c - Valgrind 报告从 stdin 获取 getline 后释放指针的内存泄漏

Question

有这段代码:

#include <stdlib.h>
#include <stdio.h>
void main()
{   
    char *line = calloc(1024, 1);
    size_t size = 0;
    getline(&line, &size, stdin);
    free(line);
}

Valgrind 提示:

==5931== HEAP SUMMARY:
==5931==     in use at exit: 1,024 bytes in 1 blocks
==5931==   total heap usage: 3 allocs, 2 frees, 2,168 bytes allocated
==5931== 
==5931== 1,024 bytes in 1 blocks are definitely lost in loss record 1 of 1
==5931==    at 0x4837B65: calloc (vg_replace_malloc.c:752)
==5931==    by 0x10916B: main (test.c:5)
==5931== 
==5931== LEAK SUMMARY:
==5931==    definitely lost: 1,024 bytes in 1 blocks

我看过其他相关帖子，但找不到这个特定案例的答案:/

Answer 1

这是一个 glibc 错误(或长期存在的 glibc 行为，取决于您如何看待它):

• getdelim leaks line when n is zero

在 glibc 中很难修复，因为许多应用程序假定当长度为零时不必初始化行指针，如 klutt的 original reply .如果 glibc 在零长度情况下开始释放或以其他方式使用行指针，这将导致崩溃。