Kernel: Create /proc/pid/cmdline to expose process arguments in procfs

In typical serenity style, they are just a JSON array

5 files changed, 17 insertions, 0 deletions

diff --git a/Kernel/FileSystem/ProcFS.cpp b/Kernel/FileSystem/ProcFS.cpp
index aa44b2b849..b0af6ae9d2 100644
--- a/Kernel/FileSystem/ProcFS.cpp
+++ b/Kernel/FileSystem/ProcFS.cpp
@@ -311,6 +311,8 @@ ErrorOr<NonnullRefPtr<Inode>> ProcFSProcessDirectoryInode::lookup(StringView nam
         return TRY(ProcFSProcessPropertyInode::try_create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::PerformanceEvents, associated_pid()));
     if (name == "vm"sv)
         return TRY(ProcFSProcessPropertyInode::try_create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::VirtualMemoryStats, associated_pid()));
+    if (name == "cmdline"sv)
+        return TRY(ProcFSProcessPropertyInode::try_create_for_pid_property(procfs(), SegmentedProcFSIndex::MainProcessProperty::CommandLine, associated_pid()));
     return ENOENT;
 }
 
@@ -571,6 +573,8 @@ ErrorOr<void> ProcFSProcessPropertyInode::try_to_acquire_data(Process& process,
         return process.procfs_get_perf_events(builder);
     case SegmentedProcFSIndex::MainProcessProperty::VirtualMemoryStats:
         return process.procfs_get_virtual_memory_stats(builder);
+    case SegmentedProcFSIndex::MainProcessProperty::CommandLine:
+        return process.procfs_get_command_line(builder);
     default:
         VERIFY_NOT_REACHED();
     }
diff --git a/Kernel/Process.h b/Kernel/Process.h
index 3302f90a8f..686c39ec00 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -585,6 +585,7 @@ public:
     ErrorOr<void> procfs_get_virtual_memory_stats(KBufferBuilder& builder) const;
     ErrorOr<void> procfs_get_binary_link(KBufferBuilder& builder) const;
     ErrorOr<void> procfs_get_current_work_directory_link(KBufferBuilder& builder) const;
+    ErrorOr<void> procfs_get_command_line(KBufferBuilder& builder) const;
     mode_t binary_link_required_mode() const;
     ErrorOr<void> procfs_get_thread_stack(ThreadID thread_id, KBufferBuilder& builder) const;
     ErrorOr<void> traverse_stacks_directory(FileSystemID, Function<ErrorOr<void>(FileSystem::DirectoryEntryView const&)> callback) const;
diff --git a/Kernel/ProcessExposed.h b/Kernel/ProcessExposed.h
index 5f8248e75a..5a15725c56 100644
--- a/Kernel/ProcessExposed.h
+++ b/Kernel/ProcessExposed.h
@@ -30,6 +30,7 @@ enum class MainProcessProperty {
     CurrentWorkDirectoryLink = 5,
     PerformanceEvents = 6,
     VirtualMemoryStats = 7,
+    CommandLine = 8,
 };
 
 enum class ProcessSubDirectory {
diff --git a/Kernel/ProcessProcFSTraits.cpp b/Kernel/ProcessProcFSTraits.cpp
index 45ff810d90..8776a444f9 100644
--- a/Kernel/ProcessProcFSTraits.cpp
+++ b/Kernel/ProcessProcFSTraits.cpp
@@ -63,6 +63,7 @@ ErrorOr<void> Process::ProcessProcFSTraits::traverse_as_directory(FileSystemID f
     TRY(callback({ "cwd", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(process->pid(), SegmentedProcFSIndex::MainProcessProperty::CurrentWorkDirectoryLink) }, DT_LNK }));
     TRY(callback({ "perf_events", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(process->pid(), SegmentedProcFSIndex::MainProcessProperty::PerformanceEvents) }, DT_REG }));
     TRY(callback({ "vm", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(process->pid(), SegmentedProcFSIndex::MainProcessProperty::VirtualMemoryStats) }, DT_REG }));
+    TRY(callback({ "cmdline", { fsid, SegmentedProcFSIndex::build_segmented_index_for_main_property_in_pid_directory(process->pid(), SegmentedProcFSIndex::MainProcessProperty::CommandLine) }, DT_REG }));
     return {};
 }
 
diff --git a/Kernel/ProcessSpecificExposed.cpp b/Kernel/ProcessSpecificExposed.cpp
index 5f9c9399d4..d4fd0eff8c 100644
--- a/Kernel/ProcessSpecificExposed.cpp
+++ b/Kernel/ProcessSpecificExposed.cpp
@@ -314,6 +314,16 @@ ErrorOr<void> Process::procfs_get_current_work_directory_link(KBufferBuilder& bu
     return builder.append(TRY(const_cast<Process&>(*this).current_directory()->try_serialize_absolute_path())->view());
 }
 
+ErrorOr<void> Process::procfs_get_command_line(KBufferBuilder& builder) const
+{
+    auto array = TRY(JsonArraySerializer<>::try_create(builder));
+    for (auto const& arg : arguments()) {
+        TRY(array.add(arg.view()));
+    }
+    TRY(array.finish());
+    return {};
+}
+
 mode_t Process::binary_link_required_mode() const
 {
     if (!executable())