generator: Introduce error code (errcode) concept.

There was a lot of repeated code to map return types (eg. RErr)
to error cases (eg. -1 or NULL).

This commit introduces an error code type and two functions to
map return types to error codes and error codes to strings.

Cherry picked from commit 8037da06feea097716ce700f38c0eac0d5411a7c
and rebased against stable 1.8 branch.

1 files changed, 32 insertions, 25 deletions

diff --git a/generator/generator_php.ml b/generator/generator_php.ml
index d405656d..4431147f 100644
--- a/generator/generator_php.ml
+++ b/generator/generator_php.ml
@@ -357,28 +357,27 @@ PHP_FUNCTION (guestfs_last_error)
       );
 
       (* Return value. *)
-      let error_code =
-        match ret with
-        | RErr -> pr "  int r;\n"; "-1"
-        | RBool _
-        | RInt _ -> pr "  int r;\n"; "-1"
-        | RInt64 _ -> pr "  int64_t r;\n"; "-1"
-        | RConstString _ -> pr "  const char *r;\n"; "NULL"
-        | RConstOptString _ -> pr "  const char *r;\n"; "NULL"
-        | RString _ ->
-            pr "  char *r;\n"; "NULL"
-        | RStringList _ ->
-            pr "  char **r;\n"; "NULL"
-        | RStruct (_, typ) ->
-            pr "  struct guestfs_%s *r;\n" typ; "NULL"
-        | RStructList (_, typ) ->
-            pr "  struct guestfs_%s_list *r;\n" typ; "NULL"
-        | RHashtable _ ->
-            pr "  char **r;\n"; "NULL"
-        | RBufferOut _ ->
-            pr "  char *r;\n";
-            pr "  size_t size;\n";
-            "NULL" in
+      (match ret with
+       | RErr -> pr "  int r;\n"
+       | RBool _
+       | RInt _ -> pr "  int r;\n"
+       | RInt64 _ -> pr "  int64_t r;\n"
+       | RConstString _ -> pr "  const char *r;\n"
+       | RConstOptString _ -> pr "  const char *r;\n"
+       | RString _ ->
+           pr "  char *r;\n"
+       | RStringList _ ->
+           pr "  char **r;\n"
+       | RStruct (_, typ) ->
+           pr "  struct guestfs_%s *r;\n" typ
+       | RStructList (_, typ) ->
+           pr "  struct guestfs_%s_list *r;\n" typ
+       | RHashtable _ ->
+           pr "  char **r;\n"
+       | RBufferOut _ ->
+           pr "  char *r;\n";
+           pr "  size_t size;\n"
+      );
 
       (* Call the function. *)
       if optargs = [] then
@@ -410,9 +409,17 @@ PHP_FUNCTION (guestfs_last_error)
         ) args;
 
       (* Check for errors. *)
-      pr "  if (r == %s) {\n" error_code;
-      pr "    RETURN_FALSE;\n";
-      pr "  }\n";
+      (match errcode_of_ret ret with
+       | `CannotReturnError -> ()
+       | `ErrorIsMinusOne ->
+           pr "  if (r == -1) {\n";
+           pr "    RETURN_FALSE;\n";
+           pr "  }\n"
+       | `ErrorIsNULL ->
+           pr "  if (r == NULL) {\n";
+           pr "    RETURN_FALSE;\n";
+           pr "  }\n"
+      );
       pr "\n";
 
       (* Convert the return value. *)