musl-gcc：对 __memcpy_chk 的未定义引用答案

【问题标题】：musl-gcc: undefined reference to __memcpy_chkmusl-gcc：对 __memcpy_chk 的未定义引用
【发布时间】：2019-08-10 06:53:07
【问题描述】：

我需要针对 musl-libc 编译一个 C 程序以使其在嵌入式设备上运行。但是，我无法编译该程序。源代码取决于我传递给链接器的几个库，如下所示：

/usr/local/musl/bin/musl-gcc app.c -o app -I../lib -lzlog -lfilter

这是我得到的输出：

/usr/local/musl/lib/libzlog.a(category.o): In function `strcpy':
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__memcpy_chk'
/usr/local/musl/lib/libzlog.a(conf.o): In function `strcpy':
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__strcpy_chk'
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__strcpy_chk'
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__strcpy_chk'
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__strcpy_chk'
/usr/local/musl/lib/libzlog.a(event.o): In function `sprintf':
/usr/include/x86_64-linux-gnu/bits/stdio2.h:33: undefined reference to `__sprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:33: undefined reference to `__sprintf_chk'
/usr/local/musl/lib/libzlog.a(format.o): In function `memcpy':
/usr/include/x86_64-linux-gnu/bits/string3.h:53: undefined reference to `__memcpy_chk'
/usr/local/musl/lib/libzlog.a(record.o): In function `strcpy':
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__memcpy_chk'
/usr/local/musl/lib/libzlog.a(rotater.o): In function `snprintf':
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64: undefined reference to `__snprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64: undefined reference to `__snprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64: undefined reference to `__snprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64: undefined reference to `__snprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64: undefined reference to `__snprintf_chk'
/usr/local/musl/lib/libzlog.a(rule.o): In function `syslog':
/usr/include/x86_64-linux-gnu/bits/syslog.h:31: undefined reference to `__syslog_chk'
/usr/local/musl/lib/libzlog.a(rule.o): In function `strcpy':
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__strcpy_chk'
/usr/local/musl/lib/libzlog.a(rule.o): In function `memcpy':
/usr/include/x86_64-linux-gnu/bits/string3.h:53: undefined reference to `__memcpy_chk'
/usr/local/musl/lib/libzlog.a(spec.o): In function `sprintf':
/usr/include/x86_64-linux-gnu/bits/stdio2.h:33: undefined reference to `__sprintf_chk'
/usr/local/musl/lib/libzlog.a(zc_profile.o): In function `vfprintf':
/usr/include/x86_64-linux-gnu/bits/stdio2.h:127: undefined reference to `__vfprintf_chk'
/usr/local/musl/lib/libzlog.a(zc_profile.o): In function `fprintf':
/usr/include/x86_64-linux-gnu/bits/stdio2.h:97: undefined reference to `__fprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:97: undefined reference to `__fprintf_chk'
/usr/local/musl/lib/libzlog.a(zc_util.o): In function `snprintf':
/usr/include/x86_64-linux-gnu/bits/stdio2.h:64: undefined reference to `__snprintf_chk'
/usr/local/musl/lib/libzlog.a(buf.o): In function `strcpy':
/usr/include/x86_64-linux-gnu/bits/string3.h:110: undefined reference to `__memcpy_chk'
/usr/local/musl/lib/libzlog.a(buf.o): In function `vsnprintf':
/usr/include/x86_64-linux-gnu/bits/stdio2.h:77: undefined reference to `__vsnprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:77: undefined reference to `__vsnprintf_chk'
/usr/include/x86_64-linux-gnu/bits/stdio2.h:77: undefined reference to `__vsnprintf_chk'
collect2: error: ld returned 1 exit status

与 gcc 相同的命令可以正常工作。这些函数不是用musl实现的吗？

【问题讨论】：

关于：-I../lib 这是告诉编译器头文件的位置，而不是库的位置。要告诉链接器库所在的位置，请使用-L../lib 注意大写“L”而不是大写“I”`
你当然是对的。设置有点奇怪。相关库不需要头文件。该库位于链接器的标准查找路径中。

标签： c gcc musl

【解决方案1】：

您问题中的包含路径都是 glibc 文件，因此看起来您尝试链接的库是使用 glibc 构建的。这有时可以工作，但有一些限制。在您的情况下，它是使用 _FORTIFY_SOURCE 的 glibc 版本构建的，它使用 glibc 中目前在 musl 中不可用的符号（通常在 musl 上使用的 _FORTIFY_SOURCE 实现的工作方式不同）。长期以来，这项工作一直在长期议程上，但不是优先事项；如果可以，最好针对 musl 重建库。

【讨论】：

@Antti 你的意思是来自 musl 的作者本人？
当然，就是这样。我可以得到源代码并针对 musl 编译它。工作正常。

【解决方案2】：

也许这与你的情况无关，但我在 linux 下使用 MinGW 进行交叉编译时遇到了同样的__memcpy_chk 问题。

通过将-lssp 标志添加到链接器来修复这个未定义的引用。如果你有configure，那么你可以做LDFLAGS="-lssp" ./configure ...

【讨论】：