kernel/ELF+Scheduler: Use VFS instead of TarStream

kernel/src/ELF.cpp

@@ -26,13 +26,14 @@ static bool can_write_segment(u32 flags)
 namespace ELFLoader
 {
     // FIXME: Check that all calls to read_contents() read the proper amount of bytes.
-    Result<ELFData> load(const TarStream::Entry& elf_entry, const TarStream& stream)
+    Result<ELFData> load(SharedPtr<VFS::Inode> inode)
     {
         Elf64_Ehdr elf_header;
-        usize nread = stream.read_contents(elf_entry, &elf_header, 0, sizeof elf_header);
+        usize nread = TRY(inode->read((u8*)&elf_header, 0, sizeof elf_header));
+
         if (nread < sizeof elf_header)
         {
-            kdbgln("Error while loading ELF: ELF header does not fit in entry");
+            kdbgln("Error while loading ELF: ELF header does not fit in file");
             return err(ENOEXEC);
         }
 
@@ -78,10 +79,10 @@ namespace ELFLoader
         usize i;
         Elf64_Phdr program_header;
 
-        for (stream.read_contents(elf_entry, &program_header, elf_header.e_phoff, sizeof program_header), i = 0;
+        for (TRY(inode->read((u8*)&program_header, elf_header.e_phoff, sizeof program_header)), i = 0;
              i < elf_header.e_phnum;
-             i++, stream.read_contents(elf_entry, &program_header, elf_header.e_phoff + (i * elf_header.e_phentsize),
-                                       sizeof program_header))
+             i++, TRY(inode->read((u8*)&program_header, elf_header.e_phoff + (i * elf_header.e_phentsize),
+                                  sizeof program_header)))
         {
             if (program_header.p_type == PT_LOAD)
             {
@@ -103,8 +104,7 @@ namespace ELFLoader
                     base_vaddr, get_blocks_from_size(program_header.p_memsz + vaddr_diff, ARCH_PAGE_SIZE), flags));
 
                 // Load the file section of the segment
-                stream.read_contents(elf_entry, (void*)program_header.p_vaddr, program_header.p_offset,
-                                     program_header.p_filesz);
+                inode->read((u8*)program_header.p_vaddr, program_header.p_offset, program_header.p_filesz);
 
                 // Fill out the rest of the segment with 0s
                 memset((void*)(program_header.p_vaddr + program_header.p_filesz), 0,

kernel/src/ELF.h

@@ -1,6 +1,6 @@
 #pragma once
+#include "fs/VFS.h"
 #include <luna/LinkedList.h>
-#include <luna/TarStream.h>
 #include <luna/Types.h>
 
 #define ELFMAG "\177ELF"
@@ -54,5 +54,5 @@ struct ELFData
 
 namespace ELFLoader
 {
-    Result<ELFData> load(const TarStream::Entry& elf_entry, const TarStream& stream);
+    Result<ELFData> load(SharedPtr<VFS::Inode> inode);
 };

kernel/src/InitRD.cpp

@@ -1,6 +1,7 @@
 #include "InitRD.h"
 #include "arch/MMU.h"
 #include "boot/bootboot.h"
+#include "fs/VFS.h"
 
 TarStream g_initrd;
 extern const BOOTBOOT bootboot;
@@ -11,3 +12,29 @@ void InitRD::initialize()
 
     g_initrd.initialize((void*)virtual_initrd_address, bootboot.initrd_size);
 }
+
+static Result<void> vfs_create_dir_if_not_exists(const char* path)
+{
+    auto rc = VFS::create_directory(path);
+    if (rc.has_error())
+    {
+        if (rc.error() == EEXIST) return {};
+        return rc.release_error();
+    }
+    return {};
+}
+
+Result<void> InitRD::populate_vfs()
+{
+    TarStream::Entry entry;
+    while (TRY(g_initrd.read_next_entry(entry)))
+    {
+        if (entry.type == TarStream::EntryType::RegularFile)
+        {
+            auto file = TRY(VFS::create_file(entry.name));
+            file->write(entry.data(), 0, entry.size);
+        }
+        else if (entry.type == TarStream::EntryType::Directory) { TRY(vfs_create_dir_if_not_exists(entry.name)); }
+    }
+    return {};
+}

