From ffeece6ac2d4e4d2bf28c910b51c74ffc881c963 Mon Sep 17 00:00:00 2001 From: Nick Alcock Date: Tue, 5 Jan 2021 13:25:56 +0000 Subject: libctf, ld: prohibit getting the size or alignment of forwards C allows you to do only a very few things with entities of incomplete type (as opposed to pointers to them): make pointers to them and give them cv-quals, roughly. In particular you can't sizeof them and you can't get their alignment. We cannot impose all the requirements the standard imposes on CTF users, because the deduplicator can transform any structure type into a forward for the purposes of breaking cycles: so CTF type graphs can easily contain things like arrays of forward type (if you want to figure out their size or alignment, you need to chase down the types this forward might be a forward to in child TU dicts: we will soon add API functions to make doing this much easier). Nonetheless, it is still meaningless to ask for the size or alignment of forwards: but libctf didn't prohibit this and returned nonsense from internal implementation details when you asked (it returned the kind of the pointed-to type as both the size and alignment, because forwards reuse ctt_type as a type kind, and ctt_type and ctt_size overlap). So introduce a new error, ECTF_INCOMPLETE, which is returned when you try to get the size or alignment of forwards: we also return it when you try to do things that require libctf itself to get the size or alignment of a forward, notably using a forward as an array index type (which C should never do in any case) or adding forwards to structures without specifying their offset explicitly. The dumper will not emit size or alignment info for forwards any more. (This should not be an API break since ctf_type_size and ctf_type_align could both return errors before now: any code that isn't expecting error returns is already potentially broken.) include/ChangeLog 2021-01-05 Nick Alcock * ctf-api.h (ECTF_INCOMPLETE): New. (ECTF_NERR): Adjust. ld/ChangeLog 2021-01-05 Nick Alcock * testsuite/ld-ctf/conflicting-cycle-1.parent.d: Adjust for dumper changes. * testsuite/ld-ctf/cross-tu-cyclic-conflicting.d: Likewise. * testsuite/ld-ctf/forward.c: New test... * testsuite/ld-ctf/forward.d: ... and results. libctf/ChangeLog 2021-01-05 Nick Alcock * ctf-types.c (ctf_type_resolve): Improve comment. (ctf_type_size): Yield ECTF_INCOMPLETE when applied to forwards. Emit errors into the right dict. (ctf_type_align): Likewise. * ctf-create.c (ctf_add_member_offset): Yield ECTF_INCOMPLETE when adding a member without explicit offset when this member, or the previous member, is incomplete. * ctf-dump.c (ctf_dump_format_type): Do not try to print the size of forwards. (ctf_dump_member): Do not try to print their alignment. --- include/ChangeLog | 5 +++++ include/ctf-api.h | 5 +++-- 2 files changed, 8 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/ChangeLog b/include/ChangeLog index 048ba61..1b56987 100644 --- a/include/ChangeLog +++ b/include/ChangeLog @@ -1,3 +1,8 @@ +2021-01-05 Nick Alcock + + * ctf-api.h (ECTF_INCOMPLETE): New. + (ECTF_NERR): Adjust. + 2021-01-01 Nicolas Boulenguez * coff/internal.h: Correct comment spelling. diff --git a/include/ctf-api.h b/include/ctf-api.h index f221d17..b3cfd39 100644 --- a/include/ctf-api.h +++ b/include/ctf-api.h @@ -230,7 +230,8 @@ typedef struct ctf_snapshot_id _CTF_ITEM (ECTF_NEXT_WRONGFUN, "Wrong iteration function called.") \ _CTF_ITEM (ECTF_NEXT_WRONGFP, "Iteration entity changed in mid-iterate.") \ _CTF_ITEM (ECTF_FLAGS, "CTF header contains flags unknown to libctf.") \ - _CTF_ITEM (ECTF_NEEDSBFD, "This feature needs a libctf with BFD support.") + _CTF_ITEM (ECTF_NEEDSBFD, "This feature needs a libctf with BFD support.") \ + _CTF_ITEM (ECTF_INCOMPLETE, "Type is not a complete type.") #define ECTF_BASE 1000 /* Base value for libctf errnos. */ @@ -243,7 +244,7 @@ _CTF_ERRORS #undef _CTF_FIRST }; -#define ECTF_NERR (ECTF_NEEDSBFD - ECTF_BASE + 1) /* Count of CTF errors. */ +#define ECTF_NERR (ECTF_INCOMPLETE - ECTF_BASE + 1) /* Count of CTF errors. */ /* The CTF data model is inferred to be the caller's data model or the data model of the given object, unless ctf_setmodel is explicitly called. */ -- cgit v1.1