Bundle relevant parts of sqlite 2.8.0.

# sqlite has a completely non-restrictive license

1 files changed, 1477 insertions, 0 deletions

diff --git a/ext/sqlite/libsqlite/src/os.c b/ext/sqlite/libsqlite/src/os.c
new file mode 100644
index 0000000000..d0b50dc4f1
--- /dev/null
+++ b/ext/sqlite/libsqlite/src/os.c
@@ -0,0 +1,1477 @@
+/*
+** 2001 September 16
+**
+** 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.
+**
+******************************************************************************
+**
+** This file contains code that is specific to particular operating
+** systems.  The purpose of this file is to provide a uniform abstraction
+** on which the rest of SQLite can operate.
+*/
+#include "os.h"          /* Must be first to enable large file support */
+#include "sqliteInt.h"
+
+#if OS_UNIX
+# include <time.h>
+# include <errno.h>
+# include <unistd.h>
+# ifndef O_LARGEFILE
+#  define O_LARGEFILE 0
+# endif
+# ifdef SQLITE_DISABLE_LFS
+#  undef O_LARGEFILE
+#  define O_LARGEFILE 0
+# endif
+# ifndef O_NOFOLLOW
+#  define O_NOFOLLOW 0
+# endif
+#endif
+
+#if OS_WIN
+# include <winbase.h>
+#endif
+
+#if OS_MAC
+# include <extras.h>
+# include <path2fss.h>
+# include <TextUtils.h>
+# include <FinderRegistry.h>
+# include <Folders.h>
+# include <Timer.h>
+# include <OSUtils.h>
+#endif
+
+/*
+** Macros for performance tracing.  Normally turned off
+*/
+#if 0
+static int last_page = 0;
+__inline__ unsigned long long int hwtime(void){
+  unsigned long long int x;
+  __asm__("rdtsc\n\t"
+          "mov %%edx, %%ecx\n\t"
+          :"=A" (x));
+  return x;
+}
+static unsigned long long int g_start;
+static unsigned int elapse;
+#define TIMER_START       g_start=hwtime()
+#define TIMER_END         elapse=hwtime()-g_start
+#define SEEK(X)           last_page=(X)
+#define TRACE1(X)         fprintf(stderr,X)
+#define TRACE2(X,Y)       fprintf(stderr,X,Y)
+#define TRACE3(X,Y,Z)     fprintf(stderr,X,Y,Z)
+#define TRACE4(X,Y,Z,A)   fprintf(stderr,X,Y,Z,A)
+#define TRACE5(X,Y,Z,A,B) fprintf(stderr,X,Y,Z,A,B)
+#else
+#define TIMER_START
+#define TIMER_END
+#define SEEK(X)
+#define TRACE1(X)
+#define TRACE2(X,Y)
+#define TRACE3(X,Y,Z)
+#define TRACE4(X,Y,Z,A)
+#define TRACE5(X,Y,Z,A,B)
+#endif
+
+
+#if OS_UNIX
+/*
+** Here is the dirt on POSIX advisory locks:  ANSI STD 1003.1 (1996)
+** section 6.5.2.2 lines 483 through 490 specify that when a process
+** sets or clears a lock, that operation overrides any prior locks set
+** by the same process.  It does not explicitly say so, but this implies
+** that it overrides locks set by the same process using a different
+** file descriptor.  Consider this test case:
+**
+**       int fd1 = open("./file1", O_RDWR|O_CREAT, 0644);
+**       int fd2 = open("./file2", O_RDWR|O_CREAT, 0644);
+**
+** Suppose ./file1 and ./file2 are really be the same file (because
+** one is a hard or symbolic link to the other) then if you set
+** an exclusive lock on fd1, then try to get an exclusive lock
+** on fd2, it works.  I would have expected the second lock to
+** fail since there was already a lock on the file due to fd1.
+** But not so.  Since both locks came from the same process, the
+** second overrides the first, even though they were on different
+** file descriptors opened on different file names.
+**
+** Bummer.  If you ask me, this is broken.  Badly broken.  It means
+** that we cannot use POSIX locks to synchronize file access among
+** competing threads of the same process.  POSIX locks will work fine
+** to synchronize access for threads in separate processes, but not
+** threads within the same process.
+**
+** To work around the problem, SQLite has to manage file locks internally
+** on its own.  Whenever a new database is opened, we have to find the
+** specific inode of the database file (the inode is determined by the
+** st_dev and st_ino fields of the stat structure that fstat() fills in)
+** and check for locks already existing on that inode.  When locks are
+** created or removed, we have to look at our own internal record of the
+** locks to see if another thread has previously set a lock on that same
+** inode.
+**
+** The OsFile structure for POSIX is no longer just an integer file
+** descriptor.  It is now a structure that holds the integer file
+** descriptor and a pointer to a structure that describes the internal
+** locks on the corresponding inode.  There is one locking structure
+** per inode, so if the same inode is opened twice, both OsFile structures
+** point to the same locking structure.  The locking structure keeps
+** a reference count (so we will know when to delete it) and a "cnt"
+** field that tells us its internal lock status.  cnt==0 means the
+** file is unlocked.  cnt==-1 means the file has an exclusive lock.
+** cnt>0 means there are cnt shared locks on the file.
+**
+** Any attempt to lock or unlock a file first checks the locking
+** structure.  The fcntl() system call is only invoked to set a 
+** POSIX lock if the internal lock structure transitions between
+** a locked and an unlocked state.
+*/
+
+/*
+** An instance of the following structure serves as the key used
+** to locate a particular lockInfo structure given its inode. 
+*/
+struct inodeKey {
+  dev_t dev;   /* Device number */
+  ino_t ino;   /* Inode number */
+};
+
+/*
+** An instance of the following structure is allocated for each inode.
+** 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 inodeKey key;  /* The lookup key */
+  int cnt;              /* 0: unlocked.  -1: write lock.  1...: read lock. */
+  int nRef;             /* Number of pointers to this structure */
+};
+
+/* 
+** This hash table maps inodes (in the form of inodeKey structures) into
+** pointers to lockInfo structures.
+*/
+static Hash lockHash = { SQLITE_HASH_BINARY, 0, 0, 0, 0, 0 };
+
+/*
+** Given a file descriptor, locate a lockInfo structure that describes
+** that file descriptor.  Create a new one if necessary.  NULL might
+** be returned if malloc() fails.
