[infer] Create missing result directories

Summary:
This diff creates missing result directories in its running.

The problem was that `infer-out/captured` and its sub-directories were not ready at the step 3 below, which crashed with exceptions.

1. `infer capture -- [target build]`
2. `infer analyze --merge`
3. `infer analyze --merge --debug --reanalyze --procedures-filter '.*foo.*'`

Reviewed By: ngorogiannis

Differential Revision: D19274672

fbshipit-source-id: af84000d7

infer/src/IR/DotCfg.ml

@@ -108,7 +108,7 @@ let print_pdesc source fmt pdesc =
 
 
 let with_dot_file fname ~pp =
-  let chan = Out_channel.create fname in
+  let chan = Utils.out_channel_create_with_dir fname in
   let fmt = Format.formatter_of_out_channel chan in
   (* avoid phabricator thinking this file was generated by substituting substring with %s *)
   F.fprintf fmt "@[/* %@%s */@\ndigraph cfg {@\n%t}@]@." "generated" pp ;

infer/src/base/Utils.ml

@@ -265,13 +265,13 @@ let with_process_lines ~(debug : ('a, F.formatter, unit) format -> 'a) ~cmd ~tmp
         shell_cmd output
 
 
-(** Create a directory if it does not exist already. *)
+(** Recursively create a directory if it does not exist already. *)
 let create_dir dir =
   try
     if (Unix.stat dir).Unix.st_kind <> Unix.S_DIR then
       L.(die ExternalError) "file '%s' already exists and is not a directory" dir
   with Unix.Unix_error _ -> (
-    try Unix.mkdir dir ~perm:0o700
+    try Unix.mkdir_p dir ~perm:0o700
     with Unix.Unix_error _ ->
       let created_concurrently =
         (* check if another process created it meanwhile *)
@@ -280,6 +280,13 @@ let create_dir dir =
       if not created_concurrently then L.(die ExternalError) "cannot create directory '%s'" dir )
 
 
+let out_channel_create_with_dir fname =
+  try Out_channel.create fname
+  with Sys_error _ ->
+    Unix.mkdir_p ~perm:0o700 (Filename.dirname fname) ;
+    Out_channel.create fname
+
+
 let realpath_cache = Hashtbl.create 1023
 
 let realpath ?(warn_on_error = true) path =

infer/src/base/Utils.mli

@@ -94,7 +94,10 @@ val with_process_lines :
     information, and [tmp_prefix] as a prefix for temporary files. *)
 
 val create_dir : string -> unit
-(** create a directory if it does not exist already *)
+(** recursively create a directory if it does not exist already *)
+
+val out_channel_create_with_dir : Filename.t -> Out_channel.t
+(** create an out channel with creating missing directories *)
 
 val realpath : ?warn_on_error:bool -> string -> string
 (** [realpath warn_on_error path] returns path with all symbolic links resolved. It caches results