SQLite

** prematurely, old temporary files can be easily identified. This can be done
** using -DTEMP_FILE_PREFIX=myprefix_ on the compiler command line.
*/
#ifndef TEMP_FILE_PREFIX
# define TEMP_FILE_PREFIX "sqlite_"
#endif

/*
** The following values may be passed as the second argument to
** sqlite3OsLock().
*/
#define SHARED_LOCK     1
#define RESERVED_LOCK   2
#define PENDING_LOCK    3
#define EXCLUSIVE_LOCK  4

int sqlite3OsDelete(const char*);
int sqlite3OsFileExists(const char*);
int sqliteOsFileRename(const char*, const char*);
int sqlite3OsOpenReadWrite(const char*, OsFile*, int*);
int sqlite3OsOpenExclusive(const char*, OsFile*, int);
int sqlite3OsOpenReadOnly(const char*, OsFile*);

int sqlite3OsUnlock(OsFile*);
int sqlite3OsRandomSeed(char*);
int sqlite3OsSleep(int ms);
int sqlite3OsCurrentTime(double*);
void sqlite3OsEnterMutex(void);
void sqlite3OsLeaveMutex(void);
char *sqlite3OsFullPathname(const char*);
int sqlite3OsLock(OsFile*, int);

#endif /* _SQLITE_OS_H_ */

** A single inode can have multiple file descriptors, so each OsFile
** structure contains a pointer to an instance of this object and this
** object keeps a count of the number of OsFiles pointing to it.
*/
struct lockInfo {
  struct lockKey key;  /* The lookup key */
  int cnt;             /* 0: unlocked.  -1: write lock.  1...: read lock. */
  int locktype;        /* One of SHARED_LOCK, RESERVED_LOCK etc. */
  int nRef;            /* Number of pointers to this structure */
};

/*
** An instance of the following structure serves as the key used
** to locate a particular openCnt structure given its inode.  This
** is the same as the lockKey except that the process ID is omitted.

  if( pLock==0 ){
    struct lockInfo *pOld;
    pLock = sqliteMallocRaw( sizeof(*pLock) );
    if( pLock==0 ) return 1;
    pLock->key = key1;
    pLock->nRef = 1;
    pLock->cnt = 0;
    pLock->locktype = 0;
    pOld = sqlite3HashInsert(&lockHash, &pLock->key, sizeof(key1), pLock);
    if( pOld!=0 ){
      assert( pOld==pLock );
      sqliteFree(pLock);
      return 1;
    }
  }else{

**
** Return SQLITE_OK on success and SQLITE_BUSY on failure.  If this
** library was compiled with large file support (LFS) but LFS is not
** available on the host, then an SQLITE_NOLFS is returned.
*/
int sqlite3OsReadLock(OsFile *id){
  int rc;





























  return sqlite3OsLock(id, SHARED_LOCK);
}

/*
** Change the lock status to be an exclusive or write lock.  Return
** SQLITE_OK on success and SQLITE_BUSY on a failure.  If this
** library was compiled with large file support (LFS) but LFS is not
** available on the host, then an SQLITE_NOLFS is returned.
*/
int sqlite3OsWriteLock(OsFile *id){
  int rc;
  return sqlite3OsLock(id, EXCLUSIVE_LOCK);
}

/*
** Lock the file with the lock specified by parameter locktype - one
** of the following:
**
** SHARED_LOCK
** RESERVED_LOCK
** PENDING_LOCK
** EXCLUSIVE_LOCK
*/
int sqlite3OsLock(OsFile *id, int locktype){
  int rc = SQLITE_OK;
  struct lockInfo *pLock = id->pLock;
  struct flock lock;
  int s;

  /* It is an error to request any kind of lock before a shared lock */
  if( locktype>SHARED_LOCK && id->locked==0 ){
    rc = sqlite3OsLock(id, SHARED_LOCK);
    if( rc!=SQLITE_OK ) return rc;
  }
  assert( locktype==SHARED_LOCK || id->locked!=0 );

  /* If there is already a lock of this type or more restrictive on the
  ** OsFile, do nothing. Don't use the end_lock: exit path, as
  ** sqlite3OsEnterMutex() hasn't been called yet.
  */
  if( id->locked>=locktype ){
    return SQLITE_OK;
  }

  sqlite3OsEnterMutex();

  /* If some thread using this PID has a lock via a different OsFile*
  ** handle that precludes the requested lock, return BUSY.
  */
  if( (id->locked!=pLock->locktype && 
      (pLock->locktype>RESERVED_LOCK || locktype!=SHARED_LOCK)) ||
      (locktype>RESERVED_LOCK && pLock->cnt>1)
  ){
    rc = SQLITE_BUSY;
    goto end_lock;
  }