+*/
+static struct lockInfo *findLockInfo(int fd){
+  int rc;
+  struct inodeKey key;
+  struct stat statbuf;
+  struct lockInfo *pInfo;
+  rc = fstat(fd, &statbuf);
+  if( rc!=0 ) return 0;
+  memset(&key, 0, sizeof(key));
+  key.dev = statbuf.st_dev;
+  key.ino = statbuf.st_ino;
+  pInfo = (struct lockInfo*)sqliteHashFind(&lockHash, &key, sizeof(key));
+  if( pInfo==0 ){
+    struct lockInfo *pOld;
+    pInfo = sqliteMalloc( sizeof(*pInfo) );
+    if( pInfo==0 ) return 0;
+    pInfo->key = key;
+    pInfo->nRef = 1;
+    pInfo->cnt = 0;
+    pOld = sqliteHashInsert(&lockHash, &pInfo->key, sizeof(key), pInfo);
+    if( pOld!=0 ){
+      assert( pOld==pInfo );
+      sqliteFree(pInfo);
+      pInfo = 0;
+    }
+  }else{
+    pInfo->nRef++;
+  }
+  return pInfo;
+}
+
+/*
+** Release a lockInfo structure previously allocated by findLockInfo().
+*/
+static void releaseLockInfo(struct lockInfo *pInfo){
+  pInfo->nRef--;
+  if( pInfo->nRef==0 ){
+    sqliteHashInsert(&lockHash, &pInfo->key, sizeof(pInfo->key), 0);
+    sqliteFree(pInfo);
+  }
+}
+#endif  /** POSIX advisory lock work-around **/
+
+/*
+** If we compile with the SQLITE_TEST macro set, then the following block
+** of code will give us the ability to simulate a disk I/O error.  This
+** is used for testing the I/O recovery logic.
+*/
+#ifdef SQLITE_TEST
+int sqlite_io_error_pending = 0;
+#define SimulateIOError(A)  \
+   if( sqlite_io_error_pending ) \
+     if( sqlite_io_error_pending-- == 1 ){ local_ioerr(); return A; }
+static void local_ioerr(){
+  sqlite_io_error_pending = 0;  /* Really just a place to set a breakpoint */
+}
+#else
+#define SimulateIOError(A)
+#endif
+
+/*
+** When testing, keep a count of the number of open files.
+*/
+#ifdef SQLITE_TEST
+int sqlite_open_file_count = 0;
+#define OpenCounter(X)  sqlite_open_file_count+=(X)
+#else
+#define OpenCounter(X)
+#endif
+
+
+/*
+** Delete the named file
+*/
+int sqliteOsDelete(const char *zFilename){
+#if OS_UNIX
+  unlink(zFilename);
+#endif
+#if OS_WIN
+  DeleteFile(zFilename);
+#endif
+#if OS_MAC
+  unlink(zFilename);
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** Return TRUE if the named file exists.
+*/
+int sqliteOsFileExists(const char *zFilename){
+#if OS_UNIX
+  return access(zFilename, 0)==0;
+#endif
+#if OS_WIN
+  return GetFileAttributes(zFilename) != 0xffffffff;
+#endif
+#if OS_MAC
+  return access(zFilename, 0)==0;
+#endif
+}
+
+
+/*
+** Attempt to open a file for both reading and writing.  If that
+** fails, try opening it read-only.  If the file does not exist,
+** try to create it.
+**
+** On success, a handle for the open file is written to *id
+** and *pReadonly is set to 0 if the file was opened for reading and
+** writing or 1 if the file was opened read-only.  The function returns
+** SQLITE_OK.
+**
+** On failure, the function returns SQLITE_CANTOPEN and leaves
+** *id and *pReadonly unchanged.
+*/
+int sqliteOsOpenReadWrite(
+  const char *zFilename,
+  OsFile *id,
+  int *pReadonly
+){
+#if OS_UNIX
+  id->fd = open(zFilename, O_RDWR|O_CREAT|O_LARGEFILE, 0644);
+  if( id->fd<0 ){
+    id->fd = open(zFilename, O_RDONLY|O_LARGEFILE);
+    if( id->fd<0 ){
+      return SQLITE_CANTOPEN; 
+    }
+    *pReadonly = 1;
+  }else{
+    *pReadonly = 0;
+  }
+  sqliteOsEnterMutex();
+  id->pLock = findLockInfo(id->fd);
+  sqliteOsLeaveMutex();
+  if( id->pLock==0 ){
+    close(id->fd);
+    return SQLITE_NOMEM;
+  }
+  id->locked = 0;
+  TRACE3("OPEN    %-3d %s\n", id->fd, zFilename);
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  HANDLE h = CreateFile(zFilename,
+     GENERIC_READ | GENERIC_WRITE,
+     FILE_SHARE_READ | FILE_SHARE_WRITE,
+     NULL,
+     OPEN_ALWAYS,
+     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
+     NULL
+  );
+  if( h==INVALID_HANDLE_VALUE ){
+    h = CreateFile(zFilename,
+       GENERIC_READ,
+       FILE_SHARE_READ,
+       NULL,
+       OPEN_ALWAYS,
+       FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
+       NULL
+    );
+    if( h==INVALID_HANDLE_VALUE ){
+      return SQLITE_CANTOPEN;
+    }
+    *pReadonly = 1;
+  }else{
+    *pReadonly = 0;
+  }
+  id->h = h;
+  id->locked = 0;
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+  FSSpec fsSpec;
+# ifdef _LARGE_FILE
+  HFSUniStr255 dfName;
+  FSRef fsRef;
+  if( __path2fss(zFilename, &fsSpec) != noErr ){
+    if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
+      return SQLITE_CANTOPEN;
+  }
+  if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
+    return SQLITE_CANTOPEN;
+  FSGetDataForkName(&dfName);
+  if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
+                 fsRdWrShPerm, &(id->refNum)) != noErr ){
+    if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
+                   fsRdWrPerm, &(id->refNum)) != noErr ){
+      if (FSOpenFork(&fsRef, dfName.length, dfName.unicode,
+                   fsRdPerm, &(id->refNum)) != noErr )
+        return SQLITE_CANTOPEN;
+      else
+        *pReadonly = 1;
+    } else
+      *pReadonly = 0;
+  } else
+    *pReadonly = 0;
+# else
+  __path2fss(zFilename, &fsSpec);
+  if( !sqliteOsFileExists(zFilename) ){
+    if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
+      return SQLITE_CANTOPEN;
+  }
+  if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNum)) != noErr ){
+    if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrPerm, &(id->refNum)) != noErr ){
+      if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdPerm, &(id->refNum)) != noErr )
+        return SQLITE_CANTOPEN;
+      else
+        *pReadonly = 1;
+    } else
+      *pReadonly = 0;
+  } else
+    *pReadonly = 0;
+# endif
+  if( HOpenRF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNumRF)) != noErr){
+    id->refNumRF = -1;
+  }
+  id->locked = 0;
+  id->delOnClose = 0;
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+}
+
+
+/*
+** Attempt to open a new file for exclusive access by this process.
