为什么这里不传播DYLD_LIBRARY_PATH？ [英] Why isn't DYLD_LIBRARY_PATH being propagated here?

问题描述

我有一个简单的C ++程序，我试图运行，它链接到我之前构建的Boost.Thread库的一个版本。我似乎无法理解运行时库路径在OS X上的运行方式。

由于我的Boost库没有一个 RPATH相对安装名称，我使用 DYLD_LIBRARY_PATH 环境变量告诉动态链接器在运行时查找 libboost_thread.dylib

如果我直接在我的（ bash ）shell中运行程序，这样可以正常工作：

  [〜/ git / project] $ echo $ DYLD_LIBRARY_PATH 
 / Users / jasonr / git / project / boost / lib 
 [〜/ git / project] $ .sconf_temp / conftest_7 
 [〜/ git / project] $＃程序运行成功;这是我的期望。 
  

但是，该程序作为一系列测试的一部分运行，由我正在使用的autoconf 类框架。它使用 sh -c 在子shell中运行该程序。如果我尝试，会发生什么：

  [〜/ git / project] $＃确保环境变量导出为子炮弹。 
 [〜/ git / project] $ export DYLD_LIBRARY_PATH = $ DYLD_LIBRARY_PATH 
 [〜/ git / project] $＃尝试在子shell中运行它。 
 [〜/ git / project] $ sh -c .sconf_temp / conftest_7 
 dyld：库未加载：libboost_thread.dylib 
引用来自：/Users/jasonr/git/project/.sconf_temp / conftest_7 
原因：图像未找到
跟踪/ BPT陷阱：5 
  

在这种情况下，环境变量就不会传播到 dyld 。为什么会这样呢？我更熟悉Linux上的 LD_LIBRARY_PATH 的行为，我认为应该使用上面的例子。为了使这项工作有什么需要做的吗？

解决方案

大概你正在运行El Capitan 10.11）。这是系统完整性保护的副作用。从系统完整性保护指南：运行时保护文章：

当进程启动时，内核检查主
可执行文件是否受保护磁盘或使用特殊系统
授权签署。如果两者都为真，则设置一个标志来表示
被保护以防修改。 ...

...任何动态链接器（ dyld ）
环境变量，如启动受保护的进程时，将清除DYLD_LIBRARY_PATH 。

所有系统提供包括 / bin / sh 在内的口译员受到这种保护。因此，当您调用 sh 时，将清除所有DYLD_ *环境变量。

您可以编写一个shell脚本，设置 DYLD_LIBRARY_PATH ，然后执行 .sconf_temp / conftest_7 。您可以使用shell解释器来执行 - 实际上，您必须 - 并且环境变量会很好，因为清除在受保护的可执行文件启动时发生。基本上，这种方法类似于您的问题中的工作示例，但封装在shell脚本中。

I have a simple C++ program that I'm trying to run that is linked against a version of the Boost.Thread library that I built previously. I seem to be having trouble understanding the way that runtime library paths behave on OS X.

Since my Boost library doesn't have an RPATH-relative install name, I'm using the DYLD_LIBRARY_PATH environment variable to tell the dynamic linker where to find libboost_thread.dylib at runtime.

This works fine if I run the program directly in my (bash) shell:

[~/git/project]$ echo $DYLD_LIBRARY_PATH
/Users/jasonr/git/project/boost/lib
[~/git/project]$ .sconf_temp/conftest_7
[~/git/project]$ # Program runs successfully; this is what I expect.

However, this program is run as part of a series of tests by an autoconf-like framework that I'm using. It runs the program in a child shell using sh -c. Here's what happens if I try that:

[~/git/project]$ # Make sure the environment variable is exported to child shells.
[~/git/project]$ export DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH
[~/git/project]$ # Try to run it in a child shell.
[~/git/project]$ sh -c .sconf_temp/conftest_7
dyld: Library not loaded: libboost_thread.dylib
  Referenced from: /Users/jasonr/git/project/.sconf_temp/conftest_7
  Reason: image not found
Trace/BPT trap: 5

It's as if the environment variable isn't propagated to dyld in this case. Why would this occur? I'm more familiar with the behavior of LD_LIBRARY_PATH on Linux, which (I think) should work with the above example. Is there something else I need to do in order to make this work?

解决方案

Presumably, you are running El Capitan (OS X 10.11). It's a side effect of System Integrity Protection. From the System Integrity Protection Guide: Runtime Protections article:

When a process is started, the kernel checks to see whether the main executable is protected on disk or is signed with an special system entitlement. If either is true, then a flag is set to denote that it is protected against modification. …

… Any dynamic linker (dyld) environment variables, such as DYLD_LIBRARY_PATH, are purged when launching protected processes.

All of the system-provided interpreters, including /bin/sh, are protected in this fashion. Therefore, when you invoke sh, all DYLD_* environment variables are purged.

You could write a shell script which sets DYLD_LIBRARY_PATH and then executes .sconf_temp/conftest_7. You can use the the shell interpreter to execute that — indeed, you must — and the environment variable will be fine, since the purging happens when a protected executable is started. Basically, this approach is analogous to the working example in your question, but encapsulated in a shell script.

这篇关于为什么这里不传播DYLD_LIBRARY_PATH？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！