CrashDaemon: Add service that acts on new coredumps

Currently we only print a backtrace. In the future, we could do something nice in the GUI.

Applications/CMakeLists.txt

@@ -2,6 +2,7 @@ add_subdirectory(About)
 add_subdirectory(Browser)
 add_subdirectory(Calculator)
 add_subdirectory(Calendar)
+add_subdirectory(CrashDaemon)
 add_subdirectory(Debugger)
 add_subdirectory(DisplaySettings)
 add_subdirectory(FileManager)

Applications/CrashDaemon/CMakeLists.txt

@@ -0,0 +1,6 @@
+set(SOURCES
+    main.cpp
+)
+
+serenity_bin(CrashDaemon)
+target_link_libraries(CrashDaemon LibC LibCore LibCoreDump)

Applications/CrashDaemon/main.cpp

@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * 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/Assertions.h>
+#include <AK/LogStream.h>
+#include <AK/ScopeGuard.h>
+#include <LibCore/DirectoryWatcher.h>
+#include <LibCoreDump/CoreDumpReader.h>
+#include <LibELF/Loader.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <time.h>
+#include <unistd.h>
+
+static void wait_until_coredump_is_ready(const String& coredump_path)
+{
+    while (true) {
+        struct stat statbuf;
+        if (stat(coredump_path.characters(), &statbuf) < 0) {
+            perror("stat");
+            ASSERT_NOT_REACHED();
+        }
+        if (statbuf.st_mode & 0400) // Check if readable
+            break;
+
+        usleep(10000); // sleep for 10ms
+    }
+}
+
+static String object_name(StringView memory_region_name)
+{
+    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();
+}
+
+static String symbolicate(FlatPtr eip, const ELF::Core::MemoryRegionInfo* region)
+{
+    StringView region_name { region->region_name };
+
+    auto name = object_name(region_name);
+
+    String path;
+    if (name.contains(".so"))
+        path = String::format("/usr/lib/%s", name.characters());
+    else {
+        path = name;
+    }
+
+    struct stat st;
+    if (stat(path.characters(), &st)) {
+        return {};
+    }
+
+    auto mapped_file = make<MappedFile>(path);
+    if (!mapped_file->is_valid())
+        return {};
+
+    auto loader = ELF::Loader::create((const u8*)mapped_file->data(), mapped_file->size());
+    return loader->symbolicate(eip - region->region_start);
+}
+
+static String backtrace_line(const CoreDumpReader& coredump, FlatPtr eip)
+{
+    auto* region = coredump.region_containing((FlatPtr)eip);
+    if (!region) {
+        return String::format("%p: ???", eip);
+    }
+
+    StringView region_name { region->region_name };
+    if (region_name.contains("Loader.so"))
+        return {};
+
+    auto func_name = symbolicate(eip, region);
+
+    return String::format("%p: [%s] %s", eip, object_name(region_name).characters(), func_name.is_null() ? "???" : func_name.characters());
+}
+
+static void backtrace(const String& coredump_path)
+{
+    size_t thread_index = 0;
+    auto coredump = CoreDumpReader::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;
+    });
+}
+
+int main()
+{
+    static constexpr const char* coredumps_dir = "/tmp/coredump";
+    mkdir(coredumps_dir, 0777);
+    Core::DirectoryWatcher watcher { coredumps_dir };
+    while (true) {
+        auto event = watcher.wait_for_event();
+        ASSERT(event.has_value());
+        if (event.value().type != Core::DirectoryWatcher::Event::Type::ChildAdded)
+            continue;
+        auto coredump_path = event.value().child_path;
+        dbgln("New coredump file: {}", coredump_path);
+
+        wait_until_coredump_is_ready(coredump_path);
+
+        backtrace(coredump_path);
+    }
+}

Base/etc/SystemServer.ini

@@ -157,3 +157,8 @@ Lazy=1
 User=anon
 MultiInstance=1
 AcceptSocketConnections=1
+
+[CrashDaemon]
+Executable=/bin/CrashDaemon
+KeepAlive=1
+User=anon