Gentoo ld在使用-Wl,-rpath时在库中生成RUNPATH

Question

我有这样一个目录结构：指向目录的符号链接和指向库的符号链接：

$ libtrotl.so -> /usr/local/lib64/tora-3.1/../libtrotl.so
$ instantclient -> /usr/lib/oracle/12.1/client64/lib

当我 dlopen 库 libtrotl.so 时，所有依赖库都已解析并加载。感谢 RPATH。

$ readelf -d libtrotl.so

Dynamic section at offset 0x17e7a8 contains 31 entries:
  Tag        Type                         Name/Value
 0x0000000000000001 (NEEDED)             Shared library: [libclntsh.so.12.1]
 0x0000000000000001 (NEEDED)             Shared library: [libboost_system.so.1.60.0]
 0x0000000000000001 (NEEDED)             Shared library: [libstdc++.so.6]
 0x0000000000000001 (NEEDED)             Shared library: [libm.so.6]
 0x0000000000000001 (NEEDED)             Shared library: [libgcc_s.so.1]
 0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
 0x000000000000000e (SONAME)             Library soname: [libtrotl.so]
 0x000000000000000f (RPATH)              Library rpath: [$ORIGIN/instantclient/]
 0x000000000000000c (INIT)               0xe7898

$ ldd libtrotl.so 
    linux-vdso.so.1 (0x00007ffdc25d1000)
    libclntsh.so.12.1 => /home/ivan/.TOra3/poracle/./instantclient/libclntsh.so.12.1 (0x00007f6cd0c37000)
    libboost_system.so.1.60.0 => /lib64/libboost_system.so.1.60.0 (0x00007f6cd0a24000)
    libstdc++.so.6 => /lib64/libstdc++.so.6 (0x00007f6cd069c000)
    libm.so.6 => /lib64/libm.so.6 (0x00007f6cd0393000)
    libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00007f6cd017b000)
    libc.so.6 => /lib64/libc.so.6 (0x00007f6ccfdb9000)
    libmql1.so => /home/ivan/.TOra3/poracle/./instantclient/libmql1.so (0x00007f6ccfb43000)
    libipc1.so => /home/ivan/.TOra3/poracle/./instantclient/libipc1.so (0x00007f6ccf7c4000)
    libnnz12.so => /home/ivan/.TOra3/poracle/./instantclient/libnnz12.so (0x00007f6ccf0ba000)

我只使用 -Wl,-rpath,"$ORIGIN/instantclient/" 作为编译标志，它在任何地方都有效——除了 Gentoo。

Gentoo 链接器(GNU gold (Gentoo 2.25.1 p1.1 2.25.1) 1.11) 添加 RUNPATH insead of RPATH。

 0x000000000000001d (RUNPATH)            Library runpath: [$ORIGIN/instantclient/]

然后动态链接器不解析库。

(Gentoo)$ ldd libtrotl.so 
    linux-vdso.so.1 (0x00007ffe5c3e9000)
    libclntsh.so.12.1 => /home/ivan/.TOra3/poracle/./instantclient/libclntsh.so.12.1 (0x00007f245dc9e000)
    libstdc++.so.6 => /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.4/libstdc++.so.6 (0x00007f245d933000)
    libm.so.6 => /lib64/libm.so.6 (0x00007f245d62e000)
    libgcc_s.so.1 => /usr/lib/gcc/x86_64-pc-linux-gnu/4.9.4/libgcc_s.so.1 (0x00007f245d417000)
    libc.so.6 => /lib64/libc.so.6 (0x00007f245d07d000)
    libmql1.so => not found
    libipc1.so => not found
    libnnz12.so => not found
    libons.so => not found

如您所见，在第二种情况下，库 libmql1.so 未找到，尽管它存在于 instantclient 子目录中。我如何在 Gentoo 上设置 RPATH？

Answer 1

DT_RPATH 标签已弃用，DT_RUNPATH 是具有几个不同语义的现代实现。 Gentoo link 编辑器（ld 和 gold）默认情况下不会生成已弃用的标签。您可以（但可能不应该）通过传递 -Wl,--disable-new-dtags 来禁用它们，但正如我所说，不推荐这样做。

Qt有个老锅解释了这两者在使用插件时的区别：http://blog.qt.io/blog/2011/10/28/rpath-and-runpath/

Gentoo ld在使用-Wl,-rpath时在库中生成RUNPATH

Gentoo ld generates RUNPATH in library when -Wl,-rpath is used

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gentoo

rpath

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