+** The file will be opened for both reading and writing.  To avoid
+** a potential security problem, we do not allow the file to have
+** previously existed.  Nor do we allow the file to be a symbolic
+** link.
+**
+** If delFlag is true, then make arrangements to automatically delete
+** the file when it is closed.
+**
+** On success, write the file handle into *id and return SQLITE_OK.
+**
+** On failure, return SQLITE_CANTOPEN.
+*/
+int sqliteOsOpenExclusive(const char *zFilename, OsFile *id, int delFlag){
+#if OS_UNIX
+  if( access(zFilename, 0)==0 ){
+    return SQLITE_CANTOPEN;
+  }
+  id->fd = open(zFilename, O_RDWR|O_CREAT|O_EXCL|O_NOFOLLOW|O_LARGEFILE, 0600);
+  if( id->fd<0 ){
+    return SQLITE_CANTOPEN;
+  }
+  sqliteOsEnterMutex();
+  id->pLock = findLockInfo(id->fd);
+  sqliteOsLeaveMutex();
+  if( id->pLock==0 ){
+    close(id->fd);
+    unlink(zFilename);
+    return SQLITE_NOMEM;
+  }
+  id->locked = 0;
+  if( delFlag ){
+    unlink(zFilename);
+  }
+  TRACE3("OPEN-EX %-3d %s\n", id->fd, zFilename);
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  HANDLE h;
+  int fileflags;
+  if( delFlag ){
+    fileflags = FILE_ATTRIBUTE_TEMPORARY | FILE_FLAG_RANDOM_ACCESS 
+                     | FILE_FLAG_DELETE_ON_CLOSE;
+  }else{
+    fileflags = FILE_FLAG_RANDOM_ACCESS;
+  }
+  h = CreateFile(zFilename,
+     GENERIC_READ | GENERIC_WRITE,
+     0,
+     NULL,
+     CREATE_ALWAYS,
+     fileflags,
+     NULL
+  );
+  if( h==INVALID_HANDLE_VALUE ){
+    return SQLITE_CANTOPEN;
+  }
+  id->h = h;
+  id->locked = 0;
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+  FSSpec fsSpec;
+# ifdef _LARGE_FILE
+  HFSUniStr255 dfName;
+  FSRef fsRef;
+  __path2fss(zFilename, &fsSpec);
+  if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
+    return SQLITE_CANTOPEN;
+  if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
+    return SQLITE_CANTOPEN;
+  FSGetDataForkName(&dfName);
+  if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
+                 fsRdWrPerm, &(id->refNum)) != noErr )
+    return SQLITE_CANTOPEN;
+# else
+  __path2fss(zFilename, &fsSpec);
+  if( HCreate(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, 'SQLI', cDocumentFile) != noErr )
+    return SQLITE_CANTOPEN;
+  if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrPerm, &(id->refNum)) != noErr )
+    return SQLITE_CANTOPEN;
+# endif
+  id->refNumRF = -1;
+  id->locked = 0;
+  id->delOnClose = delFlag;
+  if (delFlag)
+    id->pathToDel = sqliteOsFullPathname(zFilename);
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+}
+
+/*
+** Attempt to open a new file for read-only access.
+**
+** On success, write the file handle into *id and return SQLITE_OK.
+**
+** On failure, return SQLITE_CANTOPEN.
+*/
+int sqliteOsOpenReadOnly(const char *zFilename, OsFile *id){
+#if OS_UNIX
+  id->fd = open(zFilename, O_RDONLY|O_LARGEFILE);
+  if( id->fd<0 ){
+    return SQLITE_CANTOPEN;
+  }
+  sqliteOsEnterMutex();
+  id->pLock = findLockInfo(id->fd);
+  sqliteOsLeaveMutex();
+  if( id->pLock==0 ){
+    close(id->fd);
+    return SQLITE_NOMEM;
+  }
+  id->locked = 0;
+  TRACE3("OPEN-RO %-3d %s\n", id->fd, zFilename);
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  HANDLE h = CreateFile(zFilename,
+     GENERIC_READ,
+     0,
+     NULL,
+     OPEN_EXISTING,
+     FILE_ATTRIBUTE_NORMAL | FILE_FLAG_RANDOM_ACCESS,
+     NULL
+  );
+  if( h==INVALID_HANDLE_VALUE ){
+    return SQLITE_CANTOPEN;
+  }
+  id->h = h;
+  id->locked = 0;
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+  FSSpec fsSpec;
+# ifdef _LARGE_FILE
+  HFSUniStr255 dfName;
+  FSRef fsRef;
+  if( __path2fss(zFilename, &fsSpec) != noErr )
+    return SQLITE_CANTOPEN;
+  if( FSpMakeFSRef(&fsSpec, &fsRef) != noErr )
+    return SQLITE_CANTOPEN;
+  FSGetDataForkName(&dfName);
+  if( FSOpenFork(&fsRef, dfName.length, dfName.unicode,
+                 fsRdPerm, &(id->refNum)) != noErr )
+    return SQLITE_CANTOPEN;
+# else
+  __path2fss(zFilename, &fsSpec);
+  if( HOpenDF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdPerm, &(id->refNum)) != noErr )
+    return SQLITE_CANTOPEN;
+# endif
+  if( HOpenRF(fsSpec.vRefNum, fsSpec.parID, fsSpec.name, fsRdWrShPerm, &(id->refNumRF)) != noErr){
+    id->refNumRF = -1;
+  }
+  id->locked = 0;
+  id->delOnClose = 0;
+  OpenCounter(+1);
+  return SQLITE_OK;
+#endif
+}
+
+/*
+** Create a temporary file name in zBuf.  zBuf must be big enough to
+** hold at least SQLITE_TEMPNAME_SIZE characters.