kernel/src/InitRD.h

@@ -6,4 +6,5 @@ extern TarStream g_initrd;
 namespace InitRD
 {
     void initialize();
+    Result<void> populate_vfs();
 }

kernel/src/fs/VFS.cpp

@@ -15,24 +15,41 @@ namespace VFS
     {
         auto parser = TRY(PathParser::create(path));
 
-        kdbgln("vfs: trying to resolve path %s", path);
+        SharedPtr<Inode> current_inode = root_fs->root_inode();
 
-        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);
-        }
+        // FIXME: Properly handle relative paths.
 
         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));
-        }
+        while (parser.next().try_set_value(section)) { current_inode = TRY(current_inode->find(section)); }
 
         return current_inode;
     }
+
+    Result<SharedPtr<Inode>> create_directory(const char* path)
+    {
+        auto parser = TRY(PathParser::create(path));
+        auto parent_path = TRY(parser.dirname());
+
+        auto parent_inode = TRY(resolve_path(parent_path.chars()));
+
+        auto child_name = TRY(parser.basename());
+
+        // kdbgln("vfs: creating directory '%s' in parent '%s'", child_name.chars(), parent_path.chars());
+
+        return parent_inode->create_subdirectory(child_name.chars());
+    }
+
+    Result<SharedPtr<Inode>> create_file(const char* path)
+    {
+        auto parser = TRY(PathParser::create(path));
+        auto parent_path = TRY(parser.dirname());
+
+        auto parent_inode = TRY(resolve_path(parent_path.chars()));
+
+        auto child_name = TRY(parser.basename());
+
+        // kdbgln("vfs: creating file '%s' in parent '%s'", child_name.chars(), parent_path.chars());
+
+        return parent_inode->create_file(child_name.chars());
+    }
 }

kernel/src/fs/VFS.h

@@ -21,6 +21,11 @@ namespace VFS
 
         virtual Result<SharedPtr<Inode>> create_subdirectory(const char* name) = 0;
 
+        // File-specific methods
+        virtual Result<usize> read(u8* buf, usize offset, usize length) const = 0;
+
+        virtual Result<usize> write(const u8* buf, usize offset, usize length) = 0;
+
         // Generic methods
         virtual FileSystem& fs() const = 0;
 
@@ -73,5 +78,8 @@ namespace VFS
 
     Result<SharedPtr<Inode>> resolve_path(const char* path);
 
+    Result<SharedPtr<Inode>> create_directory(const char* path);
+    Result<SharedPtr<Inode>> create_file(const char* path);
+
     Inode& root_inode();
 }

kernel/src/fs/tmpfs/FileSystem.cpp

@@ -66,6 +66,8 @@ namespace TmpFS
 
     Result<SharedPtr<VFS::Inode>> DirInode::create_file(const char* name)
     {
+        if (find(name).has_value()) return err(EEXIST);
+
         auto inode = TRY(m_fs->create_file_inode());
 
         TRY(add_entry(inode, name));
@@ -75,10 +77,45 @@ namespace TmpFS
 
     Result<SharedPtr<VFS::Inode>> DirInode::create_subdirectory(const char* name)
     {
+        if (find(name).has_value()) return err(EEXIST);
+
         auto inode = TRY(m_fs->create_dir_inode(m_self));
 
