# define UNIXFILE_DIRSYNC    0x00
#endif
#define UNIXFILE_PSOW        0x10     /* SQLITE_IOCAP_POWERSAFE_OVERWRITE */
#define UNIXFILE_DELETE      0x20     /* Delete on close */
#define UNIXFILE_URI         0x40     /* Filename might have query parameters */
#define UNIXFILE_NOLOCK      0x80     /* Do no file locking */
#define UNIXFILE_WARNED    0x0100     /* verifyDbFile() warnings issued */
#define UNIXFILE_BLOCK     0x0200     /* Next SHM lock might block */

/*
** Include code that is common to all os_*.c files
*/
#include "os_common.h"

/*

/*
** Apply posix advisory locks for all bytes from ofst through ofst+n-1.
**
** Locks block if the mask is exactly UNIX_SHM_C and are non-blocking
** otherwise.
*/
static int unixShmSystemLock(
  unixFile *pFile,       /* Open connection to the WAL file */
  int lockType,          /* F_UNLCK, F_RDLCK, or F_WRLCK */
  int ofst,              /* First byte of the locking range */
  int n                  /* Number of bytes to lock */
){
  unixShmNode *pShmNode; /* Apply locks to this open shared-memory segment */
  struct flock f;        /* The posix advisory locking structure */
  int rc = SQLITE_OK;    /* Result code form fcntl() */

  /* Access to the unixShmNode object is serialized by the caller */
  pShmNode = pFile->pInode->pShmNode;
  assert( sqlite3_mutex_held(pShmNode->mutex) || pShmNode->nRef==0 );

  /* Shared locks never span more than one byte */
  assert( n==1 || lockType!=F_RDLCK );

  /* Locks are within range */
  assert( n>=1 && n<SQLITE_SHM_NLOCK );

  if( pShmNode->h>=0 ){
    int lkType;
    /* Initialize the locking parameters */
    memset(&f, 0, sizeof(f));
    f.l_type = lockType;
    f.l_whence = SEEK_SET;
    f.l_start = ofst;
    f.l_len = n;

    lkType = (pFile->ctrlFlags & UNIXFILE_BLOCK)!=0 ? F_SETLKW : F_SETLK;
    rc = osFcntl(pShmNode->h, lkType, &f);
    rc = (rc!=(-1)) ? SQLITE_OK : SQLITE_BUSY;
    pFile->ctrlFlags &= ~UNIXFILE_BLOCK;
  }

  /* Update the global lock state and do debug tracing */
#ifdef SQLITE_DEBUG
  { u16 mask;
  OSTRACE(("SHM-LOCK "));
  mask = ofst>31 ? 0xffff : (1<<(ofst+n)) - (1<<ofst);

      */
      osFchown(pShmNode->h, sStat.st_uid, sStat.st_gid);
  
      /* Check to see if another process is holding the dead-man switch.
      ** If not, truncate the file to zero length. 
      */
      rc = SQLITE_OK;
      if( unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1)==SQLITE_OK ){
        if( robust_ftruncate(pShmNode->h, 0) ){
          rc = unixLogError(SQLITE_IOERR_SHMOPEN, "ftruncate", zShmFilename);
        }
      }
      if( rc==SQLITE_OK ){
        rc = unixShmSystemLock(pDbFd, F_RDLCK, UNIX_SHM_DMS, 1);
      }
      if( rc ) goto shm_open_err;
    }
  }

  /* Make the new connection a child of the unixShmNode */
  p->pShmNode = pShmNode;

      if( pX==p ) continue;
      assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
      allMask |= pX->sharedMask;
    }

    /* Unlock the system-level locks */
    if( (mask & allMask)==0 ){
      rc = unixShmSystemLock(pDbFd, F_UNLCK, ofst+UNIX_SHM_BASE, n);
    }else{
      rc = SQLITE_OK;
    }

    /* Undo the local locks */
    if( rc==SQLITE_OK ){
      p->exclMask &= ~mask;

      }
      allShared |= pX->sharedMask;
    }

    /* Get shared locks at the system level, if necessary */
    if( rc==SQLITE_OK ){
      if( (allShared & mask)==0 ){
        rc = unixShmSystemLock(pDbFd, F_RDLCK, ofst+UNIX_SHM_BASE, n);
      }else{
        rc = SQLITE_OK;
      }
    }

    /* Get the local shared locks */
    if( rc==SQLITE_OK ){

      }
    }
  
    /* Get the exclusive locks at the system level.  Then if successful
    ** also mark the local connection as being locked.
    */
    if( rc==SQLITE_OK ){
      rc = unixShmSystemLock(pDbFd, F_WRLCK, ofst+UNIX_SHM_BASE, n);
      if( rc==SQLITE_OK ){
        assert( (p->sharedMask & mask)==0 );
        p->exclMask |= mask;
      }
    }
  }
  sqlite3_mutex_leave(pShmNode->mutex);

