Resolve binary symlinks before finding its separate .debug file

I have found LLDB cannot find separate debug info of Fedora /usr/bin/gdb.
It is because:

lrwxrwxrwx 1 root root       14 Jan 25 20:41 /usr/bin/gdb -> ../libexec/gdb*
-rwxr-xr-x 1 root root 10180296 Jan 25 20:41 /usr/libexec/gdb*
ls: cannot access '/usr/lib/debug/usr/bin/gdb-8.0.1-35.fc27.x86_64.debug': No such file or directory
-r--r--r-- 1 root root 29200464 Jan 25 20:41 /usr/lib/debug/usr/libexec/gdb-8.0.1-35.fc27.x86_64.debug

FYI that -8.0.1-35.fc27.x86_64.debug may look confusing, it was always just
.debug before.
Why is /usr/bin/gdb a symlink is offtopic for this bugreport, Fedora has it so
for some reasons.

It is always safest to look at the .debug file only after resolving all
symlinks on the binary file.

Differential revision: https://reviews.llvm.org/D42853

llvm-svn: 324224

4 files changed, 52 insertions, 2 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/Makefile b/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/Makefile
new file mode 100644
index 00000000000..3fd14a74bf3
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/Makefile
@@ -0,0 +1,20 @@
+LEVEL = ../../make
+C_SOURCES := main.c
+
+all: dirsymlink
+
+dirreal: a.out
+	$(RM) -r $@
+	mkdir $@
+	$(OBJCOPY) --only-keep-debug $< $@/stripped.debug
+	$(OBJCOPY) --strip-all --add-gnu-debuglink=$@/stripped.debug $< $@/stripped.out
+
+dirsymlink: dirreal
+	$(RM) -r $@
+	mkdir $@
+	ln -s ../$</stripped.out $@/stripped.symlink
+
+clean::
+	$(RM) -r dirreal dirsymlink
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/TestTargetSymbolsSepDebugSymlink.py b/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/TestTargetSymbolsSepDebugSymlink.py
new file mode 100644
index 00000000000..51866df48d3
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/TestTargetSymbolsSepDebugSymlink.py
@@ -0,0 +1,22 @@
+""" 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 TestTargetSymbolsSepDebugSymlink(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"])
+    def test_target_symbols_sepdebug_symlink_case(self):
+        self.build(clean=True)
+        exe = self.getBuildArtifact("dirsymlink/stripped.symlink")
+
+        lldbutil.run_to_name_breakpoint(self, "main", exe_name = exe)
diff --git a/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/main.c b/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/main.c
new file mode 100644
index 00000000000..4cce7f667ff
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/linux/sepdebugsymlink/main.c
@@ -0,0 +1,3 @@
+int main() {
+  return 0;
+}
diff --git a/lldb/source/Host/common/Symbols.cpp b/lldb/source/Host/common/Symbols.cpp
index 3f7afab794b..0bbee7adf8e 100644
--- a/lldb/source/Host/common/Symbols.cpp
+++ b/lldb/source/Host/common/Symbols.cpp
@@ -9,6 +9,7 @@
 
 #include "lldb/Host/Symbols.h"
 #include "lldb/Core/ModuleSpec.h"
+#include "lldb/Host/FileSystem.h"
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Utility/ArchSpec.h"
@@ -221,7 +222,11 @@ FileSpec Symbols::LocateExecutableSymbolFile(const ModuleSpec &module_spec) {
         Target::GetDefaultDebugFileSearchPaths());
 
     // Add module directory.
-    const ConstString &file_dir = module_spec.GetFileSpec().GetDirectory();
+    FileSpec module_file_spec = module_spec.GetFileSpec();
+    // We keep the unresolved pathname if it fails.
+    FileSystem::ResolveSymbolicLink(module_file_spec, module_file_spec);
+
+    const ConstString &file_dir = module_file_spec.GetDirectory();
     debug_file_search_paths.AppendIfUnique(
         FileSpec(file_dir.AsCString("."), true));
 
@@ -276,7 +281,7 @@ FileSpec Symbols::LocateExecutableSymbolFile(const ModuleSpec &module_spec) {
         FileSpec file_spec(filename, true);
 
         if (llvm::sys::fs::equivalent(file_spec.GetPath(),
-                                      module_spec.GetFileSpec().GetPath()))
+                                      module_file_spec.GetPath()))
           continue;
 
         if (file_spec.Exists()) {