clsMMapFile::MMap里的mmap返回码判断问题

[dyx2025]

paxoskv/dbcomm/mmap_file.cc 里的 mmap 返回码没有判断 MAP_FAILED。
man page mmap 返回码文档：On success, mmap() returns a pointer to the mapped area. On error, the value MAP_FAILED (that is, (void *) -1) is returned, and errno is set to indicate the cause of the error.

原代码

    char* pMMapFile = reinterpret_cast<char*>(
        mmap(NULL, iFileSize, PROT_READ, MAP_PRIVATE, fd, 0));
    if (NULL == pMMapFile) {
        return -3;
    }

改后代码

    
    void* mmap_ret = mmap(NULL, iFileSize, PROT_READ, MAP_PRIVATE, fd, 0));
    if (MAP_FAILED == mmap_ret) {
         return -3;  // The specific return code depends on the developer.
    }

    char* pMMapFile = reinterpret_cast<char*>(mmap_ret);
    if (NULL == pMMapFile) {
        return -3;
    }