Re: [PATCH] fix PR gdb/19914

[Doug Evans <dje at google dot com>]

Yunlian Jiang writes:
 > ping?
 >
 > On Wed, Apr 13, 2016 at 11:18 AM, Yunlian Jiang <yunlian@google.com>  
wrote:
 > > I have a updated one. It uses separate_debug_objfile_backlink to get
 > > the real dwp file name if it is a debug file.
 > >
 > > --- a/gdb/dwarf2read.c
 > > +++ b/gdb/dwarf2read.c
 > > @@ -10835,13 +10835,28 @@ open_and_init_dwp_file (void)
 > >  {
 > >    struct objfile *objfile = dwarf2_per_objfile->objfile;
 > >    struct dwp_file *dwp_file;
 > > +  char *dwp_base_name;
 > >    char *dwp_name;
 > >    bfd *dbfd;
 > >    struct cleanup *cleanups;
 > >
 > >    /* Try to find first .dwp for the binary file before any symbolic  
links
 > >       resolving.  */
 > > +
 > > +  /* If the objfile is a debug file, find the name of the real binary
 > > +     file and get the name of dwp file from there. */
 > > +  if (objfile->separate_debug_objfile_backlink)
 > > +    {
 > > +      dwp_base_name = xstrprintf ("%s.dwp",
 > > +        lbasename  
(objfile->separate_debug_objfile_backlink->original_name));
 > > +    }
 > > +  else
 > > +    dwp_base_name = xstrprintf ("%s.dwp", lbasename  
(objfile->original_name));
 > > +  dwp_name = xstrprintf ("%s%s%s", ldirname(objfile->original_name),
 > > +                         SLASH_STRING, dwp_base_name);
 > > +
 > >    dwp_name = xstrprintf ("%s.dwp", objfile->original_name);
 > > +  cleanups = make_cleanup (xfree, dwp_base_name);
 > >    cleanups = make_cleanup (xfree, dwp_name);
 > >
 > >    dbfd = open_dwp_file (dwp_name);
 > >
 > > On Fri, Apr 8, 2016 at 3:54 PM, Doug Evans <dje@google.com> wrote:
 > >> Yunlian Jiang writes:
 > >>  > Hi.
 > >>  >
 > >>  > This tries to fix PR gdb/19914. When the object file is not
 > >>  > a binary but a .debug file, the function to try to find the .dwp
 > >>  > file in the debug directory does not work. This one tries to solve
 > >>  > this problem.
 > >>  >
 > >>  > 2016-04-05  Yunlian Jiang <yunlian@google.com>
 > >>  >                * gdb/dwarf2read.c: Try to find .dwp for .debug
 > >>  >
 > >>  >
 > >>  > diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
 > >>  > index dcd49e3..551376a 100644
 > >>  > --- a/gdb/dwarf2read.c
 > >>  > +++ b/gdb/dwarf2read.c
 > >>  > @@ -10854,6 +10854,18 @@ open_and_init_dwp_file (void)
 > >>  >        dbfd = open_dwp_file (dwp_name);
 > >>  >      }
 > >>  >
 > >>  > +  if (dbfd == NULL && strlen(dwp_name) > 10)
 > >>  > +    {
 > >>  > +      /* Try to find .dwp for the debug file.  */
 > >>  > +      if (!strcmp(dwp_name + strlen(dwp_name) - 10, ".debug.dwp"))
 > >>  > +        {
 > >>  > +           dwp_name[strlen(dwp_name) - 10] = '\0';
 > >>  > +           dwp_name = xstrprintf ("%s.dwp", dwp_name);
 > >>  > +           make_cleanup (xfree, dwp_name);
 > >>  > +           dbfd = open_dwp_file (dwp_name);
 > >>  > +        }
 > >>  > +    }
 > >>  > +
 > >>  >    if (dbfd == NULL)
 > >>  >      {
 > >>  >        if (dwarf_read_debug)
 > >>
 > >> Hi.
 > >>
 > >> I've looked at this a little bit.
 > >> I don't have time for a complete review at the moment,
 > >> but one thing I'm wondering about is whether this extra
 > >> test should go in open_dwp_file instead.
 > >>
 > >> Plus, while we're making the assumption that the separate debug
 > >> file ends with ".debug" that's not necessarily true.
 > >> Not sure we can do better, but one thought is to look in
 > >> separate_debug_objfile_backlink and use that.

Ok, had time to fully dig into this.

There are a couple of problems with the patch.
E.g., ldirname malloc's its result, so that needs to be freed.

I came up with this (which includes a testcase).

Look ok?

2016-04-24  Yunlian Jiang <yunlian@google.com>
	    Doug Evans  <dje@google.com>

	PR symtab/19914
	* dwarf2read.c (open_and_init_dwp_file): Look at backlink if objfile
	is separate debug file.

	testsuite/
	* gdb.dwarf2/dwp-sepdebug.c: New file.
	* gdb.dwarf2/dwp-sepdebug.exp: New file.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 7bbf080..eb81151 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -10838,12 +10838,26 @@ open_and_init_dwp_file (void)
   struct dwp_file *dwp_file;
   char *dwp_name;
   bfd *dbfd;
-  struct cleanup *cleanups;
+  struct cleanup *cleanups = make_cleanup (null_cleanup, 0);

   /* Try to find first .dwp for the binary file before any symbolic links
      resolving.  */
-  dwp_name = xstrprintf ("%s.dwp", objfile->original_name);
-  cleanups = make_cleanup (xfree, dwp_name);
+
+  /* If the objfile is a debug file, find the name of the real binary
+     file and get the name of dwp file from there.  */
+  if (objfile->separate_debug_objfile_backlink != NULL)
+    {
+      struct objfile *backlink = objfile->separate_debug_objfile_backlink;
+      const char *backlink_basename = lbasename (backlink->original_name);
+      char *debug_dirname = ldirname (objfile->original_name);
+
+      make_cleanup (xfree, debug_dirname);
+      dwp_name = xstrprintf ("%s%s%s.dwp", debug_dirname,
+			     SLASH_STRING, backlink_basename);
+    }
+  else
+    dwp_name = xstrprintf ("%s.dwp", objfile->original_name);
+  make_cleanup (xfree, dwp_name);

   dbfd = open_dwp_file (dwp_name);
   if (dbfd == NULL
diff --git a/gdb/testsuite/gdb.dwarf2/dwp-sepdebug.c  
b/gdb/testsuite/gdb.dwarf2/dwp-sepdebug.c
new file mode 100644
index 0000000..bb11da2
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dwp-sepdebug.c
@@ -0,0 +1,22 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 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;
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dwp-sepdebug.exp  
b/gdb/testsuite/gdb.dwarf2/dwp-sepdebug.exp
new file mode 100644
index 0000000..a4e7068
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dwp-sepdebug.exp
@@ -0,0 +1,40 @@
+# Copyright 2016 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 { [build_executable ${testfile}.exp ${testfile} ${srcfile}] == -1 } {
+    return -1
+}
+if ![remote_file host exists [standard_output_file ${testfile}.dwp]] {
+    unsupported "testsuite run does not produce dwp files"
+    return 0
+}
+
+# Note: the procedure gdb_gnu_strip_debug will produce an executable called
+# ${binfile}, which is just like the executable ($binfile) but without
+# the debuginfo. Instead $binfile has a .gnu_debuglink section which  
contains
+# the name of a debuginfo only file. This file will be stored in the
+# gdb.base/ subdirectory.
+
+if [gdb_gnu_strip_debug $binfile$EXEEXT] {
+    # check that you have a recent version of strip and objcopy installed
+    unsupported "cannot produce separate debug info files"
+    return -1
+}
+
+clean_restart "$testfile"
+
+gdb_test "ptype main" {type = int \(int, char \*\*\)}