+*/
+int sqliteOsTempFileName(char *zBuf){
+#if OS_UNIX
+  static const char *azDirs[] = {
+     "/var/tmp",
+     "/usr/tmp",
+     "/tmp",
+     ".",
+  };
+  static char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  int i, j;
+  struct stat buf;
+  const char *zDir = ".";
+  for(i=0; i<sizeof(azDirs)/sizeof(azDirs[0]); i++){
+    if( stat(azDirs[i], &buf) ) continue;
+    if( !S_ISDIR(buf.st_mode) ) continue;
+    if( access(azDirs[i], 07) ) continue;
+    zDir = azDirs[i];
+    break;
+  }
+  do{
+    sprintf(zBuf, "%s/"TEMP_FILE_PREFIX, zDir);
+    j = strlen(zBuf);
+    for(i=0; i<15; i++){
+      int n = sqliteRandomByte() % (sizeof(zChars)-1);
+      zBuf[j++] = zChars[n];
+    }
+    zBuf[j] = 0;
+  }while( access(zBuf,0)==0 );
+#endif
+#if OS_WIN
+  static char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  int i, j;
+  char zTempPath[SQLITE_TEMPNAME_SIZE];
+  GetTempPath(SQLITE_TEMPNAME_SIZE-30, zTempPath);
+  for(i=strlen(zTempPath); i>0 && zTempPath[i-1]=='\\'; i--){}
+  zTempPath[i] = 0;
+  for(;;){
+    sprintf(zBuf, "%s\\"TEMP_FILE_PREFIX, zTempPath);
+    j = strlen(zBuf);
+    for(i=0; i<15; i++){
+      int n = sqliteRandomByte() % sizeof(zChars);
+      zBuf[j++] = zChars[n];
+    }
+    zBuf[j] = 0;
+    if( !sqliteOsFileExists(zBuf) ) break;
+  }
+#endif
+#if OS_MAC
+  static char zChars[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789";
+  int i, j;
+  char zTempPath[SQLITE_TEMPNAME_SIZE];
+  char zdirName[32];
+  CInfoPBRec infoRec;
+  Str31 dirName;
+  memset(&infoRec, 0, sizeof(infoRec));
+  memset(zTempPath, 0, SQLITE_TEMPNAME_SIZE);
+  if( FindFolder(kOnSystemDisk, kTemporaryFolderType,  kCreateFolder,
+       &(infoRec.dirInfo.ioVRefNum), &(infoRec.dirInfo.ioDrParID)) == noErr ){
+    infoRec.dirInfo.ioNamePtr = dirName;
+    do{
+      infoRec.dirInfo.ioFDirIndex = -1;
+      infoRec.dirInfo.ioDrDirID = infoRec.dirInfo.ioDrParID;
+      if( PBGetCatInfoSync(&infoRec) == noErr ){
+        CopyPascalStringToC(dirName, zdirName);
+        i = strlen(zdirName);
+        memmove(&(zTempPath[i+1]), zTempPath, strlen(zTempPath));
+        strcpy(zTempPath, zdirName);
+        zTempPath[i] = ':';
+      }else{
+        *zTempPath = 0;
+        break;
+      }
+    } while( infoRec.dirInfo.ioDrDirID != fsRtDirID );
+  }
+  if( *zTempPath == 0 )
+    getcwd(zTempPath, SQLITE_TEMPNAME_SIZE-24);
+  for(;;){
+    sprintf(zBuf, "%s"TEMP_FILE_PREFIX, zTempPath);
+    j = strlen(zBuf);
+    for(i=0; i<15; i++){
+      int n = sqliteRandomByte() % sizeof(zChars);
+      zBuf[j++] = zChars[n];
+    }
+    zBuf[j] = 0;
+    if( !sqliteOsFileExists(zBuf) ) break;
+  }
+#endif
+  return SQLITE_OK; 
+}
+
+/*
+** Close a file
+*/
+int sqliteOsClose(OsFile *id){
+#if OS_UNIX
+  close(id->fd);
+  sqliteOsEnterMutex();
+  releaseLockInfo(id->pLock);
+  sqliteOsLeaveMutex();
+  TRACE2("CLOSE   %-3d\n", id->fd);
+  OpenCounter(-1);
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  CloseHandle(id->h);
+  OpenCounter(-1);
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+  if( id->refNumRF!=-1 )
+    FSClose(id->refNumRF);
+# ifdef _LARGE_FILE
+  FSCloseFork(id->refNum);
+# else
+  FSClose(id->refNum);
+# endif
+  if( id->delOnClose ){
+    unlink(id->pathToDel);
+    sqliteFree(id->pathToDel);
+  }
+  OpenCounter(-1);
+  return SQLITE_OK;
+#endif
+}
+
+/*
+** Read data from a file into a buffer.  Return SQLITE_OK if all
+** bytes were read successfully and SQLITE_IOERR if anything goes
+** wrong.
+*/
+int sqliteOsRead(OsFile *id, void *pBuf, int amt){
+#if OS_UNIX
+  int got;
+  SimulateIOError(SQLITE_IOERR);
+  TIMER_START;
+  got = read(id->fd, pBuf, amt);
+  TIMER_END;
+  TRACE4("READ    %-3d %7d %d\n", id->fd, last_page, elapse);
+  SEEK(0);
+  /* if( got<0 ) got = 0; */
+  if( got==amt ){
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR;
+  }
+#endif
+#if OS_WIN
+  DWORD got;
+  SimulateIOError(SQLITE_IOERR);
+  TRACE2("READ %d\n", last_page);
+  if( !ReadFile(id->h, pBuf, amt, &got, 0) ){
+    got = 0;
+  }
+  if( got==(DWORD)amt ){
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR;
+  }
+#endif
+#if OS_MAC
+  int got;
+  SimulateIOError(SQLITE_IOERR);
+  TRACE2("READ %d\n", last_page);
+# ifdef _LARGE_FILE
+  FSReadFork(id->refNum, fsAtMark, 0, (ByteCount)amt, pBuf, (ByteCount*)&got);
+# else
+  got = amt;
+  FSRead(id->refNum, &got, pBuf);
+# endif
+  if( got==amt ){
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR;
+  }
+#endif
+}
+
+/*
+** Write data from a buffer into a file.  Return SQLITE_OK on success
+** or some other error code on failure.
