gdb: use bfd_get_section_contents to read section contents in is_linked_with_cygwin_dll

The function is_linked_with_cygwin_dll currently uses
gdb_bfd_map_section to get some section contents.  This is not ideal
because that memory, which is only used in this function, can't be
released.  Instead, it was suggested to use
bfd_get_full_section_contents.

However, bfd_get_full_section_contents returns a newly allocated buffer,
which is not very practical to use with C++ automatic memory management
constructs.  I decided to make gdb_bfd_get_full_section_contents, a
small alternative to bfd_get_full_section_contents.  It is a small
wrapper around bfd_get_section_contents which returns the full contents
of the section in a gdb::byte_vector.

gdb_bfd_get_full_section_contents could be used at many places that
already allocate a vector of the size of the section and then call
bfd_get_section_contents.  I think these call sites can be updated over
time.

gdb/ChangeLog:

	* gdb_bfd.h: Include gdbsupport/byte-vector.h.
	(gdb_bfd_get_full_section_contents): New declaration.
	* gdb_bfd.c (gdb_bfd_get_full_section_contents): New function.
	* windows-tdep.c (is_linked_with_cygwin_dll): Use
	gdb_bfd_get_full_section_contents.

1 files changed, 13 insertions, 1 deletions

diff --git a/gdb/gdb_bfd.c b/gdb/gdb_bfd.c
index 5a6dee2..26262bf 100644
--- a/gdb/gdb_bfd.c
+++ b/gdb/gdb_bfd.c
@@ -926,7 +926,19 @@ gdb_bfd_requires_relocations (bfd *abfd)
   return gdata->needs_relocations;
 }
 
-
+/* See gdb_bfd.h.  */
+
+bool
+gdb_bfd_get_full_section_contents (bfd *abfd, asection *section,
+				   gdb::byte_vector *contents)
+{
+  bfd_size_type section_size = bfd_section_size (section);
+
+  contents->resize (section_size);
+
+  return bfd_get_section_contents (abfd, section, contents->data (), 0,
+				   section_size);
+}
 
 /* A callback for htab_traverse that prints a single BFD.  */