feat(filter): --cachedir-ignore option

README.md

@@ -112,6 +112,7 @@ eza’s options are almost, but not quite, entirely unlike `ls`’s. Quick overv
 - **-f**, **--only-files**: list only files
 - **--git-ignore**: ignore files mentioned in `.gitignore`
 - **-I**, **--ignore-glob=(globs)**: glob patterns (pipe-separated) of files to ignore
+- **--cachedir-ignore**: Ignore directories with a `CACHEDIR.TAG` file.
 
 Pass the `--all` option twice to also show the `.` and `..` directories.
 

completions/fish/eza.fish

@@ -48,6 +48,7 @@ complete -c eza -l smart-group -d "Only show group if it has a different name fr
 # Filtering and sorting options
 complete -c eza -l group-directories-first -d "Sort directories before other files"
 complete -c eza -l git-ignore -d "Ignore files mentioned in '.gitignore'"
+complete -c eza -l cachedir-ignore -d "Ignore directories with a 'CACHEDIR.TAG' file"
 complete -c eza -s a -l all -d "Show hidden and 'dot' files. Use this twice to also show the '.' and '..' directories"
 complete -c eza -s A -l almost-all -d "Equivalent to --all; included for compatibility with `ls -A`"
 complete -c eza -s d -l list-dirs -d "List directories like regular files"

completions/nush/eza.nu

@@ -21,6 +21,7 @@ export extern "eza" [
     --absolute                 # Display entries with their absolute path
     --group-directories-first  # Sort directories before other files
     --git-ignore               # Ignore files mentioned in '.gitignore'
+    --cachedir-ignore          # Ignore directories with a 'CACHEDIR.TAG' file
     --all(-a)                  # Show hidden and 'dot' files. Use this twice to also show the '.' and '..' directories
     --almost-all(-A)           # Equivalent to --all; included for compatibility with `ls -A`
     --list-dirs(-d)            # List directories like regular files

completions/zsh/_eza

@@ -29,6 +29,7 @@ __eza() {
         --absolute"[Display entries with their absolute path]:(mode):(on follow off)" \
         --group-directories-first"[Sort directories before other files]" \
         --git-ignore"[Ignore files mentioned in '.gitignore']" \
+        --ignore-cachedir"[Ignore directories with a 'CACHEDIR.TAG' file]" \
         {-a,--all}"[Show hidden and 'dot' files. Use this twice to also show the '.' and '..' directories]" \
         {-A,--almost-all}"[Equivalent to --all; included for compatibility with \'ls -A\']" \
         {-d,--list-dirs}"[List directories like regular files]" \

man/eza.1.md

@@ -154,6 +154,9 @@ Sort fields starting with a capital letter will sort uppercase before lowercase:
 `-I`, `--ignore-glob=GLOBS`
 : Glob patterns, pipe-separated, of files to ignore.
 
+`--ignore-cachedir`
+: Ignore directories with a 'CACHEDIR.TAG' file.
+
 `--git-ignore` [if eza was built with git support]
 : Do not list files that are ignored by Git.
 

src/fs/filter.rs

@@ -8,6 +8,9 @@ use std::os::unix::fs::MetadataExt;
 use crate::fs::DotFilter;
 use crate::fs::File;
 
+/// magic number of CACHEDIR.TAG files
+const CACHEDIR_MAGIC: &[u8; 43] = b"Signature: 8a477f597d28d172789f06886806bc55";
+
 /// Flags used to manage the **file filter** process
 #[derive(PartialEq, Eq, Debug, Clone)]
 pub enum FileFilterFlags {
@@ -68,6 +71,10 @@ pub struct FileFilter {
 
     /// Whether to ignore Git-ignored patterns.
     pub git_ignore: GitIgnore,
+
+    /// Whether to ignore CACHEDIR.TAG directories.
+    /// see also https://bford.info/cachedir/
+    pub ignore_cachedir: IgnoreCacheDir,
 }
 
 impl FileFilter {
@@ -77,6 +84,7 @@ impl FileFilter {
         use FileFilterFlags::{OnlyDirs, OnlyFiles};
 
         files.retain(|f| !self.ignore_patterns.is_ignored(&f.name));
+        self.filter_cachedirs(files);
 
         match (
             self.flags.contains(&OnlyDirs),
@@ -94,6 +102,53 @@ impl FileFilter {
         }
     }
 
