Inline the alpine patch

Ruby bugtracker gives 500 occasionally
GitHub goes down too of course but now the eggs are all in one basket

Dockerfile.template

@@ -210,7 +210,7 @@ RUN set -eux; \
 # https://github.com/docker-library/ruby/issues/196
 # https://bugs.ruby-lang.org/issues/14387#note-13 (patch source)
 # https://bugs.ruby-lang.org/issues/14387#note-16 ("Therefore ncopa's patch looks good for me in general." -- only breaks glibc which doesn't matter here)
-	wget -O 'thread-stack-fix.patch' 'https://bugs.ruby-lang.org/attachments/download/7081/0001-thread_pthread.c-make-get_main_stack-portable-on-lin.patch'; \
+	wget -O 'thread-stack-fix.patch' 'https://raw.githubusercontent.com/docker-ruby-nightly/ruby/master/thread-stack-fix.patch'; \
 	echo '3ab628a51d92fdf0d2b5835e93564857aea73e0c1de00313864a94a6255cb645 *thread-stack-fix.patch' | sha256sum --check --strict; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \

thread-stack-fix.patch

@@ -0,0 +1,92 @@
+From 2cd56ff98bdb291b9b5e2d0e3fd4cd315076c904 Mon Sep 17 00:00:00 2001
+From: Natanael Copa <[email protected]>
+Date: Wed, 14 Mar 2018 14:14:11 +0100
+Subject: [PATCH] thread_pthread.c: make get_main_stack portable on linux
+
+We can not rely on the calculated stack size from pthread_getattr_np()
+for the main thread, because the way this is calculated may differ
+depending on implementation. The _np means non-portable.
+
+So we test if it is a known implementation (__GLIBC__) and fallback to a
+portable way on Linux by parsing /proc/self/maps to get the stack for
+main thread. We also add a 100MB safety limit so we don't reserve_stack
+with an insane value.
+
+Credit goes to Szabolcs Nagy for this code.
+---
+ thread_pthread.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
+ 1 file changed, 49 insertions(+), 3 deletions(-)
+
+diff --git a/thread_pthread.c b/thread_pthread.c
+index 951885ffa0..cf90321d1d 100644
+--- a/thread_pthread.c
++++ b/thread_pthread.c
+@@ -530,9 +530,6 @@ hpux_attr_getstackaddr(const pthread_attr_t *attr, void **addr)
+ #   define MAINSTACKADDR_AVAILABLE 0
+ # endif
+ #endif
+-#if MAINSTACKADDR_AVAILABLE && !defined(get_main_stack)
+-# define get_main_stack(addr, size) get_stack(addr, size)
+-#endif
+
+ #ifdef STACKADDR_AVAILABLE
+ /*
+@@ -614,6 +611,55 @@ get_stack(void **addr, size_t *size)
+     return 0;
+ #undef CHECK_ERR
+ }
++
++#if defined(__linux__) && !defined(__GLIBC__) && defined(HAVE_GETRLIMIT)
++
++#ifndef PAGE_SIZE
++#include <unistd.h>
++#define PAGE_SIZE sysconf(_SC_PAGE_SIZE)
++#endif
++
++static int
++get_main_stack(void **addr, size_t *size)
++{
++    size_t start, end, limit, prevend = 0;
++    struct rlimit r;
++    FILE *f;
++    char buf[PATH_MAX+80], s[8];
++    int n;
++    STACK_GROW_DIR_DETECTION;
++
++    f = fopen("/proc/self/maps", "re");
++    if (!f)
++        return -1;
++    n = 0;
++    while (fgets(buf, sizeof buf, f)) {
++        n = sscanf(buf, "%zx-%zx %*s %*s %*s %*s %7s", &start, &end, s);
++        if (n >= 2) {
++            if (n == 3 && strcmp(s, "[stack]") == 0)
++                break;
++            prevend = end;
++        }
++        n = 0;
++    }
++    fclose(f);
++    if (n == 0)
++        return -1;
++
++    limit = 100 << 20; /* 100MB stack limit */
++    if (getrlimit(RLIMIT_STACK, &r)==0 && r.rlim_cur < limit)
++        limit = r.rlim_cur & -PAGE_SIZE;
++    if (limit > end) limit = end;
++    if (prevend < end - limit) prevend = end - limit;
++    if (start > prevend) start = prevend;
++    *addr = IS_STACK_DIR_UPPER() ? (void *)start : (void *)end;
++    *size = end - start;
++    return 0;
++}
++#else
++# define get_main_stack(addr, size) get_stack(addr, size)
++#endif
++
+ #endif
+
+ static struct {
+-- 
+2.16.2
+