+*/
+int sqliteOsWrite(OsFile *id, const void *pBuf, int amt){
+#if OS_UNIX
+  int wrote = 0;
+  SimulateIOError(SQLITE_IOERR);
+  TIMER_START;
+  while( amt>0 && (wrote = write(id->fd, pBuf, amt))>0 ){
+    amt -= wrote;
+    pBuf = &((char*)pBuf)[wrote];
+  }
+  TIMER_END;
+  TRACE4("WRITE   %-3d %7d %d\n", id->fd, last_page, elapse);
+  SEEK(0);
+  if( amt>0 ){
+    return SQLITE_FULL;
+  }
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  int rc;
+  DWORD wrote;
+  SimulateIOError(SQLITE_IOERR);
+  TRACE2("WRITE %d\n", last_page);
+  while( amt>0 && (rc = WriteFile(id->h, pBuf, amt, &wrote, 0))!=0 && wrote>0 ){
+    amt -= wrote;
+    pBuf = &((char*)pBuf)[wrote];
+  }
+  if( !rc || amt>(int)wrote ){
+    return SQLITE_FULL;
+  }
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+  OSErr oserr;
+  int wrote = 0;
+  SimulateIOError(SQLITE_IOERR);
+  TRACE2("WRITE %d\n", last_page);
+  while( amt>0 ){
+# ifdef _LARGE_FILE
+    oserr = FSWriteFork(id->refNum, fsAtMark, 0,
+                        (ByteCount)amt, pBuf, (ByteCount*)&wrote);
+# else
+    wrote = amt;
+    oserr = FSWrite(id->refNum, &wrote, pBuf);
+# endif
+    if( wrote == 0 || oserr != noErr)
+      break;
+    amt -= wrote;
+    pBuf = &((char*)pBuf)[wrote];
+  }
+  if( oserr != noErr || amt>wrote ){
+    return SQLITE_FULL;
+  }
+  return SQLITE_OK;
+#endif
+}
+
+/*
+** Move the read/write pointer in a file.
+*/
+int sqliteOsSeek(OsFile *id, off_t offset){
+  SEEK(offset/1024 + 1);
+#if OS_UNIX
+  lseek(id->fd, offset, SEEK_SET);
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  {
+    LONG upperBits = offset>>32;
+    LONG lowerBits = offset & 0xffffffff;
+    DWORD rc;
+    rc = SetFilePointer(id->h, lowerBits, &upperBits, FILE_BEGIN);
+    /* TRACE3("SEEK rc=0x%x upper=0x%x\n", rc, upperBits); */
+  }
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+  {
+    off_t curSize;
+    if( sqliteOsFileSize(id, &curSize) != SQLITE_OK ){
+      return SQLITE_IOERR;
+    }
+    if( offset >= curSize ){
+      if( sqliteOsTruncate(id, offset+1) != SQLITE_OK ){
+        return SQLITE_IOERR;
+      }
+    }
+# ifdef _LARGE_FILE
+    if( FSSetForkPosition(id->refNum, fsFromStart, offset) != noErr ){
+# else
+    if( SetFPos(id->refNum, fsFromStart, offset) != noErr ){
+# endif
+      return SQLITE_IOERR;
+    }else{
+      return SQLITE_OK;
+    }
+  }
+#endif
+}
+
+/*
+** Make sure all writes to a particular file are committed to disk.
+*/
+int sqliteOsSync(OsFile *id){
+#if OS_UNIX
+  SimulateIOError(SQLITE_IOERR);
+  TRACE2("SYNC    %-3d\n", id->fd);
+  if( fsync(id->fd) ){
+    return SQLITE_IOERR;
+  }else{
+    return SQLITE_OK;
+  }
+#endif
+#if OS_WIN
+  if( FlushFileBuffers(id->h) ){
+    return SQLITE_OK;
+  }else{
+    return SQLITE_IOERR;
+  }
+#endif
+#if OS_MAC
+# ifdef _LARGE_FILE
+  if( FSFlushFork(id->refNum) != noErr ){
+# else
+  ParamBlockRec params;
+  memset(&params, 0, sizeof(ParamBlockRec));
+  params.ioParam.ioRefNum = id->refNum;
+  if( PBFlushFileSync(&params) != noErr ){
+# endif
+    return SQLITE_IOERR;
+  }else{
+    return SQLITE_OK;
+  }
+#endif
+}
+
+/*
+** Truncate an open file to a specified size
+*/
+int sqliteOsTruncate(OsFile *id, off_t nByte){
+  SimulateIOError(SQLITE_IOERR);
+#if OS_UNIX
+  return ftruncate(id->fd, nByte)==0 ? SQLITE_OK : SQLITE_IOERR;
+#endif
+#if OS_WIN
+  {
+    LONG upperBits = nByte>>32;
+    SetFilePointer(id->h, nByte, &upperBits, FILE_BEGIN);
+    SetEndOfFile(id->h);
+  }
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+# ifdef _LARGE_FILE
+  if( FSSetForkSize(id->refNum, fsFromStart, nByte) != noErr){
+# else
+  if( SetEOF(id->refNum, nByte) != noErr ){
+# endif
+    return SQLITE_IOERR;
+  }else{
+    return SQLITE_OK;
+  }
+#endif
+}
+
+/*
+** Determine the current size of a file in bytes
+*/
+int sqliteOsFileSize(OsFile *id, off_t *pSize){
+#if OS_UNIX
+  struct stat buf;
+  SimulateIOError(SQLITE_IOERR);
+  if( fstat(id->fd, &buf)!=0 ){
+    return SQLITE_IOERR;
+  }
+  *pSize = buf.st_size;
+  return SQLITE_OK;
+#endif
+#if OS_WIN
+  DWORD upperBits, lowerBits;
+  SimulateIOError(SQLITE_IOERR);
+  lowerBits = GetFileSize(id->h, &upperBits);
+  *pSize = (((off_t)upperBits)<<32) + lowerBits;
+  return SQLITE_OK;
+#endif
+#if OS_MAC
+# ifdef _LARGE_FILE
+  if( FSGetForkSize(id->refNum, pSize) != noErr){
+# else
+  if( GetEOF(id->refNum, pSize) != noErr ){
+# endif
+    return SQLITE_IOERR;
+  }else{
+    return SQLITE_OK;
+  }
+#endif
+}
+
+#if OS_WIN
+/*
+** Return true (non-zero) if we are running under WinNT, Win2K or WinXP.