+    /// remove directories if they contain a CACHEDIR.TAG with the correct signature.
+    /// does nothing if `self.cachedir_ignore == Off`
+    pub fn filter_cachedirs(&self, files: &mut Vec<File<'_>>) {
+        if self.ignore_cachedir == IgnoreCacheDir::CheckAndIgnore {
+            files.retain(|f| {
+                if !f.is_directory() {
+                    return true;
+                }
+                let Ok(read_dir) = std::fs::read_dir(&f.path) else {
+                    return true;
+                };
+                let mut found_tag = false;
+                for child in read_dir {
+                    let Ok(child) = child else {
+                        continue;
+                    };
+                    let is_cachedir_tag = Self::is_cachedir_tag(&child.path());
+                    if is_cachedir_tag {
+                        found_tag = true;
+                        break;
+                    }
+                }
+                !found_tag
+            });
+        }
+    }
+
+    /// check if `path` is named "CACHEDIR.TAG" and has the correct magic number ([`CACHEDIR_MAGIC`]).
+    fn is_cachedir_tag(path: &std::path::Path) -> bool {
+        use std::ffi::OsStr;
+        use std::io::Read;
+        if path.file_name() != Some(OsStr::new("CACHEDIR.TAG")) {
+            return false;
+        }
+        if path.is_symlink() {
+            return false;
+        }
+        let Ok(mut reader) = std::fs::File::open(path) else {
+            return false;
+        };
+        let mut buf = [0u8; 43];
+        let Ok(()) = reader.read_exact(&mut buf) else {
+            return false;
+        };
+        &buf == CACHEDIR_MAGIC
+    }
+
     /// Remove every file in the given vector that does *not* pass the
     /// filter predicate for file names specified on the command-line.
     ///
@@ -354,6 +409,15 @@ pub enum GitIgnore {
     Off,
 }
 
+/// Whether to ignore or display files that Git would ignore.
+#[derive(PartialEq, Eq, Debug, Copy, Clone)]
+pub enum IgnoreCacheDir {
+    /// Ignore directories with CACHEDIR.TAG and have the correct signature
+    CheckAndIgnore,
+    /// Do not check for CACHEDIR.TAG
+    Off,
+}
+
 #[cfg(test)]
 mod test_ignores {
     use super::*;

src/options/filter.rs

@@ -1,7 +1,7 @@
 //! Parsing the options for `FileFilter`.
 
 use crate::fs::filter::{
-    FileFilter, FileFilterFlags, GitIgnore, IgnorePatterns, SortCase, SortField,
+    FileFilter, FileFilterFlags, GitIgnore, IgnoreCacheDir, IgnorePatterns, SortCase, SortField,
 };
 use crate::fs::DotFilter;
 
@@ -32,6 +32,7 @@ impl FileFilter {
             dot_filter:       DotFilter::deduce(matches)?,
             ignore_patterns:  IgnorePatterns::deduce(matches)?,
             git_ignore:       GitIgnore::deduce(matches)?,
+            ignore_cachedir:  IgnoreCacheDir::deduce(matches)?,
         });
     }
 }
@@ -193,6 +194,16 @@ impl GitIgnore {
     }
 }
 
+impl IgnoreCacheDir {
+    pub fn deduce(matches: &MatchedFlags<'_>) -> Result<Self, OptionsError> {
+        if matches.has(&flags::IGNORE_CACHEDIR)? {
+            Ok(Self::CheckAndIgnore)
+        } else {
+            Ok(Self::Off)
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;

src/options/flags.rs

@@ -30,17 +30,18 @@ const SCALES: Values = &["all", "size", "age"];
 const COLOR_SCALE_MODES: Values = &["fixed", "gradient"];
 
