add stubs for dlopen, dlsym, etc.

Makefile

@@ -80,6 +80,7 @@ LIBWASI_EMULATED_SIGNAL_SOURCES = \
 LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES = \
     $(LIBC_TOP_HALF_MUSL_SRC_DIR)/signal/psignal.c \
     $(LIBC_TOP_HALF_MUSL_SRC_DIR)/string/strsignal.c
+LIBDL_SOURCES = $(LIBC_TOP_HALF_MUSL_SRC_DIR)/misc/dl.c
 LIBC_BOTTOM_HALF_CRT_SOURCES = $(wildcard $(LIBC_BOTTOM_HALF_DIR)/crt/*.c)
 LIBC_TOP_HALF_DIR = libc-top-half
 LIBC_TOP_HALF_MUSL_DIR = $(LIBC_TOP_HALF_DIR)/musl
@@ -379,6 +380,7 @@ LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS = $(call objs,$(LIBWASI_EMULATED_PROCESS_CL
 LIBWASI_EMULATED_GETPID_OBJS = $(call objs,$(LIBWASI_EMULATED_GETPID_SOURCES))
 LIBWASI_EMULATED_SIGNAL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_SOURCES))
 LIBWASI_EMULATED_SIGNAL_MUSL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES))
+LIBDL_OBJS = $(call objs,$(LIBDL_SOURCES))
 LIBC_BOTTOM_HALF_CRT_OBJS = $(call objs,$(LIBC_BOTTOM_HALF_CRT_SOURCES))
 
 # These variables describe the locations of various files and
@@ -445,7 +447,6 @@ MUSL_OMIT_HEADERS += \
     "netdb.h" \
     "resolv.h" \
     "pty.h" \
-    "dlfcn.h" \
     "setjmp.h" \
     "ulimit.h" \
     "sys/xattr.h" \
@@ -481,6 +482,7 @@ LIBWASI_EMULATED_PROCESS_CLOCKS_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULA
 LIBWASI_EMULATED_GETPID_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_GETPID_OBJS))
 LIBWASI_EMULATED_SIGNAL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_SIGNAL_OBJS))
 LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS))
+LIBDL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBDL_OBJS))
 BULK_MEMORY_SO_OBJS = $(patsubst %.o,%.pic.o,$(BULK_MEMORY_OBJS))
 DLMALLOC_SO_OBJS = $(patsubst %.o,%.pic.o,$(DLMALLOC_OBJS))
 LIBC_BOTTOM_HALF_ALL_SO_OBJS = $(patsubst %.o,%.pic.o,$(LIBC_BOTTOM_HALF_ALL_OBJS))
@@ -521,6 +523,8 @@ $(OBJDIR)/libwasi-emulated-getpid.so.a: $(LIBWASI_EMULATED_GETPID_SO_OBJS)
 
 $(OBJDIR)/libwasi-emulated-signal.so.a: $(LIBWASI_EMULATED_SIGNAL_SO_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS)
 
+$(OBJDIR)/libdl.so.a: $(LIBDL_SO_OBJS)
+
 $(SYSROOT_LIB)/libc.a: $(LIBC_OBJS)
 
 $(SYSROOT_LIB)/libc-printscan-long-double.a: $(MUSL_PRINTSCAN_LONG_DOUBLE_OBJS)
@@ -535,6 +539,8 @@ $(SYSROOT_LIB)/libwasi-emulated-getpid.a: $(LIBWASI_EMULATED_GETPID_OBJS)
 
 $(SYSROOT_LIB)/libwasi-emulated-signal.a: $(LIBWASI_EMULATED_SIGNAL_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS)
 
+$(SYSROOT_LIB)/libdl.a: $(LIBDL_OBJS)
+
 %.a:
 	@mkdir -p "$(@D)"
 	# On Windows, the commandline for the ar invocation got too long, so it needs to be split up.
@@ -603,7 +609,7 @@ startup_files $(LIBC_BOTTOM_HALF_ALL_OBJS) $(LIBC_BOTTOM_HALF_ALL_SO_OBJS): CFLA
     -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/include \
     -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/internal
 
