libdispatch now builds on Linux and ping/pong test runs successfully.

Set of changes to stub out missing functionality and adapt to Linux.
Key changes are:
  (1) introduction of linux_base.h and linux_stubs.[h,c] to
      contain stubbed out type definitions and functions.
  (2) Copied in BSD's sys/queue.h to shims/sys_queue.h to
      provide _SAFE macros that are not available in Linux
      version of sys/queue.h
  (3) made inclusion of os/base.h conditional
  (4) worked around pthread_workqueue only providing 4 levels of
      priority by skipping initializing of two pairs of queues:
        DISPATCH_ROOT_QUEUE_IDX_BACKGROUND_QOS and
        DISPATCH_ROOT_QUEUE_IDX_USER_INTERACTIVE_QOS
  (5) temporarily stubbed out a few functions in transpose.c
      until an approach to the ByteSwap headers is finalized.
      These are marked with #ifdef LINUX_PORT_HDD
  (6) partial fix to a bug in semaphore.c where the linux clause
      was returning a stack address instead of mallocing memory.
      The fix is only partial because the memory should be freed
      when the semaphore is destroyed (not done).

Small changes
  (a) augmented various .gitignore files for generated artifacts
  (b) a few additional functions bodies disabled with
      #ifdef LINUX_PORT_HDD (need better fixes, but functions
      may not be called).

Author: dgrove-oss

.gitignore

@@ -16,3 +16,16 @@ project.xcworkspace
 Build
 .build
 
+# build files generated by autotools
+Makefile
+Makefile.in
+config.log
+configure
+aclocal.m4
+autom4te.cache
+config.log
+config.status
+config
+configure
+libtool
+

configure.ac

@@ -297,15 +297,17 @@ AS_IF([test "x$dispatch_cv_cc_omit_leaf_fp" != "xno"], [
 ])
 AC_SUBST([OMIT_LEAF_FP_FLAGS])
 
-AC_CACHE_CHECK([for darwin linker], [dispatch_cv_ld_darwin], [
-  saveLDFLAGS="$LDFLAGS"
-  LDFLAGS="$LDFLAGS -dynamiclib -compatibility_version 1.2.3 -current_version 4.5.6 -dead_strip"
-  AC_LINK_IFELSE([AC_LANG_PROGRAM([
-    extern int foo; int foo;], [foo = 0;])],
-    [dispatch_cv_ld_darwin="yes"], [dispatch_cv_ld_darwin="no"])
-  LDFLAGS="$saveLDFLAGS"
+AS_IF([test "x$have_mach" = "xtrue"], [
+  AC_CACHE_CHECK([for darwin linker], [dispatch_cv_ld_darwin], [
+    saveLDFLAGS="$LDFLAGS"
+    LDFLAGS="$LDFLAGS -dynamiclib -compatibility_version 1.2.3 -current_version 4.5.6 -dead_strip"
+    AC_LINK_IFELSE([AC_LANG_PROGRAM([
+      extern int foo; int foo;], [foo = 0;])],
+      [dispatch_cv_ld_darwin="yes"], [dispatch_cv_ld_darwin="no"])
+    LDFLAGS="$saveLDFLAGS"
+  ])
 ])
-AM_CONDITIONAL(HAVE_DARWIN_LD, [test "x$dispatch_cv_ld_darwin" != "xno"])
+AM_CONDITIONAL(HAVE_DARWIN_LD, [test "x$dispatch_cv_ld_darwin" == "xyes"])
 
 #
 # Temporary: some versions of clang do not mark __builtin_trap() as

m4/.gitignore

@@ -0,0 +1,5 @@
+libtool.m4
+ltoptions.m4
+ltsugar.m4
+ltversion.m4
+lt~obsolete.m4

