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SQLite training in Houston TX on 2019-11-05 (details)
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Overview
Comment:Add the new optional "unix-excl" VFS. This VFS grabs an exclusive lock on the database preventing other processes from accessing it, but continues to allow other database connections from the same process.
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Timelines: family | ancestors | descendants | both | unix-excl
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SHA1: 00051c3296e11211b2bb5ae28f016b17dca857d7
User & Date: drh 2011-03-12 17:02:57
Context
2011-03-12
18:10
In the "unix-excl" VFS, use the heap for shared memory, since only a single process is able to read or write the database. Closed-Leaf check-in: a05a6d40 user: drh tags: unix-excl
17:02
Add the new optional "unix-excl" VFS. This VFS grabs an exclusive lock on the database preventing other processes from accessing it, but continues to allow other database connections from the same process. check-in: 00051c32 user: drh tags: unix-excl
04:58
More tests for SQLITE_OMIT_UNIQUE_ENFORCEMENT and minor change to implementation. check-in: b8699943 user: shaneh tags: trunk
Changes
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Changes to src/os_unix.c.

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typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  unixInodeInfo *pInode;              /* Info about locks on this inode */
  int h;                              /* The file descriptor */
  int dirfd;                          /* File descriptor for the directory */
  unsigned char eFileLock;            /* The type of lock held on this fd */

  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
#if SQLITE_ENABLE_LOCKING_STYLE
................................................................................
  /* In test mode, increase the size of this structure a bit so that 
  ** it is larger than the struct CrashFile defined in test6.c.
  */
  char aPadding[32];
#endif
};






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

/*
** Define various macros that are missing from some systems.
................................................................................
** A single inode can have multiple file descriptors, so each unixFile
** structure contains a pointer to an instance of this object and this
** object keeps a count of the number of unixFile pointing to it.
*/
struct unixInodeInfo {
  struct unixFileId fileId;       /* The lookup key */
  int nShared;                    /* Number of SHARED locks held */
  int eFileLock;                  /* One of SHARED_LOCK, RESERVED_LOCK etc. */

  int nRef;                       /* Number of pointers to this structure */
  unixShmNode *pShmNode;          /* Shared memory associated with this inode */
  int nLock;                      /* Number of outstanding file locks */
  UnixUnusedFd *pUnused;          /* Unused file descriptors to close */
  unixInodeInfo *pNext;           /* List of all unixInodeInfo objects */
  unixInodeInfo *pPrev;           /*    .... doubly linked */
#if defined(SQLITE_ENABLE_LOCKING_STYLE)
................................................................................
  if( pFile->pInode->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it.
  */
#ifndef __DJGPP__
  if( !reserved ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    if (-1 == osFcntl(pFile->h, F_GETLK, &lock)) {
      int tErrno = errno;
................................................................................
  
  unixLeaveMutex();
  OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));

  *pResOut = reserved;
  return rc;
}



































/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
................................................................................
  lock.l_len = 1L;
  lock.l_whence = SEEK_SET;
  if( eFileLock==SHARED_LOCK 
      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
  ){
    lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = osFcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
      goto end_lock;
................................................................................
  if( eFileLock==SHARED_LOCK ){
    assert( pInode->nShared==0 );
    assert( pInode->eFileLock==0 );

    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    if( (s = osFcntl(pFile->h, F_SETLK, &lock))==(-1) ){
      tErrno = errno;
    }
    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( osFcntl(pFile->h, F_SETLK, &lock)!=0 ){
      if( s != -1 ){
        /* This could happen with a network mount */
        tErrno = errno; 
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); 
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
................................................................................
      case EXCLUSIVE_LOCK:
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        break;
      default:
        assert(0);
    }
    s = osFcntl(pFile->h, F_SETLK, &lock);
    if( s==(-1) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
................................................................................
** 
** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
** the byte range is divided into 2 parts and the first part is unlocked then
** set to a read lock, then the other part is simply unlocked.  This works 
** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to 
** remove the write lock on a region when a read lock is set.
*/
static int _posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode;
  struct flock lock;
  int rc = SQLITE_OK;
  int h;
  int tErrno;                      /* Error code from system call errors */

