c# – 当P /调用dlopen时的SIGSEGV

2022-11-28 22:01:22

我正在尝试编写一个抽象来在Windows和Linux上加载动态库.在Windows平台上,一切都很顺利,当我调用dlopen时,我得到一个SIGSEGV：

    // File: Main.cs
using System;
using System.Runtime.InteropServices;

namespace DlopenTest
{
    class MainClass
    {
        const int RTLD_NOW = 2;

        [DllImport("dl")]
        static extern IntPtr dlopen([MarshalAs(UnmanagedType.LPTStr)] string filename, int flags);

        [DllImport("dl")]
        static extern IntPtr dlsym(IntPtr handle, [MarshalAs(UnmanagedType.LPTStr)] string symbol);

        public static void Main (string[] args)
        {
            IntPtr libraryHandle = dlopen("libc.so.6", RTLD_NOW);

            Console.WriteLine ("Success!");
        }
    }
}

输出如下：

Stacktrace:

  at (wrapper managed-to-native) DlopenTest.MainClass.dlopen (string,int) <0x00004>
  at (wrapper managed-to-native) DlopenTest.MainClass.dlopen (string,int) <0x00004>
  at DlopenTest.MainClass.Main (string[]) [0x00000] in     /home/luca/Projects/DlopenTest/DlopenTest/Main.cs:18
  at (wrapper runtime-invoke) <Module>.runtime_invoke_void_object     (object,intptr,intptr,intptr) <IL 0x0001d, 0x00043>

Native stacktrace:

    /usr/bin/mono() [0x80d5b19]
    /usr/bin/mono() [0x810f7ab]
    [0xb771940c]
    /lib/ld-linux.so.2(+0x119a8) [0xb772b9a8]
/usr/lib/libdl.so(+0xc0b) [0xb536dc0b]
/lib/ld-linux.so.2(+0xdb36) [0xb7727b36]
/usr/lib/libdl.so(+0x109c) [0xb536e09c]
/usr/lib/libdl.so(dlopen+0x41) [0xb536db41]
[0xb58672f1]
[0xb58671bd]
[0xb5867234]
/usr/bin/mono() [0x8064428]
/usr/bin/mono(mono_runtime_invoke+0x40) [0x812d4e0]
/usr/bin/mono(mono_runtime_exec_main+0xde) [0x8130f8e]
/usr/bin/mono(mono_runtime_run_main+0x112) [0x8131292]
/usr/bin/mono(mono_main+0x15ec) [0x80b3bdc]
/usr/bin/mono() [0x805b675]
/lib/i686/cmov/libc.so.6(__libc_start_main+0xe6) [0xb74b8ca6]
/usr/bin/mono() [0x805b5b1]

Debug info from gdb:

=================================================================
Got a SIGSEGV while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries 
used by your application.
=================================================================

这是怎么回事？

我的glibc版本是2.11.3,单声道运行时是2.6.3.

编译程序：mono-csc Main.cs
要运行该程序：./ Main.exe

我刚刚完成了测试应用程序的执行.这是SIGSGV之前的系统调用：

...
open("/usr/lib/libdl.so", O_RDONLY)     = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@\n\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=9736, ...}) = 0
mmap2(NULL, 12408, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb598b000
mmap2(0xb598d000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3,     0x1) = 0xb598d000
close(3)                                = 0
mprotect(0xb598d000, 4096, PROT_READ)   = 0
munmap(0xb598f000, 76774)               = 0
gettimeofday({1333269422, 515602}, NULL) = 0
gettimeofday({1333269422, 515653}, NULL) = 0
gettimeofday({1333269422, 515828}, NULL) = 0
gettimeofday({1333269422, 515884}, NULL) = 0
gettimeofday({1333269422, 515986}, NULL) = 0
gettimeofday({1333269422, 516059}, NULL) = 0
gettimeofday({1333269422, 516613}, NULL) = 0
gettimeofday({1333269422, 516670}, NULL) = 0
brk(0x98e3000)                          = 0x98e3000
brk(0x98e1000)                          = 0x98e1000
gettimeofday({1333269422, 516916}, NULL) = 0
brk(0x98de000)                          = 0x98de000
brk(0x98dc000)                          = 0x98dc000
brk(0x98db000)                          = 0x98db000
gettimeofday({1333269422, 517092}, NULL) = 0
gettimeofday({1333269422, 517200}, NULL) = 0
gettimeofday({1333269422, 517261}, NULL) = 0
gettimeofday({1333269422, 517368}, NULL) = 0
gettimeofday({1333269422, 517525}, NULL) = 0
gettimeofday({1333269422, 517762}, NULL) = 0
gettimeofday({1333269422, 517823}, NULL) = 0
gettimeofday({1333269422, 518007}, NULL) = 0
gettimeofday({1333269422, 518074}, NULL) = 0
gettimeofday({1333269422, 518435}, NULL) = 0
gettimeofday({1333269422, 518486}, NULL) = 0
gettimeofday({1333269422, 518648}, NULL) = 0
gettimeofday({1333269422, 518699}, NULL) = 0
gettimeofday({1333269422, 518803}, NULL) = 0
futex(0xb598e06c, FUTEX_WAKE_PRIVATE, 2147483647) = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---

通过调用“strace /opt/mono-2.10/bin/mono ./DlopenTest.exe 2> strace”生成此跟踪

默认单声道安装(2.6)它几乎相似,它总是在同一点崩溃.

如何调试这个条件？我没有想法……也许dlopen只是一个包装器,所以我可以调用替代函数？也许我在一个错误的环境中执行单声道2.10(也许我必须指定一些环境变量才能使这个工作)？

解决方法:

您的代码适用于Mono 2.10.

$mono --version
Mono JIT compiler version 2.10.5 (Debian 2.10.5-1)
Copyright (C) 2002-2011 Novell, Inc, Xamarin, Inc and Contributors. www.mono-project.com
    TLS:           __thread
    SIGSEGV:       altstack
    Notifications: epoll
    Architecture:  x86
    Disabled:      none
    Misc:          softdebug 
    LLVM:          supported, not enabled.
    GC:            Included Boehm (with typed GC and Parallel Mark)
$cat so.cs
using System;
using System.Runtime.InteropServices;

namespace DlopenTest
{
    class MainClass
    {
        const int RTLD_NOW = 2;

        [DllImport("dl")]
        static extern IntPtr dlopen([MarshalAs(UnmanagedType.LPTStr)] string filename, int flags);

        [DllImport("dl")]
        static extern IntPtr dlsym(IntPtr handle, [MarshalAs(UnmanagedType.LPTStr)] string symbol);

        public static void Main (string[] args)
        {
            IntPtr libraryHandle = dlopen("libc.so.6", RTLD_NOW);

            Console.WriteLine ("Success!");
        }
    }
}
$mcs so.cs
so.cs(18,20): warning CS0219: The variable `libraryHandle' is assigned but its value is never used
Compilation succeeded - 1 warning(s)
$mono so.exe
Success!

它似乎在2.6下失败了(这是很常见的东西)但是这个版本如果已经很多年了……我强烈建议你升级.

码农公寓

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