         TRY(add_entry(inode, name));
 
         return inode;
     }
+
+    Result<usize> FileInode::read(u8* buf, usize offset, usize length) const
+    {
+        if (length == 0) return 0;
+
+        if (offset > m_data_buffer.size()) return 0;
+        if (offset + length > m_data_buffer.size()) length = m_data_buffer.size() - offset;
+
+        memcpy(buf, m_data_buffer.data() + offset, length);
+
+        return length;
+    }
+
+    Result<usize> FileInode::write(const u8* buf, usize offset, usize length)
+    {
+        if (length == 0) return 0;
+
+        if (offset > m_data_buffer.size())
+        {
+            // Fill the in-between space with zeroes.
+            usize old_size = m_data_buffer.size();
+            usize zeroes = offset - old_size;
+
+            TRY(m_data_buffer.try_resize(offset));
+
+            memset(m_data_buffer.data() + old_size, 0, zeroes);
+        }
+
+        u8* slice = TRY(m_data_buffer.slice(offset, length));
+        memcpy(slice, buf, length);
+
+        return length;
+    }
 }

kernel/src/fs/tmpfs/FileSystem.h

@@ -2,6 +2,7 @@
 #include "fs/VFS.h"
 #include <luna/Atomic.h>
 #include <luna/Badge.h>
+#include <luna/Buffer.h>
 #include <luna/StaticString.h>
 #include <luna/Vector.h>
 
@@ -58,10 +59,15 @@ namespace TmpFS
             return m_inode_number;
         }
 
+        Result<usize> read(u8*, usize, usize) const override;
+
+        Result<usize> write(const u8*, usize, usize) override;
+
         virtual ~FileInode() = default;
 
       private:
         VFS::FileSystem* m_fs;
+        Buffer m_data_buffer;
         usize m_inode_number;
     };
 
@@ -87,6 +93,16 @@ namespace TmpFS
 
         Result<SharedPtr<VFS::Inode>> find(const char* name) const override;
 
+        Result<usize> read(u8*, usize, usize) const override
+        {
+            return err(EISDIR);
+        }
+
+        Result<usize> write(const u8*, usize, usize) override
+        {
+            return err(EISDIR);
+        }
+
         VFS::FileSystem& fs() const override
         {
             return *m_fs;

kernel/src/main.cpp

@@ -51,29 +51,7 @@ static Result<void> try_init_vfs()
 {
     VFS::root_fs = TRY(TmpFS::FileSystem::create());
 
-    VFS::Inode& root_inode = VFS::root_inode();
-
-    kinfoln("root inode number: %zu", root_inode.inode_number());
-
-    kinfoln("root inode's '.' entry inode number: %zu", TRY(root_inode.find("."))->inode_number());
-    kinfoln("root inode's '..' entry inode number: %zu", TRY(root_inode.find(".."))->inode_number());
-
-    TRY(root_inode.create_subdirectory("etc"));
-
-    kinfoln("root inode's 'etc' entry inode number: %zu", TRY(root_inode.find("etc"))->inode_number());
-
-    auto& etc = *TRY(root_inode.find("etc"));
-
-    kinfoln("etc inode's '.' entry inode number: %zu", TRY(etc.find("."))->inode_number());
-    kinfoln("etc inode's '..' entry inode number: %zu", TRY(etc.find(".."))->inode_number());
-
-    TRY(etc.create_file("passwd"));
-
-    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());
+    InitRD::populate_vfs();
 
     return {};
 }
@@ -85,17 +63,9 @@ static void init_vfs()
 
 static Result<void> try_init_userspace()
 {
-    TarStream::Entry entry;
-    while (TRY(g_initrd.read_next_entry(entry)))
-    {
-        if (entry.type == TarStream::EntryType::RegularFile)
-        {
-            kinfoln("Found file %s in initial ramdisk, of size %s and mode %#ho", entry.name,
-                    to_dynamic_unit(entry.size).release_value().chars(), entry.mode);
+    auto app = TRY(VFS::resolve_path("/bin/app"));
 
-            if (!strcmp(entry.name, "bin/app")) { TRY(Scheduler::new_userspace_thread(entry, g_initrd)); }
-        }
-    }
+    TRY(Scheduler::new_userspace_thread(app));
 
     return {};
 }

kernel/src/thread/Scheduler.cpp

@@ -118,7 +118,7 @@ namespace Scheduler
         return {};
     }
 
-    Result<void> new_userspace_thread(const TarStream::Entry& entry, const TarStream& stream)
+    Result<void> new_userspace_thread(SharedPtr<VFS::Inode> inode)
     {
         Thread* const thread = TRY(new_thread());
 