................................................................................
      if( handleNFSUnlock ){
        off_t divSize = SHARED_SIZE - 1;
        
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( osFcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( osFcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST+divSize;
        lock.l_len = SHARED_SIZE-divSize;
        if( osFcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
................................................................................
      }else
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
      {
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        if( osFcntl(h, F_SETLK, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( osFcntl(h, F_SETLK, &lock)!=(-1) ){
      pInode->eFileLock = SHARED_LOCK;
    }else{
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
................................................................................
    if( pInode->nShared==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( osFcntl(h, F_SETLK, &lock)!=(-1) ){
        pInode->eFileLock = NO_LOCK;
      }else{
        tErrno = errno;
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
................................................................................
** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int eFileLock){
  return _posixUnlock(id, eFileLock, 0);
}

/*
** This function performs the parts of the "close file" operation 
** common to all locking schemes. It closes the directory and file
** handles, if they are valid, and sets all fields of the unixFile
** structure to 0.
................................................................................
 ** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
 ** must be either NO_LOCK or SHARED_LOCK.
 **
 ** If the locking level of the file descriptor is already at or below
 ** the requested locking level, this routine is a no-op.
 */
static int nfsUnlock(sqlite3_file *id, int eFileLock){
  return _posixUnlock(id, eFileLock, 1);
}

#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
/*
** The code above is the NFS lock implementation.  The code is specific
** to MacOSX and does not work on other unix platforms.  No alternative
** is available.  
................................................................................
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->dirfd = dirfd;
  pNew->zPath = zFilename;






#if OS_VXWORKS
  pNew->pId = vxworksFindFileId(zFilename);
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
................................................................................
#if SQLITE_ENABLE_LOCKING_STYLE && (OS_VXWORKS || defined(__APPLE__))
    UNIXVFS("unix",          autolockIoFinder ),
#else
    UNIXVFS("unix",          posixIoFinder ),
#endif
    UNIXVFS("unix-none",     nolockIoFinder ),
    UNIXVFS("unix-dotfile",  dotlockIoFinder ),

#if OS_VXWORKS
    UNIXVFS("unix-namedsem", semIoFinder ),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
    UNIXVFS("unix-posix",    posixIoFinder ),
#if !OS_VXWORKS
    UNIXVFS("unix-flock",    flockIoFinder ),







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typedef struct unixFile unixFile;
struct unixFile {
  sqlite3_io_methods const *pMethod;  /* Always the first entry */
  unixInodeInfo *pInode;              /* Info about locks on this inode */
  int h;                              /* The file descriptor */
  int dirfd;                          /* File descriptor for the directory */
  unsigned char eFileLock;            /* The type of lock held on this fd */
  unsigned char ctrlFlags;            /* Behavioral bits.  UNIXFILE_* flags */
  int lastErrno;                      /* The unix errno from last I/O error */
  void *lockingContext;               /* Locking style specific state */
  UnixUnusedFd *pUnused;              /* Pre-allocated UnixUnusedFd */
  const char *zPath;                  /* Name of the file */
  unixShm *pShm;                      /* Shared memory segment information */
  int szChunk;                        /* Configured by FCNTL_CHUNK_SIZE */
#if SQLITE_ENABLE_LOCKING_STYLE
................................................................................
  /* In test mode, increase the size of this structure a bit so that 
  ** it is larger than the struct CrashFile defined in test6.c.
  */
  char aPadding[32];
#endif
};

/*
** Allowed values for the unixFile.ctrlFlags bitmask:
*/
#define UNIXFILE_EXCL   0x01     /* Connections from one process only */

