[Linux-kernel-mentees] [PATCH v3 01/26] parsing_cocci: Add Function Prototype token

Jaskaran Singh jaskaransingh7654321 at gmail.com
Fri Mar 20 07:01:32 UTC 2020


To add the types ParenType and FunctionType to the SmPL AST, a
reduce/reduce conflict with the funproto rule of the SmPL parser
must be resolved. This requires explicitly identifying a function
prototype by use of a token (TFunProto).

While the correct method of identifying a function prototype would be to
check if an identifier is preceded by a return type, it is challenging
to implement. This is because implementing an OCaml function, to
correctly determine a C type in SmPL, without the aid of Yacc, would
have to handle a number of cases (disjunctions, typeof expressions,
etc.).

Thus, a slightly hacky approach is taken to determine a function
prototype with not the best certainty but what works for most cases
in SmPL. If the identifier is preceded by any token that does not
seem to be part of a type, then it is not identified as a function
prototype. Else, it is.

Signed-off-by: Jaskaran Singh <jaskaransingh7654321 at gmail.com>
---
 parsing_cocci/parse_cocci.ml          | 97 +++++++++++++++++++++------
 parsing_cocci/parser_cocci_menhir.mly |  9 ++-
 2 files changed, 83 insertions(+), 23 deletions(-)

diff --git a/parsing_cocci/parse_cocci.ml b/parsing_cocci/parse_cocci.ml
index 679d213a..e92a01d0 100644
--- a/parsing_cocci/parse_cocci.ml
+++ b/parsing_cocci/parse_cocci.ml
@@ -295,6 +295,7 @@ let token2c (tok,_) add_clt =
   | PC.TLineEnd(clt) -> "line end"
   | PC.TInvalid -> "invalid"
   | PC.TFunDecl(clt) -> "fundecl"
+  | PC.TFunProto(clt) -> "funproto"
 
   | PC.TIso -> "<=>"
   | PC.TRightIso -> "=>"
@@ -480,7 +481,7 @@ let get_clt (tok,_) =
 
   | PC.TOPar0(_,clt) | PC.TMid0(_,clt) | PC.TAnd0(_,clt) | PC.TCPar0(_,clt)
   | PC.TOEllipsis(clt) | PC.TCEllipsis(clt)
-  | PC.TPOEllipsis(clt) | PC.TPCEllipsis(clt)
+  | PC.TPOEllipsis(clt) | PC.TPCEllipsis(clt) | PC.TFunProto(clt)
   | PC.TFunDecl(clt) | PC.TDirective(_,clt) | PC.TAttr_(clt)
   | PC.TLineEnd(clt) -> clt
   | PC.TVAEllipsis(clt) -> clt
@@ -718,6 +719,7 @@ let update_clt (tok,x) clt =
 
   | PC.TLineEnd(_) -> (PC.TLineEnd(clt),x)
   | PC.TFunDecl(_) -> (PC.TFunDecl(clt),x)
+  | PC.TFunProto(_) -> (PC.TFunProto(clt),x)
   | PC.TTildeExclEq(_) -> (PC.TTildeExclEq(clt),x)
   | PC.TDirective(a,_) -> (PC.TDirective(a,clt),x)
   | PC.TAttr_(_) -> (PC.TAttr_(clt),x)
@@ -925,7 +927,7 @@ let split_token ((tok,_) as t) =
   | PC.TInitialize | PC.TFinalize -> ([t],[t])
   | PC.TPArob clt | PC.TMetaPos(_,_,_,clt) | PC.TMetaCom(_,_,clt) -> split t clt
 
