add support for accessing embedded JARs as if they were directories

This allows OpenJDK to access time zone data which is normally found
under java.home, but which we must embed in the executable itself to
create a self-contained build.  The VM intercepts various file
operations, looking for paths which start with a prefix specified by
the avian.embed.prefix property and redirecting those operations to an
embedded JAR.

For example, if avian.embed.prefix is "/avian-embedded", and code
calls File.exists() with a path of
"/avian-embedded/javahomeJar/foo.txt", the VM looks for a function
named javahomeJar via dlsym, calls the function to find the memory
region containing the embeded JAR, and finally consults the JAR to see
if the file "foo.txt" exists.

Author: dicej

makefile

@@ -52,25 +52,29 @@ classpath = avian
 
 test-executable = $(executable)
 boot-classpath = $(classpath-build)
-java-home = /avian-embedded
+embed-prefix = /avian-embedded
 
 ifdef openjdk
 	ifdef openjdk-src
 		include openjdk-src.mk
 	  options := $(options)-openjdk-src
 		classpath-objects = $(openjdk-objects)
-		classpath-cflags = -DAVIAN_OPENJDK_SRC
+		classpath-cflags = -DAVIAN_OPENJDK_SRC -DBOOT_JAVAHOME
 		openjdk-jar-dep = $(build)/openjdk-jar.dep
 		classpath-jar-dep = $(openjdk-jar-dep)
+		javahome = $(embed-prefix)/javahomeJar
+		javahome-files = lib/zi
+		javahome-object = $(build)/javahome-jar.o
 	else
 	  options := $(options)-openjdk
 		test-executable = $(executable-dynamic)
 		library-path = LD_LIBRARY_PATH=$(build)
-		java-home = $(openjdk)/jre
+		javahome = $(openjdk)/jre
 	endif
 
   classpath = openjdk
 	boot-classpath := $(boot-classpath):$(openjdk)/jre/lib/rt.jar
+	build-javahome = $(openjdk)/jre
 endif
 
 ifeq ($(classpath),avian)
@@ -120,7 +124,8 @@ warnings = -Wall -Wextra -Werror -Wunused-parameter -Winit-self \
 common-cflags = $(warnings) -fno-rtti -fno-exceptions -fno-omit-frame-pointer \
 	"-I$(JAVA_HOME)/include" -idirafter $(src) -I$(build) $(classpath-cflags) \
 	-D__STDC_LIMIT_MACROS -D_JNI_IMPLEMENTATION_ -DAVIAN_VERSION=\"$(version)\" \
-	-DUSE_ATOMIC_OPERATIONS -DAVIAN_JAVA_HOME=\"$(java-home)\"
+	-DUSE_ATOMIC_OPERATIONS -DAVIAN_JAVA_HOME=\"$(javahome)\" \
+	-DAVIAN_EMBED_PREFIX=\"$(embed-prefix)\"
 
 build-cflags = $(common-cflags) -fPIC -fvisibility=hidden \
 	"-I$(JAVA_HOME)/include/linux" -I$(src) -pthread
@@ -593,12 +598,6 @@ $(driver-dynamic-object): $(driver-source)
 $(boot-object): $(boot-source)
 	$(compile-object)
 
-$(build)/classpath.jar: $(classpath-dep) $(classpath-jar-dep)
-	@echo "creating $(@)"
-	(wd=$$(pwd) && \
-	 cd $(classpath-build) && \
-	 $(jar) c0f "$$($(native-path) "$${wd}/$(@)")" .)
-
 $(build)/binaryToObject-main.o: $(src)/binaryToObject/main.cpp
 	$(build-cxx) -c $(^) -o $(@)
 
@@ -620,11 +619,28 @@ $(build)/binaryToObject-pe.o: $(src)/binaryToObject/pe.cpp
 $(converter): $(converter-objects)
 	$(build-cxx) $(^) -o $(@)
 
+$(build)/classpath.jar: $(classpath-dep) $(classpath-jar-dep)
+	@echo "creating $(@)"
+	(wd=$$(pwd) && \
+	 cd $(classpath-build) && \
+	 $(jar) c0f "$$($(native-path) "$${wd}/$(@)")" .)
+
 $(classpath-object): $(build)/classpath.jar $(converter)
 	@echo "creating $(@)"
 	$(converter) $(<) $(@) _binary_classpath_jar_start \
 		_binary_classpath_jar_end $(platform) $(arch)
 