+** Return false (zero) for Win95, Win98, or WinME.
+*/
+int isNT(void){
+  static osType = 0;   /* 0=unknown 1=win95 2=winNT */
+  if( osType==0 ){
+    OSVERSIONINFO sInfo;
+    sInfo.dwOSVersionInfoSize = sizeof(sInfo);
+    GetVersionEx(&sInfo);
+    osType = sInfo.dwPlatformId==VER_PLATFORM_WIN32_NT ? 2 : 1;
+  }
+  return osType==2;
+}
+#endif
+
+/*
+** Windows file locking notes:  [the same/equivalent applies to MacOS]
+**
+** We cannot use LockFileEx() or UnlockFileEx() because those functions
+** are not available under Win95/98/ME.  So we use only LockFile() and
+** UnlockFile().
+**
+** LockFile() prevents not just writing but also reading by other processes.
+** (This is a design error on the part of Windows, but there is nothing
+** we can do about that.)  So the region used for locking is at the
+** end of the file where it is unlikely to ever interfere with an
+** actual read attempt.
+**
+** A database read lock is obtained by locking a single randomly-chosen 
+** byte out of a specific range of bytes. The lock byte is obtained at 
+** random so two separate readers can probably access the file at the 
+** same time, unless they are unlucky and choose the same lock byte.
+** A database write lock is obtained by locking all bytes in the range.
+** There can only be one writer.
+**
+** A lock is obtained on the first byte of the lock range before acquiring
+** either a read lock or a write lock.  This prevents two processes from
+** attempting to get a lock at a same time.  The semantics of 
+** sqliteOsReadLock() require that if there is already a write lock, that
+** lock is converted into a read lock atomically.  The lock on the first
+** byte allows us to drop the old write lock and get the read lock without
+** another process jumping into the middle and messing us up.  The same
+** argument applies to sqliteOsWriteLock().
+**
+** Note: On MacOS we use the resource fork for locking.
+**
+** The following #defines specify the range of bytes used for locking.
+** N_LOCKBYTE is the number of bytes available for doing the locking.
+** The first byte used to hold the lock while the lock is changing does
+** not count toward this number.  FIRST_LOCKBYTE is the address of
+** the first byte in the range of bytes used for locking.
+*/
+#define N_LOCKBYTE       10239
+#if OS_MAC
+# define FIRST_LOCKBYTE   (0x000fffff - N_LOCKBYTE)
+#else
+# define FIRST_LOCKBYTE   (0xffffffff - N_LOCKBYTE)
+#endif
+
+/*
+** Change the status of the lock on the file "id" to be a readlock.
+** If the file was write locked, then this reduces the lock to a read.
+** If the file was read locked, then this acquires a new read lock.
+**
+** 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 sqliteOsReadLock(OsFile *id){
+#if OS_UNIX
+  int rc;
+  sqliteOsEnterMutex();
+  if( id->pLock->cnt>0 ){
+    if( !id->locked ){
+      id->pLock->cnt++;
+      id->locked = 1;
+    }
+    rc = SQLITE_OK;
+  }else if( id->locked || id->pLock->cnt==0 ){
+    struct flock lock;
+    int s;
+    lock.l_type = F_RDLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = lock.l_len = 0L;
+    s = fcntl(id->fd, F_SETLK, &lock);
+    if( s!=0 ){
+      rc = (s==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
+    }else{
+      rc = SQLITE_OK;
+      id->pLock->cnt = 1;
+      id->locked = 1;
+    }
+  }else{
+    rc = SQLITE_BUSY;
+  }
+  sqliteOsLeaveMutex();
+  return rc;
+#endif
+#if OS_WIN
+  int rc;
+  if( id->locked>0 ){
+    rc = SQLITE_OK;
+  }else{
+    int lk = (sqliteRandomInteger() & 0x7ffffff)%N_LOCKBYTE+1;
+    int res;
+    int cnt = 100;
+    int page = isNT() ? 0xffffffff : 0;
+    while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, page, 1, 0))==0 ){
+      Sleep(1);
+    }
+    if( res ){
+      UnlockFile(id->h, FIRST_LOCKBYTE+1, page, N_LOCKBYTE, 0);
+      res = LockFile(id->h, FIRST_LOCKBYTE+lk, page, 1, 0);
+      UnlockFile(id->h, FIRST_LOCKBYTE, page, 1, 0);
+    }
+    if( res ){
+      id->locked = lk;
+      rc = SQLITE_OK;
+    }else{
+      rc = SQLITE_BUSY;
+    }
+  }
+  return rc;
+#endif
+#if OS_MAC
+  int rc;
+  if( id->locked>0 || id->refNumRF == -1 ){
+    rc = SQLITE_OK;
+  }else{
+    int lk = (sqliteRandomInteger() & 0x7ffffff)%N_LOCKBYTE+1;
+    OSErr res;
+    int cnt = 5;
+    ParamBlockRec params;
+    memset(&params, 0, sizeof(params));
+    params.ioParam.ioRefNum = id->refNumRF;
+    params.ioParam.ioPosMode = fsFromStart;
+    params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
+    params.ioParam.ioReqCount = 1;
+    while( cnt-->0 && (res = PBLockRangeSync(&params))!=noErr ){
+      UInt32 finalTicks;
+      Delay(1, &finalTicks); /* 1/60 sec */
+    }
+    if( res == noErr ){
+      params.ioParam.ioPosOffset = FIRST_LOCKBYTE+1;
+      params.ioParam.ioReqCount = N_LOCKBYTE;
+      PBUnlockRangeSync(&params);
