VFS: Implement resolve_path() using PathParser

Already works better than old luna (handles .. correctly)

kernel/src/fs/VFS.cpp

@@ -1,4 +1,6 @@
 #include "fs/VFS.h"
+#include "Log.h"
+#include <luna/PathParser.h>
 
 namespace VFS
 {
@@ -6,6 +8,31 @@ namespace VFS
 
     Inode& root_inode()
     {
-        return root_fs->root_inode();
+        return *root_fs->root_inode();
+    }
+
+    Result<SharedPtr<Inode>> resolve_path(const char* path)
+    {
+        auto parser = TRY(PathParser::create(path));
+
+        kdbgln("vfs: trying to resolve path %s", path);
+
+        SharedPtr<Inode> current_inode;
+
+        if (parser.is_absolute()) { current_inode = root_fs->root_inode(); }
+        else
+        {
+            kwarnln("vfs: cannot resolve path '%s', as relative paths are not supported yet", path);
+            return err(ENOTSUP);
+        }
+
+        const char* section;
+        while (parser.next().try_set_value(section))
+        {
+            kdbgln("vfs: searching for entry '%s' in inode %zu", section, current_inode->inode_number());
+            current_inode = TRY(current_inode->find(section));
+        }
+
+        return current_inode;
     }
 }

kernel/src/fs/VFS.h

@@ -60,7 +60,7 @@ namespace VFS
     class FileSystem
     {
       public:
-        virtual Inode& root_inode() const = 0;
+        virtual SharedPtr<Inode> root_inode() const = 0;
 
         virtual Result<SharedPtr<Inode>> create_file_inode() = 0;
 
@@ -71,7 +71,7 @@ namespace VFS
 
     extern SharedPtr<FileSystem> root_fs;
 
-    Result<Inode*> resolve_path(const char* path);
+    Result<SharedPtr<Inode>> resolve_path(const char* path);
 
     Inode& root_inode();
 }

kernel/src/fs/tmpfs/FileSystem.h

@@ -10,9 +10,9 @@ namespace TmpFS
     class FileSystem : public VFS::FileSystem
     {
       public:
-        VFS::Inode& root_inode() const override
+        SharedPtr<VFS::Inode> root_inode() const override
         {
-            return *m_root_inode;
+            return m_root_inode;
         }
 
         Result<SharedPtr<VFS::Inode>> create_file_inode() override;

kernel/src/main.cpp

@@ -71,6 +71,10 @@ static Result<void> try_init_vfs()
 
     kinfoln("etc inode's 'passwd' entry inode number: %zu", TRY(etc.find("passwd"))->inode_number());
 
+    auto& passwd = *TRY(VFS::resolve_path("/etc/passwd"));
+
+    kinfoln("/etc/passwd's inode number: %zu", passwd.inode_number());
+
     return {};
 }
 

libluna/CMakeLists.txt

@@ -17,6 +17,7 @@ set(FREESTANDING_SOURCES
     src/DebugLog.cpp
     src/Heap.cpp
     src/Spinlock.cpp
+    src/PathParser.cpp
     src/UBSAN.cpp
 )
 

libluna/include/luna/CString.h

@@ -13,6 +13,11 @@ extern "C"
 
     int strcmp(const char* a, const char* b);
 
+    usize strspn(const char* str, const char* accept);
+    usize strcspn(const char* str, const char* reject);
+
+    char* strtok(char* str, const char* delim);
+
     usize wcslen(const wchar_t* str);
 
     char* strdup(const char* str);

libluna/include/luna/PathParser.h

@@ -0,0 +1,28 @@
+#pragma once
+#include <luna/CString.h>
+#include <luna/Heap.h>
+
+class PathParser
+{
+  public:
+    static Result<PathParser> create(const char* path);
+
+    PathParser(PathParser&& other);
+    PathParser(const PathParser&) = delete;
+
+    ~PathParser();
+
+    bool is_absolute() const
+    {
+        return *m_original == '/';
+    }
+
+    Option<const char*> next();
+
+  private:
+    PathParser(const char* original, char* copy);
+
+    const char* m_original { nullptr };
+    char* m_copy { nullptr };
+    bool m_already_called_next { false };
+};

libluna/src/CString.cpp

@@ -136,4 +136,71 @@ extern "C"
         dest[copy_len] = 0;
         return src_len;
     }
+
+    usize strcspn(const char* str, const char* reject)
+    {
+        const char* s = str;
+        while (*s)
+        {
+            const char* rp = reject;
+            while (*rp)
+            {
+                if (*s == *rp) return (usize)(s - str);
+                rp++;
+            }
+            s++;
+        }
+        return (usize)(s - str);
+    }
+
+    usize strspn(const char* str, const char* accept)
+    {
+        const char* s = str;
+        while (*s)
+        {
+            const char* ap = accept;
+            bool match = false;
+            while (*ap)
+            {
+                if (*s == *ap)
+                {
+                    match = true;
+                    break;
+                }
+                ap++;
+            }
+            if (!match) return (usize)(s - str);
+            s++;
+        }
+        return (usize)(s - str);
+    }
+
+    char* strtok(char* str, const char* delim)
+    {
+        static char* s = nullptr;
+        if (str) s = str;
+        if (!s) return nullptr;
+
+        if (*s)
+        {
+            usize skip = strspn(s, delim);
+            s += skip;
+
+            if (*s == 0) return nullptr;
+
+            usize use = strcspn(s, delim);
+            char* result = s;
+
+            if (s[use] != 0)
+            {
+                s[use] = 0;
+                s += (use + 1);
+            }
+            else { s = nullptr; }
+
+            return result;
+        }
+
+        return nullptr;
+    }
 }

libluna/src/PathParser.cpp

@@ -0,0 +1,33 @@
+#include <luna/PathParser.h>
+
+Result<PathParser> PathParser::create(const char* path)
+{
+    char* copy = strdup(path);
+    if (!copy) return err(ENOMEM);
+
+    return PathParser { path, copy };
+}
+
+PathParser::PathParser(const char* original, char* copy) : m_original(original), m_copy(copy)
+{
+}
+
+PathParser::PathParser(PathParser&& other) : m_original(other.m_original), m_copy(other.m_copy)
+{
+    other.m_copy = nullptr;
+}
+
+PathParser::~PathParser()
+{
+    if (m_copy) free_impl(m_copy);
+}
+
+Option<const char*> PathParser::next()
+{
+    char* result = strtok(m_already_called_next ? nullptr : m_copy, "/");
+    m_already_called_next = true;
+
+    if (!result) return {};
+
+    return result;
+}

tools/replace-stdint.sh

@@ -6,8 +6,8 @@ source $(dirname $0)/env.sh
 cd $LUNA_ROOT
 
 SOURCES=($(find kernel/src -type f | grep -v "\.asm" | grep -v "bootboot.h"))
-SOURCES+=($(find luna/src -type f))
+SOURCES+=($(find libluna/src -type f))
-SOURCES+=($(find luna/include/luna -type f | grep -v "Types.h"))
+SOURCES+=($(find libluna/include/luna -type f | grep -v "Types.h"))
 
 for f in ${SOURCES[@]}
 do
@@ -23,4 +23,4 @@ do
 
     sed -i 's/size_t/usize/g' $f
     sed -i 's/ssize_t/isize/g' $f
-done
+done