Add --system flag for system-wide install/disable

Cargo.toml

@@ -6,6 +6,7 @@ edition = "2024"
 [dependencies]
 clap = { version = "4.5.57", features = ["derive"] }
 env_logger = "0.11.9"
+libc = "0.2.183"
 log = "0.4.29"
 serde = { version = "1.0.228", features = ["derive"] }
 serde_yaml = "0.9.34"

README.md

@@ -27,13 +27,25 @@ for repo configs), where `<ext>` is `yml`, `yaml`, `json`, `jsonc`, or `toml`.
 
 ### `lhm install`
 
-- Creates symlinks for all standard git hooks in `~/.lhm/hooks/`, each pointing to the `lhm` binary
-- Sets `git config --global core.hooksPath ~/.lhm/hooks`
-- Writes a default `~/.lefthook.yaml` if no global config exists
+- Creates symlinks for all standard git hooks in `~/.local/libexec/lhm/hooks/`, each pointing to the `lhm` binary
+- Sets `git config --global core.hooksPath ~/.local/libexec/lhm/hooks`
+- Writes a default `~/.local/etc/lefthook.yaml` if no user config exists
+
+### `lhm install --system`
+
+Same as `lhm install` but targets a system-wide location (requires root):
+
+- Creates symlinks in `/usr/local/libexec/lhm/hooks/`
+- Sets `git config --system core.hooksPath /usr/local/libexec/lhm/hooks`
+- Writes a default `/usr/local/etc/lefthook.yaml` if no system config exists
 
 ### `lhm disable`
 
-Unsets `git config --global core.hooksPath`, disabling lhm. The hook symlinks in `~/.lhm/hooks/` are left in place so `lhm install` can re-enable quickly.
+Unsets `git config --global core.hooksPath`, disabling lhm. The hook symlinks in `~/.local/libexec/lhm/hooks/` are left in place so `lhm install` can re-enable quickly.
+
+### `lhm disable --system`
+
+Unsets `git config --system core.hooksPath` (requires root). The hook symlinks in `/usr/local/libexec/lhm/hooks/` are left in place.
 
 ### `lhm dry-run`
 
@@ -61,18 +73,23 @@ LHM_LOCAL_CONFIG=./other.yml git commit
 
 ### Hook execution
 
-When git triggers a hook, it invokes the symlink in `~/.lhm/hooks/`. `lhm` detects the hook name from `argv[0]` and:
+When git triggers a hook, it invokes the symlink in the hooks directory. `lhm` detects the hook name from `argv[0]` and:
 
 0. **lefthook not in PATH**: falls back to executing `.git/hooks/<hook>` directly (if it exists), bypassing all config merging
-1. **No config at all** (no global, no repo, no adapter): hook is skipped silently
-2. **Both configs exist** (`~/.lefthook.yaml` + `$REPO/lefthook.yaml`): merges global and repo configs, runs `lefthook run <hook>` with `LEFTHOOK_CONFIG` pointing to the merged temp file
-3. **Global only** (no repo config or adapter): runs `lefthook run <hook>` with the global config
-4. **Repo/adapter only** (no global config): runs `lefthook run <hook>` with the repo or adapter config
-5. **No repo config, but adapter detected**: generates a dynamic lefthook config from the adapter, merges it with the global config (if present), and runs `lefthook run <hook>`
+1. **No config at all** (no system, no global, no repo, no adapter): hook is skipped silently
+2. **Configs exist**: merges all available layers in order (system, global, repo/adapter), runs `lefthook run <hook>` with `LEFTHOOK_CONFIG` pointing to the merged temp file
+
+Config is resolved as a three-layer merge, where later layers override earlier ones:
+
+1. **System** (`/usr/local/etc/lefthook.yaml`) — organizational baseline
+2. **User global** (`~/.local/etc/lefthook.yaml`) — per-user overrides
+3. **Repo** (`$REPO/lefthook.yaml` or adapter) — per-repo overrides
+
+Any layer may be absent. When a repo has no lefthook config, the adapter system is used in its place (see below).
 
 ### Adapters
 
-When a repo has no `lefthook.yaml`, lhm checks for other git hook managers and transparently adapts them. The generated adapter config is merged with `~/.lefthook.yaml` using the standard merging system, so global hooks still apply.
+When a repo has no `lefthook.yaml`, lhm checks for other git hook managers and transparently adapts them. The generated adapter config is merged with `~/.local/etc/lefthook.yaml` using the standard merging system, so global hooks still apply.
 