+      params.ioParam.ioPosOffset = FIRST_LOCKBYTE+lk;
+      params.ioParam.ioReqCount = 1;
+      res = PBLockRangeSync(&params);
+      params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
+      params.ioParam.ioReqCount = 1;
+      PBUnlockRangeSync(&params);
+    }
+    if( res == noErr ){
+      id->locked = lk;
+      rc = SQLITE_OK;
+    }else{
+      rc = SQLITE_BUSY;
+    }
+  }
+  return rc;
+#endif
+}
+
+/*
+** 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 sqliteOsWriteLock(OsFile *id){
+#if OS_UNIX
+  int rc;
+  sqliteOsEnterMutex();
+  if( id->pLock->cnt==0 || (id->pLock->cnt==1 && id->locked==1) ){
+    struct flock lock;
+    int s;
+    lock.l_type = F_WRLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = lock.l_len = 0L;
+    s = fcntl(id->fd, F_SETLK, &lock);
+    if( s!=0 ){
+      rc = (s==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
+    }else{
+      rc = SQLITE_OK;
+      id->pLock->cnt = -1;
+      id->locked = 1;
+    }
+  }else{
+    rc = SQLITE_BUSY;
+  }
+  sqliteOsLeaveMutex();
+  return rc;
+#endif
+#if OS_WIN
+  int rc;
+  if( id->locked<0 ){
+    rc = SQLITE_OK;
+  }else{
+    int res;
+    int cnt = 100;
+    int page = isNT() ? 0xffffffff : 0;
+    while( cnt-->0 && (res = LockFile(id->h, FIRST_LOCKBYTE, page, 1, 0))==0 ){
+      Sleep(1);
+    }
+    if( res ){
+      if( id->locked==0 
+            || UnlockFile(id->h, FIRST_LOCKBYTE + id->locked, page, 1, 0) ){
+        res = LockFile(id->h, FIRST_LOCKBYTE+1, page, N_LOCKBYTE, 0);
+      }else{
+        res = 0;
+      }
+      UnlockFile(id->h, FIRST_LOCKBYTE, page, 1, 0);
+    }
+    if( res ){
+      id->locked = -1;
+      rc = SQLITE_OK;
+    }else{
+      rc = SQLITE_BUSY;
+    }
+  }
+  return rc;
+#endif
+#if OS_MAC
+  int rc;
+  if( id->locked<0 || id->refNumRF == -1 ){
+    rc = SQLITE_OK;
+  }else{
+    OSErr res;
+    int cnt = 5;
+    ParamBlockRec params;
+    memset(&params, 0, sizeof(params));
+    params.ioParam.ioRefNum = id->refNumRF;
+    params.ioParam.ioPosMode = fsFromStart;
+    params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
+    params.ioParam.ioReqCount = 1;
+    while( cnt-->0 && (res = PBLockRangeSync(&params))!=noErr ){
+      UInt32 finalTicks;
+      Delay(1, &finalTicks); /* 1/60 sec */
+    }
+    if( res == noErr ){
+      params.ioParam.ioPosOffset = FIRST_LOCKBYTE + id->locked;
+      params.ioParam.ioReqCount = 1;
+      if( id->locked==0 
+            || PBUnlockRangeSync(&params)==noErr ){
+        params.ioParam.ioPosOffset = FIRST_LOCKBYTE+1;
+        params.ioParam.ioReqCount = N_LOCKBYTE;
+        res = PBLockRangeSync(&params);
+      }else{
+        res = afpRangeNotLocked;
+      }
+      params.ioParam.ioPosOffset = FIRST_LOCKBYTE;
+      params.ioParam.ioReqCount = 1;
+      PBUnlockRangeSync(&params);
+    }
+    if( res == noErr ){
+      id->locked = -1;
+      rc = SQLITE_OK;
+    }else{
+      rc = SQLITE_BUSY;
+    }
+  }
+  return rc;
+#endif
+}
+
+/*
+** 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 sqliteOsUnlock(OsFile *id){
+#if OS_UNIX
+  int rc;
+  if( !id->locked ) return SQLITE_OK;
+  sqliteOsEnterMutex();
+  assert( id->pLock->cnt!=0 );
+  if( id->pLock->cnt>1 ){
+    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 = (s==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY;
+    }else{
+      rc = SQLITE_OK;
+      id->pLock->cnt = 0;
+    }
+  }
+  sqliteOsLeaveMutex();
+  id->locked = 0;
+  return rc;
+#endif
+#if OS_WIN
+  int rc;
+  int page = isNT() ? 0xffffffff : 0;
+  if( id->locked==0 ){
+    rc = SQLITE_OK;
+  }else if( id->locked<0 ){
+    UnlockFile(id->h, FIRST_LOCKBYTE+1, page, N_LOCKBYTE, 0);
+    rc = SQLITE_OK;
+    id->locked = 0;
+  }else{
+    UnlockFile(id->h, FIRST_LOCKBYTE+id->locked, page, 1, 0);
+    rc = SQLITE_OK;
+    id->locked = 0;
+  }
+  return rc;
+#endif
+#if OS_MAC
+  int rc;
+  ParamBlockRec params;
+  memset(&params, 0, sizeof(params));
+  params.ioParam.ioRefNum = id->refNumRF;
+  params.ioParam.ioPosMode = fsFromStart;
+  if( id->locked==0 || id->refNumRF == -1 ){
+    rc = SQLITE_OK;
+  }else if( id->locked<0 ){
+    params.ioParam.ioPosOffset = FIRST_LOCKBYTE+1;
+    params.ioParam.ioReqCount = N_LOCKBYTE;
+    PBUnlockRangeSync(&params);
+    rc = SQLITE_OK;
+    id->locked = 0;
+  }else{
+    params.ioParam.ioPosOffset = FIRST_LOCKBYTE+id->locked;
+    params.ioParam.ioReqCount = 1;
+    PBUnlockRangeSync(&params);
+    rc = SQLITE_OK;
+    id->locked = 0;
+  }
+  return rc;
+#endif
+}
+
+/*
+** Get information to seed the random number generator.  The seed
+** is written into the buffer zBuf[256].  The calling function must
+** supply a sufficiently large buffer.
+*/
+int sqliteOsRandomSeed(char *zBuf){
+#ifdef SQLITE_TEST
+  /* When testing, always use the same random number sequence.