  /* If a SHARED lock is requested, and some thread using this PID already
  ** has a SHARED or RESERVED lock, then increment reference counts and
  ** return SQLITE_OK.
  */
  if( locktype==SHARED_LOCK && 
      (pLock->locktype==SHARED_LOCK || pLock->locktype==RESERVED_LOCK) ){
    assert( locktype==SHARED_LOCK );
    assert( id->locked==0 );
    id->locked = SHARED_LOCK;
    pLock->cnt++;
    id->pOpen->nLock++;
    goto end_lock;
  }

  lock.l_len = 1L;
  lock.l_whence = SEEK_SET;

  /* If control gets to this point, then actually go ahead and make
  ** operating system calls for the specified lock.
  */
  if( locktype==SHARED_LOCK ){
    assert( pLock->cnt==0 );
    assert( id->pOpen->nLock==0 );
    assert( pLock->locktype==0 );
  
    /* Grab a read-lock on byte 2. This ensures that no other process
    ** has a PENDING lock.
    */
    lock.l_type = F_RDLCK;
    lock.l_start = 2;
    s = fcntl(id->fd, F_SETLK, &lock);
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
      goto end_lock;
    }

    /* Now get a read-lock on byte 0 and renege on the byte 2 lock. */
    lock.l_start = 0;
    s = fcntl(id->fd, F_SETLK, &lock);
    lock.l_start = 2;
    lock.l_type = F_UNLCK;
    fcntl(id->fd, F_SETLK, &lock);
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
    }else{

      id->locked = SHARED_LOCK;
      id->pOpen->nLock = 1;
      pLock->cnt = 1;
    }
  }else{
    /* The request was for a RESERVED, PENDING or EXCLUSIVE lock.  It is
    ** assumed that there is a SHARED or greater lock on the file
    ** already.
    */
    assert( 0!=id->locked );
    lock.l_type = F_WRLCK;
    switch( locktype ){
      case RESERVED_LOCK:
        lock.l_start = 1;
        break;
      case PENDING_LOCK:
        lock.l_start = 2;
        break;
      case EXCLUSIVE_LOCK:
        lock.l_start = 0;
        break;
      default:
        assert(0);
    }
    s = fcntl(id->fd, F_SETLK, &lock);
    if( s ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
    }
  }
  
  id->locked = locktype;
  pLock->locktype = locktype;
  assert(pLock->locktype==RESERVED_LOCK||(id->pOpen->nLock==1&&pLock->cnt==1));

end_lock:
  sqlite3OsLeaveMutex();
  return rc;
}

/*
** Unlock the given file descriptor.  If the file descriptor was
** not previously locked, then this routine is a no-op.  If this
** library was compiled with large file support (LFS) but LFS is not
** available on the host, then an SQLITE_NOLFS is returned.
*/
int sqlite3OsUnlock(OsFile *id){
  int rc;
  if( !id->locked ) return SQLITE_OK;
  sqlite3OsEnterMutex();
  assert( id->pLock->cnt!=0 );
  if( id->pLock->cnt>1 ){
    id->locked = 0;
    id->pLock->cnt--;
    rc = SQLITE_OK;
  }else{
    struct flock lock;
    int s;
    lock.l_type = F_UNLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = lock.l_len = 0L;
    s = fcntl(id->fd, F_SETLK, &lock);
    if( s!=0 ){
      rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
    }else{
      rc = SQLITE_OK;
      id->pLock->cnt = 0;
      id->pLock->locktype = 0;
      id->locked = 0;
    }
  }
  if( rc==SQLITE_OK ){
    /* Decrement the count of locks against this same file.  When the
    ** count reaches zero, close any other file descriptors whose close
    ** was deferred because of outstanding locks.
    */

**    May you share freely, never taking more than you give.
**
*************************************************************************
** Code for testing the printf() interface to SQLite.  This code
** is not included in the SQLite library.  It is used for automated
** testing of the SQLite library.
**
** $Id: test1.c,v 1.69 2004/06/01 14:09:29 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "tcl.h"
#include "os.h"
#include <stdlib.h>
#include <string.h>

){
  if( sscanf(zArg, PTR_FMT, (void**)ppStmt)!=1 ){
    Tcl_AppendResult(interp, "\"", zArg, "\" is not a valid pointer value", 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}

/*
** Decode a pointer to an sqlite3_stmt object.
*/
static int getFilePointer(
  Tcl_Interp *interp, 
  const char *zArg,  
  OsFile **ppFile
){
  if( sscanf(zArg, PTR_FMT, (void**)ppFile)!=1 ){
    Tcl_AppendResult(interp, "\"", zArg, "\" is not a valid pointer value", 0);
    return TCL_ERROR;
  }
  return TCL_OK;
}

