src/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 "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 */