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Re: [PATCH] libelf: Add ELF compression types and defines to libelf.h for older glibc.


On Wed, 2016-01-13 at 18:01 +0100, Kurt Roeckx wrote:
> On Wed, Jan 13, 2016 at 05:22:35PM +0100, Mark Wielaard wrote:
> > Older glibc elf.h might not define the new ELF compression defines and
> > types. If not just define them in libelf.h directly to make the libelf
> > headers work on older glibc systems.
> > 
> > Also include a testcase to check the libelf headers build against the
> > system elf.h.
> 
> That seems to fail with:
>   CC       system_elf_libelf_test-system-elf-libelf-test.o
> In file included from system-elf-libelf-test.c:22:0:
> ../libelf/gelf.h:32:20: fatal error: libelf.h: No such file or directory
> compilation terminated.

Ah, right :{ I failed to test with a system that doesn't have any
version of elfutils headers installed. In my case the source gelf.h
includes the system libelf.h... Even though just before the the source
source libefl.h was correctly included. Hohum.

Lets see. I made the test try too many different things. Lets just make
it test libelf.h on its own, without confusing it about gelf too.
libelf.h is the important header in any case.

Does the attached work for you?

Thanks,

Mark
From b9d70fb9fb0bd0bf84eb2302cba1691aea74c42e Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mjw@redhat.com>
Date: Wed, 13 Jan 2016 17:16:48 +0100
Subject: [PATCH] libelf: Add ELF compression types and defines to libelf.h for
 older glibc.

Older glibc elf.h might not define the new ELF compression defines and
types. If not just define them in libelf.h directly to make the libelf
headers work on older glibc systems.

Also include a testcase to check the libelf headers build against the
system elf.h.

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=810885

Signed-off-by: Mark Wielaard <mjw@redhat.com>
---
 libelf/ChangeLog               |  5 +++++
 libelf/libelf.h                | 28 ++++++++++++++++++++++++++++
 tests/ChangeLog                |  8 ++++++++
 tests/Makefile.am              |  9 +++++++--
 tests/system-elf-libelf-test.c | 35 +++++++++++++++++++++++++++++++++++
 5 files changed, 83 insertions(+), 2 deletions(-)
 create mode 100644 tests/system-elf-libelf-test.c

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index 3a1fe91..aabf6f6 100644
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,8 @@
+2016-01-13  Mark Wielaard  <mjw@redhat.com>
+
+	* libelf.h: Check SHF_COMPRESSED is defined. If not define it and the
+	associated ELF compression types/defines.
+
 2015-11-26  Mark Wielaard  <mjw@redhat.com>
 
 	* elf_compress.c (__libelf_decompress_elf): New function, extracted
diff --git a/libelf/libelf.h b/libelf/libelf.h
index 364e776..c0d6389 100644
--- a/libelf/libelf.h
+++ b/libelf/libelf.h
@@ -35,6 +35,34 @@
 /* Get the ELF types.  */
 #include <elf.h>
 
+#ifndef SHF_COMPRESSED
+ /* Older glibc elf.h might not yet define the ELF compression types.  */
+ #define SHF_COMPRESSED      (1 << 11)  /* Section with compressed data. */
+
+ /* Section compression header.  Used when SHF_COMPRESSED is set.  */
+
+ typedef struct
+ {
+   Elf32_Word   ch_type;        /* Compression format.  */
+   Elf32_Word   ch_size;        /* Uncompressed data size.  */
+   Elf32_Word   ch_addralign;   /* Uncompressed data alignment.  */
+ } Elf32_Chdr;
+
+ typedef struct
+ {
+   Elf64_Word   ch_type;        /* Compression format.  */
+   Elf64_Word   ch_reserved;
+   Elf64_Xword  ch_size;        /* Uncompressed data size.  */
+   Elf64_Xword  ch_addralign;   /* Uncompressed data alignment.  */
+ } Elf64_Chdr;
+
+ /* Legal values for ch_type (compression algorithm).  */
+ #define ELFCOMPRESS_ZLIB       1          /* ZLIB/DEFLATE algorithm.  */
+ #define ELFCOMPRESS_LOOS       0x60000000 /* Start of OS-specific.  */
+ #define ELFCOMPRESS_HIOS       0x6fffffff /* End of OS-specific.  */
+ #define ELFCOMPRESS_LOPROC     0x70000000 /* Start of processor-specific.  */
+ #define ELFCOMPRESS_HIPROC     0x7fffffff /* End of processor-specific.  */
+#endif
 
 /* Known translation types.  */
 typedef enum
diff --git a/tests/ChangeLog b/tests/ChangeLog
index 366aea9..234ae56 100644
--- a/tests/ChangeLog
+++ b/tests/ChangeLog
@@ -1,3 +1,11 @@
+2016-01-13  Mark Wielaard  <mjw@redhat.com>
+
+	* system-elf-libelf-test.c: New test.
+	* Makefile.am (TESTS): Add system-elf-libelf-test, if !STANDALONE.
+	(check_PROGRAMS): Likewise.
+	(system_elf_libelf_test_CPPFLAGS): New variable.
+	(system_elf_libelf_test_LDADD): Likewise.
+
 2016-01-08  Mark Wielaard  <mjw@redhat.com>
 
 	* elfputzdata.c (main): Fix parentheses in strncmp test.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index d09a6d7..7b9e108 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -136,8 +136,8 @@ export ELFUTILS_DISABLE_DEMANGLE = 1
 endif
 
 if !STANDALONE
-check_PROGRAMS += msg_tst md5-sha1-test
-TESTS += msg_tst md5-sha1-test
+check_PROGRAMS += msg_tst md5-sha1-test system-elf-libelf-test
+TESTS += msg_tst md5-sha1-test system-elf-libelf-test
 endif
 
 if LZMA
@@ -473,6 +473,11 @@ elfgetzdata_LDADD = $(libelf)
 elfputzdata_LDADD = $(libelf)
 zstrptr_LDADD = $(libelf)
 
+# We want to test the libelf header against the system elf.h header.
+# Don't include any -I CPPFLAGS.
+system_elf_libelf_test_CPPFLAGS =
+system_elf_libelf_test_LDADD = $(libelf)
+
 if GCOV
 check: check-am coverage
 .PHONY: coverage
diff --git a/tests/system-elf-libelf-test.c b/tests/system-elf-libelf-test.c
new file mode 100644
index 0000000..7dfe498
--- /dev/null
+++ b/tests/system-elf-libelf-test.c
@@ -0,0 +1,35 @@
+/* Explicit test compiling with system elf.h header plus libelf header.
+
+   Copyright (C) 2016 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/>.  */
+
+#include <elf.h>
+#include <stddef.h>
+#include "../libelf/libelf.h"
+
+int
+main (void)
+{
+  /* Trivial test, this is really a compile test anyway.  */
+  if (elf_version (EV_CURRENT) == EV_NONE)
+    return -1;
+
+  /* This will obviously fail. It is just to check that Elf32_Chdr and
+     elf32_getchdr are available (both at compile time and runtime).  */
+  Elf32_Chdr *chdr = elf32_getchdr (NULL);
+
+  return chdr == NULL ? 0 : -1;
+}
-- 
1.8.3.1


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