Simplify the winRead and winWrite VFS functions to reduce the number

of system calls.

FossilOrigin-Name: b34491869c4fb31d2fdd14c94a7db2e1c0e572ba

manifest

@@ -1,5 +1,5 @@
-C When\sa\snamed\sCHECK\sconstraint\sfails,\sinclude\sthe\sname\sof\sthe\sconstraint\nin\sthe\serror\smessage.
-D 2012-03-30T15:48:48.787
+C Simplify\sthe\swinRead\sand\swinWrite\sVFS\sfunctions\sto\sreduce\sthe\snumber\nof\ssystem\scalls.
+D 2012-03-30T15:57:45.451
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2f37e468503dbe79d35c9f6dffcf3fae1ae9ec20
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -168,7 +168,7 @@ F src/os.h 59beba555b65a450bd1d804220532971d4299f60
 F src/os_common.h 92815ed65f805560b66166e3583470ff94478f04
 F src/os_os2.c 4a75888ba3dfc820ad5e8177025972d74d7f2440
 F src/os_unix.c 0e3d2942d228d0366fb80a3640f35caf413b66d1
-F src/os_win.c 5ac061ae1326a71500cee578ed0fd9113b4f6a37
+F src/os_win.c c7b26b78c5e62de7355ad79e0ce79d7b0f5fccc4
 F src/pager.c 85988507fa20acc60defb834722eddf4633e4aeb
 F src/pager.h ef1eaf8593e78f73885c1dfac27ad83bee23bdc5
 F src/parse.y eb054bb40a5bf90d3422a01ed0e5df229461727a
@@ -999,7 +999,7 @@ F tool/tostr.awk e75472c2f98dd76e06b8c9c1367f4ab07e122d06
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
 F tool/warnings-clang.sh 9f406d66e750e8ac031c63a9ef3248aaa347ef2a
 F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
-P cb7a850439c9a4a7887650d6b81d95ab8025de5b 9a0f90d9deb335ac71044b8afa81538d85cc7ccf
-R 3383713cde4154ba8c7927e87d965912
+P 1b75f301affac654bee24fa247046ea0782d3c4d
+R 2cc6bffd476fbc89b05bef18789bd072
 U drh
-Z 044e1c348f17a4e06833c51581164485
+Z 6ac97e4f60396b50617248087122bd36

manifest.uuid

@@ -1 +1 @@
-1b75f301affac654bee24fa247046ea0782d3c4d
+b34491869c4fb31d2fdd14c94a7db2e1c0e572ba

src/os_win.c

@@ -1616,6 +1616,9 @@ static int winClose(sqlite3_file *id){
   }
 #endif
   OSTRACE(("CLOSE %d %s\n", pFile->h, rc ? "ok" : "failed"));
+  if( rc ){
+    pFile->h = NULL;
+  }
   OpenCounter(-1);
   return rc ? SQLITE_OK
             : winLogError(SQLITE_IOERR_CLOSE, osGetLastError(),
@@ -1633,6 +1636,7 @@ static int winRead(
   int amt,                   /* Number of bytes to read */
   sqlite3_int64 offset       /* Begin reading at this offset */
 ){
+  OVERLAPPED overlapped;          /* The offset for ReadFile. */
   winFile *pFile = (winFile*)id;  /* file handle */
   DWORD nRead;                    /* Number of bytes actually read from file */
   int nRetry = 0;                 /* Number of retrys */
@@ -1641,10 +1645,11 @@ static int winRead(
   SimulateIOError(return SQLITE_IOERR_READ);
   OSTRACE(("READ %d lock=%d\n", pFile->h, pFile->locktype));
 
-  if( seekWinFile(pFile, offset) ){
-    return SQLITE_FULL;
-  }
-  while( !osReadFile(pFile->h, pBuf, amt, &nRead, 0) ){
+  memset(&overlapped, 0, sizeof(OVERLAPPED));
+  overlapped.Offset = (LONG)(offset & 0xffffffff);
+  overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
+  while( !osReadFile(pFile->h, pBuf, amt, &nRead, &overlapped) &&
+         osGetLastError()!=ERROR_HANDLE_EOF ){
     DWORD lastErrno;
     if( retryIoerr(&nRetry, &lastErrno) ) continue;
     pFile->lastErrno = lastErrno;
@@ -1671,7 +1676,7 @@ static int winWrite(
   int amt,                        /* Number of bytes to write */
   sqlite3_int64 offset            /* Offset into the file to begin writing at */
 ){
-  int rc;                         /* True if error has occured, else false */
+  int rc = 0;                     /* True if error has occured, else false */
   winFile *pFile = (winFile*)id;  /* File handle */
   int nRetry = 0;                 /* Number of retries */
 
@@ -1682,19 +1687,29 @@ static int winWrite(
 
   OSTRACE(("WRITE %d lock=%d\n", pFile->h, pFile->locktype));
 
-  rc = seekWinFile(pFile, offset);
-  if( rc==0 ){
+  {
+    OVERLAPPED overlapped;        /* The offset for WriteFile. */
     u8 *aRem = (u8 *)pBuf;        /* Data yet to be written */
     int nRem = amt;               /* Number of bytes yet to be written */
     DWORD nWrite;                 /* Bytes written by each WriteFile() call */
     DWORD lastErrno = NO_ERROR;   /* Value returned by GetLastError() */
 
+    memset(&overlapped, 0, sizeof(OVERLAPPED));
+    overlapped.Offset = (LONG)(offset & 0xffffffff);
+    overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
+
     while( nRem>0 ){
-      if( !osWriteFile(pFile->h, aRem, nRem, &nWrite, 0) ){
+      if( !osWriteFile(pFile->h, aRem, nRem, &nWrite, &overlapped) ){
         if( retryIoerr(&nRetry, &lastErrno) ) continue;
         break;
       }
-      if( nWrite<=0 ) break;
+      if( nWrite<=0 ){
+        lastErrno = osGetLastError();
+        break;
+      }
+      offset += nWrite;
+      overlapped.Offset = (LONG)(offset & 0xffffffff);
+      overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
       aRem += nWrite;
       nRem -= nWrite;
     }