openbsd.rtld: init

rtld contains ld.so, the dynamic linker on OpenBSD.
This package does not include related scripts (ldd and ldconfig),
because they would create a dependency loop.
rtld (run-time ld) is an os-agnostic term for dynamic linker.

For simplicity, also link this into the libc symlinkJoin package

pkgs/os-specific/bsd/openbsd/pkgs/libc.nix

@@ -1,11 +1,13 @@
 {
   lib,
+  stdenvNoLibc,
   symlinkJoin,
   libcMinimal,
   librthread,
   libm,
   librpcsvc,
   libutil,
+  rtld,
   version,
 }:
 
@@ -27,13 +29,16 @@ symlinkJoin rec {
         (lib.getLib p)
         (lib.getMan p)
       ])
+      (
         [
           libcMinimal
           libm
           librthread
           librpcsvc
           libutil
-      ];
+        ]
+        ++ (lib.optional (!stdenvNoLibc.hostPlatform.isStatic) rtld)
+      );
 
   postBuild = ''
     rm -r "$out/nix-support"

pkgs/os-specific/bsd/openbsd/pkgs/rtld/ldso-fix-makefile.patch

@@ -0,0 +1,57 @@
+diff --git a/libexec/ld.so/Makefile b/libexec/ld.so/Makefile
+index 7f8f6ef2961..469c34bb6de 100644
+--- a/libexec/ld.so/Makefile
++++ b/libexec/ld.so/Makefile
+@@ -1,6 +1,5 @@
+ #	$OpenBSD: Makefile,v 1.88 2024/04/05 13:51:47 deraadt Exp $
+ 
+-SUBDIR=ldconfig ldd
+ MAN=	ld.so.1
+ 
+ .include <bsd.own.mk>
+@@ -70,21 +69,15 @@ ELF_LDFLAGS+=--shared -Bsymbolic --no-undefined
+ 
+ .ifdef	RELATIVE_RELOC
+ CHECK_LDSO=c() {					\
+-	! readelf -Wr $$1 |				\
++	! $(READELF) -Wr $$1 |				\
+ 	  egrep -qv '^($$|[ R])| (${RELATIVE_RELOC}) ';	\
+ 	}; c
+ .endif
+ 
+-test_prog=	test-$(PROG)
+-CLEANFILES+=	test-$(PROG)
+ candidate=	$(PROG).test
+ CLEANFILES+=	${candidate}
+ 
+-$(test_prog):
+-	printf '#include <stdio.h>\n#include <pthread.h>\nint main(int argc, char **argv){ pthread_attr_t attr; printf("%%s: ", argv[0]); pthread_attr_init(&attr); printf("%%s!\\n", argv[1] ? argv[1] : "foo"); }\n' | \
+-	$(CC) -P -x c - -Wl,-dynamic-linker,./$(candidate) -o $@ -lpthread
+-
+-$(PROG): $(test_prog) ${VERSION_SCRIPT} $(OBJS) ${LD_SCRIPT}
++$(PROG): ${VERSION_SCRIPT} $(OBJS) ${LD_SCRIPT}
+ .if defined(SYSPATCH_PATH)
+ 	$(LD) -e _dl_start $(ELF_LDFLAGS) -o $(candidate) \
+             `readelf -Ws ${SYSPATCH_PATH}/usr/libexec/${.TARGET} | \
+@@ -96,9 +89,6 @@ $(PROG): $(test_prog) ${VERSION_SCRIPT} $(OBJS) ${LD_SCRIPT}
+ .endif
+ .ifdef	CHECK_LDSO
+ 	${CHECK_LDSO} $(candidate)
+-.endif
+-.ifndef CROSSDIR
+-	ulimit -c 0; [ "`${.OBJDIR}/$(test_prog) ok`" = "${.OBJDIR}/$(test_prog): ok!" ]
+ .endif
+ 	cp $(candidate) $@
+ .endif
+@@ -113,10 +103,4 @@ CLEANFILES+=	ld.so.a
+ all: ld.so.a
+ 
+ ld.so.a: ${OBJS} ${.CURDIR}/Symbols.map ${test_prog} ${LD_SCRIPT}
+-	ar cqD $@ $?
+-
+-afterinstall: ld.so.a
+-	install -d -o root -g wheel -m 755 \
+-	    ${DESTDIR}/usr/share/relink/usr/libexec
+-	install -o ${BINOWN} -g ${BINGRP} -m ${NONBINMODE} \
+-	    ld.so.a ${DESTDIR}/usr/share/relink/usr/libexec/ld.so.a
++	$(AR) cqD $@ $?

pkgs/os-specific/bsd/openbsd/pkgs/rtld/package.nix

@@ -0,0 +1,31 @@
+{
+  lib,
+  mkDerivation,
+}:
+
+mkDerivation {
+  path = "libexec/ld.so";
+  extraPaths = [
+    "lib/libc/string"
+    "lib/csu/os-note-elf.h"
+  ];
+  patches = [
+    ./ldso-fix-makefile.patch
+  ];
+
+  libcMinimal = true;
+
+  NIX_CFLAGS_COMPILE = "-Wno-error";
+
+  # DESTDIR is overridden in bsdSetupHook, just fixup afterwards
+  postInstall = ''
+    mv $out/bin $out/libexec
+  '';
+
+  outputs = [
+    "out"
+    "man"
+  ];
+
+  meta.platforms = lib.platforms.openbsd;
+}