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>

26 files changed, 676 insertions, 18 deletions

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index fbe8e3ae..2ed4a674 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,31 @@
+2015-11-19  Mark Wielaard  <mjw@redhat.com>
+
+	* Makefile.am (libelf_a_SOURCES): Add elf32_getchdr.c,
+	elf64_getchdr.c and gelf_getchdr.c.
+	(noinst_HEADERS): Add chdr_xlate.h.
+	* abstract.h: Define Chdr32 and Chdr64.
+	* chdr_xlate.h: New file.
+	* elf32_getchdr.c: New file.
+	* elf64_getchdr.c: New file.
+	* elf_error.c: Add ELF_E_NOT_COMPRESSED, ELF_E_INVALID_SECTION_TYPE
+	and ELF_E_INVALID_SECTION_FLAGS.
+	* elf_getdata.c (__libelf_set_rawdata_wrlock): Set d_type to
+	ELF_T_CHDR for SHF_COMPRESSED sections.
+	* exttypes.h: Add Chdr32 and Chdr64.
+	* gelf.h (GElf_Chdr): New typedef.
+	(gelf_getchdr): New function definition.
+	* gelf_fsize.c (__libelf_type_sizes): Add ELF_T_CHDR.
+	* gelf_getchdr.c: New file.
+	* gelf_xlate.c (__elf_xfctstom): Add ELF_T_CHDR cvt_chdr.
+	* gelf_xlate.h: Add Chdr.
+	* libelf.h (Elf_Type): Add ELF_T_CHDR.
+	(elf32_getchdr): New function definition.
+	(elf64_getchdr): Likewise.
+	* libelf.map (ELFUTILS_1.7): New sections add elf32_getchdr,
+	elf64_getchdr and gelf_getchdr.
+	* libelfP.h: Add ELF_E_NOT_COMPRESSED, ELF_E_INVALID_SECTION_TYPE
+	and ELF_E_INVALID_SECTION_FLAGS.
+
 2015-10-16  Mark Wielaard  <mjw@redhat.com>
 
 	* Makefile.am (libelf_so_LDLIBS): Add -lz.
diff --git a/libelf/Makefile.am b/libelf/Makefile.am
index 4a4131c1..8a678b84 100644
--- a/libelf/Makefile.am
+++ b/libelf/Makefile.am
@@ -1,6 +1,6 @@
 ## Process this file with automake to create Makefile.in
 ##
-## Copyright (C) 1996-2010 Red Hat, Inc.
+## Copyright (C) 1996-2010, 2015 Red Hat, Inc.
 ## This file is part of elfutils.
 ##
 ## This file is free software; you can redistribute it and/or modify
@@ -88,7 +88,8 @@ libelf_a_SOURCES = elf_version.c elf_hash.c elf_error.c elf_fill.c \
 		   elf32_offscn.c elf64_offscn.c gelf_offscn.c \
 		   elf_getaroff.c \
 		   elf_gnu_hash.c \
-		   elf_scnshndx.c
+		   elf_scnshndx.c \
+		   elf32_getchdr.c elf64_getchdr.c gelf_getchdr.c
 
 libelf_pic_a_SOURCES =
 am_libelf_pic_a_OBJECTS = $(libelf_a_SOURCES:.c=.os)
@@ -118,7 +119,8 @@ uninstall: uninstall-am
 	rm -f $(DESTDIR)$(libdir)/libelf.so
 
 noinst_HEADERS = elf.h abstract.h common.h exttypes.h gelf_xlate.h libelfP.h \
-		 version_xlate.h gnuhash_xlate.h note_xlate.h dl-hash.h
+		 version_xlate.h gnuhash_xlate.h note_xlate.h dl-hash.h \
+		 chdr_xlate.h
 EXTRA_DIST = libelf.map
 
 CLEANFILES += $(am_libelf_pic_a_OBJECTS) libelf.so.$(VERSION)
diff --git a/libelf/abstract.h b/libelf/abstract.h
index 53713eec..d4515f27 100644
--- a/libelf/abstract.h
+++ b/libelf/abstract.h
@@ -1,5 +1,5 @@
 /* Abstract description of component ELF types.
-   Copyright (C) 1998, 1999, 2000, 2002, 2004, 2007 Red Hat, Inc.
+   Copyright (C) 1998, 1999, 2000, 2002, 2004, 2007, 2015 Red Hat, Inc.
    This file is part of elfutils.
    Written by Ulrich Drepper <drepper@redhat.com>, 1998.
 
