path: root/src/fs/file.rs

//! Files, and methods and fields to access their metadata.

use std::io::Error as IOError;
use std::io::Result as IOResult;
use std::os::unix::fs::{MetadataExt, PermissionsExt, FileTypeExt};
use std::path::{Path, PathBuf};
use std::time::{Duration, SystemTime, UNIX_EPOCH};

use log::*;

use crate::fs::dir::Dir;
use crate::fs::fields as f;

/// A **File** is a wrapper around one of Rust's Path objects, along with
/// associated data about the file.
///
/// Each file is definitely going to have its filename displayed at least
/// once, have its file extension extracted at least once, and have its metadata
/// information queried at least once, so it makes sense to do all this at the
/// start and hold on to all the information.
pub struct File<'dir> {

    /// The filename portion of this file’s path, including the extension.
    ///
    /// This is used to compare against certain filenames (such as checking if
    /// it’s “Makefile” or something) and to highlight only the filename in
    /// colour when displaying the path.
    pub name: String,

    /// The file’s name’s extension, if present, extracted from the name.
    ///
    /// This is queried many times over, so it’s worth caching it.
    pub ext: Option<String>,

    /// The path that begat this file.
    ///
    /// Even though the file’s name is extracted, the path needs to be kept
    /// around, as certain operations involve looking up the file’s absolute
    /// location (such as searching for compiled files) or using its original
    /// path (following a symlink).
    pub path: PathBuf,

    /// A cached `metadata` (`stat`) call for this file.
    ///
    /// This too is queried multiple times, and is *not* cached by the OS, as
    /// it could easily change between invocations — but exa is so short-lived
    /// it's better to just cache it.
    pub metadata: std::fs::Metadata,

    /// A reference to the directory that contains this file, if any.
    ///
    /// Filenames that get passed in on the command-line directly will have no
    /// parent directory reference — although they technically have one on the
    /// filesystem, we’ll never need to look at it, so it’ll be `None`.
    /// However, *directories* that get passed in will produce files that
    /// contain a reference to it, which is used in certain operations (such
    /// as looking up compiled files).
    pub parent_dir: Option<&'dir Dir>,

    /// Whether this is one of the two `--all all` directories, `.` and `..`.
    ///
    /// Unlike all other entries, these are not returned as part of the
    /// directory's children, and are in fact added specifically by exa; this
    /// means that they should be skipped when recursing.
    pub is_all_all: bool,
}

impl<'dir> File<'dir> {
    pub fn from_args<PD, FN>(path: PathBuf, parent_dir: PD, filename: FN) -> IOResult<File<'dir>>
    where PD: Into<Option<&'dir Dir>>,
          FN: Into<Option<String>>
    {
        let parent_dir = parent_dir.into();
        let name       = filename.into().unwrap_or_else(|| File::filename(&path));
        let ext        = File::ext(&path);

        debug!("Statting file {:?}", &path);
        let metadata   = std::fs::symlink_metadata(&path)?;
        let is_all_all = false;

        Ok(File { path, parent_dir, metadata, ext, name, is_all_all })
    }

    pub fn new_aa_current(parent_dir: &'dir Dir) -> IOResult<File<'dir>> {
        let path       = parent_dir.path.to_path_buf();
        let ext        = File::ext(&path);

        debug!("Statting file {:?}", &path);
        let metadata   = std::fs::symlink_metadata(&path)?;
        let is_all_all = true;

        Ok(File { path, parent_dir: Some(parent_dir), metadata, ext, name: ".".to_string(), is_all_all })
    }

    pub fn new_aa_parent(path: PathBuf, parent_dir: &'dir Dir) -> IOResult<File<'dir>> {
        let ext        = File::ext(&path);

        debug!("Statting file {:?}", &path);
        let metadata   = std::fs::symlink_metadata(&path)?;
        let is_all_all = true;

        Ok(File { path, parent_dir: Some(parent_dir), metadata, ext, name: "..".to_string(), is_all_all })
    }

