From 379b9c8be30ee14eb8703ec00c7ea5da5337c6b6 Mon Sep 17 00:00:00 2001
From: Artturin <Artturin@artturin.com>
Date: Tue, 5 Apr 2022 01:10:44 +0300
Subject: [PATCH] lib/meta: add getExe to get the main program of a drv

---
 lib/default.nix |  2 +-
 lib/meta.nix    | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/lib/default.nix b/lib/default.nix
index 1f06283790a8..ec7f536bbdde 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -108,7 +108,7 @@ let
       makeScope makeScopeWithSplicing;
     inherit (self.meta) addMetaAttrs dontDistribute setName updateName
       appendToName mapDerivationAttrset setPrio lowPrio lowPrioSet hiPrio
-      hiPrioSet getLicenseFromSpdxId;
+      hiPrioSet getLicenseFromSpdxId getExe;
     inherit (self.sources) pathType pathIsDirectory cleanSourceFilter
       cleanSource sourceByRegex sourceFilesBySuffices
       commitIdFromGitRepo cleanSourceWith pathHasContext
diff --git a/lib/meta.nix b/lib/meta.nix
index 5b1f7ee5ff2d..74b94211552b 100644
--- a/lib/meta.nix
+++ b/lib/meta.nix
@@ -126,4 +126,18 @@ rec {
         lib.warn "getLicenseFromSpdxId: No license matches the given SPDX ID: ${licstr}"
         { shortName = licstr; }
       );
+
+  /* Get the path to the main program of a derivation with either
+     meta.mainProgram or pname or name
+
+     Type: getExe :: derivation -> string
+
+     Example:
+       getExe pkgs.hello
+       => "/nix/store/g124820p9hlv4lj8qplzxw1c44dxaw1k-hello-2.12/bin/hello"
+       getExe pkgs.mustache-go
+       => "/nix/store/am9ml4f4ywvivxnkiaqwr0hyxka1xjsf-mustache-go-1.3.0/bin/mustache"
+  */
+  getExe = x:
+    "${lib.getBin x}/bin/${x.meta.mainProgram or (lib.getName x)}";
 }