@@ -310,3 +310,21 @@ START (64, auxv_t, Ext##auxv_t)						      \
   TYPE_XLATE (Elf64_cvt_Addr1 (&tdest->a_un.a_val, &tsrc->a_un.a_val);)	      \
   TYPE_EXTRA (} a_un;)							      \
 END (64, Ext##auxv_t)
+
+/* Note that there is actual compression data right after the Chdr.
+   So we also have a separate conversion function for the whole
+   section.  */
+#define Chdr32(Ext) \
+START (32, Chdr, Ext##Chdr)						\
+  TYPE_NAME (ElfW2(32, Ext##Word), ch_type)				\
+  TYPE_NAME (ElfW2(32, Ext##Word), ch_size)				\
+  TYPE_NAME (ElfW2(32, Ext##Word), ch_addralign)			\
+END (32, Ext##Chdr)
+
+#define Chdr64(Ext) \
+START (64, Chdr, Ext##Chdr)						\
+  TYPE_NAME (ElfW2(64, Ext##Word), ch_type)				\
+  TYPE_NAME (ElfW2(64, Ext##Word), ch_reserved)				\
+  TYPE_NAME (ElfW2(64, Ext##Xword), ch_size)				\
+  TYPE_NAME (ElfW2(64, Ext##Xword), ch_addralign)			\
+END (64, Ext##Chdr)
diff --git a/libelf/chdr_xlate.h b/libelf/chdr_xlate.h
new file mode 100644
index 00000000..70782b43
--- /dev/null
+++ b/libelf/chdr_xlate.h
@@ -0,0 +1,33 @@
+#include "common.h"
+
+/* These functions convert a while section, one Chdr plus compression data.  */
+
+static void
+Elf32_cvt_chdr (void *dest, const void *src, size_t len, int encode)
+{
+  if (len == 0)
+    return;
+
+  /* Move everything over, if necessary, we only need to xlate the
+     header, not the compressed data following it.  */
+  if (dest != src)
+    memmove (dest, src, len);
+
+  if (len >= sizeof (Elf32_Chdr))
+    Elf32_cvt_Chdr (dest, src, sizeof (Elf32_Chdr), encode);
+}
+
+static void
+Elf64_cvt_chdr (void *dest, const void *src, size_t len, int encode)
+{
+  if (len == 0)
+    return;
+
+  /* Move everything over, if necessary, we only need to xlate the
+     header, not the compressed data following it.  */
+  if (dest != src)
+    memmove (dest, src, len);
+
+  if (len >= sizeof (Elf64_Chdr))
+    Elf64_cvt_Chdr (dest, src, sizeof (Elf64_Chdr), encode);
+}
diff --git a/libelf/elf32_getchdr.c b/libelf/elf32_getchdr.c
new file mode 100644
index 00000000..982a614c
--- /dev/null
+++ b/libelf/elf32_getchdr.c
@@ -0,0 +1,83 @@
+/* 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 <libelf.h>
+#include "libelfP.h"
+#include "common.h"
+
+#ifndef LIBELFBITS
+# define LIBELFBITS 32
+#endif
+
+
+ElfW2(LIBELFBITS,Chdr) *
+elfw2(LIBELFBITS,getchdr) (Elf_Scn *scn)
+{
+  ElfW2(LIBELFBITS,Shdr) *shdr = elfw2(LIBELFBITS,getshdr) (scn);
+  if (shdr == NULL)
+    return NULL;
+
+  /* Must have SHF_COMPRESSED flag set.  Allocated or no bits sections
+     can never be compressed.  */
+  if ((shdr->sh_flags & SHF_ALLOC) != 0)
+    {
+      __libelf_seterrno (ELF_E_INVALID_SECTION_FLAGS);
+      return NULL;
+    }
+
+  if (shdr->sh_type == SHT_NULL
+      || shdr->sh_type == SHT_NOBITS)
+    {
+      __libelf_seterrno (ELF_E_INVALID_SECTION_TYPE);
+      return NULL;
+    }
+
+  if ((shdr->sh_flags & SHF_COMPRESSED) == 0)
+    {
+      __libelf_seterrno (ELF_E_NOT_COMPRESSED);
+      return NULL;
+    }
+
+  /* This makes sure the data is in the correct format, so we don't
+     need to swap fields. */
+  Elf_Data *d  = elf_getdata (scn, NULL);
+  if (d == NULL)
+    return NULL;
+
+  if (d->d_size < sizeof (ElfW2(LIBELFBITS,Chdr)) || d->d_buf == NULL)
+    {
+      __libelf_seterrno (ELF_E_INVALID_DATA);
+      return NULL;
+    }
+
+  return (ElfW2(LIBELFBITS,Chdr) *) d->d_buf;
+}
diff --git a/libelf/elf64_getchdr.c b/libelf/elf64_getchdr.c
new file mode 100644
index 00000000..6588b791
--- /dev/null
+++ b/libelf/elf64_getchdr.c
@@ -0,0 +1,30 @@
+/* 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/>.  */
+
+#define LIBELFBITS 64
+#include "elf32_getchdr.c"
diff --git a/libelf/elf_error.c b/libelf/elf_error.c
index d6bdaab0..d97e3bd6 100644
--- a/libelf/elf_error.c
+++ b/libelf/elf_error.c
@@ -230,6 +230,21 @@ core files")
   (ELF_E_NO_PHDR_IDX \
    + sizeof "file has no program header")
   N_("invalid offset")
+  "\0"
+#define ELF_E_INVALID_SECTION_TYPE_IDX \
+  (ELF_E_INVALID_OFFSET_IDX \
+   + sizeof "invalid offset")
+  N_("invalid section type")
+  "\0"
+#define ELF_E_INVALID_SECTION_FLAGS_IDX \
+  (ELF_E_INVALID_SECTION_TYPE_IDX \
+   + sizeof "invalid section type")
+  N_("invalid section flags")
+  "\0"
+#define ELF_E_NOT_COMPRESSED_IDX		\
+  (ELF_E_INVALID_SECTION_FLAGS_IDX			\
+   + sizeof "invalid section flags")
+  N_("section does not contain compressed data")
 };
 
 
@@ -277,7 +292,10 @@ static const uint_fast16_t msgidx[ELF_E_NUM] =
   [ELF_E_GROUP_NOT_REL] = ELF_E_GROUP_NOT_REL_IDX,
   [ELF_E_INVALID_PHDR] = ELF_E_INVALID_PHDR_IDX,
   [ELF_E_NO_PHDR] = ELF_E_NO_PHDR_IDX,
-  [ELF_E_INVALID_OFFSET] = ELF_E_INVALID_OFFSET_IDX
+  [ELF_E_INVALID_OFFSET] = ELF_E_INVALID_OFFSET_IDX,
+  [ELF_E_INVALID_SECTION_TYPE] = ELF_E_INVALID_SECTION_TYPE_IDX,
+  [ELF_E_INVALID_SECTION_FLAGS] = ELF_E_INVALID_SECTION_FLAGS_IDX,
+  [ELF_E_NOT_COMPRESSED] = ELF_E_NOT_COMPRESSED_IDX
 };
 #define nmsgidx ((int) (sizeof (msgidx) / sizeof (msgidx[0])))
 
diff --git a/libelf/elf_getdata.c b/libelf/elf_getdata.c
index 9a567e51..bd1f0682 100644
--- a/libelf/elf_getdata.c
+++ b/libelf/elf_getdata.c
@@ -106,6 +106,7 @@ const uint_fast8_t __libelf_type_aligns[EV_NUM - 1][ELFCLASSNUM - 1][ELF_T_NUM]
       [ELF_T_NHDR] = __alignof__ (ElfW2(Bits,Nhdr)),			      \
       [ELF_T_GNUHASH] = __alignof__ (Elf32_Word),			      \
       [ELF_T_AUXV] = __alignof__ (ElfW2(Bits,auxv_t)),			      \
+      [ELF_T_CHDR] = __alignof__ (ElfW2(Bits,Chdr)),			      \
     }
     [EV_CURRENT - 1] =
     {
@@ -204,6 +205,7 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn)
   Elf64_Off offset;
   Elf64_Xword size;
   Elf64_Xword align;
+  Elf64_Xword flags;
   int type;
   Elf *elf = scn->elf;
 
@@ -220,6 +222,7 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn)
       size = shdr->sh_size;
       type = shdr->sh_type;
       align = shdr->sh_addralign;
+      flags = shdr->sh_flags;
     }
   else
     {
@@ -234,6 +237,7 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn)
       size = shdr->sh_size;
       type = shdr->sh_type;
       align = shdr->sh_addralign;
+      flags = shdr->sh_flags;
     }
 
   /* If the section has no data (for whatever reason), leave the `d_buf'
@@ -243,7 +247,10 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn)
       /* First a test whether the section is valid at all.  */
       size_t entsize;
 
-      if (type == SHT_HASH)
+      /* Compressed data has a header, but then compressed data.  */
+      if ((flags & SHF_COMPRESSED) != 0)
+	entsize = 1;
+      else if (type == SHT_HASH)
 	{
 	  GElf_Ehdr ehdr_mem;
 	  GElf_Ehdr *ehdr = __gelf_getehdr_rdlock (elf, &ehdr_mem);
@@ -320,10 +327,15 @@ __libelf_set_rawdata_wrlock (Elf_Scn *scn)
     }
 
   scn->rawdata.d.d_size = size;
-  /* Some broken ELF ABI for 64-bit machines use the wrong hash table
-     entry size.  See elf-knowledge.h for more information.  */
-  if (type == SHT_HASH && elf->class == ELFCLASS64)
+
+  /* Compressed data always has type ELF_T_CHDR regardless of the
+     section type.  */
+  if ((flags & SHF_COMPRESSED) != 0)
+    scn->rawdata.d.d_type = ELF_T_CHDR;
+  else if (type == SHT_HASH && elf->class == ELFCLASS64)
     {
+      /* Some broken ELF ABI for 64-bit machines use the wrong hash table
+	 entry size.  See elf-knowledge.h for more information.  */
       GElf_Ehdr ehdr_mem;
       GElf_Ehdr *ehdr = __gelf_getehdr_rdlock (elf, &ehdr_mem);
       scn->rawdata.d.d_type
diff --git a/libelf/exttypes.h b/libelf/exttypes.h
index 8cb2aaec..7bacd654 100644
--- a/libelf/exttypes.h
+++ b/libelf/exttypes.h
@@ -1,5 +1,5 @@
 /* External ELF types.
-   Copyright (C) 1998-2010 Red Hat, Inc.
+   Copyright (C) 1998-2010, 2015 Red Hat, Inc.
    This file is part of elfutils.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 1998.
 
@@ -75,6 +75,7 @@ Syminfo32 (Ext_);
 Move32 (Ext_);
 Lib32 (Ext_);
 auxv_t32 (Ext_);
+Chdr32 (Ext_);
 
 Ehdr64 (Ext_);
 Phdr64 (Ext_);
@@ -92,6 +93,7 @@ Syminfo64 (Ext_);
 Move64 (Ext_);
 Lib64 (Ext_);
 auxv_t64 (Ext_);
+Chdr64 (Ext_);
 
 #undef START
 #undef END
diff --git a/libelf/gelf.h b/libelf/gelf.h
index e3f07404..1bc7ee72 100644
--- a/libelf/gelf.h
+++ b/libelf/gelf.h
@@ -1,5 +1,5 @@
 /* This file defines generic ELF types, structures, and macros.
-   Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2007 Red Hat, Inc.
+   Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2007, 2015 Red Hat, Inc.
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -85,6 +85,9 @@ typedef Elf64_Rela GElf_Rela;
 /* Program segment header.  */
 typedef Elf64_Phdr GElf_Phdr;
 
+/* Header of a compressed section.  */
+typedef Elf64_Chdr GElf_Chdr;
+
 /* Dynamic section entry.  */
 typedef Elf64_Dyn GElf_Dyn;
 
@@ -183,6 +186,9 @@ extern int gelf_update_phdr (Elf *__elf, int __ndx, GElf_Phdr *__src);
 /* Create new program header with PHNUM entries.  */
 extern unsigned long int gelf_newphdr (Elf *__elf, size_t __phnum);
 
+/* Get compression header of section if any.  Returns NULL and sets
+   elf_errno if the section isn't compressed or an error occurred.  */
+extern GElf_Chdr *gelf_getchdr (Elf_Scn *__scn, GElf_Chdr *__dst);
 
 /* Convert data structure from the representation in the file represented
    by ELF to their memory representation.  */
diff --git a/libelf/gelf_fsize.c b/libelf/gelf_fsize.c
index a124fa84..0c509265 100644
--- a/libelf/gelf_fsize.c
+++ b/libelf/gelf_fsize.c
@@ -68,6 +68,7 @@ const size_t __libelf_type_sizes[EV_NUM - 1][ELFCLASSNUM - 1][ELF_T_NUM] =
       [ELF_T_MOVE]	= sizeof (ElfW2(LIBELFBITS, Ext_Move)),		      \
       [ELF_T_LIB]	= sizeof (ElfW2(LIBELFBITS, Ext_Lib)),		      \
       [ELF_T_AUXV]	= sizeof (ElfW2(LIBELFBITS, Ext_auxv_t)),	      \
+      [ELF_T_CHDR]	= sizeof (ElfW2(LIBELFBITS, Ext_Chdr)),		      \
       [ELF_T_GNUHASH]	= ELFW2(LIBELFBITS, FSZ_WORD)
       TYPE_SIZES (32)
     },
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)
diff --git a/libelf/gelf_xlate.c b/libelf/gelf_xlate.c
index c5805e73..f3d3b7a0 100644
--- a/libelf/gelf_xlate.c
+++ b/libelf/gelf_xlate.c
@@ -166,6 +166,7 @@ union unaligned
 #include "version_xlate.h"
 #include "gnuhash_xlate.h"
 #include "note_xlate.h"
+#include "chdr_xlate.h"
 
 
 /* Now the externally visible table with the function pointers.  */
@@ -198,7 +199,8 @@ const xfct_t __elf_xfctstom[EV_NUM - 1][EV_NUM - 1][ELFCLASSNUM - 1][ELF_T_NUM]
 	[ELF_T_SYMINFO] = ElfW2(Bits, cvt_Syminfo),			      \
 	[ELF_T_MOVE]	= ElfW2(Bits, cvt_Move),			      \
 	[ELF_T_LIB]	= ElfW2(Bits, cvt_Lib),				      \
-	[ELF_T_AUXV]	= ElfW2(Bits, cvt_auxv_t)
+	[ELF_T_AUXV]	= ElfW2(Bits, cvt_auxv_t),			      \
+	[ELF_T_CHDR]	= ElfW2(Bits, cvt_chdr)
         define_xfcts (32),
 	[ELF_T_GNUHASH] = Elf32_cvt_Word
       },
diff --git a/libelf/gelf_xlate.h b/libelf/gelf_xlate.h
index f11eb90b..3c0e4bf6 100644
--- a/libelf/gelf_xlate.h
+++ b/libelf/gelf_xlate.h
@@ -50,6 +50,7 @@ TYPE (Syminfo, LIBELFBITS)
 TYPE (Move, LIBELFBITS)
 TYPE (Lib, LIBELFBITS)
 TYPE (auxv_t, LIBELFBITS)
+TYPE (Chdr, LIBELFBITS)
 
 
 /* Prepare for the next round.  */
diff --git a/libelf/libelf.h b/libelf/libelf.h
index 54f7c29b..49234c8a 100644
--- a/libelf/libelf.h
+++ b/libelf/libelf.h
@@ -1,5 +1,5 @@
 /* Interface for libelf.
-   Copyright (C) 1998-2010 Red Hat, Inc.
+   Copyright (C) 1998-2010, 2015 Red Hat, Inc.
    This file is part of elfutils.
 
    This file is free software; you can redistribute it and/or modify
@@ -64,6 +64,7 @@ typedef enum
   ELF_T_LIB,			/* Elf32_Lib, Elf64_Lib, ... */
   ELF_T_GNUHASH,		/* GNU-style hash section.  */
   ELF_T_AUXV,			/* Elf32_auxv_t, Elf64_auxv_t, ... */
+  ELF_T_CHDR,			/* Compressed, Elf32_Chdr, Elf64_Chdr, ... */
   /* Keep this the last entry.  */
   ELF_T_NUM
 } Elf_Type;
@@ -267,6 +268,11 @@ extern Elf32_Shdr *elf32_getshdr (Elf_Scn *__scn);
 /* Similar for ELFCLASS64.  */
 extern Elf64_Shdr *elf64_getshdr (Elf_Scn *__scn);
 
+/* Returns compression header for a section if section data is
+   compressed.  Returns NULL and sets elf_errno if the section isn't
+   compressed or an error occurred.  */
+extern Elf32_Chdr *elf32_getchdr (Elf_Scn *__scn);
+extern Elf64_Chdr *elf64_getchdr (Elf_Scn *__scn);
 
 /* Set or clear flags for ELF file.  */
 extern unsigned int elf_flagelf (Elf *__elf, Elf_Cmd __cmd,
diff --git a/libelf/libelf.map b/libelf/libelf.map
index de6d912a..d402ccc0 100644
--- a/libelf/libelf.map
+++ b/libelf/libelf.map
@@ -138,3 +138,10 @@ ELFUTILS_1.6 {
   global:
     elf_getphdrnum;
 } ELFUTILS_1.5;
+
+ELFUTILS_1.7 {
+  global:
+    elf32_getchdr;
+    elf64_getchdr;
+    gelf_getchdr;
+} ELFUTILS_1.6;
\ No newline at end of file
diff --git a/libelf/libelfP.h b/libelf/libelfP.h
index 993c6556..8ff8478c 100644
--- a/libelf/libelfP.h
+++ b/libelf/libelfP.h
@@ -1,5 +1,5 @@
 /* Internal interfaces for libelf.
-   Copyright (C) 1998-2010 Red Hat, Inc.
+   Copyright (C) 1998-2010, 2015 Red Hat, Inc.
    This file is part of elfutils.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 1998.
 
@@ -138,6 +138,9 @@ enum
   ELF_E_INVALID_PHDR,
   ELF_E_NO_PHDR,
   ELF_E_INVALID_OFFSET,
+  ELF_E_INVALID_SECTION_TYPE,
+  ELF_E_INVALID_SECTION_FLAGS,
+  ELF_E_NOT_COMPRESSED,
   /* Keep this as the last entry.  */
   ELF_E_NUM
 };
diff --git a/tests/ChangeLog b/tests/ChangeLog
index 5afe4bd2..7096f9f9 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,5 +1,22 @@
 2015-10-28  Mark Wielaard  <mjw@redhat.com>
 
