Re: [sqlite] Intermittent crash in sqlite3_prepare()

[Tito Ciuro]

Hi Doug,

This is what I see in the console:
(gdb) print *db
$2 = {
  nDb = 2,
  aDb = 0x177a750c,
  flags = 32,
  errCode = 5,
  autoCommit = 1 '\001',
  temp_store = 0 '\0',
  nTable = 1,
  pDfltColl = 0x1770f300,
  lastRowid = 0,
  priorNewRowid = 0,
  magic = -1607883113,
  nChange = 0,
  nTotalChange = 0,
  init = {
    iDb = 0,
    newTnum = 1,
    busy = 0 '\0'
  },
  pVdbe = 0x0,
  activeVdbeCnt = 0,
  xTrace = 0,
  pTraceArg = 0x0,
  xProfile = 0,
  pProfileArg = 0x0,
  pCommitArg = 0x0,
  xCommitCallback = 0,
  pRollbackArg = 0x0,
  xRollbackCallback = 0,
  pUpdateArg = 0x0,
  xUpdateCallback = 0,
  xCollNeeded = 0,
  xCollNeeded16 = 0,
  pCollNeededArg = 0x0,
  pErr = 0x17715590,
  zErrMsg = 0x0,
  zErrMsg16 = 0x0,
  xAuth = 0,
  pAuthArg = 0x0,
  xProgress = 0,
  pProgressArg = 0x0,
  nProgressOps = 0,
  pNext = 0x0,
  aFunc = {
    keyClass = 3 '\003',
    copyKey = 0 '\0',
    count = 36,
    first = 0x17737ef0,
    xMalloc = 0x44f304 <sqlite3MallocX>,
    xFree = 0x44f2b0 <sqlite3FreeX>,
    htsize = 64,
    ht = 0x1b12c00
  },
  aCollSeq = {
    keyClass = 3 '\003',
    copyKey = 0 '\0',
    count = 2,
    first = 0x17576f60,
    xMalloc = 0x44f304 <sqlite3MallocX>,
    xFree = 0x44f2b0 <sqlite3FreeX>,
    htsize = 8,
    ht = 0x1770d7d0
  },
  busyHandler = {
    xFunc = 0x2a2ae4 <sqlite3ErrStr+932>,
    pArg = 0x177a7420,
    nBusy = -1
  },
  busyTimeout = 3000,
  aDbStatic = {{
      zName = 0x2a4f44 "main",
      pBt = 0x1778a6b0,
      inTrans = 0 '\0',
      safety_level = 3 '\003',
      pAux = 0x0,
      xFreeAux = 0,
      pSchema = 0x177434f0
    }, {
      zName = 0x2a4f4c "temp",
      pBt = 0x0,
      inTrans = 0 '\0',
      safety_level = 1 '\001',
      pAux = 0x0,
      xFreeAux = 0,
      pSchema = 0x17507660
    }}
}
(gdb) print zSql
$3 = 0x1774fec0 "SELECT * FROM main.sqlite_master WHERE name =  
'documents';"

Also:

nBytes = -1
ppStmt = 0x0
pzTail = 0x0

I realized that I was initializing 'ppStmt' to NULL by mistake   
before calling sqlite3_prepare(). Removing the initialization cleared  
the error.

Thanks Doug.

-- Tito

On 24/04/2006, at 12:41, Doug Nebeker wrote:

What does the code look like that is calling sqlite3_prepare?  The  
crash
point is just dereferening a pointer that you passed in, and it looks
like the pointer value must be bad.

int sqlite3_prepare(
  sqlite3 *db,              /* Database handle. */
  const char *zSql,         /* UTF-8 encoded SQL statement. */
  int nBytes,               /* Length of zSql in bytes. */
  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared
statement */
  const char** pzTail       /* OUT: End of parsed string */
){
  Parse sParse;
  char *zErrMsg = 0;
  int rc = SQLITE_OK;
  int i;

  /* Assert that malloc() has not failed */
  assert( !sqlite3MallocFailed() );

  assert( ppStmt );
  *ppStmt = 0;  <<<<<<<<<< the crash occurs here...


Any ideas why this is happening?

Thanks,

-- Tito


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