libports: add 'compat-libc'

Implement FBSD_1.0 versions of libc functions ('stat', 'fstat'). The
functions are versioned with @FBSD_1.0, and therefore, will not clash
with libc during linking. However, to be called by our dynamic linker,
the library must be before libc in the NEEDED section of the binary
using it. This requires the lib to be in front of libc in the LIBS
variable. The library currently will call libc 'stat' and 'fstat' by
looking up the symbols via 'dlsym'.

Ref genodelabs/goa#61

repos/libports/lib/mk/compat-libc.mk

@@ -0,0 +1,15 @@
+SHARED_LIB = yes
+LIBS      += libc
+COMPAT_DIR = $(REP_DIR)/src/lib/compat-libc
+
+SRC_CC = compat.cc
+SRC_C  = libc.c
+
+vpath %.cc $(COMPAT_DIR)
+vpath %.c  $(COMPAT_DIR)
+
+LD_OPT  += --version-script=$(COMPAT_DIR)/symbol.map
+
+CC_CXX_WARN_STRICT_CONVERSION =
+
+# vi: set ft=make :

repos/libports/lib/symbols/compat-libc

@@ -0,0 +1,2 @@
+fstat T
+stat T

repos/libports/recipes/api/compat-libc/content.mk

@@ -0,0 +1,16 @@
+MIRROR_FROM_REP_DIR := lib/symbols/compat-libc
+
+content: $(MIRROR_FROM_REP_DIR) LICENSE
+
+$(MIRROR_FROM_REP_DIR):
+	$(mirror_from_rep_dir)
+
+content: lib/symbol.map
+
+lib/symbol.map:
+	cp $(REP_DIR)/src/lib/compat-libc/symbol.map $@
+
+
+LICENSE:
+	cp $(GENODE_DIR)/LICENSE $@
+

repos/libports/recipes/api/compat-libc/hash

@@ -0,0 +1 @@
+2023-06-12 1ce2539b566b8d0d1a1f9919b8c7543f32467679

repos/libports/recipes/src/compat-libc/api

@@ -0,0 +1 @@
+compat-libc

repos/libports/recipes/src/compat-libc/content.mk

@@ -0,0 +1,10 @@
+MIRROR_FROM_REP_DIR := lib/mk/compat-libc.mk src/lib/compat-libc
+
+content: $(MIRROR_FROM_REP_DIR) LICENSE
+
+$(MIRROR_FROM_REP_DIR):
+	$(mirror_from_rep_dir)
+
+LICENSE:
+	cp $(GENODE_DIR)/LICENSE $@
+

repos/libports/recipes/src/compat-libc/hash

@@ -0,0 +1 @@
+2023-06-12-a b499380d630694fbe520d666320b5bba333fce25

repos/libports/recipes/src/compat-libc/used_apis

@@ -0,0 +1,2 @@
+libc
+so

repos/libports/src/lib/compat-libc/README

@@ -0,0 +1 @@
+This library contains FBSD_1.0 symbol versions not enabled in our libc port.

repos/libports/src/lib/compat-libc/compat.cc

@@ -0,0 +1,63 @@
+/*
+ * \brief  FreeBSD-11 function versions
+ * \author Sebastian Sumpf
+ * \date   2023-06-12
+ */
+
+/*
+ * Copyright (C) 2023 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#include <stdio.h>
+#define _WANT_FREEBSD11_STAT /* enable freebsd11_stat */
+#define _KERNEL              /* disable 'stat' */
+#include <sys/stat.h>
+#include "libc.h"
+
+
+static void _to_freebsd11(struct stat *libc_buf, struct freebsd11_stat *buf)
+{
+	buf->st_dev      = libc_buf->st_dev;
+	buf->st_ino      = libc_buf->st_ino;
+	buf->st_mode     = libc_buf->st_mode;
+	buf->st_nlink    = libc_buf->st_nlink;
+	buf->st_uid      = libc_buf->st_uid;
+	buf->st_gid      = libc_buf->st_gid;
+	buf->st_atim     = libc_buf->st_atim;
+	buf->st_mtim     = libc_buf->st_mtim;
+	buf->st_ctim     = libc_buf->st_ctim;
+	buf->st_size     = libc_buf->st_size;
+	buf->st_blksize  = libc_buf->st_blksize;
+	buf->st_flags    = libc_buf->st_flags;
+	buf->st_gen      = libc_buf->st_gen;
+	buf->st_birthtim = libc_buf->st_birthtim;
+}
+
+
+extern "C" int stat(const char *path, struct freebsd11_stat *buf)
+{
+	struct stat libc_buf { };
+
+	int err = libc_stat(path, &libc_buf);
+	if (err) return err;
+
+	_to_freebsd11(&libc_buf, buf);
+
+	return 0;
+}
+
+
+extern "C" int fstat(int fd, struct freebsd11_stat *buf)
+{
+	struct stat libc_buf { };
+
+	int err = libc_fstat(fd, &libc_buf);
+	if (err) return err;
+
+	_to_freebsd11(&libc_buf, buf);
+
+	return 0;
+}

repos/libports/src/lib/compat-libc/libc.c

@@ -0,0 +1,43 @@
+/*
+ * \brief  Interface real libc
+ * \author Sebastian Sumpf
+ * \date   2023-06-12
+ */
+
+/*
+ * Copyright (C) 2023 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#include <sys/stat.h>
+#include <dlfcn.h>
+
+static void* libc_handle(void)
+{
+	static void *handle = NULL;
+	if (!handle) handle = dlopen("libc.lib.so", RTLD_LAZY);
+	return handle;
+}
+
+
+int (*_stat)(char const*, struct stat*);
+int (*_fstat)(int, struct stat *);
+
+int libc_stat(const char *path, struct stat *buf)
+{
+	if (!_stat)
+		_stat = dlsym(libc_handle(), "stat");
+
+	return _stat(path, buf);
+}
+
+
+int libc_fstat(int fd, struct stat *buf)
+{
+	if (!_fstat)
+		_fstat = dlsym(libc_handle(), "fstat");
+
+	return _fstat(fd, buf);
+}

repos/libports/src/lib/compat-libc/libc.h

@@ -0,0 +1,20 @@
+/*
+ * \brief  Interface real libc
+ * \author Sebastian Sumpf
+ * \date   2023-06-12
+ */
+
+/*
+ * Copyright (C) 2023 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _COMPAT_LIBC_H_
+#define _COMPAT_LIBC_H_
+
+extern "C" int libc_stat(const char *, struct stat*);
+extern "C" int libc_fstat(int, struct stat *);
+
+#endif /* _COMPAT_LIBC_H_ */

repos/libports/src/lib/compat-libc/symbol.map

@@ -0,0 +1,8 @@
+# compatible old version implemeted in this library
+FBSD_1.0 {
+	global:
+		stat;
+		fstat;
+	local:
+		*;
+};