+	* elfgetchdr.c: New file.
+	* run-elfgetchdr.sh: New test.
+	* testfile-zgabi32.bz2: New testfile.
+	* testfile-zgabi32be.bz2: Likewise.
+	* testfile-zgabi64.bz2: Likewise.
+	* testfile-zgabi64be.bz2: Likewise.
+	* Makefile.am (check_PROGRAMS): Add elfgetchdr.
+	(TESTS): Add run-elfgetchdr.sh.
+	(EXTRA_DIST): Add run-elfgetchdr.sh, testfile-zgabi32.bz2,
+	testfile-zgabi32be.bz2, testfile-zgabi64.bz2, testfile-zgabi64be.bz2.
+	(welfgetchdr_LDADD): New variable.
+	* msg_tst.c: Add ELF_E_NOT_COMPRESSED, ELF_E_INVALID_SECTION_TYPE
+	and ELF_E_INVALID_SECTION_FLAGS,
+
+
+2015-10-28  Mark Wielaard  <mjw@redhat.com>
+
 	* dwelfgnucompressed.c: New file.
 	* run-dwelfgnucompressed.sh: New test.
 	* testfile-zgnu32.bz2: New testfile.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 8e2f2833..2528e1c0 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -52,7 +52,7 @@ check_PROGRAMS = arextract arsymtest newfile saridx scnnames sectiondump \
 		  backtrace-data backtrace-dwarf debuglink debugaltlink \
 		  buildid deleted deleted-lib.so aggregate_size vdsosyms \
 		  getsrc_die strptr newdata elfstrtab dwfl-proc-attach \
-		  elfshphehdr elfstrmerge dwelfgnucompressed
+		  elfshphehdr elfstrmerge dwelfgnucompressed elfgetchdr
 
 asm_TESTS = asm-tst1 asm-tst2 asm-tst3 asm-tst4 asm-tst5 \
 	    asm-tst6 asm-tst7 asm-tst8 asm-tst9
@@ -120,7 +120,8 @@ TESTS = run-arextract.sh run-arsymtest.sh newfile test-nlist \
 	run-readelf-dwz-multi.sh run-allfcts-multi.sh run-deleted.sh \
 	run-linkmap-cut.sh run-aggregate-size.sh vdsosyms run-readelf-A.sh \
 	run-getsrc-die.sh run-strptr.sh newdata elfstrtab dwfl-proc-attach \
-	elfshphehdr run-lfs-symbols.sh run-dwelfgnucompressed.sh
+	elfshphehdr run-lfs-symbols.sh run-dwelfgnucompressed.sh \
+	run-elfgetchdr.sh
 
 if !BIARCH
 export ELFUTILS_DISABLE_BIARCH = 1
@@ -309,7 +310,10 @@ EXTRA_DIST = run-arextract.sh run-arsymtest.sh \
 	     run-lfs-symbols.sh lfs-symbols testfile-nolfs.bz2 \
 	     testfile-zgnu32.bz2 testfile-zgnu64.bz2 \
 	     testfile-zgnu32be.bz2 testfile-zgnu64be.bz2 \
-	     run-dwelfgnucompressed.sh
+	     run-dwelfgnucompressed.sh \
+	     testfile-zgabi32.bz2 testfile-zgabi64.bz2 \
+	     testfile-zgabi32be.bz2 testfile-zgabi64be.bz2 \
+	     run-elfgetchdr.sh
 
 if USE_VALGRIND
 valgrind_cmd='valgrind -q --leak-check=full --error-exitcode=1'
@@ -459,6 +463,7 @@ dwfl_proc_attach_LDFLAGS = -pthread $(AM_LDFLAGS)
 elfshphehdr_LDADD =$(libelf)
 elfstrmerge_LDADD = $(libebl) $(libelf)
 dwelfgnucompressed_LDADD = $(libelf) $(libdw)
+elfgetchdr_LDADD = $(libelf) $(libdw)
 