/*
** This routine handles sqlite3_file_control() calls that are specific
** to proxy locking.
*/
static int proxyFileControl(sqlite3_file *id, int op, void *pArg){
  switch( op ){
    case SQLITE_FCNTL_WAL_BLOCK: {
      id->ctrlFlags |= UNIXFILE_BLOCK;
      return SQLITE_OK;
    }
    case SQLITE_FCNTL_GET_LOCKPROXYFILE: {
      unixFile *pFile = (unixFile*)id;
      if( pFile->pMethod == &proxyIoMethods ){
        proxyLockingContext *pCtx = (proxyLockingContext*)pFile->lockingContext;
        proxyTakeConch(pFile);
        if( pCtx->lockProxyPath ){
          *(const char **)pArg = pCtx->lockProxyPath;

**
** <li>[[SQLITE_FCNTL_WIN32_SET_HANDLE]]
** The [SQLITE_FCNTL_WIN32_SET_HANDLE] opcode is used for debugging.  This
** opcode causes the xFileControl method to swap the file handle with the one
** pointed to by the pArg argument.  This capability is used during testing
** and only needs to be supported when SQLITE_TEST is defined.
**
** <li>[[SQLITE_FCNTL_WAL_BLOCK]]
** The [SQLITE_FCNTL_WAL_BLOCK] is a single to the VFS layer that it might
** be advantageous to block on the next WAL lock if the lock is not immediately
** available.  The WAL subsystem issues this ioctl() during some rare
** circumstances in order to fix a problem with priority inversion.
** Applications should <em>not</em> use this file-control.
**
** </ul>
*/
#define SQLITE_FCNTL_LOCKSTATE               1
#define SQLITE_FCNTL_GET_LOCKPROXYFILE       2
#define SQLITE_FCNTL_SET_LOCKPROXYFILE       3
#define SQLITE_FCNTL_LAST_ERRNO              4
#define SQLITE_FCNTL_SIZE_HINT               5

#define SQLITE_FCNTL_TEMPFILENAME           16
#define SQLITE_FCNTL_MMAP_SIZE              18
#define SQLITE_FCNTL_TRACE                  19
#define SQLITE_FCNTL_HAS_MOVED              20
#define SQLITE_FCNTL_SYNC                   21
#define SQLITE_FCNTL_COMMIT_PHASETWO        22
#define SQLITE_FCNTL_WIN32_SET_HANDLE       23
#define SQLITE_FCNTL_WAL_BLOCK              24

/* deprecated names */
#define SQLITE_GET_LOCKPROXYFILE      SQLITE_FCNTL_GET_LOCKPROXYFILE
#define SQLITE_SET_LOCKPROXYFILE      SQLITE_FCNTL_SET_LOCKPROXYFILE
#define SQLITE_LAST_ERRNO             SQLITE_FCNTL_LAST_ERRNO

  return rc;
}

static void tvfsShmBarrier(sqlite3_file *pFile){
  TestvfsFd *pFd = tvfsGetFd(pFile);
  Testvfs *p = (Testvfs *)(pFd->pVfs->pAppData);

  if( p->pScript && p->mask&TESTVFS_SHMBARRIER_MASK ){
    const char *z = pFd->pShm ? pFd->pShm->zFile : "";
    tvfsExecTcl(p, "xShmBarrier", Tcl_NewStringObj(z, -1), pFd->pShmId, 0, 0);
  }

  if( p->isFullshm ){
    sqlite3OsShmBarrier(pFd->pReal);
    return;
  }






}

static int tvfsShmUnmap(
  sqlite3_file *pFile,
  int deleteFlag
){
  int rc = SQLITE_OK;

  p->mask = TESTVFS_ALL_MASK;

  sqlite3_vfs_register(pVfs, isDefault);

  return TCL_OK;

 bad_args:
  Tcl_WrongNumArgs(interp, 1, objv, "VFSNAME ?-noshm BOOL? ?-fullshm BOOL? ?-default BOOL? ?-mxpathname INT? ?-szosfile INT? ?-iversion INT?");
  return TCL_ERROR;
}

int Sqlitetestvfs_Init(Tcl_Interp *interp){
  Tcl_CreateObjCommand(interp, "testvfs", testvfs_cmd, 0, 0);
  return TCL_OK;
}

