libctf, open: fix opening CTF in binaries with no symtab

This is a perfectly possible case, and half of ctf_bfdopen_ctfsect
handled it fine.  The other half hit a divide by zero or two before we
got that far, and had no code path to load the strtab from anywhere
in the absence of a symtab to point at it in any case.

So, as a fallback, if there is no symtab, try loading ".strtab"
explicitly by name, like we used to before we started looking for the
strtab the symtab used.

Of course, such a strtab is not kept hold of by BFD, so this means we
have to bring back the code to possibly explicitly free the strtab that
we read in.

libctf/
	* ctf-impl.h (struct ctf_archive_internal) <ctfi_free_strsect>
	New.
	* ctf-open-bfd.c (ctf_bfdopen_ctfsect): Explicitly open a strtab
	if the input has no symtab, rather than dividing by
	zero. Arrange to free it later via ctfi_free_ctfsect.
	* ctf-archive.c (ctf_new_archive_internal): Do not
	ctfi_free_strsect by default.
	(ctf_arc_close): Possibly free it here.

1 files changed, 1 insertions, 0 deletions

diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index 47a3927..913a264 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -333,6 +333,7 @@ struct ctf_archive_internal
   ctf_sect_t ctfi_symsect;
   ctf_sect_t ctfi_strsect;
   int ctfi_free_symsect;
+  int ctfi_free_strsect;
   void *ctfi_data;
   bfd *ctfi_abfd;		    /* Optional source of section data.  */
   void (*ctfi_bfd_close) (struct ctf_archive_internal *);