Add getDefaultProfile() function

src/libstore/profiles.cc

@@ -256,4 +256,22 @@ string optimisticLockProfile(const Path & profile)
 }
 
 
+Path getDefaultProfile()
+{
+    Path profileLink = getHome() + "/.nix-profile";
+    try {
+        if (!pathExists(profileLink)) {
+            replaceSymlink(
+                getuid() == 0
+                ? settings.nixStateDir + "/profiles/default"
+                : fmt("%s/profiles/per-user/%s/profile", settings.nixStateDir, getUserName()),
+                profileLink);
+        }
+        return absPath(readLink(profileLink), dirOf(profileLink));
+    } catch (Error &) {
+        return profileLink;
+    }
+}
+
+
 }

src/libstore/profiles.hh

@@ -64,4 +64,8 @@ void lockProfile(PathLocks & lock, const Path & profile);
    rebuilt. */
 string optimisticLockProfile(const Path & profile);
 
+/* Resolve ~/.nix-profile. If ~/.nix-profile doesn't exist yet, create
+   it. */
+Path getDefaultProfile();
+
 }

src/nix-env/nix-env.cc

@@ -1427,21 +1427,8 @@ static int _main(int argc, char * * argv)
         if (globals.profile == "")
             globals.profile = getEnv("NIX_PROFILE", "");
 
-        if (globals.profile == "") {
-            Path profileLink = getHome() + "/.nix-profile";
-            try {
-                if (!pathExists(profileLink)) {
-                    replaceSymlink(
-                        getuid() == 0
-                        ? settings.nixStateDir + "/profiles/default"
-                        : fmt("%s/profiles/per-user/%s/profile", settings.nixStateDir, getUserName()),
-                        profileLink);
-                }
-                globals.profile = absPath(readLink(profileLink), dirOf(profileLink));
-            } catch (Error &) {
-                globals.profile = profileLink;
-            }
-        }
+        if (globals.profile == "")
+            globals.profile = getDefaultProfile();
 
         op(globals, opFlags, opArgs);