-$(LIBC_TOP_HALF_ALL_OBJS) $(LIBC_TOP_HALF_ALL_SO_OBJS) $(MUSL_PRINTSCAN_LONG_DOUBLE_OBJS) $(MUSL_PRINTSCAN_LONG_DOUBLE_SO_OBJS) $(MUSL_PRINTSCAN_NO_FLOATING_POINT_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS): CFLAGS += \
+$(LIBC_TOP_HALF_ALL_OBJS) $(LIBC_TOP_HALF_ALL_SO_OBJS) $(MUSL_PRINTSCAN_LONG_DOUBLE_OBJS) $(MUSL_PRINTSCAN_LONG_DOUBLE_SO_OBJS) $(MUSL_PRINTSCAN_NO_FLOATING_POINT_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_SO_OBJS) $(LIBDL_OBJS) $(LIBDL_SO_OBJS): CFLAGS += \
     -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/include \
     -I$(LIBC_TOP_HALF_MUSL_SRC_DIR)/internal \
     -I$(LIBC_TOP_HALF_MUSL_DIR)/arch/wasm32 \
@@ -664,7 +670,8 @@ LIBC_SO = \
 	$(SYSROOT_LIB)/libwasi-emulated-mman.so \
 	$(SYSROOT_LIB)/libwasi-emulated-process-clocks.so \
 	$(SYSROOT_LIB)/libwasi-emulated-getpid.so \
-	$(SYSROOT_LIB)/libwasi-emulated-signal.so
+	$(SYSROOT_LIB)/libwasi-emulated-signal.so \
+	$(SYSROOT_LIB)/libdl.so
 endif
 
 libc_so: include_dirs $(LIBC_SO)
@@ -676,13 +683,14 @@ libc: include_dirs \
     $(SYSROOT_LIB)/libwasi-emulated-mman.a \
     $(SYSROOT_LIB)/libwasi-emulated-process-clocks.a \
     $(SYSROOT_LIB)/libwasi-emulated-getpid.a \
-    $(SYSROOT_LIB)/libwasi-emulated-signal.a
+    $(SYSROOT_LIB)/libwasi-emulated-signal.a \
+    $(SYSROOT_LIB)/libdl.a
 
 finish: startup_files libc
 	#
 	# Create empty placeholder libraries.
 	#
-	for name in m rt pthread crypt util xnet resolv dl; do \
+	for name in m rt pthread crypt util xnet resolv; do \
 	    $(AR) crs "$(SYSROOT_LIB)/lib$${name}.a"; \
 	done
 

expected/wasm32-wasi-threads/include-all.c

@@ -75,6 +75,7 @@
 #include <crypt.h>
 #include <ctype.h>
 #include <dirent.h>
+#include <dlfcn.h>
 #include <endian.h>
 #include <err.h>
 #include <errno.h>

expected/wasm32-wasi-threads/predefined-macros.txt

@@ -1499,6 +1499,14 @@
 #define RRFIXEDSZ NS_RRFIXEDSZ
 #define RRQ 01
 #define RS_HIPRI 0x01
+#define RTLD_DEFAULT ((void *)0)
+#define RTLD_GLOBAL 256
+#define RTLD_LAZY 1
+#define RTLD_LOCAL 8
+#define RTLD_NEXT ((void *)-1)
+#define RTLD_NODELETE 4096
+#define RTLD_NOLOAD 4
+#define RTLD_NOW 2
 #define RUSAGE_CHILDREN 2
 #define RUSAGE_SELF 1
 #define R_OK (4)
@@ -2044,6 +2052,7 @@
 #define _Complex_I (0.0f+1.0fi)
 #define _DIRENT_H 
 #define _DIRENT_HAVE_D_TYPE 
+#define _DLFCN_H
 #define _ENDIAN_H 
 #define _ERRNO_H 
 #define _ERR_H 

expected/wasm32-wasi/include-all.c

@@ -75,6 +75,7 @@
 #include <crypt.h>
 #include <ctype.h>
 #include <dirent.h>
+#include <dlfcn.h>
 #include <endian.h>
 #include <err.h>
 #include <errno.h>

