Question

am尝试释放用户定义函数中分配的内存。我正在计划在具有64Kb Flash和16KB SRAM的嵌入式设备STM32F303k8上运行代码。我还没有尝试过该代码，但是我担心它不会执行它应该做的事情。由于无法重新分配已分配的内存，它将耗尽内存

我试图在名为split的自定义程序中释放内存。但是，它甚至不编译，并且总是在free（）函数时崩溃。

[2019-03-28 18:20:27,311] INFO in views: In create_form
[2019-03-28 18:20:27,312] INFO in views: 140045316455232
[2019-03-28 18:20:27,312] INFO in views: Host: 127.0.0.1:5000
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[2019-03-28 18:20:27,316] INFO in views: Access token ok for user dummy_user42
172.23.0.1 - - [28/Mar/2019 18:20:27] "GET /admin/admin_project/new/?url=%2Fadmin%2Fadmin_project%2F HTTP/1.1" 200 -
[2019-03-28 18:21:11,496] INFO in views: In create_form
[2019-03-28 18:21:11,496] INFO in views: 140045316455232
[2019-03-28 18:21:11,496] INFO in views: Host: 127.0.0.1:5000
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:66.0) Gecko/20100101 Firefox/66.0
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Referer: http://127.0.0.1:5000/admin/admin_project/new/?url=%2Fadmin%2Fadmin_project%2F
Content-Type: multipart/form-data; boundary=---------------------------209115246111667105161673380
Content-Length: 857
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Cookie: session_id=0c89eb809ae01aa65aa58bbc45faf79b31af32db; access_token_cookie=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpYXQiOjE1NTM3OTcxOTYsIm5iZiI6MTU1Mzc5NzE5NiwianRpIjoiMWU0ZTA3YzItMjJjOC00NTFhLWJkNjAtYjllNzZmNWYzMTYyIiwiZXhwIjoxNTUzNzk3Mzc2LCJpZGVudGl0eSI6ImR1bW15X3VzZXI0MiIsImZyZXNoIjp0cnVlLCJ0eXBlIjoiYWNjZXNzIiwiY3NyZiI6IjkwZTY5ZjM1LWQwNDctNDM0NC1hOWVlLTg2NDM4OWFiNzM4OCJ9.0p1CBGxpUzLgIR369I1yP-FTRel4-fhAIeL084YV_O0; csrf_access_token=90e69f35-d047-4344-a9ee-864389ab7388; refresh_token_cookie=eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpYXQiOjE1NTM3OTcxOTYsIm5iZiI6MTU1Mzc5NzE5NiwianRpIjoiODI0MGJkODItYjg0NC00MjI5LWFiN2MtZTRhN2IwYzgxYzYzIiwiZXhwIjoxNTUzNzk3NTU2LCJpZGVudGl0eSI6ImR1bW15X3VzZXI0MiIsInR5cGUiOiJyZWZyZXNoIiwiY3NyZiI6Ijg1M2FiYzk0LWU2YjctNGZkZi05YzRhLTczNDMxZWE4NGRlOCJ9.CcHzlWsT9kBURZ1FaeCjG8du7FGXLD-fm5-HF0sBdJ8; csrf_refresh_token=853abc94-e6b7-4fdf-9c4a-73431ea84de8
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Answer 1

您的代码中有两个无效的免费

这里一个：

char *ptrTemp_string_holder;

// Points to the first character of a split string from the main string 
char *t;

   free(ptrTemp_string_holder );

ptrTemp_string_holder尚未初始化

即将结束的第二秒：

// Free the space that was allocated to this pointer
free(ptr_main_array);

因为您尝试在调用函数中释放局部变量 arr

这两个免费的必须删除。

请注意，ptrTemp_string_holder的定义必须为

const char *ptrTemp_string_holder;

因为它收到了ptr_original_string的值

由于无法重新分配已分配的内存，它将耗尽内存

您需要释放*ptr_main_array和存储的数组，在 split 中执行此操作似乎很奇怪，否则 split 不会返回可用的结果，必须可以在调用方函数中完成，例如添加以下 main ：

int main()
{
  char **arr = NULL;
  int count = split("aze,qsd", ',', &arr);

  if (arr != NULL) {
    for (int i = 0; i != count; ++i)
      free(arr[i]);

    free(arr);
  }
}

在 valgrind 下的编译和执行：

pi@raspberrypi:/tmp $ gcc -pedantic -Wall -Wextra -g s.c
pi@raspberrypi:/tmp $ valgrind --leak-check=full ./a.out
==10755== Memcheck, a memory error detector
==10755== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==10755== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==10755== Command: ./a.out
==10755== 
==10755== 
==10755== HEAP SUMMARY:
==10755==     in use at exit: 0 bytes in 0 blocks
==10755==   total heap usage: 3 allocs, 3 frees, 16 bytes allocated
==10755== 
==10755== All heap blocks were freed -- no leaks are possible
==10755== 
==10755== For counts of detected and suppressed errors, rerun with: -v
==10755== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 6 from 3)

Answer 2

这对我来说完全没有意义：

    // str_gprmc is a string thats trying to be split 
    // "$GPRMC,130133.00,A,5741.6029848,N,01158.3855831,E,11.522,170.0,270319"

    for (int k = 0; k < ARRAY_SIZE(str_gprmc); k++)
    {
        char **arr = NULL;

        // Now do the splitting please
        split(str_gprmc[k], ',', &arr);
    }´

    // and the split function
int split(const char *ptr_original_string, char delimiter, char ***ptr_main_array)

如果我正确理解，str_gprmc是类型为char []的变量，具有一定的大小，此处未指定。您可以使用for(int k=....)循环遍历整个数组。表达式str_gprmc[k]从数组中提取第k个字符，并将其作为第一个参数传递给split()函数，该函数需要一个 char指针作为第一个参数。

这意味着char类型数据的数字表示形式被解释为指针(const char *)的数字表示形式。结果，您可以有效地对数据进行split()处理，该数据位于最初的120字节左右的内存中的随机地址上，这取决于NMEA消息中字符的数字值（ASCII码），但是您肯定 not < / em>处理消息本身。

在另一个循环中调用的函数中释放分配的内存

2 个答案: