I got Janet working on OS X Tiger/PowerPC!

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Blog 2020/6/25

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I got Janet working on OS X Tiger/PowerPC!

I've been excitely watching the growth of janet-lang, a lisp with Clojure-like syntax, lightning-fast start-up latency, and good performance for a byte-code VM.

In particular, this lisp shows a lot of promise for less-than-beefy machines.

Of course, janet builds out-of-the-box on modern Linux and macOS. However, it doesn't build under OS X Tiger, because the following are missing:

• posix_spawn()
• clock_gettime()
• arc4random_buf()
• O_CLOEXEC

I spent the day digging into these and managed to get it working!

To get this working on your machine:

• Install tigerbrew
• Install gcc 7: brew install --verbose wget gcc
• Download the attached build-janet-tiger.sh and tiger.patch
• Run ./build-janet-tiger.sh

build-janet-tiger.sh

#!/bin/bash

# Build and install janet-lang on OS X Tiger, as a user,
# into ~/opt/janet-x.x.x, and symlink into ~/local/bin or ~/bin.

# Note: this does not build the janet shared library (libjanet.so).
# TODO: figure out how to build a libjanet.dylib instead :)

version=1.10.1
tarball=janet-${version}.tar.gz
url=https://github.com/janet-lang/janet/archive/v${version}.tar.gz

set -e -x

mkdir -p $HOME/dist $HOME/tmp $HOME/opt/janet-$version

# Fetch:
test -e $HOME/dist/$tarball || wget -O $HOME/dist/$tarball $url

# Unpack:
cd $HOME/tmp
rm -rf janet-$version
tar xzf $HOME/dist/$tarball

# Patch:
cd janet-$version
patch -p1 < ../tiger.patch

# The default CFLAGS from janet's Makefile:
cflags="-std=c99 -Wall -Wextra -Isrc/include -Isrc/conf -fPIC -fvisibility=hidden"
# Tiger-specific build flags:
cflags="$cflags -mmacosx-version-min=10.4"
# Indicate which features Tiger is missing:
cflags="$cflags -DNO_CLOEXEC -DNO_SPAWN_H -DNO_CLOCK_GETTIME -DNO_ARC4RANDOM_BUF -DNO_POSIX_SPAWN"

# CPU-specific optimization flags.
# See /usr/include/mach/machine.h
cputype=$( sysctl hw.cputype | cut -d' ' -f2 )
cpusubtype=$( sysctl hw.cpusubtype | cut -d' ' -f2 )
if test "$cputype" = "18" -a "$cpusubtype" = "9" ; then
    cflags="$cflags -mcpu=750 -Os"   # PowerPC G3
elif test "$cputype" = "18" -a "$cpusubtype" = "10" ; then
    cflags="$cflags -mcpu=7400 -Os"  # PowerPC G4
elif test "$cputype" = "18" -a "$cpusubtype" = "11" ; then
    cflags="$cflags -mcpu=7450 -Os"  # PowerPC G4e
elif test "$cputype" = "18" -a "$cpusubtype" = "100" ; then
    cflags="$cflags -mcpu=970 -Os"   # PowerPC G5
fi

# Homebrew's MANPATH disrupts janet's Makefile.
unset MANPATH

# Note: gcc 4 and 4.2 fail with "error: thread-local storage not supported for this target".
# However, using gcc-7 (via tigerbrew's "brew install gcc") works.

# Build janet_boot faster using -O0:
make build/janet_boot \
    PREFIX=$HOME/opt/janet-$version \
    CC=gcc-7 \
    CFLAGS="$cflags -O0"

make test install \
    PREFIX=$HOME/opt/janet-$version \
    CC=gcc-7 \
    CFLAGS="$cflags"  \
    LDFLAGS=""  # Remove -rdynamic from LDFLAGS