 Adapters are tried in this order (first match wins):
 

src/config.rs

@@ -6,6 +6,9 @@ use std::io::Write;
 use std::path::{Path, PathBuf};
 use tempfile::NamedTempFile;
 
+/// System-wide config directory.
+pub const SYSTEM_CONFIG_DIR: &str = "/usr/local/etc";
+
 /// Overrides for the global and local (repo) config paths.
 /// CLI flags take precedence; env vars (`LHM_GLOBAL_CONFIG`, `LHM_LOCAL_CONFIG`)
 /// are used as fallback so that overrides work during hook invocations too.
@@ -81,6 +84,7 @@ pub fn find_config(dir: &Path, check_dot_config: bool) -> Option<PathBuf> {
     None
 }
 
+/// Find the user-level lefthook config in the given directory (e.g. `~/.local/etc`).
 pub fn global_config(home: &Path, overrides: &ConfigOverrides) -> Option<PathBuf> {
     if let Some(ref p) = overrides.global_config {
         debug!("using global config override: {}", p.display());
@@ -89,6 +93,11 @@ pub fn global_config(home: &Path, overrides: &ConfigOverrides) -> Option<PathBuf
     find_config(home, false)
 }
 
+/// Find the system-wide lefthook config in `/usr/local/etc`.
+pub fn system_config() -> Option<PathBuf> {
+    find_config(Path::new(SYSTEM_CONFIG_DIR), false)
+}
+
 pub fn repo_config(root: &Path, overrides: &ConfigOverrides) -> Option<PathBuf> {
     if let Some(ref p) = overrides.local_config {
         debug!("using local config override: {}", p.display());
@@ -97,24 +106,41 @@ pub fn repo_config(root: &Path, overrides: &ConfigOverrides) -> Option<PathBuf>
     find_config(root, true)
 }
 
-/// Write the default global config to `~/.lefthook.yaml` if no global config exists.
-pub fn install_default_global_config(home: &Path) -> Result<(), String> {
-    if find_config(home, false).is_some() {
+/// Write a default `lefthook.yaml` in `dir` if no lefthook config exists there.
+pub fn install_default_global_config(dir: &Path) -> Result<(), String> {
+    if find_config(dir, false).is_some() {
         debug!("global config already exists, skipping default");
         return Ok(());
     }
-    let path = home.join(".lefthook.yaml");
+    let path = dir.join("lefthook.yaml");
+    if let Some(parent) = path.parent() {
+        fs::create_dir_all(parent).map_err(|e| format!("failed to create {}: {e}", parent.display()))?;
+    }
     fs::write(&path, DEFAULT_GLOBAL_CONFIG).map_err(|e| format!("failed to write {}: {e}", path.display()))?;
     info!("created default global config at {}", path.display());
     Ok(())
 }
 
-/// Load the global config from `~/.lefthook.yaml` (or override) if it exists.
-pub fn load_global_config(home: &Path, overrides: &ConfigOverrides) -> Result<Option<Value>, String> {
-    match global_config(home, overrides) {
+/// Load the user-level config from `~/.local/etc/lefthook.yaml` (or override) if it exists.
+pub fn load_global_config(dir: &Path, overrides: &ConfigOverrides) -> Result<Option<Value>, String> {
+    match global_config(dir, overrides) {
         Some(path) => read_yaml(&path).map(Some),
         None => {
-            debug!("no global config file found");
+            debug!("no user config file found");
+            Ok(None)
+        }
+    }
+}
+
+/// Load the system-wide config from `/usr/local/etc/lefthook.yaml` if it exists.
+pub fn load_system_config() -> Result<Option<Value>, String> {
+    match system_config() {
+        Some(path) => {
+            debug!("system config: {}", path.display());
+            read_yaml(&path).map(Some)
+        }
+        None => {
+            debug!("no system config file found");
             Ok(None)
         }
     }
@@ -212,7 +238,7 @@ mod tests {
         let dir = tempfile::tempdir().unwrap();
         install_default_global_config(dir.path()).unwrap();
 
-        let created = dir.path().join(".lefthook.yaml");
+        let created = dir.path().join("lefthook.yaml");
         assert!(created.is_file());
         let content = fs::read_to_string(&created).unwrap();
         assert!(content.contains("pre-push:"));
@@ -229,8 +255,8 @@ mod tests {
 
         // Original file untouched
         assert_eq!(fs::read_to_string(&existing).unwrap(), "custom: true\n");
-        // No .lefthook.yaml created
-        assert!(!dir.path().join(".lefthook.yaml").exists());
+        // No lefthook.yaml created
+        assert!(!dir.path().join("lefthook.yaml").exists());
     }
 
     #[test]