.config with dllmap not working with app domains with shadow copying enabled

[chmorgan]

I'm trying to run nunit tests in Tests.dll against PacketDotNet.dll (which uses SharpPcap.dll). It's SharpPcap.dll that uses dllmap to map from wpcap to libpcap on Linux (and I guess Mac, I'm new to Mac and haven't tried).

On Linux this used to work great but something changes and it stopped working. From the debug output it looks like the SharpPcap.dll.config file isn't being honored.

Steps to Reproduce

1. Clone https://github.com/chmorgan/packetnet/tree/net_test_2
2. Build project
3. cd Test/bin/Release
4. mono /usr/lib/mono/4.5/nunit-console.exe Test.dll
5. Failure to find wpcap (should be mapped to libpcap.so by SharpPcap.dll.config file)

Directory content

$ ls
icmpv6.dat   nunit.framework.dll  PacketDotNet.pdb  SharpPcap.dll.config  Test.dll      Test.pdb
log4net.dll  PacketDotNet.dll     SharpPcap.dll     SharpPcap.xml         Test.dll.mdb  TestResult.xml

Current Behavior

$ ls /usr/lib64/libpcap*
/usr/lib64/libpcap.so.1  /usr/lib64/libpcap.so.1.8.1

ldconfig showing that pcap is found:

$ ldconfig -v |grep pcap
ldconfig: Can't stat /libx32: No such file or directory
ldconfig: Path `/usr/lib' given more than once
ldconfig: Path `/usr/lib64' given more than once
ldconfig: Can't stat /usr/libx32: No such file or directory
	libpcap.so.1 -> libpcap.so.1.8.1
ldconfig: Can't create temporary cache file /etc/ld.so.cache~: Permission denied

SharpPcap.dll.config:

<configuration>
  <dllmap dll="wpcap" target="libpcap.so.1" />
</configuration>

Mono version:

$ mono --version
Mono JIT compiler version 5.10.0.140 (tarball Sat Feb 24 14:02:40 UTC 2018)
Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com
	TLS:           __thread
	SIGSEGV:       altstack
	Notifications: epoll
	Architecture:  amd64
	Disabled:      none
	Misc:          softdebug 
	Interpreter:   yes
	LLVM:          supported, not enabled.
	GC:            sgen (concurrent by default)

Console output with debugging enabled:

...
.Mono: DllImport attempting to load: 'wpcap'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap': '/usr/lib/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap.so': '/usr/lib/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap': 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap.so': 'libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'wpcap': 'wpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap': '/usr/lib/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap.so': '/usr/lib/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap': 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap.so': 'libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap': 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport unable to load library 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport attempting to load: 'wpcap'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap': '/usr/lib/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap.so': '/usr/lib/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap': 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap.so': 'libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'wpcap': 'wpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so': '/tmp/nunit20/ShadowCopyCache/8987_636548417038525610/Tests/assembly/shadow/1d20b042/551adf96_483a6fd4_00000001/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap': '/usr/lib/libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library '/usr/lib/libwpcap.so': '/usr/lib/libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap': 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap.so': 'libwpcap.so: cannot open shared object file: No such file or directory'.
Mono: DllImport error loading library 'libwpcap': 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport unable to load library 'libwpcap: cannot open shared object file: No such file or directory'.
Mono: DllImport attempting to load: '__Internal'.
Mono: DllImport loaded library '(null)'.
Mono: DllImport searching in: '__Internal' ('(null)').
Mono: Searching for 'SetDllDirectory'.
Mono: Probing 'SetDllDirectory'.
Mono: Could not find 'SetDllDirectory' due to 'mono: undefined symbol: SetDllDirectory'.
Mono: Probing 'SetDllDirectory'.
Mono: Could not find 'SetDllDirectory' due to 'mono: undefined symbol: SetDllDirectory'.
Mono: Probing 'SetDllDirectoryA'.
Mono: Could not find 'SetDllDirectoryA' due to 'mono: undefined symbol: SetDllDirectoryA'.
Mono: Probing 'SetDllDirectoryA'.
Mono: Could not find 'SetDllDirectoryA' due to 'mono: undefined symbol: SetDllDirectoryA'.
F.F.F.F.F..F.Loading the sample capture file

[luhenry]

/cc @lambdageek

[marek-safar]

@lambdageek is this a regression?

[lambdageek]

Doesn't seem to pick up the .dll.config on OSX either. Going to try some older mono versions and after that some nunit flags (theory: it's an appdomains thing).

[lambdageek]

Works with mono 4.8.1 (mono-4.8.0-branch/22a39d7)

[lambdageek]

Yep, the issue seems to be related to shadow copying for app domains. Running NUnit with shadow copying disabled, we pick up the .dll.config and look for libpcap as expected:

mono .../nunit-console.exe -noshadow Test.dll

[lambdageek]

LOL. Mutating the same string over and over is... not a great strategy...

With some printfs in shadow_copy_sibling

shadow copying probing for file src bin/Debug/Test.dll.mdb
shadow copying did not find src bin/Debug/Test.dll.mdb
shadow copying probing for file src bin/Debug/Test.pdb
shadow copying found src, target is /var/folders/xj/lznyzvqx45j_qy49h8f09ld80000gn/T/nunit20/ShadowCopyCache/78677_636555118849448020/Tests/assembly/shadow/bf6e7da8/981b5f22_2775228a_00000001/Test.pdb
shadow copying dest copy result is true
shadow copying probing for file src bin/Debug/Test.pdb.config
shadow copying did not find src bin/Debug/Test.pdb.config

that Test.pdb.config is... not right

[chmorgan]

Thanks for taking a look at this bug report and fixing the issue!