Update binary_get_section_contents to seek using section's file position

I have a patch for GDB which opens and reads from BFDs using the
"binary" target.  However, for it to work, we need to be able to get a
section's contents based from the file position of that section.

At the moment, reading a section's contents will always read from the
start of the file regardless of where that section is located.  While
this was fine for the original use of the "binary" target, it won't
work for my use case.  This change shouldn't impact any existing
callers due to the fact that the single .data section is initialized
with a filepos of 0.

bfd/ChangeLog:

	* binary.c (binary_get_section_contents): Seek using offset
	from section's file position.

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index adbf6f3b20bce3988daae30ca52c9c5cf69816cf..5849c4ebdd56476b8665821be10e6678fac1919c 100644 (file)
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,8 @@
+2020-07-22  Kevin Buettner  <kevinb@redhat.com>
+
+       * binary.c (binary_get_section_contents): Seek using offset
+       from section's file position.
+
 2020-07-22  Kevin Buettner  <kevinb@redhat.com>
 
        * elf.c (_bfd_elf_make_section_from_phdr): Remove hack for GDB.

diff --git a/bfd/binary.c b/bfd/binary.c
index 999de0d8c41a4e7d8e5072de86983c1717ab900d..e872924a2d8d3fed73ce5358085d21834889570d 100644 (file)
--- a/bfd/binary.c
+++ b/bfd/binary.c
@@ -19,10 +19,10 @@
    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
    MA 02110-1301, USA.  */
 
-/* This is a BFD backend which may be used to write binary objects.
-   It may only be used for output, not input.  The intention is that
-   this may be used as an output format for objcopy in order to
-   generate raw binary data.
+/* This is a BFD backend which may be used to read or write binary
+   objects.  Historically, it was used as an output format for objcopy
+   in order to generate raw binary data, but is now used for other
+   purposes as well.
 
    This is very simple.  The only complication is that the real data
    will start at some address X, and in some cases we will not want to
@@ -97,12 +97,12 @@ binary_object_p (bfd *abfd)
 
 static bfd_boolean
 binary_get_section_contents (bfd *abfd,
-                            asection *section ATTRIBUTE_UNUSED,
+                            asection *section,
                             void * location,
                             file_ptr offset,
                             bfd_size_type count)
 {
-  if (bfd_seek (abfd, offset, SEEK_SET) != 0
+  if (bfd_seek (abfd, section->filepos + offset, SEEK_SET) != 0
       || bfd_bread (location, count, abfd) != count)
     return FALSE;
   return TRUE;