Implement the `file` function to read and write files

This allows us to do file reading and writing without $(shell). Besides
being simpler, this also allows faster regen times, since we can just
stat the files to be read, or directly write to the files that need to
be written.

1 files changed, 10 insertions, 0 deletions

diff --git a/func.h b/func.h
index e78deb7..ab6affb 100644
--- a/func.h
+++ b/func.h
@@ -41,7 +41,17 @@ FuncInfo* GetFuncInfo(StringPiece name);
 
 struct FindCommand;
 
+enum struct CommandOp {
+  SHELL,
+  FIND,
+  READ,
+  READ_MISSING,
+  WRITE,
+  APPEND,
+};
+
 struct CommandResult {
+  CommandOp op;
   string shell;
   string cmd;
   unique_ptr<FindCommand> find;