/*
** Generate a text representation of a pointer that can be understood
** by the getDbPointer and getVmPointer routines above.
**
** The problem is, on some machines (Solaris) if you do a printf with
** "%p" you cannot turn around and do a scanf with the same "%p" and

  if( getStmtPointer(interp, Tcl_GetString(objv[1]), &pStmt) ) return TCL_ERROR;
  if( Tcl_GetIntFromObj(interp, objv[2], &col) ) return TCL_ERROR;

  Tcl_SetObjResult(interp, Tcl_NewIntObj(xFunc(pStmt, col)));
  return TCL_OK;
}

/*
** Usage:  sqlite3OsOpenReadWrite <filename>
*/
static int test_sqlite3OsOpenReadWrite(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  OsFile * pFile;
  int rc;
  int dummy;
  char zBuf[100];

  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
       Tcl_GetString(objv[0]), " filename", 0);
    return TCL_ERROR;
  }

  pFile = sqliteMalloc(sizeof(OsFile));
  rc = sqlite3OsOpenReadWrite(Tcl_GetString(objv[1]), pFile, &dummy);
  if( rc!=SQLITE_OK ){
    sqliteFree(pFile);
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  makePointerStr(interp, zBuf, pFile);
  Tcl_SetResult(interp, zBuf, 0);
  return TCL_ERROR;
}

/*
** Usage:  sqlite3OsClose <file handle>
*/
static int test_sqlite3OsClose(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  OsFile * pFile;
  int rc;

  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
       Tcl_GetString(objv[0]), " filehandle", 0);
    return TCL_ERROR;
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }
  rc = sqlite3OsClose(pFile);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  sqliteFree(pFile);
  return TCL_OK;
}

/*
** Usage:  sqlite3OsLock <file handle> <locktype>
*/
static int test_sqlite3OsLock(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  OsFile * pFile;
  int rc;

  if( objc!=3 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
        Tcl_GetString(objv[0]), 
        " filehandle (SHARED|RESERVED|PENDING|EXCLUSIVE)", 0);
    return TCL_ERROR;
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }

  if( 0==strcmp("SHARED", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, SHARED_LOCK);
  }
  else if( 0==strcmp("RESERVED", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, RESERVED_LOCK);
  }
  else if( 0==strcmp("PENDING", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, PENDING_LOCK);
  }
  else if( 0==strcmp("EXCLUSIVE", Tcl_GetString(objv[2])) ){
    rc = sqlite3OsLock(pFile, EXCLUSIVE_LOCK);
  }else{
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
        Tcl_GetString(objv[0]), 
        " filehandle (SHARED|RESERVED|PENDING|EXCLUSIVE)", 0);
    return TCL_ERROR;
  }

  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  return TCL_OK;
}

/*
** Usage:  sqlite3OsUnlock <file handle>
*/
static int test_sqlite3OsUnlock(
  void * clientData,
  Tcl_Interp *interp,
  int objc,
  Tcl_Obj *CONST objv[]
){
  OsFile * pFile;
  int rc;

  if( objc!=2 ){
    Tcl_AppendResult(interp, "wrong # args: should be \"", 
       Tcl_GetString(objv[0]), " filehandle", 0);
    return TCL_ERROR;
  }

  if( getFilePointer(interp, Tcl_GetString(objv[1]), &pFile) ){
    return TCL_ERROR;
  }
  rc = sqlite3OsUnlock(pFile);
  if( rc!=SQLITE_OK ){
    Tcl_SetResult(interp, (char *)errorName(rc), TCL_STATIC);
    return TCL_ERROR;
  }
  return TCL_OK;
}

/*
** Register commands with the TCL interpreter.
*/
int Sqlitetest1_Init(Tcl_Interp *interp){
  extern int sqlite3_search_count;
  extern int sqlite3_interrupt_count;

     { "sqlite3_column_text", test_stmt_utf8,       sqlite3_column_text},
     { "sqlite3_column_decltype", test_stmt_utf8,   sqlite3_column_decltype},
     { "sqlite3_column_name", test_stmt_utf8,       sqlite3_column_name},
     { "sqlite3_column_text16", test_stmt_utf16,    sqlite3_column_text16},
     { "sqlite3_column_decltype16", test_stmt_utf16,sqlite3_column_decltype16},
     { "sqlite3_column_name16", test_stmt_utf16,    sqlite3_column_name16},

     /* Functions from os.h */
     { "sqlite3OsOpenReadWrite",test_sqlite3OsOpenReadWrite, 0 },
     { "sqlite3OsClose",        test_sqlite3OsClose, 0 },
     { "sqlite3OsLock",         test_sqlite3OsLock, 0 },
     { "sqlite3OsUnlock",       test_sqlite3OsUnlock, 0 },

  };
  int i;

  for(i=0; i<sizeof(aCmd)/sizeof(aCmd[0]); i++){
    Tcl_CreateCommand(interp, aCmd[i].zName, aCmd[i].xProc, 0, 0);
  }
  for(i=0; i<sizeof(aObjCmd)/sizeof(aObjCmd[0]); i++){