[lldb] DWZ 17/17: Fix symlinked /usr/lib/debug/.build-id/**.debug files

[jankratochvil]

Summary

LLDB could not find DWZ common files due to their relative symbolic link.

[jankratochvil]

My question about upstreaming of this patchset.

[jankratochvil]

I will be no longer involved with this patchset.

lldb/packages/Python/lldbsuite/test/decorators.py

 from __future__ import absolute_import
 
 # System modules
 from distutils.version import LooseVersion
 from functools import wraps
 import ctypes
 import locale
 import os
 import platform
 import re
 import sys
 import tempfile
 import subprocess
+import distutils.spawn
 
 # Third-party modules
 import six
 import unittest2
 
 # LLDB modules
 import lldb
 from . import configuration
def is_feature_enabled(self):
                 return "%s is not supported on this system." % feature
     return skipTestIfFn(is_feature_enabled)
 
 def skipIfReproducer(func):
     """Skip this test if the environment is set up to run LLDB with reproducers."""
     return unittest2.skipIf(
         configuration.capture_path or configuration.replay_path,
         "reproducers unsupported")(func)
+
+def skipUnlessDWZInstalled(func):
+    """Decorate the item to skip tests when no DWZ optimization tool is available.
+       /usr/lib/rpm/sepdebugcrcfix is not tested here but it may be needed
+       when build-ids cannot be used."""
+
+    def is_dwz_missing(self):
+        if distutils.spawn.find_executable("dwz") is None:
+            return "skipping because dwz is not found"
+        # dwz has a bug it can process only separate debug info files.
+        # Moreover dwz is compatible only with debug infos created by eu-strip.
+        if distutils.spawn.find_executable("eu-strip") is None:
+            return "skipping because eu-strip is not found"
+        return None
+    return skipTestIfFn(is_dwz_missing)(func)

lldb/packages/Python/lldbsuite/test/linux/buildidsymlink/Makefile

+LEVEL = ../../make
+C_SOURCES := main.c
+LD_EXTRAS += -Wl,--build-id=sha1
+
+all: .build-id
+
+.PHONY: .build-id
+stripped.out stripped.debug stripped.debug.dwz: a.out
+  eu-strip --remove-comment -f stripped.debug -F stripped.debugx -o stripped.out $<
+  cp -p stripped.debug stripped.debug.dup
+  dwz -m stripped.debug.dwz stripped.debug stripped.debug.dup
+
+.build-id: stripped.debug
+  $(OBJCOPY) -j .note.gnu.build-id -O binary $< tmp
+  rm -rf .build-id
+  fn=`od -An -tx1 <tmp|tr -d ' \n'|sed -e 's/^.\{32\}//' -e 's#^..#.build-id/&/#' -e 's#$$#.debug#'` && \
+  mkdir -p `dirname $$fn` && \
+  ln -s ../../$< $$fn
+  $(RM) tmp
+
+clean::
+  $(RM) -r stripped.out .build-id stripped.debug stripped.debug.dup stripped.debug.dwz
+
+include $(LEVEL)/Makefile.rules

lldb/packages/Python/lldbsuite/test/linux/buildidsymlink/TestTargetSymbolsBuildidSymlink.py

+""" Testing separate debug info loading for base binary with a symlink. """
+import os
+import time
+import lldb
+import sys
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestTargetSymbolsBuildidSymlink(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    @no_debug_info_test  # Prevent the genaration of the dwarf version of this test
+    @skipUnlessPlatform(['linux'])
+    @skipIf(hostoslist=["windows"])
+    @skipIfRemote # llvm.org/pr36237
+    @skipUnlessDWZInstalled
+    def test_target_symbols_buildid_symlink(self):
+        self.build()
+        exe = self.getBuildArtifact("stripped.out")
+
+        lldbutil.run_to_name_breakpoint(self, "main", exe_name = exe)

lldb/packages/Python/lldbsuite/test/linux/buildidsymlink/main.c

+struct s {
+  int i1, i2, i3, i4, i5, i6, i7, i8, i9;
+} v;
+int main() { return 0; }

lldb/source/Symbol/LocateSymbolFile.cpp

for (size_t idx = 0; idx < num_directories; ++idx) {
     for (size_t idx_file = 0; idx_file < num_files; ++idx_file) {
       const std::string &filename = files[idx_file];
       FileSpec file_spec(filename);
       FileSystem::Instance().Resolve(file_spec);
 
       if (llvm::sys::fs::equivalent(file_spec.GetPath(),
                                     module_file_spec.GetPath()))
         continue;
+      if (FileSystem::Instance()
+              .ResolveSymbolicLink(file_spec, file_spec)
+              .Fail())
+        continue;
 
       if (FileSystem::Instance().Exists(file_spec)) {
         lldb_private::ModuleSpecList specs;
         const size_t num_specs =
             ObjectFile::GetModuleSpecifications(file_spec, 0, 0, specs);
         assert(num_specs <= 1 &&
                "Symbol Vendor supports only a single architecture");
         if (num_specs == 1) {