Create new common/pathstuff.[ch]

This commit moves the path manipulation routines found on utils.c to a
new common/pathstuff.c, and updates the Makefile.in's accordingly.
The routines moved are "gdb_realpath", "gdb_realpath_keepfile" and
"gdb_abspath".

This will be needed because gdbserver will have to call "gdb_abspath"
on my next patch, which implements a way to expand the path of the
inferior provided by the user in order to allow specifying just the
binary name when starting gdbserver, like:

  $ gdbserver :1234 a.out

With the recent addition of the startup-with-shell feature on
gdbserver, this scenario doesn't work anymore if the user doesn't have
the current directory listed in the PATH variable.

I had to do a minor adjustment on "gdb_abspath" because we don't have
access to "tilde_expand" on gdbserver, so now the function is using
"gdb_tilde_expand" instead.  Otherwise, the code is the same.

Regression tested on the BuildBot, without regressions.

gdb/ChangeLog:
2018-02-28  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (COMMON_SFILES): Add "common/pathstuff.c".
	(HFILES_NO_SRCDIR): Add "common/pathstuff.h".
	* auto-load.c: Include "common/pathstuff.h".
	* common/common-def.h (current_directory): Move here.
	* common/gdb_tilde_expand.c (gdb_tilde_expand_up): New
	function.
	* common/gdb_tilde_expand.h (gdb_tilde_expand_up): New
	prototype.
	* common/pathstuff.c: New file.
	* common/pathstuff.h: New file.
	* compile/compile.c: Include "common/pathstuff.h".
	* defs.h (current_directory): Move to "common/common-defs.h".
	* dwarf2read.c: Include "common/pathstuff.h".
	* exec.c: Likewise.
	* guile/scm-safe-call.c: Likewise.
	* linux-thread-db.c: Likewise.
	* main.c: Likewise.
	* nto-tdep.c: Likewise.
	* objfiles.c: Likewise.
	* source.c: Likewise.
	* symtab.c: Likewise.
	* utils.c: Include "common/pathstuff.h".
	(gdb_realpath): Move to "common/pathstuff.c".
	(gdb_realpath_keepfile): Likewise.
	(gdb_abspath): Likewise.
	* utils.h (gdb_realpath): Move to "common/pathstuff.h".
	(gdb_realpath_keepfile): Likewise.
	(gdb_abspath): Likewise.

gdb/gdbserver/ChangeLog:
2018-02-28  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add "$(srcdir)/common/pathstuff.c".
	(OBJS): Add "pathstuff.o".
	* server.c (current_directory): New global variable.
	(captured_main): Initialize "current_directory".

1 files changed, 49 insertions, 0 deletions

diff --git a/gdb/common/pathstuff.h b/gdb/common/pathstuff.h
new file mode 100644
index 0000000..3cb02c8
--- /dev/null
+++ b/gdb/common/pathstuff.h
@@ -0,0 +1,49 @@
+/* Path manipulation routines for GDB and gdbserver.
+
+   Copyright (C) 1986-2018 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 PATHSTUFF_H
+#define PATHSTUFF_H
+
+/* Path utilities.  */
+
+/* Return the real path of FILENAME, expanding all the symbolic links.
+
+   Contrary to "gdb_abspath", this function does not use
+   CURRENT_DIRECTORY for path expansion.  Instead, it relies on the
+   current working directory (CWD) of GDB or gdbserver.  */
+
+extern gdb::unique_xmalloc_ptr<char> gdb_realpath (const char *filename);
+
+/* Return a copy of FILENAME, with its directory prefix canonicalized
+   by gdb_realpath.  */
+
+extern gdb::unique_xmalloc_ptr<char>
+  gdb_realpath_keepfile (const char *filename);
+
+/* Return PATH in absolute form, performing tilde-expansion if necessary.
+   PATH cannot be NULL or the empty string.
+   This does not resolve symlinks however, use gdb_realpath for that.
+
+   Contrary to "gdb_realpath", this function uses CURRENT_DIRECTORY
+   for the path expansion.  This may lead to scenarios the current
+   working directory (CWD) is different than CURRENT_DIRECTORY.  */
+
+extern gdb::unique_xmalloc_ptr<char> gdb_abspath (const char *path);
+
+#endif /* PATHSTUFF_H */