Move gdb-dlfcn.[ch] to gdbsupport/

I need to use 'gdb_dlopen' inside 'gdbsupport/', but it's not yet
supported there.  This commit moves 'gdb-dlfcn.[ch]' to 'gdbsupport/',
which makes it available also on gdbserver.

gdb/ChangeLog:
2019-08-23  Sergio Durigan Junior  <sergiodj@redhat.com>

	* configure.ac: Don't check for 'dlfcn.h' (moved to
	gdbsupport/common.m4).
	* Makefile.in (COMMON_SFILES): Move 'gdb-dlfcn.c' to
	'gdbsupport/'.
	(HFILES_NO_SRCDIR): Likewise, for 'gdb-dlfcn.h'.
	* compile/compile-c-support.c: Include
	'gdbsupport/gdb-dlfcn.h'.
	* gdbsupport/common.m4: Check for 'dlfcn.h'.
	* gdb-dlfcn.c: Move to...
	* gdbsupport/gdb-dlfcn.c: ... here.
	* gdb-dlfcn.h: Move to...
	* gdbsupport/gdb-dlfcn.h: ... here.

gdb/gdbserver/ChangeLog:
2019-08-23  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add 'gdbsupport/gdb-dlfcn.c'.
	(OBS): Add 'gdbsupport/gdb-dlfcn.o'.
	* config.in: Regenerate.
	* configure: Regenerate.

3 files changed, 171 insertions, 1 deletions

diff --git a/gdb/gdbsupport/common.m4 b/gdb/gdbsupport/common.m4
index 5701dd9..9038894 100644
--- a/gdb/gdbsupport/common.m4
+++ b/gdb/gdbsupport/common.m4
@@ -29,7 +29,8 @@ AC_DEFUN([GDB_AC_COMMON], [
 		   sys/resource.h sys/socket.h dnl
 		   sys/un.h sys/wait.h dnl
 		   thread_db.h wait.h dnl
-		   termios.h)
+		   termios.h dnl
+		   dlfcn.h)
 
   AC_CHECK_FUNCS([fdwalk getrlimit pipe pipe2 socketpair sigaction])
 
diff --git a/gdb/gdbsupport/gdb-dlfcn.c b/gdb/gdbsupport/gdb-dlfcn.c
new file mode 100644
index 0000000..921f10f
--- /dev/null
+++ b/gdb/gdbsupport/gdb-dlfcn.c
@@ -0,0 +1,118 @@
+/* Platform independent shared object routines for GDB.
+
+   Copyright (C) 2011-2019 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include "common-defs.h"
+#include "gdb-dlfcn.h"
+
+#ifdef HAVE_DLFCN_H
+#include <dlfcn.h>
+#elif __MINGW32__
+#include <windows.h>
+#else
+/* Unsupported configuration. */
+#define NO_SHARED_LIB
+#endif
+
+#ifdef NO_SHARED_LIB
+
+gdb_dlhandle_up
+gdb_dlopen (const char *filename)
+{
+  gdb_assert_not_reached ("gdb_dlopen should not be called on this platform.");
+}
+
+void *
+gdb_dlsym (const gdb_dlhandle_up &handle, const char *symbol)
+{
+  gdb_assert_not_reached ("gdb_dlsym should not be called on this platform.");
+}
+
+void
+dlclose_deleter::operator() (void *handle) const
+{
+  gdb_assert_not_reached ("gdb_dlclose should not be called on this platform.");
+}
+
+int
+is_dl_available (void)
+{
+  return 0;
+}
+
+#else /* NO_SHARED_LIB */
+
+gdb_dlhandle_up
+gdb_dlopen (const char *filename)
+{
+  void *result;
+#ifdef HAVE_DLFCN_H
+  result = dlopen (filename, RTLD_NOW);
+#elif __MINGW32__
+  result = (void *) LoadLibrary (filename);
+#endif
+  if (result != NULL)
+    return gdb_dlhandle_up (result);
+
+#ifdef HAVE_DLFCN_H
+  error (_("Could not load %s: %s"), filename, dlerror());
+#else
+  {
+    LPVOID buffer;
+    DWORD dw;
+
+    dw = GetLastError();
+
+    FormatMessage (FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
+                   FORMAT_MESSAGE_IGNORE_INSERTS,
+                   NULL, dw, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+                   (LPTSTR) &buffer,
+                   0, NULL);
+
+    error (_("Could not load %s: %s"), filename, (char *) buffer);
+  }
+#endif
+}
+
+void *
+gdb_dlsym (const gdb_dlhandle_up &handle, const char *symbol)
+{
+#ifdef HAVE_DLFCN_H
+  return dlsym (handle.get (), symbol);
+#elif __MINGW32__
+  return (void *) GetProcAddress ((HMODULE) handle.get (), symbol);
+#endif
+}
+
+void
+dlclose_deleter::operator() (void *handle) const
+{
+#ifdef HAVE_DLFCN_H
+  dlclose (handle);
+#elif __MINGW32__
+  FreeLibrary ((HMODULE) handle);
+#endif
+}
+
+int
+is_dl_available (void)
+{
+  return 1;
+}
+
+#endif /* NO_SHARED_LIB */
diff --git a/gdb/gdbsupport/gdb-dlfcn.h b/gdb/gdbsupport/gdb-dlfcn.h
new file mode 100644
index 0000000..6a39d38
--- /dev/null
+++ b/gdb/gdbsupport/gdb-dlfcn.h
@@ -0,0 +1,51 @@
+/* Platform independent shared object routines for GDB.
+
+   Copyright (C) 2011-2019 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDB_DLFCN_H
+#define GDB_DLFCN_H
+
+/* A deleter that closes an open dynamic library.  */
+
+struct dlclose_deleter
+{
+  void operator() (void *handle) const;
+};
+
+/* A unique pointer that points to a dynamic library.  */
+
+typedef std::unique_ptr<void, dlclose_deleter> gdb_dlhandle_up;
+
+/* Load the dynamic library file named FILENAME, and return a handle
+   for that dynamic library.  Return NULL if the loading fails for any
+   reason.  */
+
+gdb_dlhandle_up gdb_dlopen (const char *filename);
+
+/* Return the address of the symbol named SYMBOL inside the shared
+   library whose handle is HANDLE.  Return NULL when the symbol could
+   not be found.  */
+
+void *gdb_dlsym (const gdb_dlhandle_up &handle, const char *symbol);
+
+/* Return non-zero if the dynamic library functions are available on
+   this platform.  */
+
+int is_dl_available(void);
+
+#endif /* GDB_DLFCN_H */