使用musl编译：“错误重新定位- secure_getenv:符号未找到”

Question

我正在尝试使用musl工具链 v1.2.1在x86_64 Debian上编译一个简单的C程序。

程序secgetenv.c如下：

#define _GNU_SOURCE
#include <stdlib.h> 
#include <stdio.h>

int main()
{
    char *res;

    res = secure_getenv("TEST_ENV_VAR");

    fprintf(stdout, "%s\n", res);

    return 0;
}

编译执行时没有错误。但是，运行ldd会发现没有找到符号secure_getenv：

$ musl-ldd secgetenv-musl 
    /lib/ld-musl-x86_64.so.1 (0x7f7872779000)
    libc.so => /lib/ld-musl-x86_64.so.1 (0x7f7872779000)
Error relocating secgetenv-musl: secure_getenv: symbol not found

musl在早期的修补程序中添加了对secure_getenv的支持，我确实在/usr/local/x86_64-linux-musl/include/stdlib.h中看到了一个声明

#ifdef _GNU_SOURCE
...
char *secure_getenv(const char *);
...
#endif

在src/env/secure_getenv.c中有相应的定义

#define _GNU_SOURCE
#include <stdlib.h>
#include "libc.h"

char *secure_getenv(const char *name)
{
    return libc.secure ? NULL : getenv(name);
}

此外，musl的libc.so定义了符号：

$ readelf -s /usr/local/x86_64-linux-musl/lib/libc.so | grep secure
  1461: 0000000000020e0d    17 FUNC    GLOBAL DEFAULT    8 secure_getenv
   358: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS secure_getenv.c
  2275: 0000000000020e0d    17 FUNC    GLOBAL DEFAULT    8 secure_getenv

我尝试过将LD_LIBRARY_PATH设置为指向/usr/local/x86_64-linux-musl/lib (musl的libc驻留在其中)，但这似乎没有修复任何问题。我尝试过其他一些编译器选项，但似乎没有什么能解决它。我做错了什么吗？我怎样才能解决这个问题？

