运行ltrace时无输出

问题描述

正如标题所述，ltrace在我的系统上无法正常工作.在大多数情况下，它不显示任何输出，例如

As the title says, ltrace does not work properly on my system.It shows no output in most cases, like

$ltrace ls
[usual ls output]
+++ exited (status 0) +++

$gcc hello.c
$ltrace ./a.out
Hello world!
+++ exited (status 0) +++

我使用的是最新的ltrace版本(来自软件包0.7.3-5.1ubuntu4)，我什至尝试从源代码重新编译而没有任何区别.我正在使用Ubuntu 16.10，内核4.8.0-42-generic. gcc版本是6.2.0.

I'm using the latest ltrace version (from package 0.7.3-5.1ubuntu4), I even tried recompiling from source with no difference.I'm using Ubuntu 16.10, kernel 4.8.0-42-generic. gcc version is 6.2.0.

奇怪的是，从Internet下载的二进制文件似乎可以正常显示库调用.

Weird thing is, binaries downloaded from the Internet seem to work, correctly displaying the library calls.

我想念什么?有人能够重现该问题吗?

What am I missing? Is anyone able to reproduce the issue?

推荐答案

这可能与使用-z now编译的二进制文件有关.我创建了一个快速测试程序(我正在使用Ubuntu 16.04):

This may have to do with binaries being compiled with -z now. I created a quick test program (I'm using Ubuntu 16.04):

int main() {
  write(0, "hello\n", 6);
  return 0;
}

如果我使用gcc -O2 test.c -o test进行编译，则ltrace可以工作:

If I compile it with gcc -O2 test.c -o test then ltrace works:

$ ltrace ./test
__libc_start_main(0x400430, 1, 0x7ffc12326528, 0x400550 <unfinished ...>
write(0, "hello\n", 6hello
)                                                              = 6
+++ exited (status 0) +++

但是，当我使用gcc -O2 test.c -Wl,-z,relro -Wl,-z,now -o test2进行编译时，却没有:

However when I compile with gcc -O2 test.c -Wl,-z,relro -Wl,-z,now -o test2 then it doesn't:

$ ltrace ./test2
hello
+++ exited (status 0) +++

您可以使用Ubuntu上pax-utils包中的scanelf检查二进制文件是否像这样编译:

You can check if a binary was compiled like so using scanelf from the pax-utils package on Ubuntu:

$ scanelf -a test*
 TYPE    PAX   PERM ENDIAN STK/REL/PTL TEXTREL RPATH BIND FILE
ET_EXEC PeMRxS 0775 LE RW- R-- RW-    -      -   LAZY test
ET_EXEC PeMRxS 0775 LE RW- R-- RW-    -      -   NOW test2

请注意LAZY(ltrace可以工作)与NOW(ltrace不能).

Note the LAZY (ltrace works) versus NOW (ltrace doesn't).

这里还有更多讨论(但没有解决方案):

There is a little bit more discussion (but no resolution) here:

https://bugzilla.redhat.com/show_bug.cgi?id=1333481

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