Started on path resolution algorithm

- The algorithm will work once I am of better mind to deal with
raw C strings
- The resolution should look at each entry divided by '/'.
  if the entry is not there then we can quit early, however for
now I am mostly concerned with getting the names of directory entries
we would need to look for.

Makefile

@@ -5,7 +5,7 @@ CC = ${HOME}/opt/cross/bin/i686-elf-gcc
 CPP = ${HOME}/opt/cross/bin/i686-elf-g++ 
 CFLAGS =  -ffreestanding -Og -ggdb  -Wall -Wextra
 
-OFILES =$(BUILD_DIR)/boot.o $(BUILD_DIR)/kterm.o $(BUILD_DIR)/kernel.o $(BUILD_DIR)/memory.o  $(BUILD_DIR)/paging.o	$(BUILD_DIR)/VFS.o $(BUILD_DIR)/pit.o 	$(BUILD_DIR)/time.o	$(BUILD_DIR)/keyboard.o	 $(BUILD_DIR)/io.o 	$(BUILD_DIR)/processor.o $(BUILD_DIR)/gdtc.o $(BUILD_DIR)/idt.o $(BUILD_DIR)/pic.o $(BUILD_DIR)/sv-terminal.o $(BUILD_DIR)/string.o  $(BUILD_DIR)/prekernel.o $(BUILD_DIR)/KHeap.o $(BUILD_DIR)/pci.o $(BUILD_DIR)/pcidevice.o $(BUILD_DIR)/atapiDevice.o $(BUILD_DIR)/ataDevice.o $(BUILD_DIR)/rsdp.o $(BUILD_DIR)/acpi.o
+OFILES =$(BUILD_DIR)/boot.o $(BUILD_DIR)/Path.o $(BUILD_DIR)/kterm.o $(BUILD_DIR)/kernel.o $(BUILD_DIR)/memory.o  $(BUILD_DIR)/paging.o	$(BUILD_DIR)/VFS.o $(BUILD_DIR)/pit.o 	$(BUILD_DIR)/time.o	$(BUILD_DIR)/keyboard.o	 $(BUILD_DIR)/io.o 	$(BUILD_DIR)/processor.o $(BUILD_DIR)/gdtc.o $(BUILD_DIR)/idt.o $(BUILD_DIR)/pic.o $(BUILD_DIR)/sv-terminal.o $(BUILD_DIR)/string.o  $(BUILD_DIR)/prekernel.o $(BUILD_DIR)/KHeap.o $(BUILD_DIR)/pci.o $(BUILD_DIR)/pcidevice.o $(BUILD_DIR)/atapiDevice.o $(BUILD_DIR)/ataDevice.o $(BUILD_DIR)/rsdp.o $(BUILD_DIR)/acpi.o
 
 SRC_DIR = source
 BUILD_DIR = build
@@ -133,10 +133,11 @@ $(BUILD_DIR)/KHeap.o:
 $(BUILD_DIR)/prekernel.o:
 	$(CPP) -c $(SRC_DIR)/kernel/prekernel/prekernel.cpp -o $(BUILD_DIR)/prekernel.o $(CFLAGS) -fno-exceptions -fno-rtti
 
-
 $(BUILD_DIR)/processor.o:
 	$(CPP) -c $(SRC_DIR)/kernel/i386/processor.cpp -o $(BUILD_DIR)/processor.o $(CFLAGS) -fno-exceptions -fno-rtti
 
+$(BUILD_DIR)/Path.o:
+	$(CPP) -c $(SRC_DIR)/kernel/vfs/Path.cpp -o $(BUILD_DIR)/Path.o $(CFLAGS) -fno-exceptions -fno-rtti
 
 # Assembly -> Object files
 $(BUILD_DIR)/boot.o:

source/kernel/kernel.cpp

@@ -48,6 +48,10 @@ extern "C" void kernel ()
 
     FileSystem::initialize();
 
+    // Testing my path resolution functions
+    Path test = Path("/boot/myos.bin");
+    FileSystem::ResolvePath(test);
+
 
 #ifdef USERMODE_RELEASE
     // Lets jump into user mode

source/kernel/vfs/Path.cpp

@@ -0,0 +1,83 @@
+//
+// Created by nigel on 19/02/23.
+//
+#include "Path.h"
+#include "../memory/KernelHeap.h"
+String::String(char* characters)
+: chars(characters)
+{
+
+}
+
+char* String::str(){
+    return chars;
+}
+
+unsigned int String::length ()
+{
+    int i = 0;
+
+    while (  chars[i] != '\0'){
+        i++;
+    }
+
+    return i;
+}
+
+// Returns a null character if size exceeds limits
+char String::operator[] (size_t idx)
+{
+    if( idx  > this->length())
+        return '\0';
+
+    return chars[idx];
+}
+
+const char String::operator[](size_t idx) const {
+    return (const char) chars[idx];
+}
+
+StringView::StringView(String &string, unsigned int start, unsigned int end)
+: String(string), begin(start), end(end)
+{
+
+}
+
+char* StringView::str(){
+    char* str = (char*) malloc((this->length() * sizeof(char))+1);
+
+    int index = 0;
+    for ( int i = begin; i < end ; i++){
+        str[index] = chars[i];
+        index++;
+    }
+    chars[index+1] ='\0';
+    return str;
+}
+
+
+Path::Path(char *path)
+: path(String(path))
+{
+
+}
+
+Path::Path(String &path)
+: path(path)
+{
+
+}
+
+StringView Path::getbasename()
+{
+    unsigned int path_length = path.length();
+    int i = path_length;
+    while (path[i] != '/')
+        i--;
+
+    return StringView(path,i +1, path_length);
+}
+
+char* Path::str() {
+    return path.str();
+}

