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Overview
Comment:Failure to extend a temp file for use with mmap() in vdbesort.c is benign.
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SHA1: d4d396387d373bd1e82eda2c7c2e7ca35ec099c4
User & Date: drh 2014-05-02 16:22:55.791
Context
2014-05-02
17:33
Simplify assert() statements used to verify correct operation of record comparison routines. (check-in: 3300d62dcb user: drh tags: orderby-planning)
16:22
Failure to extend a temp file for use with mmap() in vdbesort.c is benign. (check-in: d4d396387d user: drh tags: orderby-planning)
15:25
Fix a faulty assert() statement. (check-in: 9196ce4073 user: drh tags: orderby-planning)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/vdbesort.c.
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** is guaranteed to be nByte bytes or smaller in size. This function 
** attempts to extend the file to nByte bytes in size and to ensure that
** the VFS has memory mapped it.
**
** Whether or not the file does end up memory mapped of course depends on 
** the specific VFS implementation.
*/
static int vdbeSorterExtendFile(sqlite3_file *pFile, i64 nByte){
  int rc = sqlite3OsTruncate(pFile, nByte);
  if( rc==SQLITE_OK ){
    void *p = 0;
    sqlite3OsFetch(pFile, 0, nByte, &p);
    sqlite3OsUnfetch(pFile, 0, p);
  }
  return rc;
}
#else
# define vdbeSorterExtendFile(x,y) SQLITE_OK
#endif

/*
** Write the current contents of the in-memory linked-list to a PMA. Return
** SQLITE_OK if successful, or an SQLite error code otherwise.
**
** The format of a PMA is:








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<


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** is guaranteed to be nByte bytes or smaller in size. This function 
** attempts to extend the file to nByte bytes in size and to ensure that
** the VFS has memory mapped it.
**
** Whether or not the file does end up memory mapped of course depends on 
** the specific VFS implementation.
*/
static void vdbeSorterExtendFile(sqlite3_file *pFile, i64 nByte){
  int rc = sqlite3OsTruncate(pFile, nByte);
  if( rc==SQLITE_OK ){
    void *p = 0;
    sqlite3OsFetch(pFile, 0, nByte, &p);
    sqlite3OsUnfetch(pFile, 0, p);
  }

}
#else
# define vdbeSorterExtendFile(x,y)
#endif

/*
** Write the current contents of the in-memory linked-list to a PMA. Return
** SQLITE_OK if successful, or an SQLite error code otherwise.
**
** The format of a PMA is:
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    assert( rc!=SQLITE_OK || pSorter->pTemp1 );
    assert( pSorter->iWriteOff==0 );
    assert( pSorter->nPMA==0 );
  }

  /* Try to get the file to memory map */
  if( rc==SQLITE_OK ){
    rc = vdbeSorterExtendFile(
        pSorter->pTemp1, pSorter->iWriteOff + pSorter->nInMemory + 9
    );
  }

  if( rc==SQLITE_OK ){
    SorterRecord *p;
    SorterRecord *pNext = 0;









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    assert( rc!=SQLITE_OK || pSorter->pTemp1 );
    assert( pSorter->iWriteOff==0 );
    assert( pSorter->nPMA==0 );
  }

  /* Try to get the file to memory map */
  if( rc==SQLITE_OK ){
    vdbeSorterExtendFile(
      pSorter->pTemp1, pSorter->iWriteOff + pSorter->nInMemory + 9
    );
  }

  if( rc==SQLITE_OK ){
    SorterRecord *p;
    SorterRecord *pNext = 0;
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      }

      /* Open the second temp file, if it is not already open. */
      if( pTemp2==0 ){
        assert( iWrite2==0 );
        rc = vdbeSorterOpenTempFile(db, &pTemp2);
        if( rc==SQLITE_OK ){
          rc = vdbeSorterExtendFile(pTemp2, pSorter->iWriteOff);
        }
      }

      if( rc==SQLITE_OK ){
        int bEof = 0;
        fileWriterInit(db, pTemp2, &writer, iWrite2);
        fileWriterWriteVarint(&writer, nWrite);








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      }

      /* Open the second temp file, if it is not already open. */
      if( pTemp2==0 ){
        assert( iWrite2==0 );
        rc = vdbeSorterOpenTempFile(db, &pTemp2);
        if( rc==SQLITE_OK ){
          vdbeSorterExtendFile(pTemp2, pSorter->iWriteOff);
        }
      }

      if( rc==SQLITE_OK ){
        int bEof = 0;
        fileWriterInit(db, pTemp2, &writer, iWrite2);
        fileWriterWriteVarint(&writer, nWrite);
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