c++ - free() :invalid size, 但没有调用 new() 或 free() - 使用 C++ 的 SQLite3

Question

嗨，我正在使用 C++ 玩 sqlite3。我将数组存储为 BLOB 并尝试从数据库中提取它。但是，当我从数据库中选择数据时，在函数 selectTable() 完成后和 main() 完成之前出现 free():invalid size 错误。所以我有点困惑。
命令行的输出是

selectTable func
Opened database successfully
before finalzie
after close DB
free(): invalid size
Aborted

下面是来自 gdb 的回溯和代码

Program received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
51  ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) bt
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1  0x00007ffff717a801 in __GI_abort () at abort.c:79
#2  0x00007ffff71c3897 in __libc_message (action=action@entry=do_abort, 
    fmt=fmt@entry=0x7ffff72f0b9a "%s\n") at ../sysdeps/posix/libc_fatal.c:181
#3  0x00007ffff71ca90a in malloc_printerr (
    str=str@entry=0x7ffff72eeda0 "free(): invalid size") at malloc.c:5350
#4  0x00007ffff71d1e2c in _int_free (have_lock=0, 
    p=0x7ffff7de5990 <_dl_init+864>, av=0x7ffff7525c40 <main_arena>)
    at malloc.c:4161
#5  __GI___libc_free (mem=0x7ffff7de59a0 <_dl_fini>) at malloc.c:3124
#6  0x0000555555555b48 in main ()

    int main() {
      const char* dir = "testBLOB.db";
      sqlite3* DB;
      //createDB(dir);
      //createTable(dir);
      //clearTable(dir);
      for(int i = 0; i < 50; i++) {
        //insertTable(dir);
      }
      cout << "selectTable func" << endl;
      selectTable(dir);
    
      cout << "Out of selectTable func" << endl;
      return 0;
    }
    
    static int createDB(const char* s) {
      sqlite3* DB;
      int exit = 0;
    
      exit = sqlite3_open(s, &DB);
    
      if(!exit) {
        //cout << "opened db" << endl;
      }
      sqlite3_close(DB);
    
      return 0;
    }
    
    static int createTable(const char* s) {
      sqlite3* DB;
      string sql = "CREATE TABLE IF NOT EXISTS test("
      "id INTEGER PRIMARY KEY AUTOINCREMENT,"
      "name TEXT NOT NULL, "
      "vector BLOB"
      ");";
      try {
        int exit = 0;
        exit = sqlite3_open(s, &DB);
        char* messageError;
        exit = sqlite3_exec(DB, sql.c_str(), NULL, 0, &messageError);
        //cout << "Hello, World!" << endl;
        if(exit != SQLITE_OK) {
          cerr << "Error creating table" << endl;
        } else {
          sqlite3_close(DB);
        }
      } catch (const exception & e) {
        cerr << e.what();
      }
    
      return 0;
    };
    
    
    static int insertTable(const char* s) {
      sqlite3* DB;
      long double nums [100] = {63.3448897849,56.5751700134,75.6611442415,44.4839808971,12.1012110357,39.8311006389,55.4628689524,44.1856083913,31.8941372232,36.7439371495,64.1919152947,46.6041307466,16.8129922477,26.4797506344,33.0942127905,87.7671523992,76.4743660304,26.895728291,71.6418628151,39.4279836297,33.1511476055,21.9412133656,49.2985876344,54.7288568945,61.7644413811,39.5360580159,48.2049240243,15.0657890486,74.8453755862,3.9697162327,46.3309272981,3.6967671205,29.4109279366,35.2237159178,71.2944696538,83.2668276235,8.6042287278,29.018178646,53.9090162771,74.1875874704,13.362141479,85.534882156,46.1570578637,16.6535624939,60.4663891357,46.4002226626,43.5334234645,5.9192657242,6.4233909782,70.9674985846,16.7364288218,6.140383666,1.6295357671,41.5132888558,7.0105695897,93.7402324433,67.9067125381,79.2202639865,73.9691802822,83.7211616527,95.1748897322,77.6210081594,52.6691899363,45.9668407426,30.0850082804,99.8853106577,44.4116175004,66.7492926269,80.344211132,2.9125625332,13.1282558744,77.1323341686,31.6479987137,12.0439293147,52.34792652,10.0973593886,11.1281788415,42.3558223361,26.0832770714,78.8802218674,65.7943757958,39.4931075012,62.3669620437,40.5895497709,75.5671730948,32.0576337297,97.9215110968,9.9871548843,46.6131220896,11.0937537323,59.9746432863,25.2756546914,39.1604177152,21.5325516688,55.5211448299,29.0247732257,10.4586600007,53.0534949121,77.3997550972,48.2887426956};
    
      int rc = sqlite3_open_v2(s, &DB, SQLITE_OPEN_READWRITE,NULL);
      if(rc != SQLITE_OK) {
    
      } else {
        string sql = "INSERT INTO test (name, vector) VALUES ('test', ?)";
        try {
          sqlite3_stmt *stmt = NULL;
          rc = sqlite3_prepare_v2(DB, sql.c_str(), -1, &stmt, NULL);
    
          if(rc != SQLITE_OK) {
            cerr << "Error preparing stmt" << endl;
          } else {
            rc = sqlite3_bind_blob(stmt,1, nums, 1600, SQLITE_STATIC);
            if(rc != SQLITE_OK) {
              cerr << "bind failed" << endl;
            } else {
              rc = sqlite3_step(stmt);
              if(rc != SQLITE_DONE) {
                cerr << "no" << endl;
              }
            }
    
          }
          sqlite3_finalize(stmt);
        } catch (const exception & e) {
          cerr << e.what();
        }
      }
      sqlite3_close(DB);
      return 0;
    };
    static string selectTable(const char* s) {
      sqlite3 *db;
      int rc;
    
      /* Open database */
      rc = sqlite3_open(s, &db);
    
      if( rc ) {
        fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
        return(0);
      } else {
        fprintf(stderr, "Opened database successfully\n");
      }
    
      sqlite3_stmt *stmt;
      /* Create SQL statement */
      const char* sql = "SELECT * FROM test";
      if (sqlite3_prepare_v2(db, sql, -1, &stmt, 0) != SQLITE_OK)
      {
          return 0;
      }
    
    
      int result = 0;
      while (true)
      {
          result = sqlite3_step(stmt);
          if (result == SQLITE_ROW)
          {
    
              // Get the size of the vector
              int size = sqlite3_column_bytes(stmt, 2);
              // Get the pointer to data
              long double * p = (long double *)sqlite3_column_blob(stmt,2);
              // Initialize the vector with the data
              vector<long double> data(p, p+size);
              allVects.push_back(data);
          }
          else
          {
              //cout << "not SQLITE_ROW" << endl;
              break;
          }
      }
    
      cout<< "before finalzie" << endl;
      sqlite3_finalize(stmt);
      
      while(sqlite3_close(db)!= SQLITE_OK) {
        cout << "not ok" << endl;
      }
    
    cout<< "after close db" << endl;
    
    }

Answer 1

我自己想通了。这是因为我的函数 selectTable() 的返回类型是字符串，但是在函数内部它不返回字符串。奇怪的是我的编译器没有提示它......