[PATCH] bfd: Don't check non-thin archive member file size

[PATCH] bfd: Don't check non-thin archive member file size

[H.J. Lu]

There is no need to check member file size for thin archive member.

	* bfdio.c (bfd_bread): Don't check non-thin archive member file
	size.
---
 bfd/bfdio.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/bfd/bfdio.c b/bfd/bfdio.c
index 463b3879c52..9aa15c1ffa4 100644
--- a/bfd/bfdio.c
+++ b/bfd/bfdio.c
@@ -231,9 +231,11 @@ bfd_bread (void *ptr, bfd_size_type size, bfd *abfd)
     }
   offset += abfd->origin;
 
-  /* If this is an archive element, don't read past the end of
+  /* If this is a non-thin archive element, don't read past the end of
      this element.  */
-  if (element_bfd->arelt_data != NULL)
+  if (element_bfd->arelt_data != NULL
+      && element_bfd->my_archive != NULL
+      && !bfd_is_thin_archive (element_bfd->my_archive))
     {
       bfd_size_type maxbytes = arelt_size (element_bfd);
 
-- 
2.33.1

Re: [PATCH] bfd: Don't check non-thin archive member file size

[Alan Modra]

On Fri, Dec 24, 2021 at 03:46:04PM -0800, H.J. Lu via Binutils wrote:
> There is no need to check member file size for thin archive member.

Does it hurt to check against the file size recorded in the archive
header?  Did someone report a "bug", perhaps that a thin archive
member file was updated without running ar, and then hit an error?

-- 
Alan Modra
Australia Development Lab, IBM

Re: [PATCH] bfd: Don't check non-thin archive member file size

[H.J. Lu]

On Sun, Dec 26, 2021 at 10:56 PM Alan Modra <amodra@gmail.com> wrote:
>
> On Fri, Dec 24, 2021 at 03:46:04PM -0800, H.J. Lu via Binutils wrote:
> > There is no need to check member file size for thin archive member.
>
> Does it hurt to check against the file size recorded in the archive
> header?  Did someone report a "bug", perhaps that a thin archive
> member file was updated without running ar, and then hit an error?
>

While debugging a GCC bootstrap bug, I copied a .o file without running
ar on a thin archive.  Other linkers didn't complain.  There is no need to.

-- 
H.J.

Re: [PATCH] bfd: Don't check non-thin archive member file size

[Alan Modra]

On Mon, Dec 27, 2021 at 05:31:13AM -0800, H.J. Lu wrote:
> On Sun, Dec 26, 2021 at 10:56 PM Alan Modra <amodra@gmail.com> wrote:
> >
> > On Fri, Dec 24, 2021 at 03:46:04PM -0800, H.J. Lu via Binutils wrote:
> > > There is no need to check member file size for thin archive member.
> >
> > Does it hurt to check against the file size recorded in the archive
> > header?  Did someone report a "bug", perhaps that a thin archive
> > member file was updated without running ar, and then hit an error?
> >
> 
> While debugging a GCC bootstrap bug, I copied a .o file without running
> ar on a thin archive.  Other linkers didn't complain.  There is no need to.

No doubt what you did was reasonably safe, but if an object file that
is part of a thin archive is replaced without running ar then it is
possible for the archive symbol table to be wrong.  That could lead to
linker misbehaviour.  So I'm inclined to say we should be checking
the archive header size against file size.

Such a check doesn't really belong in bfd_bread though, so please go
ahead and apply your patch.

-- 
Alan Modra
Australia Development Lab, IBM