Re: [Crash-utility] [PATCH] Fix for 'struct -o' option to display the offsets of struct fields

Hi Lianbo, On 2022/05/27 18:56, lijiang wrote: > On Fri, May 27, 2022 at 5:14 PM HAGIO KAZUHITO(萩尾 一仁) < k-hagio-ab(a)nec.com <mailto:k-hagio-ab@nec.com>> wrote: > > On 2022/05/27 16:03, lijiang wrote: > > >> If no another gdb setting, we will need to rewrite the parser. > > >> So first, I'd like to know whether there is no another setting. > > > > > > Otherwise, maybe we can patch the gdb code... > > > > > > That '{...}' is probably printed in c_type_print_base_struct_union(). > > > And found a comment for c_type_print_base_1() in gdb/c-typeprint.c: > > > > > > SHOW negative means just print the type name or struct tag if there > > > is one. If there is no name, print something sensible but concise > > > like "struct {...}". > > > > > > Just an idea and clue. > > > > > > I like the good idea. > > > > Just a rough try and I've not tested enough, but this patch might be > > somewhat good. > > > > --- gdb-10.2.orig/gdb/c-typeprint.c 2022-05-27 14:49:53.079853333 +0900 > > +++ gdb-10.2/gdb/c-typeprint.c 2022-05-27 14:47:18.729165094 +0900 > > @@ -1043,6 +1043,8 @@ > > struct type_print_options local_flags = *flags; > > local_flags.local_typedefs = NULL; > > > > + show = 1; > > + > > std::unique_ptr<typedef_hash_table> hash_holder; > > if (!flags->raw) > > { > > > > > > This looks more reasonable to me. Could you please post a patch with this fix? > > Sure. But more understanding and testing are needed, I will look into it > next week. I found that gdb-7.6 also prints "{...}" for unnamed struct/union. (gdb) ptype struct page type = struct page { unsigned long flags; struct address_space *mapping; struct { union {...}; union {...}; }; ... And crash-7.x (gdb-7.6.patch) had the following patch to print the details of unnamed struct/union. --- gdb-7.6/gdb/c-typeprint.c.orig +++ gdb-7.6/gdb/c-typeprint.c @@ -1097,7 +1097,8 @@ c_type_print_base (struct type *type, st fprintf_filtered (stream, "static "); c_print_type (TYPE_FIELD_TYPE (type, i), TYPE_FIELD_NAME (type, i), - stream, show - 1, level + 4, + stream, strlen(TYPE_FIELD_NAME (type, i)) ? + show - 1 : show, level + 4, &local_flags); if (!field_is_static (&TYPE_FIELD (type, i)) && TYPE_FIELD_PACKED (type, i)) But gdb-10.2.patch does not have it, and prints "{...}" again.

So I will post the following patch later to do the same thing in gdb-10.2. --- gdb-10.2/gdb/c-typeprint.c.orig 2022-05-31 13:15:39.099537173 +0900 +++ gdb-10.2/gdb/c-typeprint.c 2022-05-31 13:17:02.076909579 +0900 @@ -1202,6 +1202,9 @@ c_type_print_base_struct_union (struct t = podata->end_bitpos - TYPE_LENGTH (type->field (i).type ()) * TARGET_CHAR_BIT; } + else if (strlen(TYPE_FIELD_NAME (type, i)) == 0) + /* crash: Print details for unnamed struct and union. */ + newshow = show; c_print_type_1 (type->field (i).type (), TYPE_FIELD_NAME (type, i),

Thanks, Kazu