1 files changed, 288 insertions, 0 deletions
diff --git a/src/types/file_path.rs b/src/types/file_path.rs
new file mode 100644
index 0000000..7e6dbe8
--- /dev/null
+++ b/src/types/file_path.rs
@@ -0,0 +1,288 @@
+use crate::*;
+
+use std::cmp::Ordering;
+use std::ffi::OsString;
+use std::path::Component;
+
+
+#[derive(Clone)]
+pub struct BedrockFilePath {
+    /// Sandbox directory
+    base: PathBuf,
+    /// Path relative to sandbox directory
+    relative: PathBuf,
+    bytes: Vec<u8>,
+    entry_type: Option<EntryType>,
+}
+
+impl BedrockFilePath {
+    pub fn from_buffer(buffer: [u8; 256], base: &Path) -> Option<Self> {
+        let base = base.to_path_buf();
+        let relative = buffer_to_path(buffer)?;
+        let bytes = path_to_bytes(&relative)?;
+        let entry_type = get_entry_type(base.join(&relative));
+        assert_path_is_safe(&relative, &base)?;
+        Some(Self { base, relative, bytes, entry_type })
+    }
+
+    /// Construct an instance from an absolute path and a prefix of that path.
+    pub fn from_path(path: &Path, base: &Path) -> Option<Self> {
+        let base = base.to_path_buf();
+        let relative = path.strip_prefix(&base).ok()?.to_path_buf();
+        let bytes = path_to_bytes(&relative)?;
+        let entry_type = get_entry_type(base.join(&relative));
+        assert_path_is_safe(&relative, &base)?;
+        Some( Self { base, relative, bytes, entry_type } )
+    }
+
+    /// Get the base path used by this path.
+    pub fn base(&self) -> &Path {
+        &self.base
+    }
+
+    /// Get this path as a Bedrock-style path, which can be passed to
+    /// a Bedrock program.
+    pub fn as_bytes(&self) -> &[u8] {
+        &self.bytes
+    }
+
+    /// Get this path as a byte buffer, from which a CircularPathBuffer
+    /// can be populated.
+    pub fn as_buffer(&self) -> [u8; 256] {
+        let mut buffer: [u8; 256] = [0; 256];
+        buffer[..self.bytes.len()].copy_from_slice(&self.bytes);
+        return buffer;
+    }
+
+    /// Get this path as an absolute operating-system path, which can
+    /// be used to open a file or directory.
+    pub fn as_path(&self) -> PathBuf {
+        self.base.join(&self.relative)
+    }
+
+    /// Get the entry type of this path.
+    pub fn entry_type(&self) -> Option<EntryType> {
+        self.entry_type
+    }
+
+    /// Get a path which represents the parent of this path.
+    pub fn parent(&self) -> Option<Self> {
+        #[cfg(target_family = "unix")] {
+            Self::from_path(self.as_path().parent()?, &self.base)
+        }
+        #[cfg(target_family = "windows")] {
+            if self.base.components().count() != 0 {
+                // Sandboxed path, cannot ascend to a virtual root directory.
+                Self::from_path(self.as_path().parent()?, &self.base)
+            } else {
+                // Unsandboxed path, we can ascend to a virtual root directory.
+                match self.as_path().parent() {
+                    // Ascend to concrete parent directory.
+                    Some(parent) => Self::from_path(parent, &self.base),
+                    // Ascend into a virtual root directory.
+                    None => {
+                        if self.relative.components().count() != 0 {
+                            // Ascend from concrete path to virtual root.
+                            let blank = PathBuf::from("");
+                            BedrockFilePath::from_path(&blank, &blank)
+                        } else {
+                            // Cannot ascend above the virtual root.
+                            None
+                        }
+                    },
+                }
+            }
+        }
+    }
+
+    /// Returns true if the file would be hidden by the default file browser.
+    pub fn is_hidden(&self) -> bool {
+        #[cfg(target_family = "unix")] {
+            if let Some(stem) = self.relative.file_stem() {
+                if let Some(string) = stem.to_str() {
+                    return string.starts_with('.');
+                }
+            }
+        }
+        #[cfg(target_family = "windows")] {
+            use std::os::windows::fs::MetadataExt;
+            // See https://learn.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants
+            // const FILE_ATTRIBUTE_HIDDEN: u32 = 0x00000002;
+            // const FILE_ATTRIBUTE_NOT_CONTENT_INDEXED: u32 = 0x00002000;
+            if let Ok(metadata) = std::fs::metadata(self.as_path()) {
+                return metadata.file_attributes() & 0x2002 != 0;
+            }
+        }
+        return false;
+    }
+}
+
+
+/// Converts the contents of a CircularPathBuffer to a relative path.
+fn buffer_to_path(bytes: [u8; 256]) -> Option<PathBuf> {
+    // The buffer must be non-empty and slash-prefixed.
+    if bytes[0] != ('/' as u8) {
+        return None;
+    }
+
+    // Find the index of the first null byte.
+    let mut null_i = None;
+    for (i, b) in bytes.iter().enumerate() {
+        if *b == 0x00 {
+            null_i = Some(i);
+            break;
+        }
+    }
+    // Take a slice, excluding the leading slash, up to the trailing null.