 if GCOV
 check: check-am coverage
diff --git a/tests/elfgetchdr.c b/tests/elfgetchdr.c
new file mode 100644
index 00000000..44ba1789
--- /dev/null
+++ b/tests/elfgetchdr.c
@@ -0,0 +1,124 @@
+/* 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 the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   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 a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <assert.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <inttypes.h>
+
+#include ELFUTILS_HEADER(elf)
+#include ELFUTILS_HEADER(dwelf)
+#include <gelf.h>
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+
+int
+main (int argc, char *argv[])
+{
+  int result = 0;
+  int cnt;
+
+  elf_version (EV_CURRENT);
+
+  for (cnt = 1; cnt < argc; ++cnt)
+    {
+      int fd = open (argv[cnt], O_RDONLY);
+
+      Elf *elf = elf_begin (fd, ELF_C_READ, NULL);
+      if (elf == NULL)
+	{
+	  printf ("%s not usable %s\n", argv[cnt], elf_errmsg (-1));
+	  result = 1;
+	  close (fd);
+	  continue;
+	}
+
+      size_t shdrstrndx;
+      if (elf_getshdrstrndx (elf, &shdrstrndx) == -1)
+	{
+	  printf ("elf_getshdrstrnd failed %s\n", elf_errmsg (-1));
+	  result = 1;
+	  close (fd);
+	  continue;
+	}
+
+      Elf_Scn *scn = NULL;
+      while ((scn = elf_nextscn (elf, scn)) != NULL)
+	{
+	  int idx = elf_ndxscn (scn);
+	  GElf_Shdr shdr;
+	  if (gelf_getshdr (scn, &shdr) == NULL)
+	    {
+	      printf ("gelf_getshdr failed: %s\n", elf_errmsg (-1));
+	      result = 1;
+	      break;
+	    }
+
+	  if ((shdr.sh_flags & SHF_COMPRESSED) != 0)
+	    {
+	      GElf_Chdr chdr;
+	      if (gelf_getchdr (scn, &chdr) == NULL)
+		{
+		  printf ("gelf_getchdr failed: %s\n", elf_errmsg (-1));
+		  result = 1;
+		  break;
+		}
+
+	      printf ("section %d: ELF Compressed ch_type: %" PRId32
+		      ", ch_size: %" PRIx64 ", ch_addralign: %" PRIx64 "\n",
+		      idx, chdr.ch_type, chdr.ch_size, chdr.ch_addralign);
+	    }
+	  else
+	    {
+	      const char *sname = elf_strptr (elf, shdrstrndx, shdr.sh_name);
+	      if (sname == NULL)
+		{
+		  printf ("couldn't get section name: %s\n", elf_errmsg (-1));
+		  result = 1;
+		  break;
+		}
+
+	      /* This duplicates what the dwelfgnucompressed testcase does.  */
+	      if (strncmp(".zdebug", sname, strlen (".zdebug")) == 0)
+		{
+		  ssize_t size;
+		  if ((size = dwelf_scn_gnu_compressed_size (scn)) == -1)
+		    {
+		      printf ("dwelf_scn_gnu_compressed_size failed: %s\n",
+			      elf_errmsg (-1));
+		      result = 1;
+		      break;
+		    }
+		  printf ("section %d: GNU Compressed size: %zx\n", idx, size);
+		}
+	      else
+		printf ("section %d: NOT Compressed\n", idx);
+	    }
+	}
+
+      elf_end (elf);
+      close (fd);
+    }
+
+  return result;
+}
diff --git a/tests/msg_tst.c b/tests/msg_tst.c
index 10ff0f73..539c5ddb 100644
--- a/tests/msg_tst.c
+++ b/tests/msg_tst.c
@@ -74,7 +74,10 @@ static struct
       "program header only allowed in executables, shared objects, \
 and core files" },
     { ELF_E_NO_PHDR, "file has no program header" },
-    { ELF_E_INVALID_OFFSET, "invalid offset" }
+    { ELF_E_INVALID_OFFSET, "invalid offset" },
+    { ELF_E_INVALID_SECTION_TYPE , "invalid section type" },
+    { ELF_E_INVALID_SECTION_FLAGS , "invalid section flags" },
+    { ELF_E_NOT_COMPRESSED, "section does not contain compressed data" }
   };
 
