Kernel: Add KParams class for accessing kernel cmdline parameters (#188)

Author: https://github.com/deoxxa
Commit: https://github.com/SerenityOS/serenity/commit/738f9de9a9e
Pull-request: https://github.com/SerenityOS/serenity/pull/188
Reviewed-by: https://github.com/awesomekling

Kernel/KParams.cpp

@@ -0,0 +1,34 @@
+#include <Kernel/KParams.h>
+
+static KParams* s_the;
+
+KParams& KParams::the()
+{
+    return *s_the;
+}
+
+KParams::KParams(const String& cmdline)
+    : m_cmdline(cmdline)
+{
+    s_the = this;
+
+    for (auto str : m_cmdline.split(' ')) {
+        auto pair = str.split_limit('=', 2);
+
+        if (pair.size() == 1) {
+            m_params.set(pair[0], "");
+        } else {
+            m_params.set(pair[0], pair[1]);
+        }
+    }
+}
+
+String KParams::get(const String& key) const
+{
+    return m_params.get(key);
+}
+
+bool KParams::has(const String& key) const
+{
+    return m_params.contains(key);
+}

Kernel/KParams.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include <AK/AKString.h>
+#include <AK/HashMap.h>
+
+class KParams {
+    AK_MAKE_ETERNAL
+public:
+    static KParams& the();
+
+    KParams(const String& cmdline);
+
+    const String& cmdline() const { return m_cmdline; }
+    String get(const String& key) const;
+    bool has(const String& key) const;
+private:
+    String m_cmdline;
+    HashMap<String, String> m_params;
+};

Kernel/Makefile

@@ -32,6 +32,7 @@ KERNEL_OBJS = \
        Scheduler.o \
        DoubleBuffer.o \
        KSyms.o \
+       KParams.o \
        SharedMemory.o \
        FileSystem/DevPtsFS.o \
        Devices/BXVGADevice.o \

Kernel/grub.cfg

@@ -2,5 +2,5 @@ timeout=0
 
 menuentry 'Serenity' {
   root=hd0,1
-  multiboot /boot/kernel Hello from grub!
+  multiboot /boot/kernel root=hd0,1
 }

Kernel/init.cpp

@@ -28,6 +28,7 @@
 #include <Kernel/Net/NetworkTask.h>
 #include <Kernel/Devices/DebugLogDevice.h>
 #include <Kernel/Multiboot.h>
+#include <Kernel/KParams.h>
 
 //#define STRESS_TEST_SPAWNING
 
@@ -123,13 +124,14 @@ multiboot_info_t* multiboot_info_ptr;
 
 extern "C" [[noreturn]] void init()
 {
-    kprintf("Kernel command line: '%s'\n", multiboot_info_ptr->cmdline);
-
     sse_init();
 
     kmalloc_init();
     init_ksyms();
 
+    // must come after kmalloc_init because we use AK_MAKE_ETERNAL in KParams
+    new KParams(String(reinterpret_cast<const char*>(multiboot_info_ptr->cmdline)));
+
     vfs = new VFS;
     dev_debuglog = new DebugLogDevice;