+    let slice = &bytes[1..null_i?];
+
+    #[cfg(target_family = "unix")] {
+        use std::os::unix::ffi::OsStringExt;
+        let vec = Vec::from(slice);
+        return Some(OsString::from_vec(vec).into())
+    }
+    #[cfg(target_family = "windows")] {
+        use std::os::windows::ffi::OsStringExt;
+        let mut string = String::from_utf8_lossy(slice).to_string();
+        // Convert drive-current-directory paths to drive-root paths. This is
+        // needed because the paths C: and C:/ point to separate directories,
+        // but trailing forward-slashes are optional in Bedrock.
+        if string.ends_with(':') {
+            string.push('/');
+        }
+        let utf16: Vec<u16> = string.replace(r"/", r"\").encode_utf16().collect();
+        return Some(OsString::from_wide(&utf16).into())
+    }
+}
+
+/// Convert an operating system path to a Bedrock-style byte path.
+///
+/// A byte path contains at most 255 bytes, and is not null-terminated.
+fn path_to_bytes(path: &Path) -> Option<Vec<u8>> {
+    #[cfg(target_family = "unix")]
+    let string = path.as_os_str().to_str()?.to_string();
+    #[cfg(target_family = "windows")]
+    let string = path.as_os_str().to_str()?.replace(r"\", r"/");
+
+    // Remove any trailing forward-slash and add a leading forward-slash.
+    let mut prefixed_string = String::from("/");
+    prefixed_string.push_str(string.trim_end_matches('/'));
+    let slice = prefixed_string.as_bytes();
+
+    // Error if bytes does not fit into a CircularPathBuffer.
+    if slice.len() > 255 { return None; }
+
+    Some(Vec::from(slice))
+}
+
+/// Returns true if a relative path can be safely attached to a base without
+/// breaking out of the sandbox.
+fn assert_path_is_safe(relative: &Path, _base: &Path) -> Option<()> {
+    #[cfg(target_family = "unix")] {
+        // Error if path contains special components.
+        for component in relative.components() {
+            match component {
+                Component::Normal(_) => continue,
+                _ => return None,
+            }
+        }
+    }
+    #[cfg(target_family = "windows")] {
+        // If the base path is empty, the relative path needs to be able to
+        // contain the prefix and root element. If the base path is not
+        // empty, the relative path must not contain these elements else
+        // they will override the base path when joined.
+        if _base.components().count() != 0 {
+            for component in relative.components() {
+                match component {
+                    Component::Normal(_) => continue,
+                    _ => return None,
+                }
+            }
+        }
+    }
+    return Some(());
+}
+
+fn get_entry_type(absolute: PathBuf) -> Option<EntryType> {
+    #[cfg(target_family = "windows")] {
+        // If path is empty, this is a virtual root directory.
+        if absolute.components().count() == 0 {
+            return Some(EntryType::Directory)
+        }
+    }
+    let metadata = std::fs::metadata(absolute).ok()?;
+    if metadata.is_file() {
+        Some(EntryType::File)
+    } else if metadata.is_dir() {
+        Some(EntryType::Directory)
+    } else {
+        None
+    }
+}
+
+impl std::fmt::Debug for BedrockFilePath {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
+        self.as_path().fmt(f)
+    }
+}
+
+// ---------------------------------------------------------------------------
+
+impl PartialEq for BedrockFilePath {
+    fn eq(&self, other: &Self) -> bool {
+        self.bytes == other.bytes && self.entry_type == other.entry_type
+    }
+}
+
+impl Eq for BedrockFilePath {}
+
+impl PartialOrd for BedrockFilePath {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for BedrockFilePath {
+    fn cmp(&self, other: &Self) -> Ordering {
+        match self.entry_type.cmp(&other.entry_type) {
+            Ordering::Equal => compare_ascii_slices(&self.bytes, &other.bytes),
+            ordering => ordering,
+        }
+    }
+}
+
+/// Compare two ASCII byte-slices in case-agnostic alphabetic order.
+fn compare_ascii_slices(left: &[u8], right: &[u8]) -> Ordering {
+    let l = std::cmp::min(left.len(), right.len());
+    let lhs = &left[..l];
+    let rhs = &right[..l];
+
+    for i in 0..l {
+        let a = remap_ascii(lhs[i]);
+        let b = remap_ascii(rhs[i]);
+        match a.cmp(&b) {
+            Ordering::Equal => (),
+            non_eq => return non_eq,
+        }
+    }
+
+    left.len().cmp(&right.len())
+}
+
+/// Remap ASCII values so that they sort in case-agnostic alphabetic order:
+///
+/// ```text
+///    !"#$%&'()*+,-./0123456789:;<=>?
+///   @`AaBbCcDdEeFfGgHhIiJjKkLlMmNnOo
+///   PpQqRrSsTtUuVvWwXxYyZz[{\|]}^~_
+/// ```
+fn remap_ascii(c: u8) -> u8 {
+    if 0x40 <= c && c <= 0x5F {
+        (c - 0x40) * 2 + 0x40
+    } else if 0x60 <= c && c <= 0x7F {
+        (c - 0x60) * 2 + 0x41
+    } else {
+        c
+    }
+}