Perform tilde expansion when completing flake fragments

Allows completing `nix build ~/flake#<Tab>`.
We can implement expansion for `~user` later if needed.
Not using wordexp(3) since that expands way too much.

3 files changed, 18 insertions, 3 deletions

diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index b60c609a6..10f01af5b 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -282,12 +282,13 @@ static void _completePath(std::string_view prefix, bool onlyDirs)
 {
     completionType = ctFilenames;
     glob_t globbuf;
-    int flags = GLOB_NOESCAPE | GLOB_TILDE;
+    int flags = GLOB_NOESCAPE;
     #ifdef GLOB_ONLYDIR
     if (onlyDirs)
         flags |= GLOB_ONLYDIR;
     #endif
-    if (glob((std::string(prefix) + "*").c_str(), flags, nullptr, &globbuf) == 0) {
+    // using expandTilde here instead of GLOB_TILDE(_CHECK) so that ~<Tab> expands to /home/user/
+    if (glob((expandTilde(prefix) + "*").c_str(), flags, nullptr, &globbuf) == 0) {
         for (size_t i = 0; i < globbuf.gl_pathc; ++i) {
             if (onlyDirs) {
                 auto st = stat(globbuf.gl_pathv[i]);
@@ -295,8 +296,8 @@ static void _completePath(std::string_view prefix, bool onlyDirs)
             }
             completions->add(globbuf.gl_pathv[i]);
         }
-        globfree(&globbuf);
     }
+    globfree(&globbuf);
 }
 
 void completePath(size_t, std::string_view prefix)
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index deaa17a7f..d9db24397 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -200,6 +200,17 @@ std::string_view baseNameOf(std::string_view path)
 }
 
 
+std::string expandTilde(std::string_view path)
+{
+    // TODO: expand ~user ?
+    auto tilde = path.substr(0, 2);
+    if (tilde == "~/" || tilde == "~")
+        return getHome() + std::string(path.substr(1));
+    else
+        return std::string(path);
+}
+
+
 bool isInDir(std::string_view path, std::string_view dir)
 {
     return path.substr(0, 1) == "/"
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 94ae8ab7d..a1d0e0e6b 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -68,6 +68,9 @@ Path dirOf(const PathView path);
    following the final `/' (trailing slashes are removed). */
 std::string_view baseNameOf(std::string_view path);
 
+/* Perform tilde expansion on a path. */
+std::string expandTilde(std::string_view path);
+
 /* Check whether 'path' is a descendant of 'dir'. Both paths must be
    canonicalized. */
 bool isInDir(std::string_view path, std::string_view dir);