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Overview
Comment:Simplifications and additional comments on the sqlite3_get_table() implementation. Changes to facilitate full branch test coverage. (CVS 6482)
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SHA1:57e3e6b3cb54e6626bee41a084c927ee264b6d03
User & Date: drh 2009-04-10 14:28:00
Context
2009-04-10
15:02
Changes to jrnlmode.test to account for in-memory temp databases. (CVS 6483) check-in: c31d4359 user: danielk1977 tags: trunk
14:28
Simplifications and additional comments on the sqlite3_get_table() implementation. Changes to facilitate full branch test coverage. (CVS 6482) check-in: 57e3e6b3 user: drh tags: trunk
12:55
Changes to ensure that when running in shared-cache mode with a non-threadsafe build, the correct busy-handler callback is always invoked. (CVS 6481) check-in: 683e4bd7 user: danielk1977 tags: trunk
Changes
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Changes to src/table.c.

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** This file contains the sqlite3_get_table() and sqlite3_free_table()
** interface routines.  These are just wrappers around the main
** interface routine of sqlite3_exec().
**
** These routines are in a separate files so that they will not be linked
** if they are not used.
**
** $Id: table.c,v 1.39 2009/01/19 20:49:10 drh Exp $
*/
#include "sqliteInt.h"
#include <stdlib.h>
#include <string.h>

#ifndef SQLITE_OMIT_GET_TABLE

/*
** This structure is used to pass data from sqlite3_get_table() through
** to the callback function is uses to build the result.
*/
typedef struct TabResult {
  char **azResult;
  char *zErrMsg;
  int nResult;
  int nAlloc;
  int nRow;
  int nColumn;
  int nData;
  int rc;
} TabResult;

/*
** This routine is called once for each row in the result table.  Its job
** is to fill in the TabResult structure appropriately, allocating new
** memory as necessary.
*/
static int sqlite3_get_table_cb(void *pArg, int nCol, char **argv, char **colv){
  TabResult *p = (TabResult*)pArg;
  int need;
  int i;
  char *z;

  /* Make sure there is enough space in p->azResult to hold everything
  ** we need to remember from this invocation of the callback.
  */
  if( p->nRow==0 && argv!=0 ){
    need = nCol*2;
  }else{
    need = nCol;
  }
  if( p->nData + need >= p->nAlloc ){
    char **azNew;
    p->nAlloc = p->nAlloc*2 + need + 1;
    azNew = sqlite3_realloc( p->azResult, sizeof(char*)*p->nAlloc );
    if( azNew==0 ) goto malloc_failed;
    p->azResult = azNew;
  }

  /* If this is the first row, then generate an extra row containing
  ** the names of all columns.
................................................................................
  TabResult res;

  *pazResult = 0;
  if( pnColumn ) *pnColumn = 0;
  if( pnRow ) *pnRow = 0;
  if( pzErrMsg ) *pzErrMsg = 0;
  res.zErrMsg = 0;
  res.nResult = 0;
  res.nRow = 0;
  res.nColumn = 0;
  res.nData = 1;
  res.nAlloc = 20;
  res.rc = SQLITE_OK;
  res.azResult = sqlite3_malloc(sizeof(char*)*res.nAlloc );
  if( res.azResult==0 ){
................................................................................
  sqlite3_free(res.zErrMsg);
  if( rc!=SQLITE_OK ){
    sqlite3_free_table(&res.azResult[1]);
    return rc;
  }
  if( res.nAlloc>res.nData ){
    char **azNew;
    azNew = sqlite3_realloc( res.azResult, sizeof(char*)*(res.nData+1) );
    if( azNew==0 ){
      sqlite3_free_table(&res.azResult[1]);
      db->errCode = SQLITE_NOMEM;
      return SQLITE_NOMEM;
    }
    res.nAlloc = res.nData+1;
    res.azResult = azNew;
  }
  *pazResult = &res.azResult[1];
  if( pnColumn ) *pnColumn = res.nColumn;
  if( pnRow ) *pnRow = res.nRow;
  return rc;
}







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** This file contains the sqlite3_get_table() and sqlite3_free_table()
** interface routines.  These are just wrappers around the main
** interface routine of sqlite3_exec().
**
** These routines are in a separate files so that they will not be linked
** if they are not used.
**
** $Id: table.c,v 1.40 2009/04/10 14:28:00 drh Exp $
*/
#include "sqliteInt.h"
#include <stdlib.h>
#include <string.h>

#ifndef SQLITE_OMIT_GET_TABLE

/*
** This structure is used to pass data from sqlite3_get_table() through
** to the callback function is uses to build the result.
*/
typedef struct TabResult {
  char **azResult;   /* Accumulated output */
  char *zErrMsg;     /* Error message text, if an error occurs */
  int nAlloc;        /* Slots allocated for azResult[] */
  int nRow;          /* Number of rows in the result */
  int nColumn;       /* Number of columns in the result */
  int nData;         /* Slots used in azResult[].  (nRow+1)*nColumn */
  int rc;            /* Return code from sqlite3_exec() */

} TabResult;

/*
** This routine is called once for each row in the result table.  Its job
** is to fill in the TabResult structure appropriately, allocating new
** memory as necessary.
*/
static int sqlite3_get_table_cb(void *pArg, int nCol, char **argv, char **colv){
  TabResult *p = (TabResult*)pArg;  /* Result accumulator */
  int need;                         /* Slots needed in p->azResult[] */
  int i;                            /* Loop counter */
  char *z;                          /* A single column of result */

  /* Make sure there is enough space in p->azResult to hold everything
  ** we need to remember from this invocation of the callback.
  */
  if( p->nRow==0 && argv!=0 ){
    need = nCol*2;
  }else{
    need = nCol;
  }
  if( p->nData + need > p->nAlloc ){
    char **azNew;
    p->nAlloc = p->nAlloc*2 + need;
    azNew = sqlite3_realloc( p->azResult, sizeof(char*)*p->nAlloc );
    if( azNew==0 ) goto malloc_failed;
    p->azResult = azNew;
  }

  /* If this is the first row, then generate an extra row containing
  ** the names of all columns.
................................................................................
  TabResult res;

  *pazResult = 0;
  if( pnColumn ) *pnColumn = 0;
  if( pnRow ) *pnRow = 0;
  if( pzErrMsg ) *pzErrMsg = 0;
  res.zErrMsg = 0;

  res.nRow = 0;
  res.nColumn = 0;
  res.nData = 1;
  res.nAlloc = 20;
  res.rc = SQLITE_OK;
  res.azResult = sqlite3_malloc(sizeof(char*)*res.nAlloc );
  if( res.azResult==0 ){
................................................................................
  sqlite3_free(res.zErrMsg);
  if( rc!=SQLITE_OK ){
    sqlite3_free_table(&res.azResult[1]);
    return rc;
  }
  if( res.nAlloc>res.nData ){
    char **azNew;
    azNew = sqlite3_realloc( res.azResult, sizeof(char*)*res.nData );
    if( azNew==0 ){
      sqlite3_free_table(&res.azResult[1]);
      db->errCode = SQLITE_NOMEM;
      return SQLITE_NOMEM;
    }

    res.azResult = azNew;
  }
  *pazResult = &res.azResult[1];
  if( pnColumn ) *pnColumn = res.nColumn;
  if( pnRow ) *pnRow = res.nRow;
  return rc;
}