Valgrind在fclose（）处检测到内存泄漏

Question

Why does valgrind say I've got memory leak at the fclose() call?

#include <stdio.h>

class Stream
{
    public:
        Stream();
        ~Stream();
    private:
        char*  pszOutput;
        size_t size;
        FILE* file;
};

Stream::Stream()
{
    file = open_memstream(&pszOutput, &size);
}

Stream::~Stream()
{
    fclose(file);
}

int main()
{
    Stream s;   

    return 0;
}

Valgrind report:

==52387== 1 bytes in 1 blocks are definitely lost in loss record 1 of 1
==52387==    at 0x4C28CCE: realloc (vg_replace_malloc.c:632)
==52387==    by 0x5639CA3: _IO_mem_finish (memstream.c:132)
==52387==    by 0x5635956: fclose@@GLIBC_2.2.5 (iofclose.c:66)

Does it matter to initialize pszOutput or size ? Or maybe I need to add something else?

Answer 1

From : http://linux.die.net/man/3/open_memstream

The open_memstream() function opens a stream for writing to a buffer. The buffer is dynamically allocated (as with malloc(3)), and automatically grows as required. After closing the stream, the caller should free(3) this buffer.

So according to this you need to free(pszOutput) after your file descriptor is closed.