使用libmicrohttpd库时,遇到奇怪的错误一个string
至const char *
,并调用MHD_create_response_from_buffer
。从std :: string转换为const char *导致'Syscall参数socketcall.sendto(msg)指向valdrrind中的无法寻址的字节'错误
这会导致网页响应格式不正常,偶尔会显示二进制数据,而且更少见一点,会使浏览器认为它是文件并下载它。
是什么使这个非常奇怪的是,该错误不出来,如果我发送一个定期为const char,像 const char *cstring = "this is a page";
只有当我从string
转换为const char *
像 const char *cstring = page.c_str();
的Valgrind的输出:
==11105== Thread 2:
==11105== Syscall param socketcall.sendto(msg) points to unaddressable byte(s)
==11105== at 0x617464B: send (send.c:31)
==11105== by 0x565986F: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x565737D: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x565DA3C: MHD_run_from_select (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x565DC8A: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x565DDA1: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x876B0A3: start_thread (pthread_create.c:309)
==11105== by 0x617362C: clone (clone.S:111)
==11105== Address 0xe499448 is 24 bytes inside a block of size 56 free'd
==11105== at 0x4C2A360: operator delete(void*) (vg_replace_malloc.c:507)
==11105== by 0x401CA5: http_connect(void*, MHD_Connection*, char const*, char const*, char const*, char const*, unsigned long*, void**) (in /home/shpoople/projects/http/main)
==11105== by 0x5656F70: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x5658427: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x565D988: MHD_run_from_select (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x565DC8A: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x565DDA1: ??? (in /usr/lib/x86_64-linux-gnu/libmicrohttpd.so.10.27.0)
==11105== by 0x876B0A3: start_thread (pthread_create.c:309)
==11105== by 0x617362C: clone (clone.S:111)
==11105==
以及用于发送该数据的功能(在this page发现,仅修改为使用std::string
):
static int send_page (struct MHD_Connection *connection, std::string page) {
int ret;
struct MHD_Response *response;
const char* cstring = page.c_str();
response = MHD_create_response_from_buffer (strlen (cstring), (void *) cstring, MHD_RESPMEM_PERSISTENT);
if (!response) {
return MHD_NO;
}
ret = MHD_queue_response(connection, MHD_HTTP_OK, response);
MHD_destroy_response (response);
return ret;
}
感谢您的回复。该函数有一个用于复制缓冲存储器的标志'MHD_RESPMEM_MUST_COPY' – Shpoople