do not allow to ignore gitignore (fixes #825)

Author: Stephan Dilly

Diff for: CHANGELOG.md

@@ -7,6 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+## Fixed
+- do not allow to ignore .gitignore files ([#825](https://github.com/extrawurst/gitui/issues/825))
+
 ## [0.16.2] - 2021-07-10
 
 **undo last commit**

Diff for: asyncgit/src/sync/ignore.rs

@@ -1,5 +1,5 @@
 use super::utils::{repo, work_dir};
-use crate::error::Result;
+use crate::error::{Error, Result};
 use scopetime::scope_time;
 use std::{
     fs::{File, OpenOptions},
@@ -18,6 +18,14 @@ pub fn add_to_ignore(
 
     let repo = repo(repo_path)?;
 
+    if Path::new(path_to_ignore).file_name()
+        == Path::new(GITIGNORE).file_name()
+    {
+        return Err(Error::Generic(String::from(
+            "cannot ignore gitignore",
+        )));
+    }
+
     let ignore_file = work_dir(&repo)?.join(GITIGNORE);
 
     let optional_newline = ignore_file.exists()
@@ -52,8 +60,9 @@ fn file_ends_with_newline(file: &Path) -> Result<bool> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::sync::tests::repo_init;
+    use crate::sync::{tests::repo_init, utils::repo_write_file};
     use io::BufRead;
+    use pretty_assertions::assert_eq;
     use std::{fs::File, io, path::Path};
 
     #[test]
@@ -124,4 +133,20 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn test_ignore_ignore() {
+        let ignore_file_path = Path::new(".gitignore");
+        let (_td, repo) = repo_init().unwrap();
+        let root = repo.path().parent().unwrap();
+        let repo_path = root.as_os_str().to_str().unwrap();
+
+        repo_write_file(&repo, ".gitignore", "#foo").unwrap();
+
+        let res = add_to_ignore(repo_path, ".gitignore");
+        assert!(res.is_err());
+
+        let lines = read_lines(&root.join(ignore_file_path)).unwrap();
+        assert_eq!(lines.count(), 1);
+    }
 }