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sqlite3

    1: /*
    2: ** 2001 September 15
    3: **
    4: ** The author disclaims copyright to this source code.  In place of
    5: ** a legal notice, here is a blessing:
    6: **
    7: **    May you do good and not evil.
    8: **    May you find forgiveness for yourself and forgive others.
    9: **    May you share freely, never taking more than you give.
   10: **
   11: *************************************************************************
   12: ** This file contains the sqlite3_get_table() and sqlite3_free_table()
   13: ** interface routines.  These are just wrappers around the main
   14: ** interface routine of sqlite3_exec().
   15: **
   16: ** These routines are in a separate files so that they will not be linked
   17: ** if they are not used.
   18: */
   19: #include "sqliteInt.h"
   20: #include <stdlib.h>
   21: #include <string.h>
   22: 
   23: #ifndef SQLITE_OMIT_GET_TABLE
   24: 
   25: /*
   26: ** This structure is used to pass data from sqlite3_get_table() through
   27: ** to the callback function is uses to build the result.
   28: */
   29: typedef struct TabResult {
   30:   char **azResult;   /* Accumulated output */
   31:   char *zErrMsg;     /* Error message text, if an error occurs */
   32:   int nAlloc;        /* Slots allocated for azResult[] */
   33:   int nRow;          /* Number of rows in the result */
   34:   int nColumn;       /* Number of columns in the result */
   35:   int nData;         /* Slots used in azResult[].  (nRow+1)*nColumn */
   36:   int rc;            /* Return code from sqlite3_exec() */
   37: } TabResult;
   38: 
   39: /*
   40: ** This routine is called once for each row in the result table.  Its job
   41: ** is to fill in the TabResult structure appropriately, allocating new
   42: ** memory as necessary.
   43: */
   44: static int sqlite3_get_table_cb(void *pArg, int nCol, char **argv, char **colv){
   45:   TabResult *p = (TabResult*)pArg;  /* Result accumulator */
   46:   int need;                         /* Slots needed in p->azResult[] */
   47:   int i;                            /* Loop counter */
   48:   char *z;                          /* A single column of result */
   49: 
   50:   /* Make sure there is enough space in p->azResult to hold everything
   51:   ** we need to remember from this invocation of the callback.
   52:   */
   53:   if( p->nRow==0 && argv!=0 ){
   54:     need = nCol*2;
   55:   }else{
   56:     need = nCol;
   57:   }
   58:   if( p->nData + need > p->nAlloc ){
   59:     char **azNew;
   60:     p->nAlloc = p->nAlloc*2 + need;
   61:     azNew = sqlite3_realloc( p->azResult, sizeof(char*)*p->nAlloc );
   62:     if( azNew==0 ) goto malloc_failed;
   63:     p->azResult = azNew;
   64:   }
   65: 
   66:   /* If this is the first row, then generate an extra row containing
   67:   ** the names of all columns.
   68:   */
   69:   if( p->nRow==0 ){
   70:     p->nColumn = nCol;
   71:     for(i=0; i<nCol; i++){
   72:       z = sqlite3_mprintf("%s", colv[i]);
   73:       if( z==0 ) goto malloc_failed;
   74:       p->azResult[p->nData++] = z;
   75:     }
   76:   }else if( p->nColumn!=nCol ){
   77:     sqlite3_free(p->zErrMsg);
   78:     p->zErrMsg = sqlite3_mprintf(
   79:        "sqlite3_get_table() called with two or more incompatible queries"
   80:     );
   81:     p->rc = SQLITE_ERROR;
   82:     return 1;
   83:   }
   84: 
   85:   /* Copy over the row data
   86:   */
   87:   if( argv!=0 ){
   88:     for(i=0; i<nCol; i++){
   89:       if( argv[i]==0 ){
   90:         z = 0;
   91:       }else{
   92:         int n = sqlite3Strlen30(argv[i])+1;
   93:         z = sqlite3_malloc( n );
   94:         if( z==0 ) goto malloc_failed;
   95:         memcpy(z, argv[i], n);
   96:       }
   97:       p->azResult[p->nData++] = z;
   98:     }
   99:     p->nRow++;
  100:   }
  101:   return 0;
  102: 
  103: malloc_failed:
  104:   p->rc = SQLITE_NOMEM;
  105:   return 1;
  106: }
  107: 
  108: /*
  109: ** Query the database.  But instead of invoking a callback for each row,
  110: ** malloc() for space to hold the result and return the entire results
  111: ** at the conclusion of the call.
