(*
 * Copyright (c) 2013 - present Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *)

module L = Logging
module F = Format

type printf_signature = {
  unique_id: string;
  format_pos: int;
  fixed_pos: int list;
  vararg_pos: int option
}

let printf_like_functions =
  ref
    [
      { unique_id = "java.io.PrintStream.printf(java.lang.String,java.lang.Object[]):java.io.PrintStream";
        format_pos = 1;
        fixed_pos = [];
        vararg_pos = Some 2 };
      { unique_id = "java.io.PrintStream.printf(java.lang.Locale,java.lang.String,java.lang.Object[]):java.io.PrintStream";
        format_pos = 2;
        fixed_pos = [];
        vararg_pos = Some 3 };
      { unique_id = "java.lang.String(java.lang.String,java.lang.Object[]):java.lang.String";
        format_pos = 1;
        fixed_pos = [];
        vararg_pos = Some 2 };
      { unique_id = "java.lang.String(java.lang.Locale,java.lang.String,java.lang.Object[]):java.lang.String";
        format_pos = 2;
        fixed_pos = [];
        vararg_pos = Some 3 };
    ]

let add_printf_like_function plf =
  printf_like_functions := plf :: !printf_like_functions


let printf_like_function
    (proc_name: Procname.t): printf_signature option =
  try
    Some (
      IList.find
        (fun printf -> string_equal printf.unique_id (Procname.to_unique_id proc_name))
        !printf_like_functions)
  with Not_found -> None

let default_format_type_name
    (format_type: string): string =
  match format_type with
  | "d" | "i" | "u" | "x" | "X" | "o" -> "java.lang.Integer"
  | "a" | "A" | "f" | "F" | "g" | "G" | "e" | "E" -> "java.lang.Double"
  | "c" -> "java.lang.Character"
  | "b" -> "java.lang.Boolean"
  | "s" -> "java.lang.String"
  | "h" | "H" -> "java.lang.Object"
  | _ -> "unknown"

let format_type_matches_given_type
    (format_type: string)
    (given_type: string): bool =
  match format_type with
  | "d" | "i" | "u" | "x" | "X" | "o" ->
      IList.mem
        string_equal
        given_type
        ["java.lang.Integer"; "java.lang.Long"; "java.lang.Short"; "java.lang.Byte"]
  | "a" | "A" | "f" | "F" | "g" | "G" | "e" | "E" ->
      IList.mem
        string_equal
        given_type
        ["java.lang.Double"; "java.lang.Float"]
  | "c" -> string_equal given_type "java.lang.Character"
  | "b" | "h" | "H" | "s" -> true  (* accepts pretty much anything, even null *)
  | _ -> false

(* The format string and the nvar for the fixed arguments and the nvar of the varargs array *)
let format_arguments
    (printf: printf_signature)
    (args: (Sil.exp * Sil.typ) list): (string option * (Sil.exp list) * (Sil.exp option)) =

  let format_string = match IList.nth args printf.format_pos with
    | Sil.Const (Sil.Cstr fmt), _ -> Some fmt
    | _ -> None in

  let fixed_nvars = IList.map
      (fun i -> fst (IList.nth args i))
      printf.fixed_pos in
  let varargs_nvar = match printf.vararg_pos with
    | Some pos -> Some (fst (IList.nth args pos))
    | None -> None in

  format_string, fixed_nvars, varargs_nvar

(* Extract type names from format string *)
let rec format_string_type_names
    (fmt_string: string)
    (start: int): string list =
  try
    let fmt_re = Str.regexp "%[0-9]*\\.?[0-9]*[A-mo-z]" in (* matches '%2.1d' etc. *)
    let _ = Str.search_forward fmt_re fmt_string start in
    let fmt_match = Str.matched_string fmt_string in
    let fmt_type = String.sub fmt_match ((String.length fmt_match) - 1) 1 in
    fmt_type:: format_string_type_names fmt_string (Str.match_end ())
  with Not_found -> []

let printf_args_name = "CHECKERS_PRINTF_ARGS"

let check_printf_args_ok
    (node: Cfg.Node.t)
    (instr: Sil.instr)
    (proc_name: Procname.t)
    (proc_desc: Cfg.Procdesc.t): unit =