 // filtering and sorting options
-pub static ALL:         Arg = Arg { short: Some(b'a'), long: "all",         takes_value: TakesValue::Forbidden };
-pub static ALMOST_ALL:  Arg = Arg { short: Some(b'A'), long: "almost-all",  takes_value: TakesValue::Forbidden };
-pub static LIST_DIRS:   Arg = Arg { short: Some(b'd'), long: "list-dirs",   takes_value: TakesValue::Forbidden };
-pub static LEVEL:       Arg = Arg { short: Some(b'L'), long: "level",       takes_value: TakesValue::Necessary(None) };
-pub static REVERSE:     Arg = Arg { short: Some(b'r'), long: "reverse",     takes_value: TakesValue::Forbidden };
-pub static SORT:        Arg = Arg { short: Some(b's'), long: "sort",        takes_value: TakesValue::Necessary(Some(SORTS)) };
-pub static IGNORE_GLOB: Arg = Arg { short: Some(b'I'), long: "ignore-glob", takes_value: TakesValue::Necessary(None) };
-pub static GIT_IGNORE:  Arg = Arg { short: None, long: "git-ignore",           takes_value: TakesValue::Forbidden };
-pub static DIRS_FIRST:  Arg = Arg { short: None, long: "group-directories-first",  takes_value: TakesValue::Forbidden };
-pub static ONLY_DIRS:   Arg = Arg { short: Some(b'D'), long: "only-dirs", takes_value: TakesValue::Forbidden };
-pub static ONLY_FILES:  Arg = Arg { short: Some(b'f'), long: "only-files", takes_value: TakesValue::Forbidden };
+pub static ALL:              Arg = Arg { short: Some(b'a'), long: "all",         takes_value: TakesValue::Forbidden };
+pub static ALMOST_ALL:       Arg = Arg { short: Some(b'A'), long: "almost-all",  takes_value: TakesValue::Forbidden };
+pub static LIST_DIRS:        Arg = Arg { short: Some(b'd'), long: "list-dirs",   takes_value: TakesValue::Forbidden };
+pub static LEVEL:            Arg = Arg { short: Some(b'L'), long: "level",       takes_value: TakesValue::Necessary(None) };
+pub static REVERSE:          Arg = Arg { short: Some(b'r'), long: "reverse",     takes_value: TakesValue::Forbidden };
+pub static SORT:             Arg = Arg { short: Some(b's'), long: "sort",        takes_value: TakesValue::Necessary(Some(SORTS)) };
+pub static IGNORE_GLOB:      Arg = Arg { short: Some(b'I'), long: "ignore-glob", takes_value: TakesValue::Necessary(None) };
+pub static GIT_IGNORE:       Arg = Arg { short: None, long: "git-ignore",        takes_value: TakesValue::Forbidden };
+pub static IGNORE_CACHEDIR:  Arg = Arg { short: None, long: "ignore-cachedir",   takes_value: TakesValue::Forbidden };
+pub static DIRS_FIRST:       Arg = Arg { short: None, long: "group-directories-first",  takes_value: TakesValue::Forbidden };
+pub static ONLY_DIRS:        Arg = Arg { short: Some(b'D'), long: "only-dirs", takes_value: TakesValue::Forbidden };
+pub static ONLY_FILES:       Arg = Arg { short: Some(b'f'), long: "only-files", takes_value: TakesValue::Forbidden };
 const SORTS: Values = &[ "name", "Name", "size", "extension",
                          "Extension", "modified", "changed", "accessed",
                          "created", "inode", "type", "none" ];
@@ -93,7 +94,7 @@ pub static ALL_ARGS: Args = Args(&[
     &WIDTH, &NO_QUOTES, &ABSOLUTE,
 
     &ALL, &ALMOST_ALL, &LIST_DIRS, &LEVEL, &REVERSE, &SORT, &DIRS_FIRST,
-    &IGNORE_GLOB, &GIT_IGNORE, &ONLY_DIRS, &ONLY_FILES,
+    &IGNORE_GLOB, &GIT_IGNORE, &IGNORE_CACHEDIR, &ONLY_DIRS, &ONLY_FILES,
 
     &BINARY, &BYTES, &GROUP, &NUMERIC, &HEADER, &ICONS, &INODE, &LINKS, &MODIFIED, &CHANGED,
     &BLOCKSIZE, &TOTAL_SIZE, &TIME, &ACCESSED, &CREATED, &TIME_STYLE, &HYPERLINK, &MOUNTS,

src/options/help.rs

@@ -41,7 +41,8 @@ FILTERING AND SORTING OPTIONS
   --group-directories-first  list directories before other files
   -D, --only-dirs            list only directories
   -f, --only-files           list only files
-  -I, --ignore-glob GLOBS    glob patterns (pipe-separated) of files to ignore";
+  -I, --ignore-glob GLOBS    glob patterns (pipe-separated) of files to ignore
+  --cachedir-ignore          ignore directories with a 'CACHEDIR.TAG' file";
 
 static GIT_FILTER_HELP: &str = "  \
   --git-ignore               ignore files mentioned in '.gitignore'";
@@ -78,7 +79,7 @@ LONG VIEW OPTIONS
   --no-filesize              suppress the filesize field
   --no-user                  suppress the user field
   --no-time                  suppress the time field
-  --stdin                    read file names from stdin, one per line or other separator 
+  --stdin                    read file names from stdin, one per line or other separator
                              specified in environment";
 
 static GIT_VIEW_HELP: &str = "  \