# Symlink janet and jpm into either ~/local/bin or ~/bin.
if test -e $HOME/local/bin ; then
    ln -sf $HOME/opt/janet-$version/bin/janet $HOME/local/bin/
    ln -sf $HOME/opt/janet-$version/bin/jpm $HOME/local/bin/
elif test -e $HOME/bin ; then
    ln -sf $HOME/opt/janet-$version/bin/janet $HOME/bin/
    ln -sf $HOME/opt/janet-$version/bin/jpm $HOME/bin/
fi

tiger.patch

diff -urN janet-1.10.1/Makefile janet-1.10.1.tiger/Makefile
--- janet-1.10.1/Makefile	2020-06-18 19:24:17.000000000 -0500
+++ janet-1.10.1.tiger/Makefile	2020-06-25 21:37:26.000000000 -0500
@@ -259,17 +259,17 @@
 	cp -rf $(JANET_HEADERS) '$(DESTDIR)$(INCLUDEDIR)/janet'
 	mkdir -p '$(DESTDIR)$(JANET_PATH)'
 	mkdir -p '$(DESTDIR)$(LIBDIR)'
-	cp $(JANET_LIBRARY) '$(DESTDIR)$(LIBDIR)/libjanet.so.$(shell $(JANET_TARGET) -e '(print janet/version)')'
-	cp $(JANET_STATIC_LIBRARY) '$(DESTDIR)$(LIBDIR)/libjanet.a'
-	ln -sf $(SONAME) '$(DESTDIR)$(LIBDIR)/libjanet.so'
-	ln -sf libjanet.so.$(shell $(JANET_TARGET) -e '(print janet/version)') $(DESTDIR)$(LIBDIR)/$(SONAME)
+	#cp $(JANET_LIBRARY) '$(DESTDIR)$(LIBDIR)/libjanet.so.$(shell $(JANET_TARGET) -e '(print janet/version)')'
+	#cp $(JANET_STATIC_LIBRARY) '$(DESTDIR)$(LIBDIR)/libjanet.a'
+	#ln -sf $(SONAME) '$(DESTDIR)$(LIBDIR)/libjanet.so'
+	#ln -sf libjanet.so.$(shell $(JANET_TARGET) -e '(print janet/version)') $(DESTDIR)$(LIBDIR)/$(SONAME)
 	cp -rf build/jpm '$(DESTDIR)$(BINDIR)'
 	mkdir -p '$(DESTDIR)$(MANPATH)'
 	cp janet.1 '$(DESTDIR)$(MANPATH)'
 	cp jpm.1 '$(DESTDIR)$(MANPATH)'
 	mkdir -p '$(DESTDIR)$(PKG_CONFIG_PATH)'
 	cp build/janet.pc '$(DESTDIR)$(PKG_CONFIG_PATH)/janet.pc'
-	[ -z '$(DESTDIR)' ] && $(LDCONFIG) || true
+	#[ -z '$(DESTDIR)' ] && $(LDCONFIG) || true
 
 uninstall:
 	-rm '$(DESTDIR)$(BINDIR)/janet'
diff -urN janet-1.10.1/src/core/net.c janet-1.10.1.tiger/src/core/net.c
--- janet-1.10.1/src/core/net.c	2020-06-18 19:24:17.000000000 -0500
+++ janet-1.10.1.tiger/src/core/net.c	2020-06-25 20:21:18.000000000 -0500
@@ -112,7 +112,7 @@
 #endif
 static JanetStream *make_stream(int fd, int flags) {
     JanetStream *stream = janet_abstract(&StreamAT, sizeof(JanetStream));
-#ifndef SOCK_CLOEXEC
+#if !defined(SOCK_CLOEXEC) && !defined(NO_CLOEXEC)
     int extra = O_CLOEXEC;
 #else
     int extra = 0;
diff -urN janet-1.10.1/src/core/os.c janet-1.10.1.tiger/src/core/os.c
--- janet-1.10.1/src/core/os.c	2020-06-18 19:24:17.000000000 -0500
+++ janet-1.10.1.tiger/src/core/os.c	2020-06-25 21:27:28.000000000 -0500
@@ -46,7 +46,9 @@
 #include <io.h>
 #include <process.h>
 #else
+#ifndef NO_SPAWN_H
 #include <spawn.h>
+#endif
 #include <utime.h>
 #include <unistd.h>
 #include <dirent.h>
@@ -68,6 +70,18 @@
  * work/link properly if we detect a BSD */
 #if defined(JANET_BSD) || defined(JANET_APPLE)
 void arc4random_buf(void *buf, size_t nbytes);
+#ifdef NO_ARC4RANDOM_BUF
+uint32_t arc4random(void);
+/* Thanks to https://stackoverflow.com/a/12956868/558735 */
+void arc4random_buf(void *buf, size_t nbytes) {
+    size_t intBufLength = (nbytes/4)+1;
+    uint32_t randomInts[intBufLength];        
+    for (size_t i = 0; i < intBufLength; i++) {
+        randomInts[i] = arc4random();
+    }
+    memcpy(buf, randomInts, nbytes);
+}
+#endif
 #endif
 