os/Makefile.am

@@ -5,7 +5,8 @@
 osdir=$(includedir)/os
 
 os_HEADERS=	\
-	object.h
+	object.h \
+	linux_base.h
 
 noinst_HEADERS=	\
 	object_private.h

os/linux_base.h

@@ -0,0 +1,142 @@
+/*
+ * @APPLE_APACHE_LICENSE_HEADER_START@
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @APPLE_APACHE_LICENSE_HEADER_END@
+ */
+
+#ifndef __OS_LINUX_BASE__
+#define __OS_LINUX_BASE__
+
+// #include <sys/event.h>
+
+// marker for hacks we have made to make progress
+#define __LINUX_PORT_HDD__ 1 
+
+/*
+ * Stub out defines for some mach types and related macros
+ */
+
+typedef uint32_t mach_port_t;
+
+#define  MACH_PORT_NULL (0)
+#define  MACH_PORT_DEAD (-1)
+
+#define EVFILT_MACHPORT (-8)
+
+typedef uint32_t mach_error_t;
+
+typedef uint32_t mach_vm_size_t;
+
+typedef uint32_t mach_msg_return_t;
+
+typedef uintptr_t mach_vm_address_t;
+
+typedef uint32_t dispatch_mach_msg_t;
+
+typedef uint32_t dispatch_mach_t;
+
+typedef uint32_t dispatch_mach_reason_t;
+
+typedef uint32_t voucher_activity_mode_t;
+
+typedef uint32_t voucher_activity_trace_id_t;
+
+typedef uint32_t voucher_activity_id_t;
+
+typedef uint32_t _voucher_activity_buffer_hook_t;;
+
+typedef uint32_t voucher_activity_flag_t;
+
+typedef struct
+{
+} mach_msg_header_t;
+
+
+typedef void (*dispatch_mach_handler_function_t)(void*, dispatch_mach_reason_t,
+						 dispatch_mach_msg_t, mach_error_t);
+
+typedef void (*dispatch_mach_msg_destructor_t)(void*);
+
+typedef uint32_t voucher_activity_mode_t;
+
+struct voucher_offsets_s {
+  uint32_t vo_version;
+};
+
+
+/*
+ * Stub out defines for other missing types
+ */
+
+// Pulled from OS X man page for kevent
+struct kevent64_s {
+    uint64_t        ident;          /* identifier for this event */
+    int16_t         filter;         /* filter for event */
+    uint16_t        flags;          /* general flags */
+    uint32_t        fflags;         /* filter-specific flags */
+    int64_t         data;           /* filter-specific data */
+    uint64_t        udata;          /* opaque user data identifier */
+    uint64_t        ext[2];         /* filter-specific extensions */
+};
+
+
+// PAGE_SIZE and SIZE_T_MAX should not be hardcoded like this here.
+#define PAGE_SIZE (4096)
+#define SIZE_T_MAX (0x7fffffff)
+
+// Define to 0 the NOTE_ values that are not present on Linux.
+// Revisit this...would it be better to ifdef out the uses instead??
+#define NOTE_VM_PRESSURE 0
+#define NOTE_ABSOLUTE 0
+#define NOTE_NSECONDS 0
+#define NOTE_LEEWAY 0
+#define NOTE_CRITICAL 0
+#define NOTE_BACKGROUND 0
+
+/*
+ * Stub out misc linking and compilation attributes
+ */
+
+#ifdef OS_EXPORT
+#undef OS_EXPORT
+#endif
+#define OS_EXPORT
+
+#ifdef OS_WARN_RESULT_NEEDS_RELEASE 
+#undef OS_WARN_RESULT_NEEDS_RELEASE  
+#endif
+
+#ifdef OS_WARN_RESULT
+#undef OS_WARN_RESULT
+#endif
+#define OS_WARN_RESULT
+
+#ifdef OS_NOTHROW
+#undef OS_NOTHROW
+#endif
+#define OS_NOTHROW
+
+
+// These and similar macros come from Availabilty.h on OS X
+// Need a better way to do this long term.
+#define __OSX_AVAILABLE_BUT_DEPRECATED(a,b,c,d) //
+#define __OSX_AVAILABLE_BUT_DEPRECATED_MSG(a,b,c,d,msg) // 
+
+
+// Print a warning when an unported code path executes.
+#define LINUX_PORT_ERROR()  do { printf("LINUX_PORT_ERROR_CALLED %s:%d: %s\n",__FILE__,__LINE__,__FUNCTION__); } while (0)
+
+
+#endif /* __OS_LINUX_BASE__ */

os/object.h

@@ -24,7 +24,11 @@
 #ifdef __APPLE__
 #include <Availability.h>
 #endif
+#ifndef __linux__
 #include <os/base.h>
+#else
+#include <os/linux_base.h>
+#endif
 
 /*!
  * @header

private/voucher_activity_private.h

@@ -21,7 +21,9 @@
 #ifndef __OS_VOUCHER_ACTIVITY_PRIVATE__
 #define __OS_VOUCHER_ACTIVITY_PRIVATE__
 
