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

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

本文关键字：寻址 字节 socketcall 参数 recvfrom buf 系统调用      更新时间：2023-10-16

当运行此方法时，我在调用socket.getBytes时从Valgrind获得错误

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)
我真不明白是怎么回事。例如，如果我简单地在bufferRecv中写入sprintf，我不会得到任何错误。

::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);

EDIT另一个信息:如果我像这样声明缓冲区char bufferRecv[4];，我不会从Valgrind得到任何错误。

对于其他有同样问题的人:根据@alk的建议，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;
}
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