fs: assert unsafe operations are run on safe paths only

3 files changed, 23 insertions, 7 deletions

diff --git a/lua/nvim-lsp-installer/fs.lua b/lua/nvim-lsp-installer/fs.lua
index 55809767..0cfaceca 100644
--- a/lua/nvim-lsp-installer/fs.lua
+++ b/lua/nvim-lsp-installer/fs.lua
@@ -1,7 +1,23 @@
+local pathm = require("nvim-lsp-installer.path")
+
 local uv = vim.loop
 local M = {}
 
+local function assert_ownership(path)
+    if not pathm.is_subdirectory(pathm.SERVERS_ROOT_DIR, path) then
+        error(("Refusing to operate on path outside of the servers root dir (%s)."):format(pathm.SERVERS_ROOT_DIR))
+    end
+end
+
+function M.rmrf(path)
+    assert_ownership(path)
+    if vim.fn.delete(path, "rf") ~= 0 then
+        error(("rmrf: Could not remove directory %q."):format(path))
+    end
+end
+
 function M.mkdirp(path)
+    assert_ownership(path)
     if vim.fn.mkdir(path, "p") ~= 1 then
         error(("mkdirp: Could not create directory %q."):format(path))
     end
@@ -28,10 +44,4 @@ function M.fstat(path)
     return assert(uv.fs_fstat(fd))
 end
 
-function M.rmrf(path)
-    if vim.fn.delete(path, "rf") ~= 0 then
-        error(("rmrf: Could not remove directory %q."):format(path))
-    end
-end
-
 return M
diff --git a/lua/nvim-lsp-installer/path.lua b/lua/nvim-lsp-installer/path.lua
index 97e3ed20..25498beb 100644
--- a/lua/nvim-lsp-installer/path.lua
+++ b/lua/nvim-lsp-installer/path.lua
@@ -35,4 +35,10 @@ function M.realpath(relpath, depth)
     return M.concat { vim.fn.fnamemodify(callsite_abs_path, ":h"), relpath }
 end
 
+function M.is_subdirectory(root_path, path)
+    return path:find(root_path) == 1
+end
+
+M.SERVERS_ROOT_DIR = M.concat { vim.fn.stdpath "data", "lsp_servers" }
+
 return M
diff --git a/lua/nvim-lsp-installer/server.lua b/lua/nvim-lsp-installer/server.lua
index 5e3c9e87..e921d2bc 100644
--- a/lua/nvim-lsp-installer/server.lua
+++ b/lua/nvim-lsp-installer/server.lua
@@ -5,7 +5,7 @@ local path = require "nvim-lsp-installer.path"
 local M = {}
 
 function M.get_server_root_path(server)
-    return path.concat { vim.fn.stdpath "data", "lsp_servers", server }
+    return path.concat { path.SERVERS_ROOT_DIR, server }
 end
 
 M.Server = {}