[Libguestfs] [nbdkit PATCH v2] eval: Rebuild hard link if git breaks it

[Eric Blake]

Commit 39b40750dd works if you rely on 'make clean' after a git
update, but not if you rely on incremental 'make'.  Git likes to
update files by creating new inodes, which strands hard links.  We
could either use symlinks, or as done here, add a dependency to force
the hard links to be rebuilt as needed.

Fixes: 45b4877fde
Signed-off-by: Eric Blake <eblake at redhat.com>
---
 plugins/eval/Makefile.am | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/plugins/eval/Makefile.am b/plugins/eval/Makefile.am
index abbe17a0..da2e7b39 100644
--- a/plugins/eval/Makefile.am
+++ b/plugins/eval/Makefile.am
@@ -1,5 +1,5 @@
 # nbdkit
-# Copyright (C) 2017-2019 Red Hat Inc.
+# Copyright (C) 2017-2020 Red Hat Inc.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
@@ -37,14 +37,16 @@ plugin_LTLIBRARIES = nbdkit-eval-plugin.la

 # This plugin shares most of the same sources as nbdkit-sh-plugin.  In
 # RHEL 7 we cannot add the C files from ../sh directly to SOURCES
-# because subdir-objects is broken.  Instead we create hard links to
+# because subdir-objects is broken.  Instead we create symlinks to
 # them.
 BUILT_SOURCES = \
 	call.c \
 	methods.c \
 	$(NULL)
-$(BUILT_SOURCES):
-	ln -f ../sh/$@
+call.c: ../sh/call.c
+	ln -f -s ../sh/$@
+methods.c: ../sh/methods.c
+	ln -f -s ../sh/$@
 CLEANFILES += $(BUILT_SOURCES)

 nbdkit_eval_plugin_la_SOURCES = \
-- 
2.25.1