user: implement mlibc as the libc, finally.

It's finally done..

Signed-off-by: kaguya <vpshinomiya@protonmail.com>

user/include/mlibc/tests/rtld/rtld_next/libbar.c

@@ -0,0 +1,16 @@
+#include <dlfcn.h>
+
+typedef char *charFn(void);
+
+__attribute__((weak))
+char *definedInBoth() {
+	return "bar";
+}
+
+charFn *barGetDefault() {
+	return (charFn *)dlsym(RTLD_DEFAULT, "definedInBoth");
+}
+
+charFn *barGetNext() {
+	return (charFn *)dlsym(RTLD_NEXT, "definedInBoth");
+}

user/include/mlibc/tests/rtld/rtld_next/libfoo.c

@@ -0,0 +1,17 @@
+#include <dlfcn.h>
+
+typedef char *charFn(void);
+
+__attribute__((weak))
+char *definedInBoth() {
+	return "foo";
+}
+
+charFn *fooGetDefault() {
+	return (charFn *)dlsym(RTLD_DEFAULT, "definedInBoth");
+}
+
+charFn *fooGetNext() {
+	return (charFn *)dlsym(RTLD_NEXT, "definedInBoth");
+}
+

user/include/mlibc/tests/rtld/rtld_next/meson.build

@@ -0,0 +1,27 @@
+# Prevent tail calls, as it breaks libc's 'calling object' detection.
+no_tail_calls = '-fno-optimize-sibling-calls'
+
+libfoo = shared_library('foo', 'libfoo.c',
+	dependencies: libc_dep,
+	c_args: no_tail_calls,
+)
+libbar = shared_library('bar', 'libbar.c',
+	dependencies: libc_dep,
+	c_args: no_tail_calls,
+)
+test_link_with = [libfoo, libbar] # foo is linked before bar
+
+libfoo_native = shared_library('native-foo', 'libfoo.c',
+	c_args: [no_tail_calls, '-D_GNU_SOURCE'],
+	link_args: '-ldl',
+	override_options: 'b_sanitize=none',
+	native: true
+)
+libbar_native = shared_library('native-bar', 'libbar.c',
+	c_args: [no_tail_calls, '-D_GNU_SOURCE'],
+	link_args: '-ldl',
+	override_options: 'b_sanitize=none',
+	native: true
+)
+test_native_link_with = [libfoo_native, libbar_native]
+

user/include/mlibc/tests/rtld/rtld_next/test.c

@@ -0,0 +1,28 @@
+#include <string.h>
+#include <assert.h>
+
+typedef char *charFn(void);
+charFn *fooGetDefault(void);
+charFn *fooGetNext(void);
+charFn *barGetDefault(void);
+charFn *barGetNext(void);
+
+int main() {
+	charFn *ret;
+
+	ret = fooGetDefault();
+	assert(ret != NULL);
+	assert(!strcmp(ret(), "foo"));
+
+	ret = fooGetNext();
+	assert(ret != NULL);
+	assert(!strcmp(ret(), "bar"));
+
+	ret = barGetDefault();
+	assert(ret != NULL);
+	assert(!strcmp(ret(), "foo"));
+
+	assert(barGetNext() == NULL);
+
+	return 0;
+}