+#ifndef __linux__
 #include <os/base.h>
+#endif
 #include <os/object.h>
 #if !defined(__DISPATCH_BUILDING_DISPATCH__)
 #include <os/voucher_private.h>

private/voucher_private.h

@@ -21,7 +21,9 @@
 #ifndef __OS_VOUCHER_PRIVATE__
 #define __OS_VOUCHER_PRIVATE__
 
+#ifndef __linux__
 #include <os/base.h>
+#endif
 #include <os/object.h>
 
 #define OS_VOUCHER_SPI_VERSION 20141203
@@ -400,7 +402,9 @@ dispatch_queue_create_with_accounting_override_voucher(const char *label,
  * voucher ports directly.
  */
 
+#ifdef __APPLE__
 #include <mach/mach.h>
+#endif
 
 /*!
  * @function voucher_create_with_mach_msg

src/.gitignore

@@ -0,0 +1,5 @@
+provider.h
+.libs
+*.lo
+*.la
+

src/Makefile.am

@@ -39,6 +39,8 @@ libdispatch_la_SOURCES=		\
 	shims/atomic_sfb.h		\
 	shims/getprogname.h		\
 	shims/hw_config.h		\
+	shims/linux_stubs.c		\
+	shims/linux_stubs.h		\
 	shims/perfmon.h			\
 	shims/time.h			\
 	shims/tsd.h				\

src/init.c

@@ -162,7 +162,9 @@ const struct dispatch_tsd_indexes_s dispatch_tsd_indexes = {
 	.dti_qos_class_index = dispatch_priority_key,
 };
 #else // DISPATCH_USE_DIRECT_TSD
+#ifndef __LINUX_PORT_HDD__
 #error Not implemented on this platform
+#endif
 #endif // DISPATCH_USE_DIRECT_TSD
 
 // 6618342 Contact the team that owns the Instrument DTrace probe before
@@ -1157,7 +1159,10 @@ const struct dispatch_source_type_s _dispatch_source_type_vnode = {
 		.flags = EV_CLEAR|EV_UDATA_SPECIFIC,
 	},
 	.mask = NOTE_DELETE|NOTE_WRITE|NOTE_EXTEND|NOTE_ATTRIB|NOTE_LINK|
-			NOTE_RENAME|NOTE_REVOKE
+			NOTE_RENAME
+#if HAVE_DECL_NOTE_REVOKE
+	                |NOTE_REVOKE
+#endif
 #if HAVE_DECL_NOTE_NONE
 			|NOTE_NONE
 #endif

src/internal.h

@@ -208,7 +208,11 @@ DISPATCH_EXPORT DISPATCH_NOTHROW void dispatch_atfork_child(void);
 #if !TARGET_OS_WIN32 
 #include <sys/event.h>
 #include <sys/mount.h>
+#ifdef __linux__
+#include <shims/sys_queue.h>
+#else
 #include <sys/queue.h>
+#endif
 #include <sys/sysctl.h>
 #include <sys/socket.h>
 #include <sys/time.h>

src/io.c

@@ -387,9 +387,11 @@ dispatch_io_create_with_path(dispatch_io_type_t type, const char *path,
 		int err = 0;
 		struct stat st;
 		_dispatch_io_syscall_switch_noerr(err,
-			(path_data->oflag & O_NOFOLLOW) == O_NOFOLLOW ||
-					(path_data->oflag & O_SYMLINK) == O_SYMLINK ?
-					lstat(path_data->path, &st) : stat(path_data->path, &st),
+			(path_data->oflag & O_NOFOLLOW) == O_NOFOLLOW
+#ifndef __linux__
+					|| (path_data->oflag & O_SYMLINK) == O_SYMLINK
+#endif						  
+					? lstat(path_data->path, &st) : stat(path_data->path, &st),
 			case 0:
 				err = _dispatch_io_validate_type(channel, st.st_mode);
 				break;
@@ -2064,6 +2066,9 @@ _dispatch_disk_perform(void *ctxt)
 static void
 _dispatch_operation_advise(dispatch_operation_t op, size_t chunk_size)
 {
+#ifndef F_RDADVISE
+  LINUX_PORT_ERROR();
+#else
 	int err;
 	struct radvisory advise;
 	// No point in issuing a read advise for the next chunk if we are already
@@ -2090,6 +2095,7 @@ _dispatch_operation_advise(dispatch_operation_t op, size_t chunk_size)
 		// TODO: set disk status on error
 		default: (void)dispatch_assume_zero(err); break;
 	);
+#endif	
 }
 
 static int