[PATCH 3/4] Introduce gdb_chdir

[Sergio Durigan Junior <sergiodj at redhat dot com>]

In order to be able to change the inferior's directory before its
execution, it is necessary to perform a tilde expansion of the
directory provided by the user and then chdir into the resulting dir.
This is what gdb_chdir does.

Unfortunately it is not possible to use "tilde_expand" from readline
because this is common code and gdbserver doesn't use readline.  For
that reason I decided to go with "glob" and its GNU extension,
GLOB_TILDE.  With the import of the "glob" module from gnulib, this is
a no-brainer.

gdb/ChangeLog:
yyyy-mm-dd  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add gdb_chdir.c.
	(HFILES_NO_SRCDIR): Add gdb_chdir.h.
	(COMMON_OBS): Add gdb_chdir.o.
	* common/gdb_chdir.c: New file.
	* common/gdb_chdir.h: Likewise.

gdb/gdbserver/ChangeLog:
yyyy-mm-dd  Sergio Durigan Junior  <sergiodj@redhat.com>

	* Makefile.in (SFILES): Add $(srcdir)/common/gdb_chdir.c.
	(OBS): Add gdb_chdir.o.
---
 gdb/Makefile.in           |  3 +++
 gdb/common/gdb_chdir.c    | 60 +++++++++++++++++++++++++++++++++++++++++++++++
 gdb/common/gdb_chdir.h    | 26 ++++++++++++++++++++
 gdb/gdbserver/Makefile.in |  2 ++
 4 files changed, 91 insertions(+)
 create mode 100644 gdb/common/gdb_chdir.c
 create mode 100644 gdb/common/gdb_chdir.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 2aa474e598..38c89761dd 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1243,6 +1243,7 @@ SFILES = \
 	common/filestuff.c \
 	common/format.c \
 	common/job-control.c \
+	common/gdb_chdir.c \
 	common/gdb_vecs.c \
 	common/new-op.c \
 	common/print-utils.c \
@@ -1527,6 +1528,7 @@ HFILES_NO_SRCDIR = \
 	common/fileio.h \
 	common/format.h \
 	common/gdb_assert.h \
+	common/gdb_chdir.h \
 	common/gdb_locale.h \
 	common/gdb_setjmp.h \
 	common/gdb_signals.h \
@@ -1732,6 +1734,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
 	frame-unwind.o \
 	gcore.o \
 	gdb_bfd.o \
+	gdb_chdir.o \
 	gdb-dlfcn.o \
 	gdb_obstack.o \
 	gdb_regex.o \
diff --git a/gdb/common/gdb_chdir.c b/gdb/common/gdb_chdir.c
new file mode 100644
index 0000000000..16e2b3adf0
--- /dev/null
+++ b/gdb/common/gdb_chdir.c
@@ -0,0 +1,60 @@
+/* chdir(2) wrapper for GDB and gdbserver.
+
+   Copyright (C) 2017 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 <glob.h>
+#include "gdb_chdir.h"
+
+/* Perform path expansion (i.e., tilde expansion) on DIR, and return
+   the full path.  */
+
+static std::string
+expand_path (const char *dir)
+{
+  glob_t g;
+  std::string expanded_dir;
+  int err = glob (dir, GLOB_TILDE | GLOB_TILDE_CHECK | GLOB_ONLYDIR, NULL, &g);
+
+  if (err != 0)
+    {
+      if (err == GLOB_NOMATCH)
+	error (_("No such directory '%s'.  Failure to set cwd."), dir);
+
+      error (_("Could not process directory '%s'."), dir);
+    }
+
+  gdb_assert (g.gl_pathc > 0);
+  /* "glob" may return more than one match to the path provided by the
+     user, but we are only interested in the first match.  */
+  expanded_dir = g.gl_pathv[0];
+  globfree (&g);
+
+  return expanded_dir;
+}
+
+/* See gdb_chdir.h.  */
+
+void
+gdb_chdir (const char *dir)
+{
+  std::string expanded_dir = expand_path (dir);
+
+  if (chdir (expanded_dir.c_str ()) < 0)
+    perror_with_name (expanded_dir.c_str ());
+}
diff --git a/gdb/common/gdb_chdir.h b/gdb/common/gdb_chdir.h
new file mode 100644
index 0000000000..5e6253e3b5
--- /dev/null
+++ b/gdb/common/gdb_chdir.h
@@ -0,0 +1,26 @@
+/* chdir(2) wrapper for GDB and gdbserver.
+
+   Copyright (C) 2017 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 HAVE_GDB_CHDIR_H
+#define HAVE_GDB_CHDIR_H
+
+/* Perform a "chdir" to DIR, doing the proper tilde expansion before.  */
+extern void gdb_chdir (const char *dir);
+
+#endif /* ! HAVE_GDB_CHDIR_H */
diff --git a/gdb/gdbserver/Makefile.in b/gdb/gdbserver/Makefile.in
index 1bbe515629..ecd12a7dcc 100644
--- a/gdb/gdbserver/Makefile.in
+++ b/gdb/gdbserver/Makefile.in
@@ -205,6 +205,7 @@ SFILES = \
 	$(srcdir)/common/fileio.c \
 	$(srcdir)/common/filestuff.c \
 	$(srcdir)/common/job-control.c \
+	$(srcdir)/common/gdb_chdir.c \
 	$(srcdir)/common/gdb_vecs.c \
 	$(srcdir)/common/new-op.c \
 	$(srcdir)/common/print-utils.c \
@@ -247,6 +248,7 @@ OBS = \
 	fileio.o \
 	filestuff.o \
 	format.o \
+	gdb_chdir.o \
 	gdb_vecs.o \
 	hostio.o \
 	inferiors.o \
-- 
2.13.3