Initial TmpFS work

kernel/include/fs/TmpFS.h

@@ -0,0 +1,51 @@
+#pragma once
+#include "fs/VFS.h"
+
+namespace TmpFSImpl
+{
+    ssize_t read(VFS::Node* node, size_t offset, size_t size, char* buffer);
+    ssize_t write(VFS::Node* node, size_t offset, size_t size, char* buffer);
+}
+
+class TmpFS
+{
+  public:
+    VFS::Node* root()
+    {
+        return m_root;
+    }
+
+    static TmpFS* create(const char* name);
+    static void release(TmpFS* fs);
+
+    ssize_t read(VFS::Node* node, size_t offset, size_t size, char* buffer);
+    ssize_t write(VFS::Node* node, size_t offset, size_t size, char* buffer);
+
+    void purge();
+
+  private:
+    struct File
+    {
+        char* buf;
+        size_t len;
+        int valid;
+    };
+
+    struct Directory
+    {
+        VFS::Node* buf;
+        size_t len;
+        int valid;
+    };
+
+    template <typename T> struct Array
+    {
+        T* buf;
+        size_t len;
+    };
+
+    TmpFS(const char* name);
+    Array<File> m_files;
+    Array<Directory> m_dirs;
+    VFS::Node* m_root;
+};

kernel/src/fs/TmpFS.cpp

@@ -0,0 +1,99 @@
+#include "fs/TmpFS.h"
+#include "std/stdlib.h"
+#include "std/string.h"
+
+ssize_t TmpFSImpl::read(VFS::Node* node, size_t offset, size_t size, char* buffer)
+{
+    if (!node) return -1;
+    if (!node->impl) return -1;
+    return ((TmpFS*)node->impl)->read(node, offset, size, buffer);
+}
+
+ssize_t TmpFSImpl::write(VFS::Node* node, size_t offset, size_t size, char* buffer)
+{
+    if (!node) return -1;
+    if (!node->impl) return -1;
+    return ((TmpFS*)node->impl)->write(node, offset, size, buffer);
+}
+
+TmpFS* TmpFS::create(const char* name)
+{
+    return new TmpFS(name);
+}
+
+void TmpFS::release(TmpFS* fs)
+{
+    fs->purge();
+    kfree(fs->m_dirs.buf);
+    delete fs->root();
+    delete fs;
+}
+
+extern uint64_t clock_now();
+
+TmpFS::TmpFS(const char* name)
+{
+    m_root = new VFS::Node;
+    m_root->atime = m_root->ctime = m_root->mtime = clock_now();
+    m_root->impl = (uint64_t)this;
+    m_root->inode = 0;
+    m_root->gid = m_root->uid = 0;
+    m_root->mode = 0755;
+    m_root->length = 0;
+    m_root->type = VFS_DIRECTORY;
+    m_root->tty = 0;
+    strlcpy(m_root->name, name, sizeof(m_root->name));
+    m_dirs.buf = (Directory*)krealloc(nullptr, sizeof(Directory));
+    m_dirs.len = 1;
+    m_dirs.buf[0] = {nullptr, 0, 1};
+}
+
+void TmpFS::purge()
+{
+    for (size_t i = 0; i < m_dirs.len; i++)
+    {
+        if (m_dirs.buf[i].valid && m_dirs.buf[i].len) kfree(m_dirs.buf[i].buf);
+    }
+
+    m_dirs.buf = (Directory*)krealloc(m_dirs.buf, sizeof(Directory)); // leave space for the root directory
+
+    for (size_t i = 0; i < m_files.len; i++)
+    {
+        if (m_files.buf[i].valid && m_files.buf[i].len) kfree(m_files.buf[i].buf);
+    }
+
+    kfree(m_files.buf);
+}
+
+ssize_t TmpFS::read(VFS::Node* node, size_t offset, size_t size, char* buffer)
+{
+    if (!node) return -1;
+    if (node->inode >= m_files.len) return -1;
+    File& file = m_files.buf[node->inode];
+    if (!file.valid) return -1;
+    if (offset > file.len) return 0;
+    if (offset + size > file.len) { size = file.len - offset; }
+    memcpy(buffer, (void*)(file.buf + offset), size);
+    return size;
+}
+
+ssize_t TmpFS::write(VFS::Node* node, size_t offset, size_t size, char* buffer)
+{
+    if (!node) return -1;
+    if (node->inode >= m_files.len) return -1;
+    File& file = m_files.buf[node->inode];
+    if (!file.valid) return -1;
+    if (offset + size > file.len)
+    {
+        char* newbuf = (char*)krealloc(file.buf, offset + size);
+        if (!newbuf) { size = file.len - offset; }
+        else
+        {
+            file.buf = newbuf;
+            file.len = offset + size;
+            node->length = file.len;
+        }
+    }
+    memcpy((void*)(file.buf + offset), buffer, size);
+    return size;
+}