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

/*
** Define various macros that are missing from some systems.
................................................................................
** A single inode can have multiple file descriptors, so each unixFile
** structure contains a pointer to an instance of this object and this
** object keeps a count of the number of unixFile pointing to it.
*/
struct unixInodeInfo {
  struct unixFileId fileId;       /* The lookup key */
  int nShared;                    /* Number of SHARED locks held */
  unsigned char eFileLock;        /* One of SHARED_LOCK, RESERVED_LOCK etc. */
  unsigned char bProcessLock;     /* An exclusive process lock is held */
  int nRef;                       /* Number of pointers to this structure */
  unixShmNode *pShmNode;          /* Shared memory associated with this inode */
  int nLock;                      /* Number of outstanding file locks */
  UnixUnusedFd *pUnused;          /* Unused file descriptors to close */
  unixInodeInfo *pNext;           /* List of all unixInodeInfo objects */
  unixInodeInfo *pPrev;           /*    .... doubly linked */
#if defined(SQLITE_ENABLE_LOCKING_STYLE)
................................................................................
  if( pFile->pInode->eFileLock>SHARED_LOCK ){
    reserved = 1;
  }

  /* Otherwise see if some other process holds it.
  */
#ifndef __DJGPP__
  if( !reserved && !pFile->pInode->bProcessLock ){
    struct flock lock;
    lock.l_whence = SEEK_SET;
    lock.l_start = RESERVED_BYTE;
    lock.l_len = 1;
    lock.l_type = F_WRLCK;
    if (-1 == osFcntl(pFile->h, F_GETLK, &lock)) {
      int tErrno = errno;
................................................................................
  
  unixLeaveMutex();
  OSTRACE(("TEST WR-LOCK %d %d %d (unix)\n", pFile->h, rc, reserved));

  *pResOut = reserved;
  return rc;
}

/*
** Attempt to set a system-lock on the file pFile.  The lock is 
** described by pLock.
**
** If the pFile was opened from unix-excl, then the only lock ever
** obtained is an exclusive lock, and it is obtained exactly once
** the first time any lock is attempted.  All subsequent system locking
** operations become no-ops.  Locking operations still happen internally,
** in order to coordinate access between separate database connections
** within this process, but all of that is handled in memory and the
** operating system does not participate.
*/
static int unixFileLock(unixFile *pFile, struct flock *pLock){
  int rc;
  assert( unixMutexHeld() );
  if( (pFile->ctrlFlags & UNIXFILE_EXCL)!=0 || pFile->pInode->bProcessLock ){
    if( pFile->pInode->bProcessLock==0 ){
      struct flock lock;
      lock.l_whence = SEEK_SET;
      lock.l_start = SHARED_FIRST;
      lock.l_len = SHARED_SIZE;
      lock.l_type = F_WRLCK;
      rc = osFcntl(pFile->h, F_SETLK, &lock);
      if( rc<0 ) return rc;
      pFile->pInode->bProcessLock = 1;
    }else{
      rc = 0;
    }
  }else{
    rc = osFcntl(pFile->h, F_SETLK, pLock);
  }
  return rc;
}

/*
** Lock the file with the lock specified by parameter eFileLock - one
** of the following:
**
**     (1) SHARED_LOCK
**     (2) RESERVED_LOCK
................................................................................
  lock.l_len = 1L;
  lock.l_whence = SEEK_SET;
  if( eFileLock==SHARED_LOCK 
      || (eFileLock==EXCLUSIVE_LOCK && pFile->eFileLock<PENDING_LOCK)
  ){
    lock.l_type = (eFileLock==SHARED_LOCK?F_RDLCK:F_WRLCK);
    lock.l_start = PENDING_BYTE;
    s = unixFileLock(pFile, &lock);
    if( s==(-1) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
      goto end_lock;
................................................................................
  if( eFileLock==SHARED_LOCK ){
    assert( pInode->nShared==0 );
    assert( pInode->eFileLock==0 );