 /* Not POSIX, but all Unixes but Solaris have this function. */
@@ -77,6 +91,12 @@
 #define timegm _mkgmtime
 #endif
 
+#if defined(__MACH__) && defined(NO_CLOCK_GETTIME)
+/* _ANSI_SOURCE or _POSIX_C_SOURCE prevents these from being visible on older OS X. */
+struct tm *gmtime_r(const time_t *, struct tm *);
+struct tm *localtime_r(const time_t *, struct tm *);
+#endif
+
 /* Access to some global variables should be synchronized if not in single threaded mode, as
  * setenv/getenv are not thread safe. */
 #ifdef JANET_THREADS
@@ -388,6 +408,16 @@
     }
 
     pid_t pid;
+#ifdef NO_POSIX_SPAWN
+    pid = fork();
+    if (pid == 0) {
+        /* This is the child process. */
+        status = execve(child_argv[0], cargv, envp);
+        /* Note: a successful execve does not return.
+           Therefore, continued execution indicates execve has failed. */
+        exit(errno);
+    }
+#else
     if (janet_flag_at(flags, 1)) {
         status = posix_spawnp(&pid,
                               child_argv[0], NULL, NULL, cargv,
@@ -397,6 +427,7 @@
                              child_argv[0], NULL, NULL, cargv,
                              use_environ ? environ : envp);
     }
+#endif
 
     if (use_environ) {
         janet_unlock_environ();
@@ -522,7 +553,7 @@
     return 0;
 }
 #elif defined(__MACH__)
-static int gettime(struct timespec *spec) {
+int gettime(struct timespec *spec) {
     clock_serv_t cclock;
     mach_timespec_t mts;
     host_get_clock_service(mach_host_self(), CALENDAR_CLOCK, &cclock);
diff -urN janet-1.10.1/src/core/thread.c janet-1.10.1.tiger/src/core/thread.c
--- janet-1.10.1/src/core/thread.c	2020-06-18 19:24:17.000000000 -0500
+++ janet-1.10.1.tiger/src/core/thread.c	2020-06-25 20:56:05.000000000 -0500
@@ -234,7 +234,11 @@
     if (waiter->timedwait) {
         /* N seconds -> timespec of (now + sec) */
         struct timespec now;
+#if defined(__MACH__) && defined(NO_CLOCK_GETTIME)
+        gettime(&now);
+#else
         clock_gettime(CLOCK_REALTIME, &now);
+#endif
         time_t tvsec = (time_t) floor(sec);
         long tvnsec = (long) floor(1000000000.0 * (sec - ((double) tvsec)));
         tvsec += now.tv_sec;
diff -urN janet-1.10.1/src/core/util.h janet-1.10.1.tiger/src/core/util.h
--- janet-1.10.1/src/core/util.h	2020-06-18 19:24:17.000000000 -0500
+++ janet-1.10.1.tiger/src/core/util.h	2020-06-25 20:48:14.000000000 -0500
@@ -87,6 +87,11 @@
     int32_t argc,
     Janet *argv);
 
+#if defined(__MACH__)
+#include <time.h>
+int gettime(struct timespec *spec);
+#endif
+
 /* Inside the janet core, defining globals is different
  * at bootstrap time and normal runtime */
 #ifdef JANET_BOOTSTRAP

Github issue: janet-lang/janet#430