rewrite file system layer

1 files changed, 62 insertions, 0 deletions

diff --git a/include/mercury/kernel/vfile.hpp b/include/mercury/kernel/vfile.hpp
new file mode 100644
index 0000000..43dff96
--- /dev/null
+++ b/include/mercury/kernel/vfile.hpp
@@ -0,0 +1,62 @@
+#ifndef MERCURY_KERNEL_VFILE_HPP
+#define MERCURY_KERNEL_VFILE_HPP
+
+#include <mercury/kernel/storage.hpp>
+#include <mercury/kernel/utility.hpp>
+
+//TODO: mounts points.
+//maybe a two-way map between mount points and targets? one mount point per
+//target and vice versa. only directories may be mount points, and only file
+//system roots (which must be directories) may be targets.
+
+namespace mercury::kernel::vfile {
+
+  //a canon path contains no . or empty directory names, and
+  //contains no .. except for at the start of a relative path.
+  struct canon_path {
+
+    bool absolute;
+    unsigned parent_count;
+    utility::vector<utility::string> segments;
+
+    canon_path() : absolute(false), parent_count(0), segments(8) {}
+
+    void parent();
+    void rel(const canon_path &r);
+
+    utility::string to_string(bool trailing_slash) const;
+
+  };
+
+  void canonize_path(const utility::string &name, canon_path &out);
+
+  struct vfile {
+
+    //on followed symlinks, path is the source of the symlink and the
+    //rest of these are the target. in any case, path should be absolute.
+    canon_path path;
+    storage::block_device *bd;
+    storage::dir_entry dir_entry;
+
+    //TODO: instead of passing root, use saved mount points.
+    storage::fs_result follow_symlinks(
+      const vfile &root, std::optional<vfile> &out) const;
+
+    //dir_entry.type is assumed to be directory.
+    storage::fs_result get_child(
+      std::optional<vfile> &out, const utility::string &name) const;
+    //dir_entry.type is assumed to be directory. out must be empty on entry.
+    storage::fs_result get_children(utility::vector<vfile> &out) const;
+
+  };
+
+  //path must be absolute. follows symlinks on all but the last node.
+  //relative_to should be a directory to do the lookup inside; e.g.,
+  //if relative_to is /a/b and path is c, then out becomes /a/b/c.
+  //TODO: instead of passing root, use saved mount points.
+  storage::fs_result lookup_path(
+    const vfile &root, const canon_path &path, std::optional<vfile> &out);
+
+}
+
+#endif