From 207a537343ace1d39ac125059456d832a5237f2e Mon Sep 17 00:00:00 2001
From: zimbatm <zimbatm@zimbatm.com>
Date: Wed, 23 Oct 2019 16:48:28 +0200
Subject: [PATCH] libutil: add editorFor heuristic

---
 src/libutil/args.cc | 13 +++++++++++++
 src/libutil/args.hh |  3 +++
 src/nix/edit.cc     | 17 +++++------------
 src/nix/repl.cc     | 11 ++---------
 4 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index 7af2a1bf7..35ec3e4ab 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -178,6 +178,19 @@ Strings argvToStrings(int argc, char * * argv)
     return args;
 }
 
+Strings editorFor(std::string filename, int lineno)
+{
+    auto editor = getEnv("EDITOR", "cat");
+    auto args = tokenizeString<Strings>(editor);
+    if (lineno > 0 && (
+        editor.find("emacs") != std::string::npos ||
+        editor.find("nano") != std::string::npos ||
+        editor.find("vim") != std::string::npos))
+        args.push_back(fmt("+%d", lineno));
+    args.push_back(filename);
+    return args;
+}
+
 std::string renderLabels(const Strings & labels)
 {
     std::string res;
diff --git a/src/libutil/args.hh b/src/libutil/args.hh
index ad5fcca39..22702c2d8 100644
--- a/src/libutil/args.hh
+++ b/src/libutil/args.hh
@@ -190,6 +190,9 @@ public:
 
 Strings argvToStrings(int argc, char * * argv);
 
+/* Helper function to generate args that invoke $EDITOR on filename:lineno */
+Strings editorFor(std::string filename, int lineno);
+
 /* Helper function for rendering argument labels. */
 std::string renderLabels(const Strings & labels);
 
diff --git a/src/nix/edit.cc b/src/nix/edit.cc
index a6169f118..3a27b9cca 100644
--- a/src/nix/edit.cc
+++ b/src/nix/edit.cc
@@ -59,22 +59,15 @@ struct CmdEdit : InstallableCommand
             throw Error("cannot parse line number '%s'", pos);
         }
 
-        auto editor = getEnv("EDITOR", "cat");
-
-        auto args = tokenizeString<Strings>(editor);
-
-        if (editor.find("emacs") != std::string::npos ||
-            editor.find("nano") != std::string::npos ||
-            editor.find("vim") != std::string::npos)
-            args.push_back(fmt("+%d", lineno));
-
-        args.push_back(filename);
-
         stopProgressBar();
 
+        auto args = editorFor(filename, lineno);
+
         execvp(args.front().c_str(), stringsToCharPtrs(args).data());
 
-        throw SysError("cannot run editor '%s'", editor);
+        std::string command;
+        for (const auto &arg : args) command += " '" + arg + "'";
+        throw SysError("cannot run command%s", command);
     }
 };
 
diff --git a/src/nix/repl.cc b/src/nix/repl.cc
index 79f365cdb..d4334cf7f 100644
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -506,15 +506,8 @@ bool NixRepl::processLine(string line)
         }
 
         // Open in EDITOR
-        auto editor = getEnv("EDITOR", "cat");
-        auto args = tokenizeString<Strings>(editor);
-        if (lineno > 0 && (
-            editor.find("emacs") != std::string::npos ||
-            editor.find("nano") != std::string::npos ||
-            editor.find("vim") != std::string::npos))
-            args.push_back(fmt("+%d", lineno));
-        args.push_back(filename);
-        editor = args.front();
+        auto args = editorFor(filename, lineno);
+        auto editor = args.front();
         args.pop_front();
         runProgram(editor, args);