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 ** $Id: table.c,v 1.36 2008/07/08 22:28:49 shane Exp $

    20 */

    21 #include "sqliteInt.h"

    22 #include <stdlib.h>

    23 #include <string.h>

    24 

    25 #ifndef SQLITE_OMIT_GET_TABLE

    26 

    27 /*

    28 ** This structure is used to pass data from sqlite3_get_table() through

    29 ** to the callback function is uses to build the result.

    30 */

    31 typedef struct TabResult {

    32   char **azResult;

    33   char *zErrMsg;

    34   int nResult;

    35   int nAlloc;

    36   int nRow;

    37   int nColumn;

    38   int nData;

    39   int rc;

    40 } TabResult;

    41 

    42 /*

    43 ** This routine is called once for each row in the result table.  Its job

    44 ** is to fill in the TabResult structure appropriately, allocating new

    45 ** memory as necessary.

    46 */

    47 static int sqlite3_get_table_cb(void *pArg, int nCol, char **argv, char **colv){

    48   TabResult *p = (TabResult*)pArg;

    49   int need;

    50   int i;

    51   char *z;

    52 

    53   /* Make sure there is enough space in p->azResult to hold everything

    54   ** we need to remember from this invocation of the callback.

    55   */

    56   if( p->nRow==0 && argv!=0 ){

    57     need = nCol*2;

    58   }else{

    59     need = nCol;

    60   }

    61   if( p->nData + need >= p->nAlloc ){

    62     char **azNew;

    63     p->nAlloc = p->nAlloc*2 + need + 1;

    64     azNew = sqlite3_realloc( p->azResult, sizeof(char*)*p->nAlloc );

    65     if( azNew==0 ) goto malloc_failed;

    66     p->azResult = azNew;

    67   }

    68 

    69   /* If this is the first row, then generate an extra row containing

    70   ** the names of all columns.

    71   */

    72   if( p->nRow==0 ){

    73     p->nColumn = nCol;

    74     for(i=0; i<nCol; i++){

    75       z = sqlite3_mprintf("%s", colv[i]);

    76       if( z==0 ) goto malloc_failed;

    77       p->azResult[p->nData++] = z;

    78     }

    79   }else if( p->nColumn!=nCol ){

    80     sqlite3_free(p->zErrMsg);

    81     p->zErrMsg = sqlite3_mprintf(

    82        "sqlite3_get_table() called with two or more incompatible queries"

    83     );

    84     p->rc = SQLITE_ERROR;

    85     return 1;

    86   }

    87 

    88   /* Copy over the row data

    89   */

    90   if( argv!=0 ){

    91     for(i=0; i<nCol; i++){

    92       if( argv[i]==0 ){

    93         z = 0;

    94       }else{

    95         int n = strlen(argv[i])+1;

    96         z = sqlite3_malloc( n );

    97         if( z==0 ) goto malloc_failed;

    98         memcpy(z, argv[i], n);

    99       }

   100       p->azResult[p->nData++] = z;

   101     }

   102     p->nRow++;

   103   }

   104   return 0;

   105 

   106 malloc_failed:

   107   p->rc = SQLITE_NOMEM;

   108   return 1;

   109 }

   110 

   111 /*

   112 ** Query the database.  But instead of invoking a callback for each row,

   113 ** malloc() for space to hold the result and return the entire results

   114 ** at the conclusion of the call.

   115 **

   116 ** The result that is written to ***pazResult is held in memory obtained

   117 ** from malloc().  But the caller cannot free this memory directly.  

   118 ** Instead, the entire table should be passed to sqlite3_free_table() when

   119 ** the calling procedure is finished using it.

   120 */

   121 int sqlite3_get_table(

   122   sqlite3 *db,                /* The database on which the SQL executes */

   123   const char *zSql,           /* The SQL to be executed */

   124   char ***pazResult,          /* Write the result table here */

   125   int *pnRow,                 /* Write the number of rows in the result here */

   126   int *pnColumn,              /* Write the number of columns of result here */

   127   char **pzErrMsg             /* Write error messages here */

   128 ){

   129   int rc;

   130   TabResult res;

   131 

   132   *pazResult = 0;

   133   if( pnColumn ) *pnColumn = 0;

   134   if( pnRow ) *pnRow = 0;

   135   res.zErrMsg = 0;

   136   res.nResult = 0;

   137   res.nRow = 0;

   138   res.nColumn = 0;

   139   res.nData = 1;

   140   res.nAlloc = 20;

   141   res.rc = SQLITE_OK;

   142   res.azResult = sqlite3_malloc(sizeof(char*)*res.nAlloc );

   143   if( res.azResult==0 ){

   144      db->errCode = SQLITE_NOMEM;

   145      return SQLITE_NOMEM;

   146   }

   147   res.azResult[0] = 0;

   148   rc = sqlite3_exec(db, zSql, sqlite3_get_table_cb, &res, pzErrMsg);

   149   assert( sizeof(res.azResult[0])>= sizeof(res.nData) );

   150   res.azResult[0] = SQLITE_INT_TO_PTR(res.nData);

   151   if( (rc&0xff)==SQLITE_ABORT ){

   152     sqlite3_free_table(&res.azResult[1]);

   153     if( res.zErrMsg ){

   154       if( pzErrMsg ){

   155         sqlite3_free(*pzErrMsg);

   156         *pzErrMsg = sqlite3_mprintf("%s",res.zErrMsg);

   157       }

   158       sqlite3_free(res.zErrMsg);

   159     }

   160     db->errCode = res.rc;  /* Assume 32-bit assignment is atomic */

   161     return res.rc;

   162   }

   163   sqlite3_free(res.zErrMsg);

   164   if( rc!=SQLITE_OK ){

   165     sqlite3_free_table(&res.azResult[1]);

   166     return rc;

   167   }

   168   if( res.nAlloc>res.nData ){

   169     char **azNew;

   170     azNew = sqlite3_realloc( res.azResult, sizeof(char*)*(res.nData+1) );

   171     if( azNew==0 ){

   172       sqlite3_free_table(&res.azResult[1]);

   173       db->errCode = SQLITE_NOMEM;

   174       return SQLITE_NOMEM;

   175     }

   176     res.nAlloc = res.nData+1;

   177     res.azResult = azNew;

   178   }

   179   *pazResult = &res.azResult[1];

   180   if( pnColumn ) *pnColumn = res.nColumn;

   181   if( pnRow ) *pnRow = res.nRow;

   182   return rc;

   183 }

   184 

   185 /*

   186 ** This routine frees the space the sqlite3_get_table() malloced.

   187 */

   188 void sqlite3_free_table(

   189   char **azResult            /* Result returned from from sqlite3_get_table() */

   190 ){

   191   if( azResult ){

   192     int i, n;

   193     azResult--;

   194     assert( azResult!=0 );

   195     n = SQLITE_PTR_TO_INT(azResult[0]);

   196     for(i=1; i<n; i++){ if( azResult[i] ) sqlite3_free(azResult[i]); }

   197     sqlite3_free(azResult);

   198   }

   199 }

   200 

   201 #endif /* SQLITE_OMIT_GET_TABLE */