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.

Applications/CrashDaemon/CMakeLists.txt

@@ -3,4 +3,4 @@ set(SOURCES
 )
 
 serenity_bin(CrashDaemon)
-target_link_libraries(CrashDaemon LibC LibCore LibCoreDump LibDebug)
+target_link_libraries(CrashDaemon LibC LibCore LibCoreDump)

Applications/CrashDaemon/main.cpp

@@ -24,18 +24,10 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <AK/Assertions.h>
-#include <AK/HashMap.h>
 #include <AK/LexicalPath.h>
-#include <AK/LogStream.h>
-#include <AK/ScopeGuard.h>
 #include <LibCore/DirectoryWatcher.h>
-#include <LibCore/File.h>
+#include <LibCoreDump/Backtrace.h>
 #include <LibCoreDump/Reader.h>
-#include <LibDebug/DebugInfo.h>
-#include <LibELF/Image.h>
-#include <fcntl.h>
-#include <stdio.h>
 #include <sys/stat.h>
 #include <time.h>
 #include <unistd.h>
@@ -55,107 +47,15 @@ static void wait_until_coredump_is_ready(const String& coredump_path)
     }
 }
 
-static String object_name(StringView memory_region_name)
+static void print_backtrace(const String& coredump_path)
 {
-    if (memory_region_name.contains("Loader.so"))
-        return "Loader.so";
-    if (!memory_region_name.contains(":"))
-        return {};
-    return memory_region_name.substring_view(0, memory_region_name.find_first_of(":").value()).to_string();
-}
-
-struct ElfObjectInfo {
-    ElfObjectInfo(MappedFile&& file, Debug::DebugInfo&& debug_info)
-        : file(move(file))
-        , debug_info(move(debug_info))
-    {
-    }
-
-    MappedFile file;
-    Debug::DebugInfo debug_info;
-};
-
-// 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 = object_name(region->region_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;
-}
-
-static String backtrace_line(const CoreDump::Reader& coredump, FlatPtr eip)
-{
-    auto* region = coredump.region_containing((FlatPtr)eip);
-    if (!region)
-        return String::format("%p: ???", eip);
-
-    if (StringView { region->region_name }.contains("Loader.so"))
-        return {};
-
-    auto* object_info = object_info_for_region(region);
-    if (!object_info)
-        return {};
-
-    auto func_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);
-
-    auto source_position_string = String::empty();
-    if (source_position.has_value())
-        source_position_string = String::format(" (\033[34;1m%s\033[0m:%u)", LexicalPath(source_position.value().file_path).basename().characters(), source_position.value().line_number);
-
-    return String::format("%p: [%s] %s%s", eip, object_name(region->region_name).characters(), func_name.is_null() ? "???" : func_name.characters(), source_position_string.characters());
-}
-
-static void backtrace(const String& coredump_path)
-{
-    size_t thread_index = 0;
     auto coredump = CoreDump::Reader::create(coredump_path);
-    coredump->for_each_thread_info([&thread_index, &coredump](const ELF::Core::ThreadInfo& thread_info) {
-        dbgln("Backtrace for thread #{}, tid={}", thread_index++, thread_info.tid);
-
-        uint32_t* ebp = (uint32_t*)thread_info.regs.ebp;
-        uint32_t* eip = (uint32_t*)thread_info.regs.eip;
-        while (ebp && eip) {
-
-            auto line = backtrace_line(*coredump, (FlatPtr)eip);
-            if (!line.is_null())
-                dbgprintf("%s\n", line.characters());
-            auto next_eip = coredump->peek_memory((FlatPtr)(ebp + 1));
-            auto next_ebp = coredump->peek_memory((FlatPtr)(ebp));
-            if (!next_ebp.has_value() || !next_eip.has_value()) {
-                break;
-            }
-
-            eip = (uint32_t*)next_eip.value();
-            ebp = (uint32_t*)next_ebp.value();
-        }
-
-        return IterationDecision::Continue;
-    });
+    if (!coredump) {
+        dbgln("Could not open coredump '{}'", coredump_path);
+        return;
+    }
+    for (auto& entry : coredump->backtrace().entries())
+        dbgln("{}", entry.to_string(true));
 }
 
 int main()
@@ -170,9 +70,7 @@ int main()
             continue;
         auto coredump_path = event.value().child_path;
         dbgln("New coredump file: {}", coredump_path);
-
         wait_until_coredump_is_ready(coredump_path);
-
-        backtrace(coredump_path);
+        print_backtrace(coredump_path);
     }
 }

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();
+}
+
+}

Libraries/LibCoreDump/Backtrace.h

@@ -0,0 +1,68 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <LibCoreDump/Reader.h>
+#include <LibDebug/DebugInfo.h>
+
+namespace CoreDump {
+
+struct ELFObjectInfo {
+    ELFObjectInfo(MappedFile&& file, Debug::DebugInfo&& debug_info)
+        : file(move(file))
+        , debug_info(move(debug_info))
+    {
+    }
+
+    MappedFile file;
+    Debug::DebugInfo debug_info;
+};
+
+class Backtrace {
+public:
+    struct Entry {
+        FlatPtr eip;
+        String object_name;
+        String function_name;
+        Optional<Debug::DebugInfo::SourcePosition> source_position;
+
+        String to_string(bool color = false) const;
+    };
+
+    Backtrace(const Reader&);
+    ~Backtrace();
+
+    const Vector<Entry> entries() const { return m_entries; }
+
+private:
+    void add_backtrace_entry(const Reader&, FlatPtr eip);
+
+    Vector<Entry> m_entries;
+};
+
+}

Libraries/LibCoreDump/CMakeLists.txt

@@ -1,6 +1,7 @@
 set(SOURCES
+    Backtrace.cpp
     Reader.cpp
 )
 
 serenity_lib(LibCoreDump coredump)
-target_link_libraries(LibCoreDump LibC LibCore)
+target_link_libraries(LibCoreDump LibC LibCore LibDebug)

Libraries/LibCoreDump/Forward.h

@@ -0,0 +1,34 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+namespace CoreDump {
+
+class Backtrace;
+class Reader;
+
+}

Libraries/LibCoreDump/Reader.cpp

@@ -24,7 +24,8 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "Reader.h"
+#include <LibCoreDump/Backtrace.h>
+#include <LibCoreDump/Reader.h>
 #include <string.h>
 
 namespace CoreDump {
@@ -120,4 +121,9 @@ const ELF::Core::MemoryRegionInfo* Reader::region_containing(FlatPtr address) co
     return ret;
 }
 
+Backtrace Reader::backtrace() const
+{
+    return Backtrace(*this);
+}
+
 }

Libraries/LibCoreDump/Reader.h

@@ -29,6 +29,7 @@
 #include <AK/MappedFile.h>
 #include <AK/Noncopyable.h>
 #include <AK/OwnPtr.h>
+#include <LibCoreDump/Forward.h>
 #include <LibELF/CoreDump.h>
 #include <LibELF/Image.h>
 
@@ -54,6 +55,8 @@ public:
     Optional<uint32_t> peek_memory(FlatPtr address) const;
     const ELF::Core::MemoryRegionInfo* region_containing(FlatPtr address) const;
 
+    Backtrace backtrace() const;
+
 private:
     class NotesEntryIterator {
     public: