[rfc 3/3] Do not use gdb_realpath for exec_bfd and objfiles

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

Hi Doug,

in fact all the gdb_realpath() calls are IMO a bug, it is more convenient to
see I am debugging /home/user/file than to see it is /.sdb5/home/user/file
(this example comes from common 'ln -s .sdb5/home /home' joining of partitions
etc.).

As this goes against some GDB goal I do not understand I have not changed it
everywhere yet.  Still this patch already makes such change for objfiles
and exec file, such as in "info files" (but not for source files).

If the displayed filenames really should remain canonical then sure this patch
is wrong and the original filename should be stored only internally (for
open_and_init_dwp_file).


Jan


gdb/
2013-08-28  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Do not use gdb_realpath for exec_bfd and objfiles.
	* dwarf2read.c (open_and_init_dwp_file): Try DWP_NAME also with
	gdb_realpath.
	* exec.c (exec_file_attach): Remove variable canonical_pathname, use
	scratch_pathname instead.
	* symfile.c (symfile_bfd_open): Remove OPF_RETURN_REALPATH from openp
	call.  Twice.

gdb/testsuite/
2013-08-28  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.base/dwp-symlink.c: New file.
	* gdb.base/dwp-symlink.exp: New file.

--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -9637,6 +9637,14 @@ open_and_init_dwp_file (void)
   dbfd = open_dwp_file (dwp_name);
   if (dbfd == NULL)
     {
+      /* Try to find .dwp for the binary file after gdb_realpath resolving.  */
+      dwp_name = xstrprintf ("%s.dwp",
+			     gdb_realpath (dwarf2_per_objfile->objfile->name));
+      make_cleanup (xfree, dwp_name);
+      dbfd = open_dwp_file (dwp_name);
+    }
+  if (dbfd == NULL)
+    {
       if (dwarf2_read_debug)
 	fprintf_unfiltered (gdb_stdlog, "DWP file not found: %s\n", dwp_name);
       do_cleanups (cleanups);
--- a/gdb/exec.c
+++ b/gdb/exec.c
@@ -182,7 +182,7 @@ exec_file_attach (char *filename, int from_tty)
   else
     {
       struct cleanup *cleanups;
-      char *scratch_pathname, *canonical_pathname;
+      char *scratch_pathname;
       int scratch_chan;
       struct target_section *sections = NULL, *sections_end = NULL;
       char **matching;
@@ -206,16 +206,11 @@ exec_file_attach (char *filename, int from_tty)
 
       cleanups = make_cleanup (xfree, scratch_pathname);
 
-      /* gdb_bfd_open (and its variants) prefers canonicalized pathname for
-	 better BFD caching.  */
-      canonical_pathname = gdb_realpath (scratch_pathname);
-      make_cleanup (xfree, canonical_pathname);
-
       if (write_files)
-	exec_bfd = gdb_bfd_fopen (canonical_pathname, gnutarget,
+	exec_bfd = gdb_bfd_fopen (scratch_pathname, gnutarget,
 				  FOPEN_RUB, scratch_chan);
       else
-	exec_bfd = gdb_bfd_open (canonical_pathname, gnutarget, scratch_chan);
+	exec_bfd = gdb_bfd_open (scratch_pathname, gnutarget, scratch_chan);
 
       if (!exec_bfd)
 	{
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -1679,7 +1679,7 @@ symfile_bfd_open (char *name)
   name = tilde_expand (name);	/* Returns 1st new malloc'd copy.  */
 
   /* Look down path for it, allocate 2nd new malloc'd copy.  */
-  desc = openp (getenv ("PATH"), OPF_TRY_CWD_FIRST | OPF_RETURN_REALPATH, name,
+  desc = openp (getenv ("PATH"), OPF_TRY_CWD_FIRST, name,
 		O_RDONLY | O_BINARY, &absolute_name);
 #if defined(__GO32__) || defined(_WIN32) || defined (__CYGWIN__)
   if (desc < 0)
@@ -1687,8 +1687,8 @@ symfile_bfd_open (char *name)
       char *exename = alloca (strlen (name) + 5);
 
       strcat (strcpy (exename, name), ".exe");
-      desc = openp (getenv ("PATH"), OPF_TRY_CWD_FIRST | OPF_RETURN_REALPATH,
-		    exename, O_RDONLY | O_BINARY, &absolute_name);
+      desc = openp (getenv ("PATH"), OPF_TRY_CWD_FIRST, exename,
+		    O_RDONLY | O_BINARY, &absolute_name);
     }
 #endif
   if (desc < 0)
--- /dev/null
+++ b/gdb/testsuite/gdb.base/dwp-symlink.c
@@ -0,0 +1,22 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2013 Free Software Foundation, Inc.
+
+   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/>.  */
+
+int
+main (int argc, char **argv)
+{
+  return 0;
+}
--- /dev/null
+++ b/gdb/testsuite/gdb.base/dwp-symlink.exp
@@ -0,0 +1,77 @@
+# Copyright 2013 Free Software Foundation, Inc.
+
+# 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/>.
+
+standard_testfile
+
+if [is_remote host] {
+    untested "remote host"
+    return 0
+}
+
+file delete [standard_output_file ${testfile}.dwp]
+if [file exists [standard_output_file ${testfile}.dwp]] {
+    unsupported "dwp file cannot be deleted"
+    return 0
+}
+if { [build_executable ${testfile}.exp ${testfile} ${srcfile}] == -1 } {
+    return -1
+}
+if ![file exists [standard_output_file ${testfile}.dwp]] {
+    unsupported "testsuite run run does not produce dwp files"
+    return 0
+}
+
+set thelink "${testfile}-thelink"
+
+file delete [standard_output_file ${thelink}]
+file delete [standard_output_file ${thelink}.dwp]
+# file link is only Tcl 8.4+.
+exec "ln" "-sf" "${testfile}" "[standard_output_file $thelink]"
+if ![file exists [standard_output_file $thelink]] {
+    unsupported "host does not support symbolic links (binary symlink is missing)"
+    return 0
+}
+if [file exists [standard_output_file $thelink.dwp]] {
+    unsupported "host does not support symbolic links (dwp symlink exists)"
+    return 0
+}
+
+clean_restart "$testfile"
+
+gdb_test "ptype main" {type = int \(int, char \*\*\)} "binary default, dwp default"
+
+clean_restart "$thelink"
+
+gdb_test "ptype main" {type = int \(int, char \*\*\)} "binary symlink, dwp default"
+
+gdb_exit
+file rename [standard_output_file ${testfile}.dwp] [standard_output_file ${thelink}.dwp]
+if [file exists [standard_output_file ${testfile}.dwp]] {
+    unsupported "host does not support symbolic links (binary symlink exists)"
+    return 0
+}
+if ![file exists [standard_output_file ${thelink}.dwp]] {
+    unsupported "host does not support symbolic links (dwp symlink is missing)"
+    return 0
+}
+
+clean_restart "$testfile"
+
+# This case cannot work.
+gdb_test "ptype main" {type = int \(\)} "binary default, dwp at symlink"
+
+clean_restart "$thelink"
+
+gdb_test "ptype main" {type = int \(int, char \*\*\)} "binary symlink, dwp at symlink"