runtime: Alpine-Linux: System.DllNotFoundException when calling native library via P/Invoke

From @rjsathome on November 12, 2018 11:54

I have a nuget package containing native code which is called via p/invoke fromt the .NET Core assembly.

When using this on Alpine Linux I get:

vmalpine64 (1)$ dotnet run
Using launch settings from /home/rjs/src/pdflib-9.1.x/dist/PDFlib/PDFlib-9.1.2p8-Alpine-Linux-x86_64-.NET-Core/bind/dotnetcore/csharp/hello/Properties/launchSettings.json...

Unhandled Exception: System.DllNotFoundException: Unable to load shared library 'PDFlib_dotnetcore_native' or one of its dependencies. In order to help diagnose loading problems, consider setting the LD_DEBUG environment variable: Error loading shared library libPDFlib_dotnetcore_native: No such file or directory
   at PDFlib_dotnet.PDFlib.PInvoke.PDF_new()
   at PDFlib_dotnet.PDFlib..ctor()
   at Hello.Main(String[] args) in /home/rjs/src/pdflib-9.1.x/dist/PDFlib/PDFlib-9.1.2p8-Alpine-Linux-x86_64-.NET-Core/bind/dotnetcore/csharp/hello/hello.cs:line 15

The minmal code to reproduce is:

using PDFlib_dotnet;
class Hello {
    static void Main(string[] args) {
        PDFlib p;
        p = new PDFlib();
    }
}

The Nuget package content is:

vmalpine64 (1)$ unzip -l ../../PDFlib_dotnet.1.2.8.nupkg
Archive:  ../../PDFlib_dotnet.1.2.8.nupkg
  Length      Date    Time    Name
---------  ---------- -----   ----
      503  11-06-2018 15:00   _rels/.rels
      748  11-06-2018 15:00   PDFlib_dotnet.nuspec
    35840  11-06-2018 14:00   lib/netstandard2.0/PDFlib_dotnet.dll
       36  10-22-2018 18:47   readme.txt
  8617128  11-06-2018 14:00   runtimes/alpine-x64/native/PDFlib_dotnetcore_native.so
      582  11-06-2018 15:00   [Content_Types].xml
      706  11-06-2018 15:00   package/services/metadata/core-properties/5c87229948e04d93aab4633ed8c7fcc5.psmdcp
 --------                     -------
  8655543                     7 files

I would expect that dotnet run finds the nativ library at runtimes/alpine-x64/native/PDFlib_dotnetcore_native.so in the nuget package.

When I check with strace where dotnet searches I find:

vmalpine64 (1)$ strace -f -o strace.txt dotnet run
Using launch settings from /home/rjs/src/pdflib-9.1.x/dist/PDFlib/PDFlib-9.1.2p8-Alpine-Linux-x86_64-.NET-Core/bind/dotnetcore/csharp/hello/Properties/launchSettings.json...

Unhandled Exception: System.DllNotFoundException: Unable to load shared library 'PDFlib_dotnetcore_native' or one of its dependencies. In order to help diagnose loading problems, consider setting the LD_DEBUG environment variable: Error loading shared library libPDFlib_dotnetcore_native: No such file or directory
   at PDFlib_dotnet.PDFlib.PInvoke.PDF_new()
   at PDFlib_dotnet.PDFlib..ctor()
   at Hello.Main(String[] args) in /home/rjs/src/pdflib-9.1.x/dist/PDFlib/PDFlib-9.1.2p8-Alpine-Linux-x86_64-.NET-Core/bind/dotnetcore/csharp/hello/hello.cs:line 7
vmalpine64 (1)$ grep dotnetcore_native strace.txt
dotnet/runtime#852 open("/home/rjs/dotnet/shared/Microsoft.NETCore.App/2.1.2/PDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/home/rjs/.nuget/packages/pdflib_dotnet/1.2.8/lib/netstandard2.0/PDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/lib/PDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/local/lib/PDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/lib/PDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/home/rjs/dotnet/shared/Microsoft.NETCore.App/2.1.2/libPDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/home/rjs/.nuget/packages/pdflib_dotnet/1.2.8/lib/netstandard2.0/libPDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/lib/libPDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/local/lib/libPDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/lib/libPDFlib_dotnetcore_native.so", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/home/rjs/dotnet/shared/Microsoft.NETCore.App/2.1.2/PDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/home/rjs/.nuget/packages/pdflib_dotnet/1.2.8/lib/netstandard2.0/PDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/lib/PDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/local/lib/PDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/lib/PDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/home/rjs/dotnet/shared/Microsoft.NETCore.App/2.1.2/libPDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/home/rjs/.nuget/packages/pdflib_dotnet/1.2.8/lib/netstandard2.0/libPDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/lib/libPDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/local/lib/libPDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
16906 open("/usr/lib/libPDFlib_dotnetcore_native", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)

On Alpine-Linux donet run only looks in the “/home/rjs/.nuget/packages/pdflib_dotnet/1.2.8/lib/netstandard2.0/” directory, not int the “runtimes/alpine-x64/native/” directory.

The dotnet version is:

vmalpine64 (1)$  dotnet --version
2.1.400

I also tested it with the 2.1.403 version.

Alpine LInux is:

vmalpine64 (1)$ uname -a
Linux vmalpine64 4.14.69-0-vanilla dotnet/coreclr#1-Alpine SMP Mon Sep 10 19:33:23 UTC 2018 x86_64 Linux
vmalpine64 (1)$ cat /etc/alpine-release
3.8.1

On macOS or Ubuntu it is working as expected.

Copied from original issue: dotnet/corefx#33409