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;
}
