libelf: Add elf32_getchdr, elf64_getchdr and gelf_getchdr.

Elf_Data of a compressed section has type ELF_T_CHDR. This type can be
xlated to the file or memory representation. This will make sure the Chdr
is in the correct endianess. The compressed data following the Chdr isn't
translated.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

1 files changed, 69 insertions, 0 deletions

diff --git a/libelf/gelf_getchdr.c b/libelf/gelf_getchdr.c
new file mode 100644
index 00000000..394bf4b3
--- /dev/null
+++ b/libelf/gelf_getchdr.c
@@ -0,0 +1,69 @@
+/* Return section compression header.
+   Copyright (C) 2015 Red Hat, Inc.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libelfP.h"
+#include <gelf.h>
+#include <stddef.h>
+
+
+GElf_Chdr *
+gelf_getchdr (Elf_Scn *scn, GElf_Chdr *dest)
+{
+  if (scn == NULL)
+    return NULL;
+
+  if (dest == NULL)
+    {
+      __libelf_seterrno (ELF_E_INVALID_OPERAND);
+      return NULL;
+    }
+
+  if (scn->elf->class == ELFCLASS32)
+    {
+      Elf32_Chdr *chdr = elf32_getchdr (scn);
+      if (chdr == NULL)
+	return NULL;
+      dest->ch_type = chdr->ch_type;
+      dest->ch_size = chdr->ch_size;
+      dest->ch_addralign = chdr->ch_addralign;
+    }
+  else
+    {
+      Elf64_Chdr *chdr = elf64_getchdr (scn);
+      if (chdr == NULL)
+	return NULL;
+      *dest = *chdr;
+    }
+
+  return dest;
+}
+INTDEF(gelf_getchdr)