table.c
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上传日期:2022-01-25
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- /*
- ** 2001 September 15
- **
- ** The author disclaims copyright to this source code. In place of
- ** a legal notice, here is a blessing:
- **
- ** May you do good and not evil.
- ** May you find forgiveness for yourself and forgive others.
- ** May you share freely, never taking more than you give.
- **
- *************************************************************************
- ** This file contains the sqlite3_get_table() and sqlite3_free_table()
- ** interface routines. These are just wrappers around the main
- ** interface routine of sqlite3_exec().
- **
- ** These routines are in a separate files so that they will not be linked
- ** if they are not used.
- */
- #include "sqliteInt.h"
- #include <stdlib.h>
- #include <string.h>
- #ifndef SQLITE_OMIT_GET_TABLE
- /*
- ** This structure is used to pass data from sqlite3_get_table() through
- ** to the callback function is uses to build the result.
- */
- typedef struct TabResult {
- char **azResult;
- char *zErrMsg;
- int nResult;
- int nAlloc;
- int nRow;
- int nColumn;
- int nData;
- int rc;
- } TabResult;
- /*
- ** This routine is called once for each row in the result table. Its job
- ** is to fill in the TabResult structure appropriately, allocating new
- ** memory as necessary.
- */
- static int sqlite3_get_table_cb(void *pArg, int nCol, char **argv, char **colv){
- TabResult *p = (TabResult*)pArg;
- int need;
- int i;
- char *z;
- /* Make sure there is enough space in p->azResult to hold everything
- ** we need to remember from this invocation of the callback.
- */
- if( p->nRow==0 && argv!=0 ){
- need = nCol*2;
- }else{
- need = nCol;
- }
- if( p->nData + need >= p->nAlloc ){
- char **azNew;
- p->nAlloc = p->nAlloc*2 + need + 1;
- azNew = sqlite3_realloc( p->azResult, sizeof(char*)*p->nAlloc );
- if( azNew==0 ) goto malloc_failed;
- p->azResult = azNew;
- }
- /* If this is the first row, then generate an extra row containing
- ** the names of all columns.
- */
- if( p->nRow==0 ){
- p->nColumn = nCol;
- for(i=0; i<nCol; i++){
- z = sqlite3_mprintf("%s", colv[i]);
- if( z==0 ) goto malloc_failed;
- p->azResult[p->nData++] = z;
- }
- }else if( p->nColumn!=nCol ){
- sqlite3_free(p->zErrMsg);
- p->zErrMsg = sqlite3_mprintf(
- "sqlite3_get_table() called with two or more incompatible queries"
- );
- p->rc = SQLITE_ERROR;
- return 1;
- }
- /* Copy over the row data
- */
- if( argv!=0 ){
- for(i=0; i<nCol; i++){
- if( argv[i]==0 ){
- z = 0;
- }else{
- int n = strlen(argv[i])+1;
- z = sqlite3_malloc( n );
- if( z==0 ) goto malloc_failed;
- memcpy(z, argv[i], n);
- }
- p->azResult[p->nData++] = z;
- }
- p->nRow++;
- }
- return 0;
- malloc_failed:
- p->rc = SQLITE_NOMEM;
- return 1;
- }
- /*
- ** Query the database. But instead of invoking a callback for each row,
- ** malloc() for space to hold the result and return the entire results
- ** at the conclusion of the call.
- **
- ** The result that is written to ***pazResult is held in memory obtained
- ** from malloc(). But the caller cannot free this memory directly.
- ** Instead, the entire table should be passed to sqlite3_free_table() when
- ** the calling procedure is finished using it.
- */
- int sqlite3_get_table(
- sqlite3 *db, /* The database on which the SQL executes */
- const char *zSql, /* The SQL to be executed */
- char ***pazResult, /* Write the result table here */
- int *pnRow, /* Write the number of rows in the result here */
- int *pnColumn, /* Write the number of columns of result here */
- char **pzErrMsg /* Write error messages here */
- ){
- int rc;
- TabResult res;
- *pazResult = 0;
- if( pnColumn ) *pnColumn = 0;
- if( pnRow ) *pnRow = 0;
- res.zErrMsg = 0;
- res.nResult = 0;
- res.nRow = 0;
- res.nColumn = 0;
- res.nData = 1;
- res.nAlloc = 20;
- res.rc = SQLITE_OK;
- res.azResult = sqlite3_malloc(sizeof(char*)*res.nAlloc );
- if( res.azResult==0 ){
- db->errCode = SQLITE_NOMEM;
- return SQLITE_NOMEM;
- }
- res.azResult[0] = 0;
- rc = sqlite3_exec(db, zSql, sqlite3_get_table_cb, &res, pzErrMsg);
- assert( sizeof(res.azResult[0])>= sizeof(res.nData) );
- res.azResult[0] = (char*)(sqlite3_intptr_t)res.nData;
- if( (rc&0xff)==SQLITE_ABORT ){
- sqlite3_free_table(&res.azResult[1]);
- if( res.zErrMsg ){
- if( pzErrMsg ){
- sqlite3_free(*pzErrMsg);
- *pzErrMsg = sqlite3_mprintf("%s",res.zErrMsg);
- }
- sqlite3_free(res.zErrMsg);
- }
- db->errCode = res.rc; /* Assume 32-bit assignment is atomic */
- return res.rc;
- }
- sqlite3_free(res.zErrMsg);
- if( rc!=SQLITE_OK ){
- sqlite3_free_table(&res.azResult[1]);
- return rc;
- }
- if( res.nAlloc>res.nData ){
- char **azNew;
- azNew = sqlite3_realloc( res.azResult, sizeof(char*)*(res.nData+1) );
- if( azNew==0 ){
- sqlite3_free_table(&res.azResult[1]);
- db->errCode = SQLITE_NOMEM;
- return SQLITE_NOMEM;
- }
- res.nAlloc = res.nData+1;
- res.azResult = azNew;
- }
- *pazResult = &res.azResult[1];
- if( pnColumn ) *pnColumn = res.nColumn;
- if( pnRow ) *pnRow = res.nRow;
- return rc;
- }
- /*
- ** This routine frees the space the sqlite3_get_table() malloced.
- */
- void sqlite3_free_table(
- char **azResult /* Result returned from from sqlite3_get_table() */
- ){
- if( azResult ){
- sqlite3_intptr_t i, n;
- azResult--;
- assert( azResult!=0 );
- n = (sqlite3_intptr_t)azResult[0];
- for(i=1; i<n; i++){ if( azResult[i] ) sqlite3_free(azResult[i]); }
- sqlite3_free(azResult);
- }
- }
- #endif /* SQLITE_OMIT_GET_TABLE */