+$(build)/javahome.jar: $(foreach x,$(javahome-files),$(build-javahome)/$(x))
+	@echo "creating $(@)"
+	(wd=$$(pwd) && \
+	 cd $(build-javahome) && \
+	 $(jar) c0f "$$($(native-path) "$${wd}/$(@)")" $(javahome-files))
+
+$(javahome-object): $(build)/javahome.jar $(converter)
+	@echo "creating $(@)"
+	$(converter) $(<) $(@) _binary_javahome_jar_start \
+		_binary_javahome_jar_end $(platform) $(arch)
+
 $(generator-objects): $(generator-depends)
 $(generator-objects): $(build)/%-build.o: $(src)/%.cpp
 	@echo "compiling $(@)"
@@ -651,7 +667,8 @@ $(bootimage-object): $(bootimage-bin) $(converter)
 		writable executable
 
 executable-objects = $(vm-objects) $(classpath-objects) $(driver-object) \
-	$(vm-heapwalk-objects) $(boot-object) $(vm-classpath-object)
+	$(vm-heapwalk-objects) $(boot-object) $(vm-classpath-object) \
+	$(javahome-object)
 
 $(executable): $(executable-objects)
 	@echo "linking $(@)"
@@ -696,18 +713,16 @@ else
 	$(ld) $(^) $(rdynamic) $(lflags) -o $(@)
 endif
 
-dynamic-library-objects = $(vm-objects) $(dynamic-object) \
-	$(classpath-objects) $(vm-heapwalk-objects) $(boot-object) \
-	$(vm-classpath-object) $(classpath-libraries)
-
-$(dynamic-library): $(dynamic-library-objects)
+$(dynamic-library): $(vm-objects) $(dynamic-object) $(classpath-objects) \
+		$(vm-heapwalk-objects) $(boot-object) $(vm-classpath-object) \
+		$(classpath-libraries) $(javahome-object)
 	@echo "linking $(@)"
 ifdef msvc
-	$(ld) $(shared) $(lflags) $(dynamic-library-objects) -out:$(@) \
-		-PDB:$(@).pdb -IMPLIB:$(build)/$(name).lib -MANIFESTFILE:$(@).manifest
+	$(ld) $(shared) $(lflags) $(^) -out:$(@) -PDB:$(@).pdb \
+		-IMPLIB:$(build)/$(name).lib -MANIFESTFILE:$(@).manifest
 	$(mt) -manifest $(@).manifest -outputresource:"$(@);2"
 else
-	$(ld) $(dynamic-library-objects) -Wl,--version-script=openjdk.ld \
+	$(ld) $(^) -Wl,--version-script=openjdk.ld \
 		$(shared) $(lflags) $(bootimage-lflags) -o $(@)
 endif
 	$(strip) $(strip-all) $(@)

src/boot.cpp

@@ -52,6 +52,8 @@ extern "C" {
 
 }
 
+#undef SYMBOL
+
 #endif//BOOT_IMAGE
 
 #ifdef BOOT_CLASSPATH
@@ -76,4 +78,32 @@ extern "C" {
 
 }
 
+#undef SYMBOL
+
 #endif//BOOT_CLASSPATH
+
+#ifdef BOOT_JAVAHOME
+
+#if (defined __MINGW32__) || (defined _MSC_VER)
+#  define SYMBOL(x) binary_javahome_jar_##x
+#else
+#  define SYMBOL(x) _binary_javahome_jar_##x
+#endif
+
+extern "C" {
+
+  extern const uint8_t SYMBOL(start)[];
+  extern const uint8_t SYMBOL(end)[];
+
+  EXPORT const uint8_t*
+  javahomeJar(unsigned* size)
+  {
+    *size = SYMBOL(end) - SYMBOL(start);
+    return SYMBOL(start);
+  }
+
+}
+
+#undef SYMBOL
+
+#endif//BOOT_JAVAHOME

src/builtin.cpp

@@ -85,8 +85,9 @@ Avian_avian_SystemClassLoader_resourceExists
     RUNTIME_ARRAY(char, n, stringLength(t, name) + 1);
     stringChars(t, name, RUNTIME_ARRAY_BODY(n));
 
-    bool r = static_cast<Finder*>(systemClassLoaderFinder(t, loader))->exists
-      (RUNTIME_ARRAY_BODY(n));
+    unsigned length;
+    bool r = static_cast<Finder*>(systemClassLoaderFinder(t, loader))->stat
+      (RUNTIME_ARRAY_BODY(n), &length) == System::TypeFile;
 
 //     fprintf(stderr, "resource %s exists? %d\n", n, r);
 

src/classpath-avian.cpp

@@ -128,7 +128,7 @@ enumerateThreads(Thread* t, Thread* x, object array, unsigned* index,
 namespace vm {
 
 Classpath*
-makeClasspath(System*, Allocator* allocator, const char*)
+makeClasspath(System*, Allocator* allocator, const char*, const char*)
 {
   return new (allocator->allocate(sizeof(local::MyClasspath)))
     local::MyClasspath(allocator);