[Buildroot] [PATCH 2/2] libressl: fix musl build with older kernel headers

Baruch Siach baruch at tkos.co.il
Fri Sep 29 09:13:24 UTC 2017

musl provides its own SYS_getrandom definition, but not GRND_NONBLOCK.
This breaks the build with kernel headers older than v3.17. Add a patch
adding a local definition of GRND_NONBLOCK to fix the build.

The following defconfig reproduces the build failure:


The getentropy_linux.c file is in upstream tarball, but not in its git
repository. It originates form OpenBSD. For this reason the patch is
against the tarball, but not git formatted.

Cc: Adam Duskett <aduskett at gmail.com>
Signed-off-by: Baruch Siach <baruch at tkos.co.il>
 package/libressl/0002-fix-musl.patch | 38 ++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 package/libressl/0002-fix-musl.patch

diff --git a/package/libressl/0002-fix-musl.patch b/package/libressl/0002-fix-musl.patch
new file mode 100644
index 000000000000..ddb953402d91
--- /dev/null
+++ b/package/libressl/0002-fix-musl.patch
@@ -0,0 +1,38 @@
+From: Baruch Siach <baruch at tkos.co.il>
+Date: Fri, 29 Sep 2017 10:06:52 +0300
+Subject: [PATCH] Fix build with musl and older Linux kernel
+The musl libc carries its own copy of Linux system calls. When building
+with Linux headers older than v3.17, musl provides SYS_getrandom
+definition, but not GRND_NONBLOCK. This causes build failure for
+libressl and openntpd:
+getentropy_linux.c: In function 'getentropy_getrandom':
+getentropy_linux.c:205:42: error: 'GRND_NONBLOCK' undeclared (first use in this function)
+   ret = syscall(SYS_getrandom, buf, len, GRND_NONBLOCK);
+                                          ^~~~~~~~~~~~~
+Define GRND_NONBLOCK locally when its definition is missing to fix the
+build. There should be no run-time effect. Older kernels return ENOSYS
+for unsupported syscall().
+[ from upstream pull request with file location changed ]
+Signed-off-by: Baruch Siach <baruch at tkos.co.il>
+Upstream status: https://github.com/libressl-portable/openbsd/pull/82
+diff -Nuar libressl-2.5.5-orig/crypto/compat/getentropy_linux.c libressl-2.5.5/crypto/compat/getentropy_linux.c
+--- libressl-2.5.5-orig/crypto/compat/getentropy_linux.c	2017-07-09 13:59:48.000000000 +0300
++++ libressl-2.5.5/crypto/compat/getentropy_linux.c	2017-09-29 10:03:32.447958829 +0300
+@@ -194,6 +194,11 @@
+ }
+ #ifdef SYS_getrandom
++#define GRND_NONBLOCK   0x0001
+ static int
+ getentropy_getrandom(void *buf, size_t len)
+ {

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