loader: add API to load elf header

Add an API to load an elf header header from a file. Populates a
buffer with the header contents, as well as a boolean for whether the
elf is 64b or not. Both arguments are optional.

Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: Fix typo in comment]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 09c3764..358da55 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -48,6 +48,19 @@
              void *translate_opaque, uint64_t *pentry, uint64_t *lowaddr,
              uint64_t *highaddr, int big_endian, int elf_machine,
              int clear_lsb);
+
+/** load_elf_hdr:
+ * @filename: Path of ELF file
+ * @hdr: Buffer to populate with header data. Header data will not be
+ * filled if set to NULL.
+ * @is64: Set to true if the ELF is 64bit. Ignored if set to NULL
+ * @errp: Populated with an error in failure cases
+ *
+ * Inspect an ELF file's header. Read its full header contents into a
+ * buffer and/or determine if the ELF is 64bit.
+ */
+void load_elf_hdr(const char *filename, void *hdr, bool *is64, Error **errp);
+
 int load_aout(const char *filename, hwaddr addr, int max_sz,
               int bswap_needed, hwaddr target_page_size);
 int load_uimage(const char *filename, hwaddr *ep,