#endif

}
static void walUnlockShared(Wal *pWal, int lockIdx){
  if( pWal->exclusiveMode ) return;
  (void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
                         SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED);
  WALTRACE(("WAL%p: release SHARED-%s\n", pWal, walLockName(lockIdx)));
}
static int walLockExclusive(Wal *pWal, int lockIdx, int n, int fBlock){
  int rc;
  if( pWal->exclusiveMode ) return SQLITE_OK;
  if( fBlock ) sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_WAL_BLOCK, 0);
  rc = sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
                        SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE);
  WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
            walLockName(lockIdx), n, rc ? "failed" : "ok"));
  VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
  return rc;
}

  */
  assert( pWal->ckptLock==1 || pWal->ckptLock==0 );
  assert( WAL_ALL_BUT_WRITE==WAL_WRITE_LOCK+1 );
  assert( WAL_CKPT_LOCK==WAL_ALL_BUT_WRITE );
  assert( pWal->writeLock );
  iLock = WAL_ALL_BUT_WRITE + pWal->ckptLock;
  nLock = SQLITE_SHM_NLOCK - iLock;
  rc = walLockExclusive(pWal, iLock, nLock, 0);
  if( rc ){
    return rc;
  }
  WALTRACE(("WAL%p: recovery begin...\n", pWal));

  memset(&pWal->hdr, 0, sizeof(WalIndexHdr));

  int (*xBusy)(void*),            /* Function to call when busy */
  void *pBusyArg,                 /* Context argument for xBusyHandler */
  int lockIdx,                    /* Offset of first byte to lock */
  int n                           /* Number of bytes to lock */
){
  int rc;
  do {
    rc = walLockExclusive(pWal, lockIdx, n, 0);
  }while( xBusy && rc==SQLITE_BUSY && xBusy(pBusyArg) );
  return rc;
}

/*
** The cache of the wal-index header must be valid to call this function.
** Return the page-size in bytes used by the database.

  assert( badHdr==0 || pWal->writeLock==0 );
  if( badHdr ){
    if( pWal->readOnly & WAL_SHM_RDONLY ){
      if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
        walUnlockShared(pWal, WAL_WRITE_LOCK);
        rc = SQLITE_READONLY_RECOVERY;
      }
    }else if( SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1, 1)) ){
      pWal->writeLock = 1;
      if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){
        badHdr = walIndexTryHdr(pWal, pChanged);
        if( badHdr ){
          /* If the wal-index header is still malformed even while holding
          ** a WRITE lock, it can only mean that the header is corrupted and
          ** needs to be reconstructed.  So run recovery to do exactly that.

  }
  /* There was once an "if" here. The extra "{" is to preserve indentation. */
  {
    if( (pWal->readOnly & WAL_SHM_RDONLY)==0
     && (mxReadMark<pWal->hdr.mxFrame || mxI==0)
    ){
      for(i=1; i<WAL_NREADER; i++){
        rc = walLockExclusive(pWal, WAL_READ_LOCK(i), 1, 0);
        if( rc==SQLITE_OK ){
          mxReadMark = pInfo->aReadMark[i] = pWal->hdr.mxFrame;
          mxI = i;
          walUnlockExclusive(pWal, WAL_READ_LOCK(i), 1);
          break;
        }else if( rc!=SQLITE_BUSY ){
          return rc;

  if( pWal->readOnly ){
    return SQLITE_READONLY;
  }

  /* Only one writer allowed at a time.  Get the write lock.  Return
  ** SQLITE_BUSY if unable.
  */
  rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1, 0);
  if( rc ){
    return rc;
  }
  pWal->writeLock = 1;

  /* If another connection has written to the database file since the
  ** time the read transaction on this connection was started, then

  if( pWal->readLock==0 ){
    volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
    assert( pInfo->nBackfill==pWal->hdr.mxFrame );
    if( pInfo->nBackfill>0 ){
      u32 salt1;
      sqlite3_randomness(4, &salt1);
      rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1, 0);
      if( rc==SQLITE_OK ){
        /* If all readers are using WAL_READ_LOCK(0) (in other words if no
        ** readers are currently using the WAL), then the transactions
        ** frames will overwrite the start of the existing log. Update the
        ** wal-index header to reflect this.
        **
        ** In theory it would be Ok to update the cache of the header only

  assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );

  if( pWal->readOnly ) return SQLITE_READONLY;
  WALTRACE(("WAL%p: checkpoint begins\n", pWal));

  /* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive 
  ** "checkpoint" lock on the database file. */
  rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1, 0);
  if( rc ){
    /* EVIDENCE-OF: R-10421-19736 If any other process is running a
    ** checkpoint operation at the same time, the lock cannot be obtained and
    ** SQLITE_BUSY is returned.
    ** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
    ** it will not be invoked in this case.
    */

