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, 3 insertions, 0 deletions

diff --git a/libctf/ctf-archive.c b/libctf/ctf-archive.c
index 54d3d0a..e33f1cc 100644
--- a/libctf/ctf-archive.c
+++ b/libctf/ctf-archive.c
@@ -368,6 +368,7 @@ ctf_new_archive_internal (int is_archive, int unmap_on_close,
   if (strsect)
      memcpy (&arci->ctfi_strsect, strsect, sizeof (struct ctf_sect));
   arci->ctfi_free_symsect = 0;
+  arci->ctfi_free_strsect = 0;
   arci->ctfi_unmap_on_close = unmap_on_close;
 
   return arci;
@@ -493,6 +494,8 @@ ctf_arc_close (ctf_archive_t *arc)
     ctf_file_close (arc->ctfi_file);
   if (arc->ctfi_free_symsect)
     free ((void *) arc->ctfi_symsect.cts_data);
+  if (arc->ctfi_free_strsect)
+    free ((void *) arc->ctfi_strsect.cts_data);
   free (arc->ctfi_data);
   if (arc->ctfi_bfd_close)
     arc->ctfi_bfd_close (arc);