LibCoreDump+CrashDaemon: Add and use CoreDump::Backtrace

Creating a backtrace from a crashdump already existed as a few
standalone functions in CrashDaemon. This patch refactors the code
required for this to make it generally usable and moves it to
CoreDump::Backtrace, which provides both raw data as well as
stringification.

Libraries/LibCoreDump/Backtrace.cpp

@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2020, Linus Groh <mail@linusgroh.de>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/LexicalPath.h>
+#include <AK/MappedFile.h>
+#include <AK/StringBuilder.h>
+#include <AK/Types.h>
+#include <LibCore/File.h>
+#include <LibCoreDump/Backtrace.h>
+#include <LibCoreDump/Reader.h>
+#include <LibELF/CoreDump.h>
+#include <LibELF/Image.h>
+
+namespace CoreDump {
+
+// FIXME: This cache has to be invalidated when libraries/programs are re-compiled.
+// We can store the last-modified timestamp of the elf files in ELFObjectInfo to invalidate cache entries.
+static HashMap<String, NonnullOwnPtr<ELFObjectInfo>> s_debug_info_cache;
+
+static const ELFObjectInfo* object_info_for_region(const ELF::Core::MemoryRegionInfo& region)
+{
+    auto name = region.object_name();
+
+    String path;
+    if (name.contains(".so"))
+        path = String::formatted("/usr/lib/{}", name);
+    else {
+        path = name;
+    }
+
+    if (auto it = s_debug_info_cache.find(path); it != s_debug_info_cache.end())
+        return it->value.ptr();
+
+    if (!Core::File::exists(path.characters()))
+        return nullptr;
+
+    MappedFile object_file(path);
+    if (!object_file.is_valid())
+        return nullptr;
+
+    auto info = make<ELFObjectInfo>(move(object_file), Debug::DebugInfo { make<ELF::Image>((const u8*)object_file.data(), object_file.size()) });
+    auto* info_ptr = info.ptr();
+    s_debug_info_cache.set(path, move(info));
+    return info_ptr;
+}
+
+Backtrace::Backtrace(const Reader& coredump)
+{
+    coredump.for_each_thread_info([this, &coredump](const ELF::Core::ThreadInfo& thread_info) {
+        uint32_t* ebp = (uint32_t*)thread_info.regs.ebp;
+        uint32_t* eip = (uint32_t*)thread_info.regs.eip;
+        while (ebp && eip) {
+            add_backtrace_entry(coredump, (FlatPtr)eip);
+            auto next_eip = coredump.peek_memory((FlatPtr)(ebp + 1));
+            auto next_ebp = coredump.peek_memory((FlatPtr)(ebp));
+            if (!next_eip.has_value() || !next_ebp.has_value())
+                break;
+            eip = (uint32_t*)next_eip.value();
+            ebp = (uint32_t*)next_ebp.value();
+        }
+        return IterationDecision::Continue;
+    });
+}
+
+Backtrace::~Backtrace()
+{
+}
+
+void Backtrace::add_backtrace_entry(const Reader& coredump, FlatPtr eip)
+{
+    auto* region = coredump.region_containing((FlatPtr)eip);
+    if (!region) {
+        m_entries.append({ eip, {}, {}, {} });
+        return;
+    }
+    auto object_name = region->object_name();
+    if (object_name == "Loader.so")
+        return;
+    auto* object_info = object_info_for_region(*region);
+    if (!object_info)
+        return;
+    auto function_name = object_info->debug_info.elf().symbolicate(eip - region->region_start);
+    auto source_position = object_info->debug_info.get_source_position(eip - region->region_start);
+    m_entries.append({ eip, object_name, function_name, source_position });
+}
+
+String Backtrace::Entry::to_string(bool color) const
+{
+    StringBuilder builder;
+    builder.appendff("{:p}: ", eip);
+    if (object_name.is_empty()) {
+        builder.append("???");
+        return builder.build();
+    }
+    builder.appendff("[{}] {}", object_name, function_name.is_empty() ? "???" : function_name);
+    if (source_position.has_value()) {
+        auto& source_position = this->source_position.value();
+        auto fmt = color ? " (\033[34;1m{}\033[0m:{})" : " ({}:{})";
+        builder.appendff(fmt, LexicalPath(source_position.file_path).basename(), source_position.line_number);
+    }
+    return builder.build();
+}
+
+}