 
diff --git a/tests/run-elfgetchdr.sh b/tests/run-elfgetchdr.sh
new file mode 100755
index 00000000..7a422f39
--- /dev/null
+++ b/tests/run-elfgetchdr.sh
@@ -0,0 +1,188 @@
+#! /bin/sh
+# 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 the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# 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 a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+. $srcdir/test-subr.sh
+
+# = funcs.s =
+# .globl testfunc
+# testfunc:
+# 	nop
+# 	ret
+# .type testfunc, @function
+# .size testfunc, .-testfunc
+#
+# .globl testfunc2
+# testfunc2:
+# 	call testfunc
+# 	nop
+# 	nop
+# 	ret
+# .type testfunc2, @function
+# .size testfunc2, .-testfunc2
+#
+# .globl functest3
+# functest3:
+# 	jmp local
+# 	nop
+# 	nop
+# local:
+# 	call testfunc2
+# 	ret
+# .type functest3, @function
+# .size functest3, .-functest3
+
+# = start.s =
+# .global _start
+# _start:
+# 	call functest3
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	nop
+# 	ret
+# .type _start, @function
+# .size _start, .-_start
+
+# gas --compress-debug-sections=zlib-gnu -32 -g -o start.o start.s
+# gas --compress-debug-sections=zlib-gnu -32 -g -o funcs.o funcs.s
+# ld --compress-debug-sections=zlib-gnu -melf_i386 -g -o zgnu32 funcs.o start.o
+
+# gas --compress-debug-sections=zlib-gnu -64 -g -o start.o start.s
+# gas --compress-debug-sections=zlib-gnu -64 -g -o funcs.o funcs.s
+# ld --compress-debug-sections=zlib-gnu -g -o zgnu64 funcs.o start.o
+
+# gas --compress-debug-sections=zlib-gabi -32 -g -o start.o start.s
+# gas --compress-debug-sections=zlib-gabi -32 -g -o funcs.o funcs.s
+# ld --compress-debug-sections=zlib-gabi -melf_i386 -g -o zgabi32 funcs.o start.o
+
+# gas --compress-debug-sections=zlib-gabi -64 -g -o start.o start.s
+# gas --compress-debug-sections=zlib-gabi -64 -g -o funcs.o funcs.s
+# ld --compress-debug-sections=zlib-gabi -g -o zgabi64 funcs.o start.o
+
+testfiles testfile-zgnu64
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgnu64 <<\EOF
+section 1: NOT Compressed
+section 2: GNU Compressed size: 60
+section 3: GNU Compressed size: aa
+section 4: NOT Compressed
+section 5: GNU Compressed size: 8d
+section 6: NOT Compressed
+section 7: NOT Compressed
+section 8: NOT Compressed
+EOF
+
+testfiles testfile-zgabi64
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgabi64 <<\EOF
+section 1: NOT Compressed
+section 2: ELF Compressed ch_type: 1, ch_size: 60, ch_addralign: 10
+section 3: ELF Compressed ch_type: 1, ch_size: aa, ch_addralign: 1
+section 4: NOT Compressed
+section 5: ELF Compressed ch_type: 1, ch_size: 8d, ch_addralign: 1
+section 6: NOT Compressed
+section 7: NOT Compressed
+section 8: NOT Compressed
+EOF
+
+testfiles testfile-zgnu32
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgnu32 <<\EOF
+section 1: NOT Compressed
+section 2: GNU Compressed size: 40
+section 3: GNU Compressed size: 9a
+section 4: NOT Compressed
+section 5: GNU Compressed size: 85
+section 6: NOT Compressed
+section 7: NOT Compressed
+section 8: NOT Compressed
+EOF
+
+testfiles testfile-zgabi32
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgabi32 <<\EOF
+section 1: NOT Compressed
+section 2: ELF Compressed ch_type: 1, ch_size: 40, ch_addralign: 8
+section 3: ELF Compressed ch_type: 1, ch_size: 9a, ch_addralign: 1
+section 4: NOT Compressed
+section 5: ELF Compressed ch_type: 1, ch_size: 85, ch_addralign: 1
+section 6: NOT Compressed
+section 7: NOT Compressed
+section 8: NOT Compressed
+EOF
+
+testfiles testfile-zgnu64be
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgnu64be <<\EOF
+section 1: NOT Compressed
+section 2: NOT Compressed
+section 3: GNU Compressed size: 60
+section 4: GNU Compressed size: 7e
+section 5: NOT Compressed
+section 6: GNU Compressed size: 8d
+section 7: NOT Compressed
+section 8: NOT Compressed
+section 9: NOT Compressed
+EOF
+
+testfiles testfile-zgabi64be
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgabi64be <<\EOF
+section 1: NOT Compressed
+section 2: NOT Compressed
+section 3: ELF Compressed ch_type: 1, ch_size: 60, ch_addralign: 10
+section 4: ELF Compressed ch_type: 1, ch_size: 7e, ch_addralign: 1
+section 5: NOT Compressed
+section 6: ELF Compressed ch_type: 1, ch_size: 8d, ch_addralign: 1
+section 7: NOT Compressed
+section 8: NOT Compressed
+section 9: NOT Compressed
+EOF
+
+testfiles testfile-zgnu32be
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgnu32be <<\EOF
+section 1: NOT Compressed
+section 2: NOT Compressed
+section 3: GNU Compressed size: 40
+section 4: GNU Compressed size: 6e
+section 5: NOT Compressed
+section 6: GNU Compressed size: 85
+section 7: NOT Compressed
+section 8: NOT Compressed
+section 9: NOT Compressed
+EOF
+
+testfiles testfile-zgabi32be
+testrun_compare ${abs_top_builddir}/tests/elfgetchdr testfile-zgabi32be <<\EOF
+section 1: NOT Compressed
+section 2: NOT Compressed
+section 3: ELF Compressed ch_type: 1, ch_size: 40, ch_addralign: 8
+section 4: ELF Compressed ch_type: 1, ch_size: 6e, ch_addralign: 1
+section 5: NOT Compressed
+section 6: ELF Compressed ch_type: 1, ch_size: 85, ch_addralign: 1
+section 7: NOT Compressed
+section 8: NOT Compressed
+section 9: NOT Compressed
+EOF
+
+exit 0
diff --git a/tests/testfile-zgabi32.bz2 b/tests/testfile-zgabi32.bz2
new file mode 100755
index 00000000..6159dbce
--- /dev/null
+++ b/tests/testfile-zgabi32.bz2
diff --git a/tests/testfile-zgabi32be.bz2 b/tests/testfile-zgabi32be.bz2
new file mode 100755
index 00000000..f1f5eb5c
--- /dev/null
+++ b/tests/testfile-zgabi32be.bz2
diff --git a/tests/testfile-zgabi64.bz2 b/tests/testfile-zgabi64.bz2
new file mode 100755
index 00000000..3b44f089
--- /dev/null
+++ b/tests/testfile-zgabi64.bz2
diff --git a/tests/testfile-zgabi64be.bz2 b/tests/testfile-zgabi64be.bz2
new file mode 100755
index 00000000..d819ae3d
--- /dev/null
+++ b/tests/testfile-zgabi64be.bz2