    /// A file’s name is derived from its string. This needs to handle directories
    /// such as `/` or `..`, which have no `file_name` component. So instead, just
    /// use the last component as the name.
    pub fn filename(path: &Path) -> String {
        if let Some(back) = path.components().next_back() {
            back.as_os_str().to_string_lossy().to_string()
        }
        else {
            // use the path as fallback
            error!("Path {:?} has no last component", path);
            path.display().to_string()
        }
    }

    /// Extract an extension from a file path, if one is present, in lowercase.
    ///
    /// The extension is the series of characters after the last dot. This
    /// deliberately counts dotfiles, so the “.git” folder has the extension “git”.
    ///
    /// ASCII lowercasing is used because these extensions are only compared
    /// against a pre-compiled list of extensions which are known to only exist
    /// within ASCII, so it’s alright.
    fn ext(path: &Path) -> Option<String> {
        let name = path.file_name().map(|f| f.to_string_lossy().to_string())?;

        name.rfind('.').map(|p| name[p+1..].to_ascii_lowercase())
    }

    /// Whether this file is a directory on the filesystem.
    pub fn is_directory(&self) -> bool {
        self.metadata.is_dir()
    }

    /// Whether this file is a directory, or a symlink pointing to a directory.
    pub fn points_to_directory(&self) -> bool {
        if self.is_directory() {
            return true;
        }

        if self.is_link() {
            let target = self.link_target();
            if let FileTarget::Ok(target) = target {
                return target.points_to_directory();
            }
        }

        false
    }

    /// If this file is a directory on the filesystem, then clone its
    /// `PathBuf` for use in one of our own `Dir` values, and read a list of
    /// its contents.
    ///
    /// Returns an IO error upon failure, but this shouldn’t be used to check
    /// if a `File` is a directory or not! For that, just use `is_directory()`.
    pub fn to_dir(&self) -> IOResult<Dir> {
        Dir::read_dir(self.path.clone())
    }

    /// Whether this file is a regular file on the filesystem — that is, not a
    /// directory, a link, or anything else treated specially.
    pub fn is_file(&self) -> bool {
        self.metadata.is_file()
    }

    /// Whether this file is both a regular file *and* executable for the
    /// current user. An executable file has a different purpose from an
    /// executable directory, so they should be highlighted differently.
    pub fn is_executable_file(&self) -> bool {
        let bit = modes::USER_EXECUTE;
        self.is_file() && (self.metadata.permissions().mode() & bit) == bit
    }

    /// Whether this file is a symlink on the filesystem.
    pub fn is_link(&self) -> bool {
        self.metadata.file_type().is_symlink()
    }

    /// Whether this file is a named pipe on the filesystem.
    pub fn is_pipe(&self) -> bool {
        self.metadata.file_type().is_fifo()
    }

    /// Whether this file is a char device on the filesystem.
    pub fn is_char_device(&self) -> bool {
        self.metadata.file_type().is_char_device()
    }

    /// Whether this file is a block device on the filesystem.
    pub fn is_block_device(&self) -> bool {
        self.metadata.file_type().is_block_device()
    }

    /// Whether this file is a socket on the filesystem.
    pub fn is_socket(&self) -> bool {
        self.metadata.file_type().is_socket()
    }


    /// Re-prefixes the path pointed to by this file, if it’s a symlink, to
    /// make it an absolute path that can be accessed from whichever
    /// directory exa is being run from.
    fn reorient_target_path(&self, path: &Path) -> PathBuf {
        if path.is_absolute() {
            path.to_path_buf()
        }
        else if let Some(dir) = self.parent_dir {
            dir.join(&*path)
        }
        else if let Some(parent) = self.path.parent() {
            parent.join(&*path)
        }
        else {
            self.path.join(&*path)
        }
    }

    /// Again assuming this file is a symlink, follows that link and returns
    /// the result of following it.
    ///
    /// For a working symlink that the user is allowed to follow,
    /// this will be the `File` object at the other end, which can then have
    /// its name, colour, and other details read.
    ///
    /// For a broken symlink, returns where the file *would* be, if it
    /// existed. If this file cannot be read at all, returns the error that