系统调用参数 socketcall.recvfrom(buf) 指向不可寻址的字节

Question

当运行这个方法时，我在调用socket.getBytes

时收到来自Valgrind的错误

void Client::register(VMap::VType type, char *id)
{
    const int sizeOfType = sizeof(type);
    char *buffer = (char *) malloc(sizeOfType);
    memcpy(buffer, &type, sizeOfType);
    socket.send(buffer, sizeOfType);
    sleep(1);
    char *bufferRecv = (char *) malloc(sizeOfType);
    memset(bufferRecv, 0 ,sizeOfType);
    int size = socket.getBytes(bufferRecv);

    free(buffer);
    free(bufferRecv);
}


int Socket::getBytes(char *buf)
{
    int ret = ::recv(m_sock, buf, MAXRECV, 0);

    return ret;
}

错误是：

==30653== Syscall param socketcall.recvfrom(buf) points to unaddressable byte(s)
==30653==    at 0x58C214C: recv (recv.c:34)
==30653==    by 0x4E47B84: pippo::Socket::getBytes(char*) (Socket.cpp:115)
==30653==    by 0x4E48BAE: pippo::Rossi::register(pippo::sMap::Type, char*) (Rossi.cpp:80)
==30653==    by 0x4E48EEE: pippo::Rossi::initsMap(std::string) (Rossi.cpp:111)
==30653==    by 0x4E486B0: pippo::Rossi::Rossi(std::string, std::string, std::string, unsigned int) (Rossi.cpp:54)
==30653==    by 0x4E45884: test::TestRossi::testConstructor() (TestRossi.cpp:70)
==30653==    by 0x4E456D8: test::TestRossi::testBody() (TestRossi.cpp:48)
==30653==    by 0x5288D03: test::TestUnit::test() (TestUnit.cpp:42)
==30653==    by 0x5288513: test::TestRunner::run() (TestRunner.cpp:44)
==30653==    by 0x407F26: main (TestDUMBO.cpp:125)
==30653==  Address 0x67a9d64 is 0 bytes after a block of size 4 alloc'd
==30653==    at 0x4C2B6CD: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==30653==    by 0x4E48B21: pippo::Rossi::register(pippo::sMap::Type, char*) (Rossi.cpp:76)
==30653==    by 0x4E48EEE: pippo::Rossi::initsMap(std::string) (Rossi.cpp:111)
==30653==    by 0x4E486B0: pippo::Rossi::Rossi(std::string, std::string, std::string, unsigned int) (Rossi.cpp:54)
==30653==    by 0x4E45884: test::TestRossi::testConstructor() (TestRossi.cpp:70)
==30653==    by 0x4E456D8: test::TestRossi::testBody() (TestRossi.cpp:48)
==30653==    by 0x5288D03: test::TestUnit::test() (TestUnit.cpp:42)
==30653==    by 0x5288513: test::TestRunner::run() (TestRunner.cpp:44)
==30653==    by 0x407F26: main (TestDUMBO.cpp:125)

我真的不明白这是怎么回事。例如，如果我只是使用 sprintf 在 bufferRecv 中写入，我不会收到任何错误。

::recv的原型如下：

/* Read N bytes into BUF from socket FD.
   Returns the number read or -1 for errors.

   This function is a cancellation point and therefore not marked with
   __THROW.  */
extern ssize_t recv (int __fd, void *__buf, size_t __n, int __flags);

编辑另一个信息：如果我这样声明缓冲区 char bufferRecv[4]; 我不会从 Valgrind 收到任何错误。

Answer 1

对于遇到同样问题的其他人：正如@alk 所建议的，我简单地更改了 getBytes 方法，如下所示：

int Socket::getBytes(char *buf, int sizeOfBuf)
{
    int ret = ::recv(m_sock, buf, sizeOfBuf, 0);


    return ret;
}

系统调用参数 socketcall.recvfrom(buf) 指向不可寻址的字节

Syscall param socketcall.recvfrom(buf) points to unaddressable byte(s)

c++

sockets

valgrind