    /* Now get the read-lock */
    lock.l_start = SHARED_FIRST;
    lock.l_len = SHARED_SIZE;
    if( (s = unixFileLock(pFile, &lock))==(-1) ){
      tErrno = errno;
    }
    /* Drop the temporary PENDING lock */
    lock.l_start = PENDING_BYTE;
    lock.l_len = 1L;
    lock.l_type = F_UNLCK;
    if( unixFileLock(pFile, &lock)!=0 ){
      if( s != -1 ){
        /* This could happen with a network mount */
        tErrno = errno; 
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK); 
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
................................................................................
      case EXCLUSIVE_LOCK:
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        break;
      default:
        assert(0);
    }
    s = unixFileLock(pFile, &lock);
    if( s==(-1) ){
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_LOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
    }
................................................................................
** 
** If handleNFSUnlock is true, then on downgrading an EXCLUSIVE_LOCK to SHARED
** the byte range is divided into 2 parts and the first part is unlocked then
** set to a read lock, then the other part is simply unlocked.  This works 
** around a bug in BSD NFS lockd (also seen on MacOSX 10.3+) that fails to 
** remove the write lock on a region when a read lock is set.
*/
static int posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
  unixFile *pFile = (unixFile*)id;
  unixInodeInfo *pInode;
  struct flock lock;
  int rc = SQLITE_OK;
  int h;
  int tErrno;                      /* Error code from system call errors */

................................................................................
      if( handleNFSUnlock ){
        off_t divSize = SHARED_SIZE - 1;
        
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( unixFileLock(pFile,, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = divSize;
        if( unixFileLock(pFile, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
        lock.l_type = F_UNLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST+divSize;
        lock.l_len = SHARED_SIZE-divSize;
        if( unixFileLock(pFile, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
................................................................................
      }else
#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
      {
        lock.l_type = F_RDLCK;
        lock.l_whence = SEEK_SET;
        lock.l_start = SHARED_FIRST;
        lock.l_len = SHARED_SIZE;
        if( unixFileLock(pFile, &lock)==(-1) ){
          tErrno = errno;
          rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_RDLOCK);
          if( IS_LOCK_ERROR(rc) ){
            pFile->lastErrno = tErrno;
          }
          goto end_unlock;
        }
      }
    }
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = PENDING_BYTE;
    lock.l_len = 2L;  assert( PENDING_BYTE+1==RESERVED_BYTE );
    if( unixFileLock(pFile, &lock)!=(-1) ){
      pInode->eFileLock = SHARED_LOCK;
    }else{
      tErrno = errno;
      rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
      if( IS_LOCK_ERROR(rc) ){
        pFile->lastErrno = tErrno;
      }
................................................................................
    if( pInode->nShared==0 ){
      lock.l_type = F_UNLCK;
      lock.l_whence = SEEK_SET;
      lock.l_start = lock.l_len = 0L;
      SimulateIOErrorBenign(1);
      SimulateIOError( h=(-1) )
      SimulateIOErrorBenign(0);
      if( unixFileLock(pFile, &lock)!=(-1) ){
        pInode->eFileLock = NO_LOCK;
      }else{
        tErrno = errno;
        rc = sqliteErrorFromPosixError(tErrno, SQLITE_IOERR_UNLOCK);
        if( IS_LOCK_ERROR(rc) ){
          pFile->lastErrno = tErrno;
        }
................................................................................
** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
** must be either NO_LOCK or SHARED_LOCK.
**
** If the locking level of the file descriptor is already at or below
** the requested locking level, this routine is a no-op.
*/
static int unixUnlock(sqlite3_file *id, int eFileLock){
  return posixUnlock(id, eFileLock, 0);
}

