RTR3DECL(int) RTFileChangeLock(RTFILE hFile, unsigned fLock, int64_t offLock, uint64_t cbLock) { Assert(offLock >= 0); /* Check arguments. */ if (fLock & ~RTFILE_LOCK_MASK) { AssertMsgFailed(("Invalid fLock=%08X\n", fLock)); return VERR_INVALID_PARAMETER; } /* Remove old lock. */ int rc = RTFileUnlock(hFile, offLock, cbLock); if (RT_FAILURE(rc)) return rc; /* Set new lock. */ rc = RTFileLock(hFile, fLock, offLock, cbLock); if (RT_SUCCESS(rc)) return rc; /* Try to restore old lock. */ unsigned fLockOld = (fLock & RTFILE_LOCK_WRITE) ? fLock & ~RTFILE_LOCK_WRITE : fLock | RTFILE_LOCK_WRITE; rc = RTFileLock(hFile, fLockOld, offLock, cbLock); if (RT_SUCCESS(rc)) return VERR_FILE_LOCK_VIOLATION; else return VERR_FILE_LOCK_LOST; }
/** * Creates a PID File and returns the open file descriptor. * * On DOS based system, file sharing (deny write) is used for locking the PID * file. * * On Unix-y systems, an exclusive advisory lock is used for locking the PID * file since the file sharing support is usually missing there. * * This API will overwrite any existing PID Files without a lock on them, on the * assumption that they are stale files which an old process did not properly * clean up. * * @returns IPRT status code. * @param pszPath The path and filename to create the PID File under * @param phFile Where to store the file descriptor of the open (and locked * on Unix-y systems) PID File. On failure, or if another * process owns the PID File, this will be set to NIL_RTFILE. */ VBGLR3DECL(int) VbglR3PidFile(const char *pszPath, PRTFILE phFile) { AssertPtrReturn(pszPath, VERR_INVALID_PARAMETER); AssertPtrReturn(phFile, VERR_INVALID_PARAMETER); *phFile = NIL_RTFILE; RTFILE hPidFile; int rc = RTFileOpen(&hPidFile, pszPath, RTFILE_O_READWRITE | RTFILE_O_OPEN_CREATE | RTFILE_O_DENY_WRITE | (0644 << RTFILE_O_CREATE_MODE_SHIFT)); if (RT_SUCCESS(rc)) { #if !defined(RT_OS_WINDOWS) && !defined(RT_OS_OS2) /** @todo using size 0 for locking means lock all on Posix. * We should adopt this as our convention too, or something * similar. */ rc = RTFileLock(hPidFile, RTFILE_LOCK_WRITE, 0, 0); if (RT_FAILURE(rc)) RTFileClose(hPidFile); else #endif { char szBuf[256]; size_t cbPid = RTStrPrintf(szBuf, sizeof(szBuf), "%d\n", RTProcSelf()); RTFileWrite(hPidFile, szBuf, cbPid, NULL); *phFile = hPidFile; } } return rc; }
int main() { RTR3InitExeNoArguments(0); RTPrintf("tstFileLock: TESTING\n"); RTFILE File; int rc = RTFileOpen(&File, "tstLock.tst", RTFILE_O_READWRITE | RTFILE_O_OPEN | RTFILE_O_DENY_NONE); RTPrintf("File open: rc=%Rrc\n", rc); if (RT_FAILURE(rc)) { if (rc != VERR_FILE_NOT_FOUND && rc != VERR_OPEN_FAILED) { RTPrintf("FATAL\n"); return 1; } rc = RTFileOpen(&File, "tstLock.tst", RTFILE_O_READWRITE | RTFILE_O_CREATE | RTFILE_O_DENY_NONE); RTPrintf("File create: rc=%Rrc\n", rc); if (RT_FAILURE(rc)) { RTPrintf("FATAL\n"); return 2; } fRun = true; } /* grow file a little */ rc = RTFileSetSize(File, fRun ? 2048 : 20480); RTPrintf("File size: rc=%Rrc\n", rc); int buf; /* read test. */ rc = RTFileRead(File, &buf, sizeof(buf), NULL); RTPrintf("Read: rc=%Rrc\n", rc); /* write test. */ rc = RTFileWrite(File, achTest1, strlen(achTest1), NULL); RTPrintf("Write: rc=%Rrc\n", rc); /* lock: read, non-blocking. */ rc = RTFileLock(File, RTFILE_LOCK_READ | RTFILE_LOCK_IMMEDIATELY, 0, _4G); RTPrintf("Lock: read, non-blocking, rc=%Rrc\n", rc); bool fl = RT_SUCCESS(rc); /* read test. */ rc = RTFileRead(File, &buf, sizeof(buf), NULL); RTPrintf("Read: rc=%Rrc\n", rc); /* write test. */ rc = RTFileWrite(File, achTest2, strlen(achTest2), NULL); RTPrintf("Write: rc=%Rrc\n", rc); RTPrintf("Lock test will change in three seconds\n"); for (int i = 0; i < 3; i++) { RTThreadSleep(1000); RTPrintf("."); } RTPrintf("\n"); /* change lock: write, non-blocking. */ rc = RTFileLock(File, RTFILE_LOCK_WRITE | RTFILE_LOCK_IMMEDIATELY, 0, _4G); RTPrintf("Change lock: write, non-blocking, rc=%Rrc\n", rc); RTPrintf("Test will unlock in three seconds\n"); for (int i = 0; i < 3; i++) { RTThreadSleep(1000); RTPrintf("."); } RTPrintf("\n"); /* remove lock. */ if (fl) { fl = false; rc = RTFileUnlock(File, 0, _4G); RTPrintf("Unlock: rc=%Rrc\n", rc); RTPrintf("Write test will lock in three seconds\n"); for (int i = 0; i < 3; i++) { RTThreadSleep(1000); RTPrintf("."); } RTPrintf("\n"); } /* lock: write, non-blocking. */ rc = RTFileLock(File, RTFILE_LOCK_WRITE | RTFILE_LOCK_IMMEDIATELY, 0, _4G); RTPrintf("Lock: write, non-blocking, rc=%Rrc\n", rc); fl = RT_SUCCESS(rc); /* grow file test */ rc = RTFileSetSize(File, fRun ? 2048 : 20480); RTPrintf("File size: rc=%Rrc\n", rc); /* read test. */ rc = RTFileRead(File, &buf, sizeof(buf), NULL); RTPrintf("Read: rc=%Rrc\n", rc); /* write test. */ rc = RTFileWrite(File, achTest3, strlen(achTest3), NULL); RTPrintf("Write: rc=%Rrc\n", rc); RTPrintf("Continuing to next test in three seconds\n"); for (int i = 0; i < 3; i++) { RTThreadSleep(1000); RTPrintf("."); } RTPrintf("\n"); RTFileClose(File); RTFileDelete("tstLock.tst"); RTPrintf("tstFileLock: I've no recollection of this testcase succeeding or not, sorry.\n"); return 0; }