@@ -139,7 +139,7 @@ namespace Scheduler
 
         thread->init_regs_user();
 
-        const ELFData data = TRY(ELFLoader::load(entry, stream));
+        const ELFData data = TRY(ELFLoader::load(inode));
 
         thread->set_ip(data.entry);
 

kernel/src/thread/Scheduler.h

@@ -1,6 +1,6 @@
 #pragma once
+#include "fs/VFS.h"
 #include "thread/Thread.h"
-#include <luna/TarStream.h>
 
 namespace Scheduler
 {
@@ -13,7 +13,7 @@ namespace Scheduler
     Result<void> new_kernel_thread(void (*func)(void));
     Result<void> new_kernel_thread(void (*func)(void*), void* arg);
 
-    Result<void> new_userspace_thread(const TarStream::Entry& entry, const TarStream& stream);
+    Result<void> new_userspace_thread(SharedPtr<VFS::Inode> inode);
 
     Thread* pick_task();
 

libluna/CMakeLists.txt

@@ -7,6 +7,7 @@ set(FREESTANDING_SOURCES
     src/Format.cpp
     src/NumberParsing.cpp
     src/CString.cpp
+    src/CPath.cpp
     src/Units.cpp
     src/SystemError.cpp
     src/Bitmap.cpp

libluna/include/luna/Buffer.h

@@ -15,7 +15,9 @@ class Buffer
 
     Result<void> try_resize(usize new_size);
 
-    Result<u8*> create_slice_at_end(usize size);
+    Result<u8*> slice_at_end(usize size);
+
+    Result<u8*> slice(usize offset, usize size);
 
     u8* data()
     {
@@ -27,6 +29,16 @@ class Buffer
         return m_data;
     }
 
+    u8* end()
+    {
+        return m_data + m_size;
+    }
+
+    const u8* end() const
+    {
+        return m_data + m_size;
+    }
+
     usize size() const
     {
         return m_size;

libluna/include/luna/CPath.h

@@ -0,0 +1,4 @@
+#pragma once
+
+char* basename(char*);
+char* dirname(char*);

libluna/include/luna/CString.h

@@ -33,4 +33,5 @@ extern "C"
     [[deprecated]] char* strcat(char* dst, const char* src);
 
     char* strchr(const char* str, int c);
+    char* strrchr(const char* str, int c);
 }

libluna/include/luna/PathParser.h

@@ -1,6 +1,7 @@
 #pragma once
 #include <luna/CString.h>
 #include <luna/Heap.h>
+#include <luna/OwnedStringView.h>
 
 class PathParser
 {
@@ -17,6 +18,9 @@ class PathParser
         return *m_original == '/';
     }
 
+    Result<OwnedStringView> basename();
+    Result<OwnedStringView> dirname();
+
     Option<const char*> next();
 
   private:

libluna/include/luna/TarStream.h

@@ -20,8 +20,14 @@ class TarStream
         mode_t mode;
         EntryType type;
 
+        const u8* data() const
+        {
+            return m_data;
+        }
+
       private:
-        usize pos;
+        usize m_pos;
+        u8* m_data;
 
         friend class TarStream;
     };

libluna/src/Buffer.cpp

@@ -32,9 +32,15 @@ Result<void> Buffer::try_resize(usize new_size)
     return {};
 }
 
