[英]I don't understand a valgrind error I'm getting
==3275== Invalid read of size 8
==3275== at 0x53D006E: _IO_file_xsputn@@GLIBC_2.2.5 (fileops.c:1362)
==3275== by 0x53C5C6C: fwrite (iofwrite.c:45)
==3275== by 0x4EE4C9D: std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
==3275== by 0x4EE4FA6: std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
==3275== by 0x401D4C: main (q2.cc:45)
==3275== Address 0x5a254b8 is 24 bytes inside a block of size 43 free'd
==3275== at 0x4C2A4BC: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3275== by 0x4EF27BF: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string() (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
==3275== by 0x40197D: read(std::istream&, character&) (utf8char.cc:16)
==3275== by 0x401B6C: main (q2.cc:27)
这是相关代码:
infile = new ifstream(argv[1]);
character CurrChar;
character &UTF = CurrChar;
其中character是一个包含4个字节的结构。 我认为这无关紧要。
q2.cc:27 utfchar = read(*infile, UTF)
q2.cc:44 catch (UTF8err err) {
q2.cc:45 cout << err.msg << ends;
q2.cc:46 ....
err在哪里:
struct UTF8err { // exception
const char *msg;`
UTF8err( const char *msg ) : msg( msg ) {}
};
utf8char.cc:16 string pad = " : invalid padding";
调用c_str
,只要不修改或销毁字符串,结果就有效。 但是,当您抛出时,堆栈将解开,从而破坏了字符串。 因此,指针指向的东西不再存在。
也许将msg
的类型从const char*
更改为std::string
。 也许使字符串static
。 也许让UTF8err
类管理自己的内存。
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