From 4947e501153d457ce25a49d8cc3c82b4be307b1a Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sat, 19 May 2018 11:16:00 +0200
Subject: Add lower-level pre/post installation hooks to install::file_rule

---
 build2/install/rule.cxx | 36 ++++++++++++++++++++++++++++++++----
 build2/install/rule.hxx | 16 +++++++++++++++-
 2 files changed, 47 insertions(+), 5 deletions(-)

diff --git a/build2/install/rule.cxx b/build2/install/rule.cxx
index 18cbeae..7c13188 100644
--- a/build2/install/rule.cxx
+++ b/build2/install/rule.cxx
@@ -341,6 +341,18 @@ namespace build2
       return false;
     }
 
+    auto_rmfile file_rule::
+    install_pre (const file& t, const install_dir&) const
+    {
+      return auto_rmfile (t.path (), false /* active */);
+    }
+
+    bool file_rule::
+    install_post (const file& t, const install_dir& id, auto_rmfile&&) const
+    {
+      return install_extra (t, id);
+    }
+
     struct install_dir
     {
       dir_path dir;
@@ -654,9 +666,10 @@ namespace build2
                const install_dir& base,
                const path& name,
                const file& t,
+               const path& f,
                bool verbose)
     {
-      path relf (relative (t.path ()));
+      path relf (relative (f));
 
       dir_path chd (chroot_path (rs, base.dir));
 
@@ -775,10 +788,25 @@ namespace build2
         if (auto l = t["install.mode"])
           id.mode = &cast<string> (l);
 
-        // Install the target and extras.
+        // Install the target.
+        //
+        auto_rmfile f (install_pre (t, id));
+
+        // If install_pre() returned a different file name, make sure we
+        // install it as the original.
         //
-        install_f (rs, id, n ? p.leaf () : path (), t, verbose);
-        install_extra (t, id);
+        const path& tp (t.path ());
+        const path& fp (f.path);
+
+        install_f (
+          rs,
+          id,
+          n ? p.leaf () : fp.leaf () != tp.leaf () ? tp.leaf () : path (),
+          t,
+          f.path,
+          verbose);
+
+        install_post (t, id, move (f));
       };
 
       // First handle installable prerequisites.
diff --git a/build2/install/rule.hxx b/build2/install/rule.hxx
index 2ad3d4b..c84249e 100644
--- a/build2/install/rule.hxx
+++ b/build2/install/rule.hxx
@@ -11,6 +11,7 @@
 #include <build2/rule.hxx>
 #include <build2/target.hxx>
 #include <build2/operation.hxx>
+#include <build2/filesystem.hxx>
 
 namespace build2
 {
@@ -108,7 +109,7 @@ namespace build2
       static target_state
       perform_update (action, const target&);
 
-      // Extra un/installation hooks. Return true if anything was
+      // Extra un/installation hooks. Return true if anything was actually
       // un/installed.
       //
       using install_dir = install::install_dir; // For derived rules.
@@ -119,6 +120,19 @@ namespace build2
       virtual bool
       uninstall_extra (const file&, const install_dir&) const;
 
+      // Lower-level pre/post installation hooks that can be used to override
+      // the source file path being installed (for example, to implement
+      // post-processing, etc).
+      //
+      // Note that one cannot generally perform post-processing in-place
+      // because of permissions.
+      //
+      virtual auto_rmfile
+      install_pre (const file&, const install_dir&) const;
+
+      virtual bool
+      install_post (const file&, const install_dir&, auto_rmfile&&) const;
+
       // Installation/uninstallation "commands".
       //
       // If verbose is false, then only print the command at verbosity level 2
-- 
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