feat(fossil): detection of Fossil check-outs in subdirectories (#4910)

* Move PathExt::device_id() outside modules module

* Add upwards_sibling_scan-function

* Fix Fossil check-out detection in subdirectories

* Use shared upwards scanning function in hg_branch

* Let the caller specify if they're looking for a file or a folder

* fix merge

---------

Co-authored-by: David Knaack <davidkna@users.noreply.github.com>

6 files changed, 106 insertions, 51 deletions

diff --git a/src/context.rs b/src/context.rs
index 0994a8e55..b0bfc0fd5 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -1,7 +1,7 @@
 use crate::config::{ModuleConfig, StarshipConfig};
 use crate::configs::StarshipRootConfig;
 use crate::module::Module;
-use crate::utils::{create_command, exec_timeout, read_file, CommandOutput};
+use crate::utils::{create_command, exec_timeout, read_file, CommandOutput, PathExt};
 
 use crate::modules;
 use crate::utils::{self, home_dir};
@@ -248,6 +248,16 @@ impl<'a> Context<'a> {
         })
     }
 
+    /// Begins an ancestor scan at the current directory, see [`ScanAncestors`] for available
+    /// methods.
+    pub fn begin_ancestor_scan(&'a self) -> ScanAncestors<'a> {
+        ScanAncestors {
+            path: &self.current_dir,
+            files: &[],
+            folders: &[],
+        }
+    }
+
     /// Will lazily get repo root and branch when a module requests it.
     pub fn get_repo(&self) -> Result<&Repo, Box<gix::discover::Error>> {
         self.repo
@@ -607,6 +617,48 @@ impl<'a> ScanDir<'a> {
     }
 }
 
+/// Scans the ancestors of a given path until a directory containing one of the given files or
+/// folders is found.
+pub struct ScanAncestors<'a> {
+    path: &'a Path,
+    files: &'a [&'a str],
+    folders: &'a [&'a str],
+}
+
+impl<'a> ScanAncestors<'a> {
+    #[must_use]
+    pub const fn set_files(mut self, files: &'a [&'a str]) -> Self {
+        self.files = files;
+        self
+    }
+
+    #[must_use]
+    pub const fn set_folders(mut self, folders: &'a [&'a str]) -> Self {
+        self.folders = folders;
+        self
+    }
+
+    /// Scans upwards starting from the initial path until a directory containing one of the given
+    /// files or folders is found.
+    ///
+    /// The scan does not cross device boundaries.
+    pub fn scan(&self) -> Option<&'a Path> {
+        let initial_device_id = self.path.device_id();
+        for dir in self.path.ancestors() {
+            if initial_device_id != dir.device_id() {
+                break;
+            }
+
+            if self.files.iter().any(|name| dir.join(name).is_file())
+                || self.folders.iter().any(|name| dir.join(name).is_dir())
+            {
+                return Some(dir);
+            }
+        }
+        None
+    }
+}
+
 fn get_current_branch(repository: &Repository) -> Option<String> {
     let name = repository.head_name().ok()??;
     let shorthand = name.shorten();
diff --git a/src/modules/fossil_branch.rs b/src/modules/fossil_branch.rs
index da4dabbdb..7cc4d331b 100644
--- a/src/modules/fossil_branch.rs
+++ b/src/modules/fossil_branch.rs
@@ -22,15 +22,11 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
     } else {
         ".fslckout"
     };
-
-    let is_checkout = context
-        .try_begin_scan()?
+    // See if we're in a check-out by scanning upwards for a directory containing the checkout_db file
+    context
+        .begin_ancestor_scan()
         .set_files(&[checkout_db])
-        .is_match();
-
-    if !is_checkout {
-        return None;
-    }
+        .scan()?;
 
     let len = if config.truncation_length <= 0 {
         log::warn!(
@@ -144,6 +140,18 @@ mod tests {
     }
 
     #[test]
+    fn test_fossil_branch_subdir() -> io::Result<()> {
+        let tempdir = fixture_repo(FixtureProvider::Fossil)?;
+        let checkout_dir = tempdir.path();
+        expect_fossil_branch_with_config(
+            &checkout_dir.join("subdir"),
+            None,
+            &[Expect::BranchName("topic-branch"), Expect::NoTruncation],
+        );
+        tempdir.close()
+    }
+
+    #[test]
     fn test_fossil_branch_configured() -> io::Result<()> {
         let tempdir = fixture_repo(FixtureProvider::Fossil)?;
         let checkout_dir = tempdir.path();
diff --git a/src/modules/hg_branch.rs b/src/modules/hg_branch.rs
index 8a9f84ae2..c4c4a2a30 100644
--- a/src/modules/hg_branch.rs
+++ b/src/modules/hg_branch.rs
@@ -1,4 +1,4 @@
-use std::io::{Error, ErrorKind};
+use std::io::Error;
 use std::path::Path;
 
 use super::utils::truncate::truncate_text;
@@ -6,7 +6,6 @@ use super::{Context, Module, ModuleConfig};
 
 use crate::configs::hg_branch::HgBranchConfig;
 use crate::formatter::StringFormatter;
-use crate::modules::utils::path::PathExt;
 use crate::utils::read_file;
 