-Result<u8*> Buffer::create_slice_at_end(usize size)
+Result<u8*> Buffer::slice_at_end(usize size)
 {
     usize old_size = m_size;
     TRY(try_resize(m_size + size));
     return m_data + old_size;
 }
+
+Result<u8*> Buffer::slice(usize offset, usize size)
+{
+    if (offset + size > m_size) { TRY(try_resize(offset + size)); }
+    return m_data + offset;
+}

libluna/src/CPath.cpp

@@ -0,0 +1,47 @@
+#include <luna/CPath.h>
+#include <luna/CString.h>
+
+static char dot[] = ".";
+
+char* basename(char* path)
+{
+    // If path is NULL, or the string's length is 0, return .
+    if (!path) return dot;
+    size_t len = strlen(path);
+    if (!len) return dot;
+
+    // Strip trailing slashes.
+    char* it = path + len - 1;
+    while (*it == '/' && it != path) { it--; }
+    *(it + 1) = 0;
+    if (it == path) return path;
+
+    // Return path from the first character if there are no more slashes, or from the first character after the last
+    // slash.
+    char* beg = strrchr(path, '/');
+    if (!beg) return path;
+    return beg + 1;
+}
+
+char* dirname(char* path)
+{
+    // If path is NULL, or the string's length is 0, return .
+    if (!path) return dot;
+    size_t len = strlen(path);
+    if (!len) return dot;
+
+    // Strip trailing slashes.
+    char* it = path + len - 1;
+    while (*it == '/' && it != path) { it--; }
+    *(char*)(it + 1) = 0;
+    if (it == path) return path;
+
+    // Search for the last slash. If there is none, return .
+    // Otherwise, we end the string there and return.
+    char* end = strrchr(path, '/');
+    if (!end) return dot;
+    if (end != path) *end = 0;
+    else
+        *(end + 1) = 0;
+    return path;
+}

libluna/src/CString.cpp

@@ -126,6 +126,15 @@ extern "C"
         return NULL;
     }
 
+    char* strrchr(const char* str, int c)
+    {
+        const char* s = str + strlen(str);
+        while (s != str && *s != (char)c) s--;
+        if (s != str) return const_cast<char*>(s);
+        if (*s == (char)c) return const_cast<char*>(s);
+        return NULL;
+    }
+
     usize strlcpy(char* dest, const char* src, usize len)
     {
         usize src_len = strlen(src);

libluna/src/PathParser.cpp

@@ -1,4 +1,6 @@
+#include <luna/CPath.h>
 #include <luna/PathParser.h>
+#include <luna/ScopeGuard.h>
 
 Result<PathParser> PathParser::create(const char* path)
 {
@@ -31,3 +33,29 @@ Option<const char*> PathParser::next()
 
     return result;
 }
+
+Result<OwnedStringView> PathParser::basename()
+{
+    char* copy = strdup(m_original);
+    if (!copy) return err(ENOMEM);
+
+    auto guard = make_scope_guard([copy] { free_impl(copy); });
+
+    char* result = ::basename(copy);
+
+    // We must copy this as we cannot rely on the original string.
+    return OwnedStringView::from_string_literal(result);
+}
+
+Result<OwnedStringView> PathParser::dirname()
+{
+    char* copy = strdup(m_original);
+    if (!copy) return err(ENOMEM);
+
+    auto guard = make_scope_guard([copy] { free_impl(copy); });
+
+    char* result = ::dirname(copy);
+
+    // We must copy this as we cannot rely on the original string.
+    return OwnedStringView::from_string_literal(result);
+}

libluna/src/TarStream.cpp

@@ -45,7 +45,8 @@ Result<TarStream::Entry> TarStream::parse_header(const TarStream::TarHeader* hdr
 
     entry.mode = (mode_t)parse_unsigned_integer(hdr->mode, nullptr, 8);
 
-    entry.pos = m_offset;
+    entry.m_pos = m_offset;
+    entry.m_data = (u8*)m_base + m_offset;
 
     switch (hdr->typeflag)
     {
@@ -99,7 +100,7 @@ usize TarStream::read_contents(const Entry& entry, void* buf, usize offset, usiz
     if (offset >= entry.size) return 0;
     if ((length + offset) > entry.size) length = entry.size - offset;
 
-    memcpy(buf, offset_ptr(m_base, entry.pos + offset), length);
+    memcpy(buf, offset_ptr(m_base, entry.m_pos + offset), length);
 
     return length;
 }