/*
** This function performs the parts of the "close file" operation 
** common to all locking schemes. It closes the directory and file
** handles, if they are valid, and sets all fields of the unixFile
** structure to 0.
................................................................................
 ** Lower the locking level on file descriptor pFile to eFileLock.  eFileLock
 ** must be either NO_LOCK or SHARED_LOCK.
 **
 ** If the locking level of the file descriptor is already at or below
 ** the requested locking level, this routine is a no-op.
 */
static int nfsUnlock(sqlite3_file *id, int eFileLock){
  return posixUnlock(id, eFileLock, 1);
}

#endif /* defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE */
/*
** The code above is the NFS lock implementation.  The code is specific
** to MacOSX and does not work on other unix platforms.  No alternative
** is available.  
................................................................................
  assert( zFilename==0 || zFilename[0]=='/' );
#endif

  OSTRACE(("OPEN    %-3d %s\n", h, zFilename));
  pNew->h = h;
  pNew->dirfd = dirfd;
  pNew->zPath = zFilename;
  if( memcmp(pVfs->zName,"unix-excl",10)==0 ){
    pNew->ctrlFlags = UNIXFILE_EXCL;
  }else{
    pNew->ctrlFlags = 0;
  }

#if OS_VXWORKS
  pNew->pId = vxworksFindFileId(zFilename);
  if( pNew->pId==0 ){
    noLock = 1;
    rc = SQLITE_NOMEM;
  }
................................................................................
#if SQLITE_ENABLE_LOCKING_STYLE && (OS_VXWORKS || defined(__APPLE__))
    UNIXVFS("unix",          autolockIoFinder ),
#else
    UNIXVFS("unix",          posixIoFinder ),
#endif
    UNIXVFS("unix-none",     nolockIoFinder ),
    UNIXVFS("unix-dotfile",  dotlockIoFinder ),
    UNIXVFS("unix-excl",     posixIoFinder ),
#if OS_VXWORKS
    UNIXVFS("unix-namedsem", semIoFinder ),
#endif
#if SQLITE_ENABLE_LOCKING_STYLE
    UNIXVFS("unix-posix",    posixIoFinder ),
#if !OS_VXWORKS
    UNIXVFS("unix-flock",    flockIoFinder ),

Changes to src/shell.c.

415
416
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418
419
420
421

422
423
424
425
426
427
428
....
2596
2597
2598
2599
2600
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2603
2604
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....
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2687
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....
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2794
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2799
2800
  char nullvalue[20];    /* The text to print when a NULL comes back from
                         ** the database */
  struct previous_mode_data explainPrev;
                         /* Holds the mode information just before
                         ** .explain ON */
  char outfile[FILENAME_MAX]; /* Filename for *out */
  const char *zDbFilename;    /* name of the database file */

  sqlite3_stmt *pStmt;   /* Current statement if any. */
  FILE *pLog;            /* Write log output here */
};

/*
** These are the allowed modes.
*/
................................................................................
  "   -html                set output mode to HTML\n"
  "   -line                set output mode to 'line'\n"
  "   -list                set output mode to 'list'\n"
  "   -separator 'x'       set output field separator (|)\n"
  "   -stats               print memory stats before each finalize\n"
  "   -nullvalue 'text'    set text string for NULL values\n"
  "   -version             show SQLite version\n"

;
static void usage(int showDetail){
  fprintf(stderr,
      "Usage: %s [OPTIONS] FILENAME [SQL]\n"  
      "FILENAME is the name of an SQLite database. A new database is created\n"
      "if the file does not previously exist.\n", Argv0);
  if( showDetail ){
................................................................................
        if( c=='K' ){ szHeap *= 1000; break; }
        if( c=='G' ){ szHeap *= 1000000000; break; }
      }
      if( szHeap>0x7fff0000 ) szHeap = 0x7fff0000;
#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
      sqlite3_config(SQLITE_CONFIG_HEAP, malloc((int)szHeap), (int)szHeap, 64);
#endif