 /// Creates a module with the Hg bookmark or branch in the current directory
@@ -32,7 +31,7 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
         config.truncation_length as usize
     };
 
-    let repo_root = get_hg_repo_root(context).ok()?;
+    let repo_root = context.begin_ancestor_scan().set_folders(&[".hg"]).scan()?;
     let branch_name = get_hg_current_bookmark(repo_root).unwrap_or_else(|_| {
         get_hg_branch_name(repo_root).unwrap_or_else(|_| String::from("default"))
     });
@@ -73,20 +72,6 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
     Some(module)
 }
 
-fn get_hg_repo_root<'a>(ctx: &'a Context) -> Result<&'a Path, Error> {
-    let dir = ctx.current_dir.as_path();
-    let dev_id = dir.device_id();
-    for root_dir in dir.ancestors() {
-        if dev_id != root_dir.device_id() {
-            break;
-        }
-        if root_dir.join(".hg").is_dir() {
-            return Ok(root_dir);
-        }
-    }
-    Err(Error::new(ErrorKind::Other, "No .hg found!"))
-}
-
 fn get_hg_branch_name(hg_root: &Path) -> Result<String, Error> {
     match read_file(hg_root.join(".hg").join("branch")) {
         Ok(b) => Ok(b.trim().to_string()),
diff --git a/src/modules/utils/path.rs b/src/modules/utils/path.rs
index 5f5ad4847..2bbb02b51 100644
--- a/src/modules/utils/path.rs
+++ b/src/modules/utils/path.rs
@@ -13,8 +13,6 @@ pub trait PathExt {
     /// E.g. `\\?\UNC\server\share\foo` => `\foo`
     /// E.g. `/foo/bar` => `/foo/bar`
     fn without_prefix(&self) -> &Path;
-    /// Get device / volume info
-    fn device_id(&self) -> Option<u64>;
 }
 
 #[cfg(windows)]
@@ -82,11 +80,6 @@ impl PathExt for Path {
         let (_, path) = normalize::normalize_path(self);
         path
     }
-
-    fn device_id(&self) -> Option<u64> {
-        // Maybe it should use unimplemented!
-        Some(42u64)
-    }
 }
 
 // NOTE: Windows path prefixes are only parsed on Windows.
@@ -107,24 +100,6 @@ impl PathExt for Path {
     fn without_prefix(&self) -> &Path {
         self
     }
-
-    #[cfg(target_os = "linux")]
-    fn device_id(&self) -> Option<u64> {
-        use std::os::linux::fs::MetadataExt;
-        match self.metadata() {
-            Ok(m) => Some(m.st_dev()),
-            Err(_) => None,
-        }
-    }
-
-    #[cfg(all(unix, not(target_os = "linux")))]
-    fn device_id(&self) -> Option<u64> {
-        use std::os::unix::fs::MetadataExt;
-        match self.metadata() {
-            Ok(m) => Some(m.dev()),
-            Err(_) => None,
-        }
-    }
 }
 
 #[cfg(test)]
diff --git a/src/test/mod.rs b/src/test/mod.rs
index 48bb51ad3..23b0d6fb3 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -182,6 +182,7 @@ pub fn fixture_repo(provider: FixtureProvider) -> io::Result<TempDir> {
                 ".fslckout"
             };
             let path = tempfile::tempdir()?;
+            fs::create_dir(path.path().join("subdir"))?;
             fs::OpenOptions::new()
                 .create(true)
                 .write(true)
diff --git a/src/utils.rs b/src/utils.rs
index 54b9e7393..aad9f297a 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -644,6 +644,40 @@ pub fn encode_to_hex(slice: &[u8]) -> String {
     String::from_utf8(dst).unwrap()
 }
 
+pub trait PathExt {
+    /// Get device / volume info
+    fn device_id(&self) -> Option<u64>;
+}
+
+#[cfg(windows)]
+impl PathExt for Path {
+    fn device_id(&self) -> Option<u64> {
+        // Maybe it should use unimplemented!
+        Some(42u64)
+    }
+}
+
+#[cfg(not(windows))]
+impl PathExt for Path {
+    #[cfg(target_os = "linux")]
+    fn device_id(&self) -> Option<u64> {
+        use std::os::linux::fs::MetadataExt;
+        match self.metadata() {
+            Ok(m) => Some(m.st_dev()),
+            Err(_) => None,
+        }
+    }
+
+    #[cfg(all(unix, not(target_os = "linux")))]
+    fn device_id(&self) -> Option<u64> {
+        use std::os::unix::fs::MetadataExt;
+        match self.metadata() {
+            Ok(m) => Some(m.dev()),
+            Err(_) => None,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;