在递归函数内部重新分配缓冲区后，无法释放缓冲区的数据。可能是什么原因？

Question

所以我遇到了一个问题 - 当我的数据超过缓冲区的初始大小并且我在递归函数中进行重新分配时，我在释放缓冲区时遇到错误。

*malloc: *** 对象 0x100106da0 错误：未分配指针被释放*

代码如下：

void recPrint(FILE *file, char *buffer, int realBufferSize, int bufferSize, char *freeCh, NodePtr* temp){

   //some code here...

    int *intArr = temp -> usedIndices;
    int i = 0;
    for(i = 0; i < 36; i++){
        if(intArr[i] == 1){
            if(i > 9){
                *freeCh = i - 10 + 'a' ;
            }else{
                *freeCh = i + '0';
            }
            realBufferSize++;
            if (realBufferSize >= bufferSize){
                buffer = realloc(buffer, (bufferSize + 100) * sizeof(char)); // <<--- REALLOC here
                bufferSize += 100;
            }
            freeCh++;
            recPrint(file, buffer, realBufferSize, bufferSize, freeCh, &temp -> children[i]);

            //now we need to remove all extra characters till the next turn
            freeCh--;
            *freeCh = '\0';
        }
    }

}

void printTrie(FILE *file, char *initialPath){

    initPath = initialPath;
    if(root.isParent == 0) return;
    char *buffer;
    char *freeCh;
    int *intArr = root.usedIndices;
    int bufferSize = 10;
    int realBufferSize = 1000;

    int i = 0;

    for(i = 0; i < 36; i++){
        buffer = calloc(1001, sizeof(char));
        freeCh = buffer;

        if(intArr[i] == 1){
            if(i > 9){
                *freeCh = i - 10 + 'a' ;
            }else{
                *freeCh = i + '0';
            }

        freeCh++;
        realBufferSize++;
        recPrint(file, buffer, realBufferSize, bufferSize, freeCh, &root.children[i]);
        free(buffer); //<<--- getting error here
        }
    }
}

Answer 1

@WhozCraig 的评论指出了问题所在。这是一个建议的修复方法。

1. 从recPrint 返回realloced 缓冲区。

2. 在recPrint的返回值上使用free。

char* recPrint(FILE *file, char *buffer, int realBufferSize,
               int bufferSize, char *freeCh, NodePtr* temp){

   ....

   // where you recurse...
   buffer = recPrint(file, buffer, realBufferSize, 
                     bufferSize, freeCh, &temp -> children[i]);

   // and always return the *current* buffer pointer back to the caller.
   return buffer;
}

在printTrie:

    buffer = recPrint(file, buffer, realBufferSize, bufferSize, freeCh, &root.children[i]);
    free(buffer);