source/kernel/vfs/Path.h

@@ -0,0 +1,46 @@
+//
+// Created by nigel on 19/02/23.
+//
+#pragma once
+#include <stddef.h>
+
+class  String {
+public:
+    String(char* characters);
+    String(String&) = default;
+    unsigned int length();
+
+    char* str ();
+    char operator[](size_t index) ;
+    const char operator[](size_t idx) const;
+
+protected:
+    char* chars;
+
+
+};
+
+class StringView : String {
+public:
+    StringView(String& string, unsigned int start, unsigned  int end );
+    char* str ();
+private:
+    unsigned int begin;
+    unsigned int end;
+};
+
+class Path{
+public:
+    Path(String& path);
+    Path(char* path);
+
+    StringView getbasename();
+
+    char* str();
+
+private:
+    String path;
+
+};
+
+

source/kernel/vfs/VFS.cpp

@@ -4,7 +4,7 @@
 #include "../drivers/ata/ataDevice.h"
 #include "../partitiontable/mbr/MasterBootRecord.h"
 #include "../memory/KernelHeap.h"
-#include "../../lib/include/string.h"
+#include "Path.h"
 #include "../filesystem/FAT/DirectoryEntry.h"
 
 MOUNT_INFO mountInfo;
@@ -360,4 +360,59 @@ void FileSystem::initialize()
 */
 
 
+}
+
+char* FindNextEntryName (char* path )
+{
+    int length = strlen(path);
+
+    char* name = path;
+    int i = 0;
+
+    if( name[0] == '/')
+        i++;
+
+    while ( name[i] != '/' && i <= length)
+        i++;
+
+    char* s = (char*) malloc(i + 1 * sizeof(char));
+    for ( int a = 0; a < i; a++)
+        s[a] = path[a];
+
+    s[i + 1] = '\0';
+
+    return s;
+
+}
+
+
+
+void FileSystem::ResolvePath(Path &path)
+{
+    char* string_path  = path.str();
+    void* cpy = string_path;
+
+    bool isAbsolutePath = string_path[0] == '/';
+    if(isAbsolutePath)
+    {
+        // strip the first slash
+        string_path++;
+    }
+
+    char* entry_name = FindNextEntryName(string_path);
+    printf("Look for entry with name: %s\n", entry_name);
+    int skip = strlen(entry_name);
+    free(entry_name);
+
+
+    entry_name = FindNextEntryName(string_path + skip);
+    printf("Look for entry with name: %s\n", entry_name);
+    skip = strlen(entry_name);
+    free(entry_name);
+
+
+
+
+    free(cpy);
+
 }

source/kernel/vfs/VFS.h

@@ -1,5 +1,7 @@
 #pragma once
 #include <stdint.h>
+#include "Path.h"
+
 #define FS_FILE 0
 #define FS_DIRECTORY 1
 #define FS_INVALID 2
@@ -73,4 +75,6 @@ extern PFILESYSTEM _filesystems[DEVICE_MAX];
  public:
      static void initialize();
 
+     static void ResolvePath(Path& path);
+
  };

source/lib/include/mem.h

@@ -1,6 +1,7 @@
 #pragma once
 // NOTE: These should not be inline 
-inline void* memset (void* ptr, int value, size_t num){
+inline void* memset (void* ptr, int value, size_t num)
+{
     for( int i = 0; i < num; i++ )
     {
         unsigned char* data  = (unsigned char*)ptr+ i;
@@ -12,19 +13,19 @@ inline void* memset (void* ptr, int value, size_t num){
 
 
 inline int memcmp( const void* ptr1, const void* ptr2, size_t num)
-    {
-        const unsigned char * cs = (const unsigned char*) ptr1;
-        const unsigned char * ct = (const unsigned char*) ptr2;
+{
+    const unsigned char * cs = (const unsigned char*) ptr1;
+    const unsigned char * ct = (const unsigned char*) ptr2;
 
 
-        for (int i = 0 ; i < num ; i++, cs++, ct++ ){
-           if( *cs < *ct){
-               return -1;
-           } else if( *cs > *ct){
-               return 1;
-           }
-        } 
+    for (int i = 0 ; i < num ; i++, cs++, ct++ ){
+       if( *cs < *ct){
+           return -1;
+       } else if( *cs > *ct){
+           return 1;
+       }
+    }
 
-        return 0;
+    return 0;
 
-    }
+}