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libcap: add patch to fix build issue with old kernel headers

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Old kernels (before 2.6.36) were defining XATTR_NAME_CAPS in
<linux/capability.h>, but using XATTR_SECURITY_PREFIX and
XATTR_CAPS_SUFFIX which were defined in the kernel-only part of
<linux/xattr.h>.

In kernel 2.6.36 (commit af4f136056c984b0aa67feed7d3170b958370b2f),
the XATTR_NAME_CAPS definition was moved to the kernel-only part of
<linux/xattr.h>. It's only in kernel 3.0 (commit
1dbe39424a43e56a6c9aed12661192af51dcdb9f) that <linux/xattr.h> was
fixed to expose XATTR_NAME_CAPS and the related definitions to
userspace.

This is the reason why the target variant of libcap has a dependency
on headers >= 3.0 for the moment.

However, this doesn't solve the problem for the host variant of
libcap, which doesn't build properly on old systems.

To solve this, we simply add a patch that defines the missing
definitions. Their values haven't changed over time since they are
part of the kernel to userspace ABI.

Fixes:

  http://autobuild.buildroot.org/results/856b71bccf14c3334a8c0fc66c1d985b09734313/

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
This commit is contained in:
Thomas Petazzoni 2016-03-16 21:20:09 +01:00 committed by Peter Korsgaard
parent 5d8926add5
commit 604095fe9b
1 changed files with 51 additions and 0 deletions
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51
package/libcap/0003-libcap-cap_file.c-fix-build-with-old-kernel-headers.patch Normal file
View File

@ -0,0 +1,51 @@
From ace694e9574eb38e07cfe0db235434eb40003f47 Mon Sep 17 00:00:00 2001
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Date: Mon, 14 Mar 2016 22:39:15 +0100
Subject: [PATCH] libcap/cap_file.c: fix build with old kernel headers
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
---
libcap/cap_file.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/libcap/cap_file.c b/libcap/cap_file.c
index 40756ea..e3d54dd 100644
--- a/libcap/cap_file.c
+++ b/libcap/cap_file.c
@@ -23,6 +23,33 @@ extern int fsetxattr(int, const char *, const void *, size_t, int);
extern int removexattr(const char *, const char *);
extern int fremovexattr(int, const char *);
+
+/*
+ * Old kernels (before 2.6.36) were defining XATTR_NAME_CAPS in
+ * <linux/capability.h>, but using XATTR_SECURITY_PREFIX and
+ * XATTR_CAPS_SUFFIX which were defined in the kernel-only part of
+ * <linux/xattr.h>.
+ *
+ * In kernel 2.6.36 (commit af4f136056c984b0aa67feed7d3170b958370b2f),
+ * the XATTR_NAME_CAPS definition was moved to the kernel-only part of
+ * <linux/xattr.h>. It's only in kernel 3.0 (commit
+ * 1dbe39424a43e56a6c9aed12661192af51dcdb9f) that <linux/xattr.h> was
+ * fixed to expose XATTR_NAME_CAPS and the related definitions to
+ * userspace.
+ *
+ * In order to cope with kernels < 3.0, we define here the appropriate
+ * values, which we assume haven't changed over history.
+ */
+#ifndef XATTR_CAPS_SUFFIX
+#define XATTR_CAPS_SUFFIX "capability"
+#endif
+#ifndef XATTR_SECURITY_PREFIX
+#define XATTR_SECURITY_PREFIX "security."
+#endif
+#ifndef XATTR_NAME_CAPS
+#define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX
+#endif
+
#include "libcap.h"
#ifdef VFS_CAP_U32
--
2.6.4