Utilities: Add fdtdump for dumping OpenFirmware Device Trees

Use the new LibDeviceTree to dump the contents of the device tree blob
(Flattened Device Tree) file passed on the command line.

2 files changed, 45 insertions, 0 deletions

diff --git a/Userland/Utilities/CMakeLists.txt b/Userland/Utilities/CMakeLists.txt
index cb95bc5391..a252b7c03d 100644
--- a/Userland/Utilities/CMakeLists.txt
+++ b/Userland/Utilities/CMakeLists.txt
@@ -62,6 +62,7 @@ target_link_libraries(copy LibGUI)
 target_link_libraries(diff LibDiff)
 target_link_libraries(disasm LibX86)
 target_link_libraries(expr LibRegex)
+target_link_libraries(fdtdump LibDeviceTree)
 target_link_libraries(file LibGfx LibIPC LibCompress)
 target_link_libraries(functrace LibDebug LibX86)
 target_link_libraries(gml-format LibGUI)
diff --git a/Userland/Utilities/fdtdump.cpp b/Userland/Utilities/fdtdump.cpp
new file mode 100644
index 0000000000..bc59de5543
--- /dev/null
+++ b/Userland/Utilities/fdtdump.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2021, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/MappedFile.h>
+#include <AK/String.h>
+#include <LibCore/ArgsParser.h>
+#include <LibDeviceTree/Validation.h>
+#include <serenity.h>
+
+int main(int argc, char* argv[])
+{
+    if (pledge("stdio rpath", nullptr) < 0) {
+        perror("pledge");
+        return 1;
+    }
+
+    String filename;
+
+    Core::ArgsParser args;
+    args.add_positional_argument(filename, "File to process", "file", Core::ArgsParser::Required::Yes);
+    args.parse(argc, argv);
+
+    // FIXME: Figure out how to do this sanely from stdin
+    auto maybe_file = MappedFile::map(filename);
+    if (maybe_file.is_error()) {
+        warnln("Unable to dump device tree from file {}: {}", filename, maybe_file.error().string());
+        return 1;
+    }
+    auto file = maybe_file.release_value();
+
+    if (file->size() < sizeof(DeviceTree::FlattenedDeviceTreeHeader)) {
+        warnln("Not enough data in {} to contain a device tree header!", filename);
+        return 1;
+    }
+
+    auto* fdt_header = reinterpret_cast<DeviceTree::FlattenedDeviceTreeHeader const*>(file->data());
+
+    bool valid = DeviceTree::dump(*fdt_header, static_cast<u8 const*>(file->data()), file->size());
+
+    return valid ? 0 : 1;
+}