我认为如果添加了编译方式，可能会很有用，下面是详细的输出：

$ /usr/local/bin/x86_64-linux-musl-gcc -v -o secgetenv-musl secgetenv.c -fPIC -ggdb
Using built-in specs.
COLLECT_GCC=/usr/local/bin/x86_64-linux-musl-gcc
COLLECT_LTO_WRAPPER=/usr/local/bin/../libexec/gcc/x86_64-linux-musl/9.2.0/lto-wrapper
Target: x86_64-linux-musl
Configured with: ../src_gcc/configure --enable-languages=c,c++ --enable-languages=c,c++ --enable-default-pie --disable-bootstrap --disable-assembly --disable-werror --target=x86_64-linux-musl --prefix= --libdir=/lib --disable-multilib --with-sysroot=/x86_64-linux-musl --enable-tls --disable-libmudflap --disable-libsanitizer --disable-gnu-indirect-function --disable-libmpx --enable-libstdcxx-time=rt --with-build-sysroot=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_sysroot AR_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/binutils/ar AS_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/gas/as-new LD_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/ld/ld-new NM_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/binutils/nm-new OBJCOPY_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/binutils/objcopy OBJDUMP_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/binutils/objdump RANLIB_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/binutils/ranlib READELF_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/binutils/readelf STRIP_FOR_TARGET=/home/<user>/musl-cross-make/build/local/x86_64-linux-musl/obj_binutils/binutils/strip-new --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
Thread model: posix
gcc version 9.2.0 (GCC) 
COLLECT_GCC_OPTIONS='-v' '-o' 'secgetenv-musl' '-fPIC' '-ggdb' '-mtune=generic' '-march=x86-64'
 /usr/local/bin/../libexec/gcc/x86_64-linux-musl/9.2.0/cc1 -quiet -v -iprefix /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/ -isysroot /usr/local/bin/../x86_64-linux-musl secgetenv.c -quiet -dumpbase secgetenv.c -mtune=generic -march=x86-64 -auxbase secgetenv -ggdb -version -fPIC -o /tmp/cczjeoUa.s
GNU C17 (GCC) version 9.2.0 (x86_64-linux-musl)
    compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.2, MPC version 1.1.0, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/local/bin/../x86_64-linux-musl/usr/local/include"
ignoring duplicate directory "/usr/local/bin/../lib/gcc/../../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/include"
ignoring nonexistent directory "/usr/local/bin/../x86_64-linux-musl/usr/include"
ignoring duplicate directory "/usr/local/bin/../lib/gcc/../../lib/gcc/x86_64-linux-musl/9.2.0/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/include
 /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/include
End of search list.
GNU C17 (GCC) version 9.2.0 (x86_64-linux-musl)
    compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.2, MPC version 1.1.0, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 02d33dfe51251a8723bc0ce5bbca8406
COLLECT_GCC_OPTIONS='-v' '-o' 'secgetenv-musl' '-fPIC' '-ggdb' '-mtune=generic' '-march=x86-64'
 /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/bin/as -v --64 -o /tmp/ccMKBInY.o /tmp/cczjeoUa.s
GNU assembler version 2.33.1 (x86_64-linux-musl) using BFD version (GNU Binutils) 2.33.1
COMPILER_PATH=/usr/local/bin/../libexec/gcc/x86_64-linux-musl/9.2.0/:/usr/local/bin/../libexec/gcc/:/usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/bin/
LIBRARY_PATH=/usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/:/usr/local/bin/../lib/gcc/:/usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/lib/:/usr/local/bin/../x86_64-linux-musl/lib/
COLLECT_GCC_OPTIONS='-v' '-o' 'secgetenv-musl' '-fPIC' '-ggdb' '-mtune=generic' '-march=x86-64'
 /usr/local/bin/../libexec/gcc/x86_64-linux-musl/9.2.0/collect2 -plugin /usr/local/bin/../libexec/gcc/x86_64-linux-musl/9.2.0/liblto_plugin.so -plugin-opt=/usr/local/bin/../libexec/gcc/x86_64-linux-musl/9.2.0/lto-wrapper -plugin-opt=-fresolution=/tmp/ccjHWTRL.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s --sysroot=/usr/local/bin/../x86_64-linux-musl --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib/ld-musl-x86_64.so.1 -pie -o secgetenv-musl /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/lib/Scrt1.o /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/lib/crti.o /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/crtbeginS.o -L/usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0 -L/usr/local/bin/../lib/gcc -L/usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/lib -L/usr/local/bin/../x86_64-linux-musl/lib /tmp/ccMKBInY.o -lgcc --push-state --as-needed -lgcc_s --pop-state -lc -lgcc --push-state --as-needed -lgcc_s --pop-state /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/crtendS.o /usr/local/bin/../lib/gcc/x86_64-linux-musl/9.2.0/../../../../x86_64-linux-musl/lib/crtn.o
COLLECT_GCC_OPTIONS='-v' '-o' 'secgetenv-musl' '-fPIC' '-ggdb' '-mtune=generic' '-march=x86-64'

Answer 1

/lib/ld-musl-x86_64.so.1符号链接到没有定义符号的/lib/x86_64-linux-musl/libc.so。这个libc是在我安装musl工具或类似的东西时引入的。它使用MUSLVersion1.1.21，它没有消除此错误所需的secure_getenv 修补程序。符号链接到一个最近的libc.so，我得到了安装musl -交叉使我的问题。

Answer 2

但是，运行ldd会发现没有找到符号secure_getenv： $musl-secure_getenv musl /lib/ld-musl-x86_64.so.1 (0x7f7872779000) libc.so => /lib/ld-x86_64.so.1 (0x7f7872779000)

ldd似乎比没有找到符号更能说明问题。这似乎表明，某些东西，或许是musl-ldd本身，已经严重受损。输出表明，libc.so不是解析为MUSL的libc，甚至不是系统的默认libc，而是MUSL的运行时动态链接器。当然，这并不能提供想要的符号本身。

如果程序按预期运行，尽管有来自musl-ldd的投诉，那么这个问题很可能在musl-ldd中出现。如果程序没有按预期运行(可能在尝试时它会报告相同的重新定位错误)，那么问题可能在您的MUSL副本中，特别是在它的运行时动态链接器/lib/ld-musl-x86_64.so.1中。

增编：

如果对这个答案的评论是正确的，MUSL程序解释器包含C库的副本，那么这里仍然存在一个严重的问题，无论是在musl-ldd中还是在库的副本中，特别是在/lib/ld-musl-x86_64.so.1中。例如，后者可能与库不同步。这种问题可能是两个或多个不同MUSL安装组件同时出现的结果，或者是MUSL编译器工具链与已安装的MUSL版本不同步的结果。