    }
  }
  if( i<argc ){
#if defined(SQLITE_OS_OS2) && SQLITE_OS_OS2
    data.zDbFilename = (const char *)convertCpPathToUtf8( argv[i++] );
#else
    data.zDbFilename = argv[i++];
................................................................................
      printf("%s\n", sqlite3_libversion());
      return 0;
    }else if( strcmp(z,"-interactive")==0 ){
      stdin_is_interactive = 1;
    }else if( strcmp(z,"-batch")==0 ){
      stdin_is_interactive = 0;
    }else if( strcmp(z,"-heap")==0 ){


      i++;
    }else if( strcmp(z,"-help")==0 || strcmp(z, "--help")==0 ){
      usage(1);
    }else{
      fprintf(stderr,"%s: Error: unknown option: %s\n", Argv0, z);
      fprintf(stderr,"Use -help for a list of options.\n");
      return 1;







>







 







>







 







>
>
>
>
>
>
>
>
>







 







>
>







415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
....
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
....
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
....
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
  char nullvalue[20];    /* The text to print when a NULL comes back from
                         ** the database */
  struct previous_mode_data explainPrev;
                         /* Holds the mode information just before
                         ** .explain ON */
  char outfile[FILENAME_MAX]; /* Filename for *out */
  const char *zDbFilename;    /* name of the database file */
  const char *zVfs;           /* Name of VFS to use */
  sqlite3_stmt *pStmt;   /* Current statement if any. */
  FILE *pLog;            /* Write log output here */
};

/*
** These are the allowed modes.
*/
................................................................................
  "   -html                set output mode to HTML\n"
  "   -line                set output mode to 'line'\n"
  "   -list                set output mode to 'list'\n"
  "   -separator 'x'       set output field separator (|)\n"
  "   -stats               print memory stats before each finalize\n"
  "   -nullvalue 'text'    set text string for NULL values\n"
  "   -version             show SQLite version\n"
  "   -vfs NAME            use NAME as the default VFS\n"
;
static void usage(int showDetail){
  fprintf(stderr,
      "Usage: %s [OPTIONS] FILENAME [SQL]\n"  
      "FILENAME is the name of an SQLite database. A new database is created\n"
      "if the file does not previously exist.\n", Argv0);
  if( showDetail ){
................................................................................
        if( c=='K' ){ szHeap *= 1000; break; }
        if( c=='G' ){ szHeap *= 1000000000; break; }
      }
      if( szHeap>0x7fff0000 ) szHeap = 0x7fff0000;
#if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5)
      sqlite3_config(SQLITE_CONFIG_HEAP, malloc((int)szHeap), (int)szHeap, 64);
#endif
    }else if( strcmp(argv[i],"-vfs")==0 ){
      i++;
      sqlite3_vfs *pVfs = sqlite3_vfs_find(argv[i]);
      if( pVfs ){
        sqlite3_vfs_register(pVfs, 1);
      }else{
        fprintf(stderr, "no such VFS: \"%s\"\n", argv[i]);
        exit(1);
      }
    }
  }
  if( i<argc ){
#if defined(SQLITE_OS_OS2) && SQLITE_OS_OS2
    data.zDbFilename = (const char *)convertCpPathToUtf8( argv[i++] );
#else
    data.zDbFilename = argv[i++];
................................................................................
      printf("%s\n", sqlite3_libversion());
      return 0;
    }else if( strcmp(z,"-interactive")==0 ){
      stdin_is_interactive = 1;
    }else if( strcmp(z,"-batch")==0 ){
      stdin_is_interactive = 0;
    }else if( strcmp(z,"-heap")==0 ){
      i++;
    }else if( strcmp(z,"-vfs")==0 ){
      i++;
    }else if( strcmp(z,"-help")==0 || strcmp(z, "--help")==0 ){
      usage(1);
    }else{
      fprintf(stderr,"%s: Error: unknown option: %s\n", Argv0, z);
      fprintf(stderr,"Use -help for a list of options.\n");
      return 1;