
| 260 | { |
| 261 | // well, this is really weird - file doesn't exist and we can't |
| 262 | // create it |
| 263 | // |
| 264 | // normally, this just means that we don't have write access to |
| 265 | // the directory where we try to create it, so return failure, |
| 266 | // even it might also be a rare case of a race condition when |
| 267 | // another process managed to open and lock the file and terminate |
| 268 | // (erasing it) before we got here, but this should happen so |
| 269 | // rarely in practice that we don't care |
| 270 | wxLogError(_("Failed to access lock file.")); |
| 271 | |
| 272 | return false; |
| 273 | } |
| 274 | |
| 275 | char buf[256]; |
| 276 | ssize_t count = file.Read(buf, WXSIZEOF(buf)); |
| 277 | if ( count == wxInvalidOffset ) |
| 278 | { |
| 279 | wxLogError(_("Failed to read PID from lock file.")); |
| 280 | } |
| 281 | else |
| 282 | { |
| 283 | if ( sscanf(buf, "%d", (int *)&m_pidLocker) == 1 ) |
| 284 | { |
| 285 | if ( kill(m_pidLocker, 0) != 0 ) |
| 286 | { |
| 287 | if ( unlink(name.fn_str()) != 0 ) |
| 288 | { |
| 289 | wxLogError(_("Failed to remove stale lock file '%s'."), |
| 290 | name.c_str()); |
| 291 | |
| 292 | // return true in this case for now... |
| 293 | } |
| 294 | else |
| 295 | { |
| 296 | wxLogMessage(_("Deleted stale lock file '%s'."), |
| 297 | name.c_str()); |
| 298 | |
| 299 | // retry now |
| 300 | (void)CreateLockFile(); |
| 301 | } |
| 302 | } |
| 303 | //else: the other process is running |
| 304 | } |
| 305 | else |
| 306 | { |
| 307 | wxLogWarning(_("Invalid lock file '%s'."), name.c_str()); |
| 308 | } |
| 309 | } |
| 310 | |
| 311 | // return true if we could get the PID of the process owning the lock file |
| 312 | // (whether it is still running or not), FALSE otherwise as it is |
| 313 | // unexpected |
| 314 | return m_pidLocker != 0; |
| 315 | } |
| 316 | |
| 317 | void wxSingleInstanceCheckerImpl::Unlock() |
| 318 | { |
| 319 | if ( m_fdLock != -1 ) |
| 320 | { |
| 321 | if ( unlink(m_nameLock.fn_str()) != 0 ) |
| 322 | { |
| 323 | wxLogSysError(_("Failed to remove lock file '%s'"), |
| 324 | m_nameLock.c_str()); |
| 325 | } |
| 326 | |
| 327 | if ( wxLockFile(m_fdLock, UNLOCK) != 0 ) |
| 328 | { |
| 329 | wxLogSysError(_("Failed to unlock lock file '%s'"), |
| 330 | m_nameLock.c_str()); |
| 331 | } |
| 332 | |
| 333 | if ( close(m_fdLock) != 0 ) |
| 334 | { |
| 335 | wxLogSysError(_("Failed to close lock file '%s'"), |
| 336 | m_nameLock.c_str()); |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | m_pidLocker = 0; |
| 341 | } |
| 342 | |
| 343 | // ============================================================================ |
| 344 | // wxSingleInstanceChecker implementation |
| 345 | // ============================================================================ |
| 346 | |
| 347 | bool wxSingleInstanceChecker::Create(const wxString& name, |
| 348 | const wxString& path) |
| 349 | { |
| 350 | wxASSERT_MSG( !m_impl, |
| 351 | wxT("calling wxSingleInstanceChecker::Create() twice?") ); |
| 352 | |
| 353 | // must have the file name to create a lock file |
| 354 | wxASSERT_MSG( !name.empty(), wxT("lock file name can't be empty") ); |
| 355 | |
| 356 | m_impl = new wxSingleInstanceCheckerImpl; |
| 357 | |
| 358 | wxString fullname = path; |
| 359 | if ( fullname.empty() ) |
| 360 | { |
| 361 | fullname = wxGetHomeDir(); |
| 362 | } |
| 363 | |
| 364 | if ( fullname.Last() != wxT('/') ) |
| 365 | { |
| 366 | fullname += wxT('/'); |
| 367 | } |
| 368 | |
| 369 | fullname << name; |
| 370 | |
| 371 | return m_impl->Create(fullname); |
| 372 | } |
| 373 | |
| 374 | bool wxSingleInstanceChecker::DoIsAnotherRunning() const |
| 375 | { |
| 376 | wxCHECK_MSG( m_impl, false, wxT("must call Create() first") ); |
| 377 | |
| 378 | const pid_t lockerPid = m_impl->GetLockerPID(); |
| 379 | |
| 380 | if ( !lockerPid ) |
| 381 | { |
| 382 | // we failed to open the lock file, return false as we're definitely |
| 383 | // not sure that another our process is running and so it's better not |
| 384 | // to prevent this one from starting up |
| 385 | return false; |
| 386 | } |
| 387 | |
| 388 | // if another instance is running, it must own the lock file - otherwise |
| 389 | // we have it and the locker PID is ours one |
| 390 | return lockerPid != getpid(); |
| 391 | } |
| 392 | |
| 393 | wxSingleInstanceChecker::~wxSingleInstanceChecker() |
| 394 | { |
| 395 | delete m_impl; |
| 396 | } |
| 397 | |
| 398 | #endif // wxUSE_SNGLINST_CHECKER |