expected/wasm32-wasi/predefined-macros.txt

@@ -1467,6 +1467,14 @@
 #define RRFIXEDSZ NS_RRFIXEDSZ
 #define RRQ 01
 #define RS_HIPRI 0x01
+#define RTLD_DEFAULT ((void *)0)
+#define RTLD_GLOBAL 256
+#define RTLD_LAZY 1
+#define RTLD_LOCAL 8
+#define RTLD_NEXT ((void *)-1)
+#define RTLD_NODELETE 4096
+#define RTLD_NOLOAD 4
+#define RTLD_NOW 2
 #define RUSAGE_CHILDREN 2
 #define RUSAGE_SELF 1
 #define R_OK (4)
@@ -2010,6 +2018,7 @@
 #define _Complex_I (0.0f+1.0fi)
 #define _DIRENT_H 
 #define _DIRENT_HAVE_D_TYPE 
+#define _DLFCN_H
 #define _ENDIAN_H 
 #define _ERRNO_H 
 #define _ERR_H 

libc-top-half/musl/include/dlfcn.h

@@ -12,19 +12,29 @@ extern "C" {
 #define RTLD_NOLOAD 4
 #define RTLD_NODELETE 4096
 #define RTLD_GLOBAL 256
+#ifdef __wasilibc_unmodified_upstream
 #define RTLD_LOCAL  0
+#else
+/* For WASI, we give `RTLD_LOCAL` a non-zero value, avoiding ambiguity and
+ * allowing us to defer the decision of whether `RTLD_LOCAL` or `RTLD_GLOBAL`
+ * should be the default when neither is specified.
+ */
+#define RTLD_LOCAL  8
+#endif
 
 #define RTLD_NEXT    ((void *)-1)
 #define RTLD_DEFAULT ((void *)0)
 
+#ifdef __wasilibc_unmodified_upstream
 #define RTLD_DI_LINKMAP 2
+#endif
 
 int    dlclose(void *);
 char  *dlerror(void);
 void  *dlopen(const char *, int);
 void  *dlsym(void *__restrict, const char *__restrict);
 
-#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+#if defined(__wasilibc_unmodified_upstream) && (defined(_GNU_SOURCE) || defined(_BSD_SOURCE))
 typedef struct {
 	const char *dli_fname;
 	void *dli_fbase;

libc-top-half/musl/src/misc/dl.c

@@ -0,0 +1,45 @@
+/* This file is used to build libdl.so with stub versions of `dlopen`, `dlsym`,
+ * etc.  The intention is that this stubbed libdl.so can be used to build
+ * libraries and applications which use `dlopen` without committing to a
+ * specific runtime implementation.  Later, it can be replaced with a real,
+ * working libdl.so (e.g. at runtime or component composition time).
+ * 
+ * For example, the `wasm-tools component link` subcommand can be used to create
+ * a component that bundles any `dlopen`-able libraries in such a way that their
+ * function exports can be resolved symbolically at runtime using an
+ * implementation of libdl.so designed for that purpose.  In other cases, a
+ * runtime might provide Emscripten-style dynamic linking via URLs or else a
+ * more traditional, filesystem-based implementation.  Finally, even this
+ * stubbed version of libdl.so can be used at runtime in cases where dynamic
+ * library resolution cannot or should not be supported (and the application can
+ * handle this situation gracefully). */
+
+#include <stddef.h>
+#include <dlfcn.h>
+
+static const char *error = NULL;
+
+weak int dlclose(void *library)
+{
+	error = "dlclose not implemented";
+	return -1;
+}
+
+weak char *dlerror(void)
+{
+	const char *var = error;
+	error = NULL;
+	return (char*) var;
+}
+
+weak void *dlopen(const char *name, int flags)
+{
+	error = "dlopen not implemented";
+	return NULL;
+}
+
+weak void *dlsym(void *library, const char *name)
+{
+	error = "dlsym not implemented";
+	return NULL;
+}