From 8ed555dbac12e0cbf92da8c38293a54982715170 Mon Sep 17 00:00:00 2001
From: Brandon Curtis <brandon.curtis@gmail.com>
Date: Thu, 18 Aug 2016 01:40:29 -0700
Subject: [PATCH 1/2] Workaround for `glibc >2.24` compilation failure

`glibc 2.24` deprecated `readdir_r` and patched `readdir` for threadsafeness.  This Makefile upgrades warnings to errors with `CWFLAGS=-Werror`, so compilation fails in the presence of `glibc >2.24`.  This is a problem in Arch today, and other distros in the near future.

The best solution may be to check the `glibc` version and replace `readdir_r` with `readdir` if `glibc >2.24`.  In the meantime, using `CWFLAGS+=-Wno-error=deprecated-declarations` in the Makefile in the case of `glibc >2.24` allows `glibc 2.24` users to compile Urbit.

Depends on `getconf` and `expr` shell built-ins, which should be available everywhere.
---
 Makefile | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Makefile b/Makefile
index ce97c5efae..61b226bace 100644
--- a/Makefile
+++ b/Makefile
@@ -134,6 +134,20 @@ ifneq ($(OS),bsd)
   CWFLAGS+=-Wno-error=unused-result
 endif
 
+# glibc 2.24 deprecates readdir_r; iff glibc >=2.24,
+# don't upgrade 'deprecated declarations' warnings to errors
+# dependency: `getconf`, which comes w/glibc
+GLIBC := $(lastword $(shell getconf GNU_LIBC_VERSION))
+# dependency: none, uses make's native functions
+GLIBC_MAJ := $(word 1, $(subst ., ,$(GLIBC))) 
+GLIBC_MIN := $(word 2, $(subst ., ,$(GLIBC)))
+# dependency: `expr` shell built-in
+GLIBC_GE_2_24 := $(shell expr $(GLIBC_MAJ) ">" 2 "|" \
+        $(GLIBC_MAJ) "=" 2 "&" $(GLIBC_MIN) ">=" 24)
+ifeq (1,$(GLIBC_GE_2_24))
+  CWFLAGS+=-Wno-error=deprecated-declarations
+endif
+
 ifdef NO_SILENT_RULES
 %.o: %.c $(CORE)
 	$(CC) -c $(CWFLAGS) $(CFLAGS) -o $@ $<

From 5e9f4470c77b49747818410195841b88b25862fa Mon Sep 17 00:00:00 2001
From: Brandon Curtis <brandon.curtis@gmail.com>
Date: Fri, 19 Aug 2016 04:55:06 -0700
Subject: [PATCH 2/2] Use `U3_OS_LoomBits` To Set Reserved Memory Size
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The size and starting position of Urbit's reserved memory block is set by `U3_OS_LoomBits` and `U3_OS_LoomBase` in `include/c/portable.h`.

`U3_OS_LoomBase` is referenced in `include/noun/allocate.h` and sets the position in memory of u3_Loom.  This is good.

However, `U3_OS_LoomBits` is not actually used to set the size of the reserved memory block.  Instead:

in `include/allocate.h`,
 - `u3a_bits` is defined
 - `u3a_bits` → `u3a_bytes`

in `noun/manage.c`,
 - `u3a_bytes` → `len_w` in `_cm_init()`
 - `len_w` sets the reserved memory block size

This proposal puts `U3_OS_LoomBits` back to work by defining `u3a_bits` with it.
---
 include/noun/allocate.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/noun/allocate.h b/include/noun/allocate.h
index 7ab6b2139d..68de4afb8b 100644
--- a/include/noun/allocate.h
+++ b/include/noun/allocate.h
@@ -23,7 +23,7 @@
   **/
     /* u3a_bits: number of bits in word-addressed pointer.  29 == 2GB.
     */
-#     define u3a_bits  29
+#     define u3a_bits  U3_OS_LoomBits
 
     /* u3a_page: number of bits in word-addressed page.  12 == 16Kbyte page.
     */