  112: **
  113: ** The result that is written to ***pazResult is held in memory obtained
  114: ** from malloc().  But the caller cannot free this memory directly.  
  115: ** Instead, the entire table should be passed to sqlite3_free_table() when
  116: ** the calling procedure is finished using it.
  117: */
  118: int sqlite3_get_table(
  119:   sqlite3 *db,                /* The database on which the SQL executes */
  120:   const char *zSql,           /* The SQL to be executed */
  121:   char ***pazResult,          /* Write the result table here */
  122:   int *pnRow,                 /* Write the number of rows in the result here */
  123:   int *pnColumn,              /* Write the number of columns of result here */
  124:   char **pzErrMsg             /* Write error messages here */
  125: ){
  126:   int rc;
  127:   TabResult res;
  128: 
  129:   *pazResult = 0;
  130:   if( pnColumn ) *pnColumn = 0;
  131:   if( pnRow ) *pnRow = 0;
  132:   if( pzErrMsg ) *pzErrMsg = 0;
  133:   res.zErrMsg = 0;
  134:   res.nRow = 0;
  135:   res.nColumn = 0;
  136:   res.nData = 1;
  137:   res.nAlloc = 20;
  138:   res.rc = SQLITE_OK;
  139:   res.azResult = sqlite3_malloc(sizeof(char*)*res.nAlloc );
  140:   if( res.azResult==0 ){
  141:      db->errCode = SQLITE_NOMEM;
  142:      return SQLITE_NOMEM;
  143:   }
  144:   res.azResult[0] = 0;
  145:   rc = sqlite3_exec(db, zSql, sqlite3_get_table_cb, &res, pzErrMsg);
  146:   assert( sizeof(res.azResult[0])>= sizeof(res.nData) );
  147:   res.azResult[0] = SQLITE_INT_TO_PTR(res.nData);
  148:   if( (rc&0xff)==SQLITE_ABORT ){
  149:     sqlite3_free_table(&res.azResult[1]);
  150:     if( res.zErrMsg ){
  151:       if( pzErrMsg ){
  152:         sqlite3_free(*pzErrMsg);
  153:         *pzErrMsg = sqlite3_mprintf("%s",res.zErrMsg);
  154:       }
  155:       sqlite3_free(res.zErrMsg);
  156:     }
  157:     db->errCode = res.rc;  /* Assume 32-bit assignment is atomic */
  158:     return res.rc;
  159:   }
  160:   sqlite3_free(res.zErrMsg);
  161:   if( rc!=SQLITE_OK ){
  162:     sqlite3_free_table(&res.azResult[1]);
  163:     return rc;
  164:   }
  165:   if( res.nAlloc>res.nData ){
  166:     char **azNew;
  167:     azNew = sqlite3_realloc( res.azResult, sizeof(char*)*res.nData );
  168:     if( azNew==0 ){
  169:       sqlite3_free_table(&res.azResult[1]);
  170:       db->errCode = SQLITE_NOMEM;
  171:       return SQLITE_NOMEM;
  172:     }
  173:     res.azResult = azNew;
  174:   }
  175:   *pazResult = &res.azResult[1];
  176:   if( pnColumn ) *pnColumn = res.nColumn;
  177:   if( pnRow ) *pnRow = res.nRow;
  178:   return rc;
  179: }
  180: 
  181: /*
  182: ** This routine frees the space the sqlite3_get_table() malloced.
  183: */
  184: void sqlite3_free_table(
  185:   char **azResult            /* Result returned from from sqlite3_get_table() */
  186: ){
  187:   if( azResult ){
  188:     int i, n;
  189:     azResult--;
  190:     assert( azResult!=0 );
  191:     n = SQLITE_PTR_TO_INT(azResult[0]);
  192:     for(i=1; i<n; i++){ if( azResult[i] ) sqlite3_free(azResult[i]); }
  193:     sqlite3_free(azResult);
  194:   }
  195: }
  196: 
  197: #endif /* SQLITE_OMIT_GET_TABLE */