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, 9 insertions, 0 deletions

diff --git a/gdb/gdb_bfd.h b/gdb/gdb_bfd.h
index 9b1e292..ce72f78 100644
--- a/gdb/gdb_bfd.h
+++ b/gdb/gdb_bfd.h
@@ -21,6 +21,7 @@
 #define GDB_BFD_H
 
 #include "registry.h"
+#include "gdbsupport/byte-vector.h"
 #include "gdbsupport/gdb_ref_ptr.h"
 
 DECLARE_REGISTRY (bfd);
@@ -181,4 +182,12 @@ int gdb_bfd_count_sections (bfd *abfd);
 
 int gdb_bfd_requires_relocations (bfd *abfd);
 
+/* Alternative to bfd_get_full_section_contents that returns the section
+   contents in *CONTENTS, instead of an allocated buffer.
+
+   Return true on success, false otherwise.  */
+
+bool gdb_bfd_get_full_section_contents (bfd *abfd, asection *section,
+					gdb::byte_vector *contents);
+
 #endif /* GDB_BFD_H */