sqlite3/table.c

   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 <stdlib.h>
  20 #include <string.h>
  21 #include "sqliteInt.h"
  22
  23 /*
  24 ** This structure is used to pass data from sqlite3_get_table() through
  25 ** to the callback function is uses to build the result.
  26 */
  27 typedef struct TabResult {
  28   char **azResult;
  29   STRPTR zErrMsg;
  30   int nResult;
  31   int nAlloc;
  32   int nRow;
  33   int nColumn;
  34   int nData;
  35   int rc;
  36 } TabResult;
  37
  38 /*
  39 ** This routine is called once for each row in the result table.  Its job
  40 ** is to fill in the TabResult structure appropriately, allocating new
  41 ** memory as necessary.
  42 */
  43 static int sqlite3_get_table_cb(void *pArg, int nCol, char **argv, char **colv){
  44   TabResult *p = (TabResult*)pArg;
  45   int need;
  46   int i;
  47   char *z;
  48
  49   /* Make sure there is enough space in p->azResult to hold everything
  50   ** we need to remember from this invocation of the callback.
  51   */
  52   if( p->nRow==0 && argv!=0 ){
  53     need = nCol*2;
  54   }else{
  55     need = nCol;
  56   }
  57   if( p->nData + need >= p->nAlloc ){
  58     char **azNew;
  59     p->nAlloc = p->nAlloc*2 + need + 1;
  60     azNew = realloc( p->azResult, sizeof(char*)*p->nAlloc );
  61     if( azNew==0 ) goto malloc_failed;
  62     p->azResult = azNew;
  63   }
  64
  65   /* If this is the first row, then generate an extra row containing
  66   ** the names of all columns.
  67   */
  68   if( p->nRow==0 ){
  69     p->nColumn = nCol;
  70     for(i=0; i<nCol; i++){
  71       if( colv[i]==0 ){
  72         z = 0;
  73       }else{
  74         z = malloc( strlen(colv[i])+1 );
  75         if( z==0 ) goto malloc_failed;
  76         strcpy(z, 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         z = malloc( strlen(argv[i])+1 );
  96         if( z==0 ) goto malloc_failed;
  97         strcpy(z, argv[i]);
  98       }
  99       p->azResult[p->nData++] = z;
 100     }
 101     p->nRow++;
 102   }
 103   return 0;
 104
 105 malloc_failed:
 106   p->rc = SQLITE_NOMEM;
 107   return 1;
 108 }
 109
 110 /*
 111 ** Query the database.  But instead of invoking a callback for each row,
 112 ** malloc() for space to hold the result and return the entire results
 113 ** at the conclusion of the call.
 114 **
 115 ** The result that is written to ***pazResult is held in memory obtained
 116 ** from malloc().  But the caller cannot free this memory directly.
 117 ** Instead, the entire table should be passed to sqlite3_free_table() when
 118 ** the calling procedure is finished using it.
 119 */
 120 int sqlite3_get_table(
 121   sqlite3 *db,                /* The database on which the SQL executes */
 122   const char *zSql,           /* The SQL to be executed */
 123   char ***pazResult,          /* Write the result table here */
 124   int *pnRow,                 /* Write the number of rows in the result here */
 125   int *pnColumn,              /* Write the number of columns of result here */
 126   char **pzErrMsg             /* Write error messages here */
 127 ){
 128   int rc;
 129   TabResult res;
 130   if( pazResult==0 ){ return SQLITE_ERROR; }
 131   *pazResult = 0;
 132   if( pnColumn ) *pnColumn = 0;
 133   if( pnRow ) *pnRow = 0;
 134   res.zErrMsg = 0;
 135   res.nResult = 0;
 136   res.nRow = 0;
 137   res.nColumn = 0;
 138   res.nData = 1;
 139   res.nAlloc = 20;
 140   res.rc = SQLITE_OK;
 141   res.azResult = malloc( sizeof(char*)*res.nAlloc );
 142   if( res.azResult==0 ) return SQLITE_NOMEM;
 143   res.azResult[0] = 0;
 144   rc = sqlite3_exec(db, zSql, sqlite3_get_table_cb, &res, pzErrMsg);
 145   if( res.azResult ){
 146     res.azResult[0] = (char*)res.nData;
 147   }
 148   if( rc==SQLITE_ABORT ){
 149     sqlite3_free_table(&res.azResult[1]);
 150     if( res.zErrMsg ){
 151       if( pzErrMsg ){
 152         free(*pzErrMsg);
 153         *pzErrMsg = sqlite3_mprintf("%s",res.zErrMsg);
 154       }
 155       sqliteFree(res.zErrMsg);
 156     }
 157     db->errCode = res.rc;
 158     return res.rc;
 159   }
 160   sqliteFree(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 = realloc( res.azResult, sizeof(char*)*(res.nData+1) );
 168     if( azNew==0 ){
 169       sqlite3_free_table(&res.azResult[1]);
 170       return SQLITE_NOMEM;
 171     }
 172     res.nAlloc = res.nData+1;
 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     if( azResult==0 ) return;
 191     n = (int)azResult[0];
 192     for(i=1; i<n; i++){ if( azResult[i] ) free(azResult[i]); }
 193     free(azResult);
 194   }
 195 }