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;

    31   char *zErrMsg;

    32   int nResult;

    33   int nAlloc;

    34   int nRow;

    35   int nColumn;

    36   int nData;

    37   int rc;

    38 } TabResult;

    39 

    40 /*

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

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

    43 ** memory as necessary.

    44 */

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

    46   TabResult *p = (TabResult*)pArg;

    47   int need;

    48   int i;

    49   char *z;

    50 

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

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

    53   */

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

    55     need = nCol*2;

    56   }else{

    57     need = nCol;

    58   }

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

    60     char **azNew;

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

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

    63     if( azNew==0 ) goto malloc_failed;

    64     p->azResult = azNew;

    65   }

    66 

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

    68   ** the names of all columns.

    69   */

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

    71     p->nColumn = nCol;

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

    73       if( colv[i]==0 ){

    74         z = sqlite3_mprintf("");

    75       }else{

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

    77       }

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

    79     }

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

    81     sqlite3SetString(&p->zErrMsg,

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

    83        (char*)0);

    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 = (char*)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 EXPORT_C 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   if( pazResult==0 ){ return SQLITE_ERROR; }

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

   143   if( res.azResult==0 ) return SQLITE_NOMEM;

   144   res.azResult[0] = 0;

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

   146 #ifndef NDEBUG

   147   sqlite3_mutex_enter(db->mutex);

   148   assert((rc&db->errMask)==rc && (res.rc&db->errMask)==res.rc);

   149   sqlite3_mutex_leave(db->mutex);

   150 #endif

   151   if( res.azResult ){

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

   153     res.azResult[0] = (char*)res.nData;

   154   }

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

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

   157     if( res.zErrMsg ){

   158       if( pzErrMsg ){

   159         sqlite3_free(*pzErrMsg);

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

   161       }

   162       sqlite3_free(res.zErrMsg);

   163     }

   164     sqlite3_mutex_enter(db->mutex);

   165     db->errCode = res.rc;

   166     sqlite3_mutex_leave(db->mutex);

   167     return res.rc;

   168   }

   169   sqlite3_free(res.zErrMsg);

   170   if( rc!=SQLITE_OK ){

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

   172     return rc;

   173   }

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

   175     char **azNew;

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

   177     if( azNew==0 ){

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

   179       return SQLITE_NOMEM;

   180     }

   181     res.nAlloc = res.nData+1;

   182     res.azResult = azNew;

   183   }

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

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

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

   187   return rc;

   188 }

   189 

   190 /*

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

   192 */

   193 EXPORT_C void sqlite3_free_table(

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

   195 ){

   196   if( azResult ){

   197     int i, n;

   198     azResult--;

   199     if( azResult==0 ) return;

   200     n = (int)azResult[0];

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

   202     sqlite3_free(azResult);

   203   }

   204 }

   205 

   206 #endif /* SQLITE_OMIT_GET_TABLE */