  (* Check if format string lines up with arguments *)
  let rec check_type_names instr_loc n_arg instr_proc_name fmt_type_names arg_type_names =
    let instr_name = Procname.to_simplified_string instr_proc_name in
    let instr_line = Location.to_string instr_loc in
    match (fmt_type_names, arg_type_names) with
    | ft:: fs, gt:: gs ->
        if not (format_type_matches_given_type ft gt) then
          let description = Printf.sprintf
              "%s at line %s: parameter %d is expected to be of type %s but %s was given."
              instr_name
              instr_line
              n_arg
              (default_format_type_name ft)
              gt in
          Checkers.ST.report_error
            proc_name
            proc_desc
            printf_args_name
            instr_loc
            description
        else
          check_type_names instr_loc (n_arg + 1) instr_proc_name fs gs
    | [], [] -> ()
    | _ ->
        let description = Printf.sprintf
            "format string arguments don't mach provided arguments in %s at line %s"
            instr_name
            instr_line in
        Checkers.ST.report_error
          proc_name
          proc_desc
          printf_args_name
          instr_loc
          description in

  (* Get the array ivar for a given nvar *)
  let rec array_ivar instrs nvar =
    match instrs, nvar with
    | Sil.Letderef (id, Sil.Lvar iv, _, _):: _, Sil.Var nid
      when Ident.equal id nid -> iv
    | i:: is, _ -> array_ivar is nvar
    | _ -> raise Not_found in

  let rec fixed_nvar_type_name instrs nvar =
    match nvar with
    | Sil.Var nid -> (
        match instrs with
        | Sil.Letderef (id, Sil.Lvar iv, t, _):: _
          when Ident.equal id nid -> PatternMatch.get_type_name t
        | i:: is -> fixed_nvar_type_name is nvar
        | _ -> raise Not_found)
    | Sil.Const c -> PatternMatch.java_get_const_type_name c
    | _ -> raise (Failure "Could not resolve fixed type name") in

  match instr with
  | Sil.Call (_, Sil.Const (Sil.Cfun pn), args, cl, _) -> (
      match printf_like_function pn with
      | Some printf -> (
          try
            let fmt, fixed_nvars, array_nvar = format_arguments printf args in
            let instrs = Cfg.Node.get_instrs node in
            let fixed_nvar_type_names = IList.map (fixed_nvar_type_name instrs) fixed_nvars in
            let vararg_ivar_type_names = match array_nvar with
              | Some nvar -> (
                  let ivar = array_ivar instrs nvar in
                  PatternMatch.get_vararg_type_names node ivar)
              | None -> [] in
            match fmt with
            | Some fmt ->
                check_type_names
                  cl
                  (printf.format_pos + 1)
                  pn
                  (format_string_type_names fmt 0)
                  (fixed_nvar_type_names@ vararg_ivar_type_names)
            | None ->
                Checkers.ST.report_error
                  proc_name
                  proc_desc
                  printf_args_name
                  cl
                  "Format string must be string literal"
          with e ->
            L.stderr
              "%s Exception when analyzing %s: %s@."
              printf_args_name
              (Procname.to_string proc_name)
              (Printexc.to_string e))
      | None -> ())
  | _ -> ()

let callback_printf_args { Callbacks.proc_desc; proc_name } : unit =
  Cfg.Procdesc.iter_instrs (fun n i -> check_printf_args_ok n i proc_name proc_desc) proc_desc

(*
let printf_signature_to_string
    (printf: printf_signature): string =
  Printf.sprintf
    "{%s; %d [%s] %s}"
    printf.unique_id
    printf.format_pos
    (String.concat "," (IList.map string_of_int printf.fixed_pos))
    (match printf.vararg_pos with | Some i -> string_of_int i | _ -> "-")
*)