Userland: Add keymap program.

Author: https://github.com/asliturk
Commit: https://github.com/SerenityOS/serenity/commit/28ada307834
Pull-request: https://github.com/SerenityOS/serenity/pull/820

Userland/keymap.cpp

@@ -0,0 +1,78 @@
+#include <AK/JsonObject.h>
+#include <LibCore/CFile.h>
+#include <stdio.h>
+
+#include <Kernel/Syscall.h>
+#include <AK/Optional.h>
+#include <AK/StdLibExtras.h>
+#include <AK/kmalloc.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+char* read_map(const JsonObject& json, const String& name)
+{
+    char* map = new char[80];
+
+    auto map_arr = json.get(name).as_array();
+    for(int i=0; i<map_arr.size(); i++) 
+    {
+        auto key_value = map_arr.at(i).as_string();
+        char character = 0;
+        if( key_value.length() == 0) {
+            ;
+        } else if(key_value.length() == 1){
+            character = key_value.characters()[0];
+        } else if(key_value.length() == 4){
+            if(key_value == "0x08"){
+                character = 0x08;
+            }else if(key_value == "0x33"){
+                character = 0x33;
+            }
+        } else {
+            fprintf(stderr, "Unknown character in %s[%u] = %s.\n", name.characters(), i, key_value.characters());       
+            ASSERT_NOT_REACHED();
+        }
+        
+        map[i] = character;
+    }
+
+    return map;
+}
+
+int read_map_from_file(String filename){
+    auto file = CFile::construct(filename);
+    if (!file->open(CIODevice::ReadOnly)) {
+        fprintf(stderr, "Failed to open %s: %s\n", filename.characters(), file->error_string());
+        return 1;
+    }
+
+    auto file_contents = file->read_all();
+    auto json = JsonValue::from_string(file_contents).as_object();
+ 
+    char* map = read_map(json, "map");
+    char* shift_map = read_map(json, "shift_map");
+    char* alt_map = read_map(json, "alt_map");
+
+    return syscall(SC_setkeymap, map, shift_map, alt_map);
+}
+
+int main(int argc, char** argv)
+{   
+    if (argc != 2) {
+        fprintf(stderr, "usage: keymap <file>\n");
+        return 0;
+    }
+
+    String filename = argv[1];
+    int ret_val = read_map_from_file(filename);
+
+    if(ret_val == -EPERM)
+        fprintf(stderr, "Permission denied.\n");
+
+    if(ret_val == 0)
+        fprintf(stderr, "New keymap loaded from \"%s\".\n", filename.characters());
+
+    return ret_val;
+}