+  ** This makes the tests repeatable.
+  */
+  memset(zBuf, 0, 256);
+#endif
+#if OS_UNIX && !defined(SQLITE_TEST)
+  int pid;
+  time((time_t*)zBuf);
+  pid = getpid();
+  memcpy(&zBuf[sizeof(time_t)], &pid, sizeof(pid));
+#endif
+#if OS_WIN && !defined(SQLITE_TEST)
+  GetSystemTime((LPSYSTEMTIME)zBuf);
+#endif
+#if OS_MAC
+  int pid;
+  Microseconds((UnsignedWide*)zBuf);
+  pid = getpid();
+  memcpy(&zBuf[sizeof(UnsignedWide)], &pid, sizeof(pid));
+#endif
+  return SQLITE_OK;
+}
+
+/*
+** Sleep for a little while.  Return the amount of time slept.
+*/
+int sqliteOsSleep(int ms){
+#if OS_UNIX
+#if defined(HAVE_USLEEP) && HAVE_USLEEP
+  usleep(ms*1000);
+  return ms;
+#else
+  sleep((ms+999)/1000);
+  return 1000*((ms+999)/1000);
+#endif
+#endif
+#if OS_WIN
+  Sleep(ms);
+  return ms;
+#endif
+#if OS_MAC
+  UInt32 finalTicks;
+  UInt32 ticks = (((UInt32)ms+16)*3)/50;  /* 1/60 sec per tick */
+  Delay(ticks, &finalTicks);
+  return (int)((ticks*50)/3);
+#endif
+}
+
+/*
+** Macros used to determine whether or not to use threads.  The
+** SQLITE_UNIX_THREADS macro is defined if we are synchronizing for
+** Posix threads and SQLITE_W32_THREADS is defined if we are
+** synchronizing using Win32 threads.
+*/
+#if OS_UNIX && defined(THREADSAFE) && THREADSAFE
+# include <pthread.h>
+# define SQLITE_UNIX_THREADS 1
+#endif
+#if OS_WIN && defined(THREADSAFE) && THREADSAFE
+# define SQLITE_W32_THREADS 1
+#endif
+#if OS_MAC && defined(THREADSAFE) && THREADSAFE
+# include <Multiprocessing.h>
+# define SQLITE_MACOS_MULTITASKING 1
+#endif
+
+/*
+** Static variables used for thread synchronization
+*/
+static int inMutex = 0;
+#ifdef SQLITE_UNIX_THREADS
+  static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+#ifdef SQLITE_W32_THREADS
+  static CRITICAL_SECTION cs;
+#endif
+#ifdef SQLITE_MACOS_MULTITASKING
+  static MPCriticalRegionID criticalRegion;
+#endif
+
+/*
+** The following pair of routine implement mutual exclusion for
+** multi-threaded processes.  Only a single thread is allowed to
+** executed code that is surrounded by EnterMutex() and LeaveMutex().
+**
+** SQLite uses only a single Mutex.  There is not much critical
+** code and what little there is executes quickly and without blocking.
+*/
+void sqliteOsEnterMutex(){
+#ifdef SQLITE_UNIX_THREADS
+  pthread_mutex_lock(&mutex);
+#endif
+#ifdef SQLITE_W32_THREADS
+  static int isInit = 0;
+  while( !isInit ){
+    static long lock = 0;
+    if( InterlockedIncrement(&lock)==1 ){
+      InitializeCriticalSection(&cs);
+      isInit = 1;
+    }else{
+      Sleep(1);
+    }
+  }
+  EnterCriticalSection(&cs);
+#endif
+#ifdef SQLITE_MACOS_MULTITASKING
+  static volatile int notInit = 1;
+  if( notInit ){
+    if( notInit == 2 ) /* as close as you can get to thread safe init */
+      MPYield();
+    else{
+      notInit = 2;
+      MPCreateCriticalRegion(&criticalRegion);
+      notInit = 0;
+    }
+  }
+  MPEnterCriticalRegion(criticalRegion, kDurationForever);
+#endif
+  assert( !inMutex );
+  inMutex = 1;
+}
+void sqliteOsLeaveMutex(){
+  assert( inMutex );
+  inMutex = 0;
+#ifdef SQLITE_UNIX_THREADS
+  pthread_mutex_unlock(&mutex);
+#endif
+#ifdef SQLITE_W32_THREADS
+  LeaveCriticalSection(&cs);
+#endif
+#ifdef SQLITE_MACOS_MULTITASKING
+  MPExitCriticalRegion(criticalRegion);
+#endif
+}
+
+/*
+** Turn a relative pathname into a full pathname.  Return a pointer
+** to the full pathname stored in space obtained from sqliteMalloc().
+** The calling function is responsible for freeing this space once it
+** is no longer needed.
+*/
+char *sqliteOsFullPathname(const char *zRelative){
+#if OS_UNIX
+  char *zFull = 0;
+  if( zRelative[0]=='/' ){
+    sqliteSetString(&zFull, zRelative, 0);
+  }else{
+    char zBuf[5000];
+    sqliteSetString(&zFull, getcwd(zBuf, sizeof(zBuf)), "/", zRelative, 0);
+  }
+  return zFull;
+#endif
+#if OS_WIN
+  char *zNotUsed;
+  char *zFull;
+  int nByte;
+  nByte = GetFullPathName(zRelative, 0, 0, &zNotUsed) + 1;
+  zFull = sqliteMalloc( nByte );
+  if( zFull==0 ) return 0;
+  GetFullPathName(zRelative, nByte, zFull, &zNotUsed);
+  return zFull;
+#endif
+#if OS_MAC
+  char *zFull = 0;
+  if( zRelative[0]==':' ){
+    char zBuf[_MAX_PATH+1];
+    sqliteSetString(&zFull, getcwd(zBuf, sizeof(zBuf)), &(zRelative[1]), 0);
+  }else{
+    if( strchr(zRelative, ':') ){
+      sqliteSetString(&zFull, zRelative, 0);
+    }else{
+    char zBuf[_MAX_PATH+1];
+      sqliteSetString(&zFull, getcwd(zBuf, sizeof(zBuf)), zRelative, 0);
+    }
+  }
+  return zFull;
+#endif
+}