c - 在 C 中调试 Valgrind

Question

我还在学习 valgrind 和 c。如何消除“无效的 free()”？

错误:

==31415== Invalid free() / delete / delete[] / realloc()
==31415==    at 0x4C2BDEC: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31415==    by 0x400EE1: songDelete (song.c:44)
==31415==    by 0x400B70: main (songtest.c:117)
==31415==  Address 0x51fd9f0 is 0 bytes inside a block of size 14 free'd
==31415==    at 0x4C2BDEC: free (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==31415==    by 0x400EE1: songDelete (song.c:44)
==31415==    by 0x400AD3: main (songtest.c:105)
.......

代码:

void songDelete(song *s)
{
    if(s == NULL){
        return;
    }

    //artist
    free(s->artist) ;
    //title
    free(s->title) ;
    //time
    if(NULL != s->lastPlayed)
        mtimeDelete(s->lastPlayed) ;
    //song
    free(s) ;
    s = NULL;
}

我添加了 free(s); 和 s=NULL; 和 if(s == NULL)..

结构:

typedef struct song_{
    char *artist;
    char *title;
    mtime *lastPlayed;
}song;

所以我不太确定如何解决这个问题？

Answer 1

在 main 中，调用 songDelete( &song1 ); 并将 songDelete 更改为:

void songDelete(song **s)
{
  if(*s == NULL){
      return;
  }

  //artist
  free((*s)->artist) ;
  //title
  free((*s)->title) ;
  //time
  if(NULL != (*s)->lastPlayed)
      mtimeDelete((*s)->lastPlayed) ;
  //song
  free(*s) ;
  *s = NULL;
} 

这将允许您实际导致 main 中的变量，例如 song1 在释放后实际设置为 NULL。