-  | PC.TFunDecl(clt)
+  | PC.TFunDecl(clt) | PC.TFunProto(clt)
   | PC.TWhen(clt) | PC.TWhenTrue(clt) | PC.TWhenFalse(clt)
   | PC.TAny(clt) | PC.TStrict(clt) | PC.TLineEnd(clt)
   | PC.TEllipsis(clt)
@@ -1006,7 +1008,8 @@ let find_function_names l =
     | _ -> false in
   let rec split acc = function
       [] | [_] -> raise Irrelevant
-    | ((PC.TCPar(_),_) as t1) :: ((PC.TOBrace(_),_) as t2) :: rest ->
+    | ((PC.TCPar(_),_) as t1) :: ((PC.TOBrace(_),_) as t2) :: rest
+    | ((PC.TCPar(_),_) as t1) :: ((PC.TPtVirg(_),_) as t2) :: rest ->
 	(List.rev (t1::acc),(t2::rest))
     | x::xs -> split (x::acc) xs in
   let rec balanced_name level = function
@@ -1024,20 +1027,68 @@ let find_function_names l =
     | t::rest when is_ident t && level = 0 -> rest
     | t::rest when is_ident t || is_mid t -> balanced_name level rest
     | _ -> raise Irrelevant in
-  let rec balanced_args level = function
+  let rec balanced_args level reverse = function
       [] -> raise Irrelevant
     | (PC.TCPar(_),_)::rest ->
-	let level = level - 1 in
-	if level = 0
+	let level = if reverse then level + 1 else level - 1 in
+	if level = 0 && not(reverse)
 	then rest
-	else balanced_args level rest
+	else balanced_args level reverse rest
     | (PC.TOPar(_),_)::rest ->
-	let level = level + 1 in
-	balanced_args level rest
+	let level = if reverse then level - 1 else level + 1 in
+	if level = 0 && reverse
+	then rest
+	else balanced_args level reverse rest
     | (PC.TArobArob,_)::_ | (PC.TArob,_)::_ | (PC.EOF,_)::_ ->
 	raise Irrelevant
-    | t::rest -> balanced_args level rest in
-  let rec loop = function
+    | t::rest -> balanced_args level reverse rest in
+  let rec is_permissible_proto = function
+      [] -> false
+    | (PC.TCPar0(_),_)::
+      ((PC.TMid0(_),_) | (PC.TAnd0(_),_))::
+      (PC.TOPar0(_),_)::_ -> false
+    | (PC.TOPar0(_),_)::rest
+    | (PC.TCPar0(_),_)::rest -> is_permissible_proto rest
+    | x::rest when is_mid x ->
+        let rec loop = function
+          [] -> false
+        | (PC.TOPar0(_),_)::xs -> is_permissible_proto xs
+        | x::xs -> loop xs in
+        loop rest
+    | ((PC.TCPar(_),_)::rest as l) ->
+      let l = balanced_args 0 true l in
+      let x = match l with
+        (PC.TAttr_(_),_)::rest -> is_permissible_proto rest
+      | (PC.TTypeof(_),_)::_ -> true
+      | _ -> false in x
+    | _::((PC.TEq(_),_) | (PC.TNotEq(_),_))::(PC.TWhen(_),_)::_
+    | _::(PC.TWhen(_),_)::_
+    | (PC.TComma(_),_)::_
+    | (PC.TDirective(_),_)::_
+    | (PC.TElse(_),_)::_
+    | (PC.TReturn(_),_)::_
+    | (PC.TMetaStm(_),_)::_
+    | (PC.TMetaExp(_),_)::_
+    | (PC.TMetaId(_),_)::_
+    | (PC.TMetaLocalIdExp(_),_)::_
+    | (PC.TEq(_),_)::_
+    | (PC.TEllipsis(_),_)::_
+    | (PC.TOEllipsis(_),_)::_
+    | (PC.TCEllipsis(_),_)::_
+    | (PC.TPOEllipsis(_),_)::_
+    | (PC.TPCEllipsis(_),_)::_
+    | (PC.TPtVirg(_),_)::_
+    | (PC.TOBrace(_),_)::_
+    | (PC.TCBrace(_),_)::_
+    | (PC.TOPar(_),_)::_
+    | (PC.TIdent(_),_)::_ -> false
+    | _ -> true in
+  let decl_or_proto clt info bef aft =
+    match aft with
+      (PC.TOBrace(_),_)::_ -> (((PC.TFunDecl(clt),info) :: bef), aft)
+    | (PC.TPtVirg(_),_)::_ -> (((PC.TFunProto(clt),info) :: bef), aft)
+    | _ -> raise Irrelevant in
+  let rec loop acc = function
       [] -> []
     | t :: rest ->
 	if is_par t || is_mid t || is_ident t
@@ -1046,26 +1097,30 @@ let find_function_names l =
 	    try
 	      let (bef,aft) = split [] (t::rest) in
 	      let rest = balanced_name 0 bef in
+              (match aft with
+                (PC.TPtVirg(_),_)::_
+                 when not(is_permissible_proto acc) -> raise Irrelevant
+              | _ ->
 	      (match rest with
 		(PC.TOPar(_),_)::_ ->
-		  (match balanced_args 0 rest with
+		  (match balanced_args 0 false rest with
 		    [] ->
 		      let (_,info) as h = List.hd bef in
 		      let clt = get_clt h in
-		      (((PC.TFunDecl(clt),info) :: bef), aft)
+                      decl_or_proto clt info bef aft
 		  | (PC.TAttr_(_),_)::rest ->
-		      (match balanced_args 0 rest with
+		      (match balanced_args 0 false rest with
 			[] ->
 			  let (_,info) as h = List.hd bef in
 			  let clt = get_clt h in
-			  (((PC.TFunDecl(clt),info) :: bef), aft)
+                          decl_or_proto clt info bef aft
 		      | _ -> raise Irrelevant)
 		  | _ -> raise Irrelevant)
-	      | _ -> raise Irrelevant)
+	      | _ -> raise Irrelevant))
 	    with Irrelevant -> ([t],rest) in
-	  t @ (loop rest)
-	else t :: (loop rest) in
-  loop l
+          t @ (loop (t @ acc) rest)
+        else t :: (loop (t :: acc) rest) in
+  loop [] l
 
