LibCoredump: Respect coredump's LD_LIBRARY_PATH when searching libraries

Previously, we would only resolve libraries from `/usr/lib`, which is
not the only path from which the crashed process could've loaded the
libraries from.

Userland/Libraries/LibCoredump/Backtrace.cpp

@@ -17,11 +17,9 @@
 
 namespace Coredump {
 
-ELFObjectInfo const* Backtrace::object_info_for_region(MemoryRegionInfo const& region)
+ELFObjectInfo const* Backtrace::object_info_for_region(Reader const& coredump, MemoryRegionInfo const& region)
 {
- String path = region.object_name();
- if (!path.starts_with('/') && Core::File::looks_like_shared_library(path))
- path = LexicalPath::join("/usr/lib", path).string();
+ String path = coredump.resolve_object_path(region.object_name());
 
  auto maybe_ptr = m_debug_info_cache.get(path);
  if (maybe_ptr.has_value())
@@ -116,7 +114,7 @@ void Backtrace::add_entry(const Reader& coredump, FlatPtr ip)
  // the PT_LOAD header for the .text segment isn't the first one
  // in the object file.
  auto region = coredump.first_region_for_object(object_name);
- auto object_info = object_info_for_region(*region);
+ auto object_info = object_info_for_region(coredump, *region);
  if (!object_info) {
  m_entries.append({ ip, object_name, {}, {} });
  return;

Userland/Libraries/LibCoredump/Backtrace.h

@@ -45,7 +45,7 @@ class Backtrace {
 
 private:
  void add_entry(const Reader&, FlatPtr ip);
- ELFObjectInfo const* object_info_for_region(MemoryRegionInfo const&);
+ ELFObjectInfo const* object_info_for_region(Reader const&, MemoryRegionInfo const&);
 
  bool m_skip_loader_so { false };
  ELF::Core::ThreadInfo m_thread_info;

Userland/Libraries/LibCoredump/Reader.cpp

@@ -8,11 +8,13 @@
 #include <AK/HashTable.h>
 #include <AK/JsonObject.h>
 #include <AK/JsonValue.h>
+#include <AK/LexicalPath.h>
 #include <LibCompress/Gzip.h>
 #include <LibCore/File.h>
 #include <LibCoredump/Reader.h>
 #include <signal_numbers.h>
 #include <string.h>
+#include <unistd.h>
 
 namespace Coredump {
 
@@ -277,13 +279,7 @@ const Reader::LibraryData* Reader::library_containing(FlatPtr address) const
  return {};
 
  auto name = region->object_name();
-
- String path;
- if (Core::File::looks_like_shared_library(name))
- path = String::formatted("/usr/lib/{}", name);
- else {
- path = name;
- }
+ String path = resolve_object_path(name);
 
  if (!cached_libs.contains(path)) {
  auto file_or_error = Core::MappedFile::map(path);
@@ -297,6 +293,48 @@ const Reader::LibraryData* Reader::library_containing(FlatPtr address) const
  return lib_data;
 }
 
+String Reader::resolve_object_path(StringView name) const
+{
+ // TODO: There are other places where similar method is implemented or would be useful.
+ // (e.g. UserspaceEmulator, LibSymbolication, Profiler, and DynamicLinker itself)
+ // We should consider creating unified implementation in the future.
+
+ if (name.starts_with('/') || !Core::File::looks_like_shared_library(name)) {
+ return name;
+ }
+
+ Vector<String> library_search_directories;
+
+ // If LD_LIBRARY_PATH is present, check its folders first
+ for (auto& environment_variable : process_environment()) {
+ auto prefix = "LD_LIBRARY_PATH="sv;
+ if (environment_variable.starts_with(prefix)) {
+ auto ld_library_path = environment_variable.substring_view(prefix.length());
+
+ // FIXME: This code won't handle folders with ":" in the name correctly.
+ for (auto directory : ld_library_path.split_view(':')) {
+ library_search_directories.append(directory);
+ }
+ }
+ }
+
+ // Add default paths that DynamicLinker uses
+ library_search_directories.append("/usr/lib/"sv);
+ library_search_directories.append("/usr/local/lib/"sv);
+
+ // Search for the first readable library file
+ for (auto& directory : library_search_directories) {
+ auto full_path = LexicalPath::join(directory, name).string();
+
+ if (access(full_path.characters(), R_OK) != 0)
+ continue;
+
+ return full_path;
+ }
+
+ return name;
+}
+
 void Reader::for_each_library(Function<void(LibraryInfo)> func) const
 {
  HashTable<String> libraries;
@@ -307,12 +345,7 @@ void Reader::for_each_library(Function<void(LibraryInfo)> func) const
 
  libraries.set(name);
 
- String path;
- if (Core::File::looks_like_shared_library(name))
- path = String::formatted("/usr/lib/{}", name);
- else {
- path = name;
- }
+ String path = resolve_object_path(name);
 
  func(LibraryInfo { name, path, static_cast<FlatPtr>(region.region_start) });
  return IterationDecision::Continue;

Userland/Libraries/LibCoredump/Reader.h

@@ -70,6 +70,8 @@ class Reader {
  };
  const LibraryData* library_containing(FlatPtr address) const;
 
+ String resolve_object_path(StringView object_name) const;
+
  int process_pid() const;
  u8 process_termination_signal() const;
  String process_executable_path() const;