  }
  return $chan
}

# Execute a command in a child testfixture process, connected by two-way
# channel $chan. Return the result of the command, or an error message.
#
proc testfixture {chan cmd args} {

  if {[llength $args] == 0} {
    fconfigure $chan -blocking 1
    puts $chan $cmd
    puts $chan OVER

    set r ""
    while { 1 } {
      set line [gets $chan]
      if { $line == "OVER" } { 
        set res [lindex $r 1]
        if { [lindex $r 0] } { error $res }
        return $res
      }
      if {[eof $chan]} {
        return "ERROR: Child process hung up"
      }
      append r $line
    }
    return $r
  } else {
    set ::tfnb($chan) ""
    fconfigure $chan -blocking 0 -buffering none
    puts $chan $cmd
    puts $chan OVER
    fileevent $chan readable [list testfixture_script_cb $chan [lindex $args 0]]
    return ""
  }
}

proc testfixture_script_cb {chan script} {
  if {[eof $chan]} {
    append ::tfnb($chan) "ERROR: Child process hung up"
    set line "OVER"
  } else {
    set line [gets $chan]
  }

  if { $line == "OVER" } {
    uplevel #0 $script [list [lindex $::tfnb($chan) 1]]
    unset ::tfnb($chan)
    fileevent $chan readable ""
  } else {
    append ::tfnb($chan) $line
  }
}

proc testfixture_nb_cb {varname chan} {
  if {[eof $chan]} {
    append ::tfnb($chan) "ERROR: Child process hung up"
    set line "OVER"

# 2015 Mar 17
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
source $testdir/lock_common.tcl
source $testdir/wal_common.tcl

ifcapable !wal {finish_test ; return }
if {$::tcl_platform(platform)!="unix"} { finish_test ; return }
set testprefix walblock

catch { db close }
testvfs tvfs -fullshm 1
foreach f [glob test.db*] { forcedelete $f }

sqlite3 db test.db -vfs tvfs
do_execsql_test 1.1.0 {
  CREATE TABLE t1(x, y);
  INSERT INTO t1 VALUES(1, 2);
  INSERT INTO t1 VALUES(3, 4);
  INSERT INTO t1 VALUES(5, 6);
  PRAGMA journal_mode = wal;
  INSERT INTO t1 VALUES(7, 8);
} {wal}

do_test 1.1.1 { 
  lsort [glob test.db*] 
} {test.db test.db-shm test.db-wal}

do_test 1.1.2 { 
  set C [launch_testfixture]
  testfixture $C {
    sqlite3 db test.db
    db eval { SELECT * FROM t1 }
  }
} {1 2 3 4 5 6 7 8}

do_test 1.1.3 { 
  set ::out [list]
  testfixture $C {
    db eval { SELECT * FROM t1 }
  } [list set ::out]
  set ::out
} {}

do_test 1.1.4 { 
  vwait ::out
  set ::out
} {1 2 3 4 5 6 7 8}

#
# Test that if a read client cannot read the wal-index header because a
# write client is in the middle of updating it, the reader blocks until
# the writer finishes.
#
#   1. Open a write transaction using client [db] in this process.
#
#   2. Attempt to commit the write transaction. Intercept the xShmBarrier()
#      call made by the writer between updating the two copies of the
#      wal-index header.
#
#   3. Within the xShmBarrier() callback, make an asynchronous request to
#      the other process to read from the database. It should block, as it
#      cannot get read the wal-index header.
#
#   4. Still in xShmBarrier(), wait for 5 seconds. Check that the other
#      process has not answered the request.
#
#   5: Finish committing the transaction. Then wait for 0.5 seconds more.
#      Ensure that the second process has by this stage read the database
#      and that the snapshot it read included the transaction committed in
#      step (4).
#
do_execsql_test 1.2.1 {
  BEGIN;
    INSERT INTO t1 VALUES(9, 10);
} {}

tvfs script barrier_callback
tvfs filter xShmBarrier
proc barrier_callback {method args} {
  set ::out ""
  testfixture $::C { db eval { SELECT * FROM t1 } } {set ::out}

  do_test "1.2.2.(blocking 5 seconds)" { 
    set ::continue 0
    after 5000 {set ::continue 1}
    vwait ::continue
    set ::out 
  } {}
}

execsql COMMIT

do_test "1.2.3.(blocking 0.5 seconds)" { 
  set ::continue 0
  after 500 {set ::continue 1}
  vwait ::continue
  set ::out 
} {1 2 3 4 5 6 7 8 9 10}


finish_test