 (* ----------------------------------------------------------------------- *)
 (* an attribute is an identifier that precedes another identifier and
@@ -1168,6 +1223,8 @@ let detect_types in_meta_decls l =
 	delim::newid::id::(loop false infn (ident::type_names) rest)
     | ((PC.TFunDecl(_),_) as fn)::rest ->
 	fn::(loop false 1 type_names rest)
+    | ((PC.TFunProto(_),_) as fn)::rest ->
+	fn::(loop false 1 type_names rest)
     | ((PC.TOPar(_),_) as lp)::rest when infn > 0 ->
 	lp::(loop false (infn + 1) type_names rest)
     | ((PC.TCPar(_),_) as rp)::rest when infn > 0 ->
@@ -1252,7 +1309,7 @@ let token2line (tok,_) =
   | PC.TMetaDParamList(_,_,_,_,clt) | PC.TMetaFunc(_,_,_,clt)
   | PC.TMetaLocalFunc(_,_,_,clt) | PC.TMetaPos(_,_,_,clt) | PC.TMetaCom(_,_,clt)
 
-  | PC.TFunDecl(clt)
+  | PC.TFunDecl(clt) | PC.TFunProto(clt)
   | PC.TWhen(clt) | PC.TWhenTrue(clt) | PC.TWhenFalse(clt)
   | PC.TAny(clt) | PC.TStrict(clt) | PC.TEllipsis(clt)
 
diff --git a/parsing_cocci/parser_cocci_menhir.mly b/parsing_cocci/parser_cocci_menhir.mly
index 9e6c8a08..26958f63 100644
--- a/parsing_cocci/parser_cocci_menhir.mly
+++ b/parsing_cocci/parser_cocci_menhir.mly
@@ -239,7 +239,8 @@ let inline_id aft = function
 
 %token <Data.clt> TVAEllipsis
 %token <Data.clt> TIf TElse TWhile TFor TDo TSwitch TCase TDefault TReturn
-%token <Data.clt> TBreak TContinue TGoto TSizeof TTypeof TFunDecl Tdecimal Texec
+%token <Data.clt> TBreak TContinue TGoto TSizeof TTypeof TFunDecl TFunProto
+%token <Data.clt> Tdecimal Texec
 %token <string * Data.clt> TIdent TTypeId TDeclarerId TIteratorId TSymId
 %token <Ast_cocci.added_string * Data.clt> TDirective
 %token <Data.clt> TAttr_
@@ -1439,7 +1440,8 @@ reverse_separated_nonempty_llist(separator, X):
 
 funproto:
   s=ioption(storage) i=ioption(Tinline) t=ctype
-  id=fn_ident lp=TOPar arglist=arg_list(name_opt_decl) rp=TCPar pt=TPtVirg
+  TFunProto id=fn_ident
+  lp=TOPar arglist=arg_list(name_opt_decl) rp=TCPar pt=TPtVirg
       { let s = match s with None -> [] | Some s -> [Ast0.FStorage s] in
         let i =
 	  match i with
@@ -1453,7 +1455,8 @@ funproto:
 	      P.clt2mcode "(" lp, args, vararg, P.clt2mcode ")" rp,
 	      P.clt2mcode ";" pt)) }
 | i=Tinline s=storage t=ctype
-  id=fn_ident lp=TOPar arglist=arg_list(name_opt_decl) rp=TCPar pt=TPtVirg
+  TFunProto id=fn_ident
+  lp=TOPar arglist=arg_list(name_opt_decl) rp=TCPar pt=TPtVirg
       { let s = [Ast0.FStorage s] in
         let i = [Ast0.FInline (P.clt2mcode "inline" i)] in
 	let t = [Ast0.FType t] in
-- 
2.21.1



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