Pluggable fetchers

Flakes are now fetched using an extensible mechanism. Also lots of
other flake cleanups.

3 files changed, 13 insertions, 3 deletions

diff --git a/src/libutil/types.hh b/src/libutil/types.hh
index 20b96a85c..a1ce7b372 100644
--- a/src/libutil/types.hh
+++ b/src/libutil/types.hh
@@ -157,4 +157,12 @@ typedef list<Path> Paths;
 typedef set<Path> PathSet;
 
 
+/* Helper class to run code at startup. */
+template<typename T>
+struct OnStartup
+{
+    OnStartup(T && t) { t(); }
+};
+
+
 }
diff --git a/src/libutil/util.cc b/src/libutil/util.cc
index ab63ceb10..4266a5474 100644
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -98,7 +98,7 @@ void replaceEnv(std::map<std::string, std::string> newEnv)
 }
 
 
-Path absPath(Path path, std::optional<Path> dir)
+Path absPath(Path path, std::optional<Path> dir, bool resolveSymlinks)
 {
     if (path[0] != '/') {
         if (!dir) {
@@ -119,7 +119,7 @@ Path absPath(Path path, std::optional<Path> dir)
         }
         path = *dir + "/" + path;
     }
-    return canonPath(path);
+    return canonPath(path, resolveSymlinks);
 }
 
 
diff --git a/src/libutil/util.hh b/src/libutil/util.hh
index 02c505cbc..2f1613ac1 100644
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -46,7 +46,9 @@ void clearEnv();
 /* Return an absolutized path, resolving paths relative to the
    specified directory, or the current directory otherwise.  The path
    is also canonicalised. */
-Path absPath(Path path, std::optional<Path> dir = {});
+Path absPath(Path path,
+    std::optional<Path> dir = {},
+    bool resolveSymlinks = false);
 
 /* Canonicalise a path by removing all `.' or `..' components and
    double or trailing slashes.  Optionally resolves all symlink