commit bb995d00b3eef2f48d0be895c3509a7ddd8280a1

Author: Keith Seitz <keiths@redhat.com>

Date:   Fri Feb 22 09:39:35 2019 -0800

    Fix symtab/23853: symlinked default symtab

    This patch attempts to fix a bug dealing with setting breakpoints

    in default symtabs that are symlinks.  For example:

    (gdb) list

    11         GNU General Public License for more details.

    12

    13         You should have received a copy of the GNU General Public License

    14         along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

    15

    16      static int

    17      foo (void)

    18      {

    19        return 0; /* break here  */

    20      }

    (gdb)

    21

    22      int

    23      main (void)

    24      {

    25        return foo ();

    26      }

    (gdb) b 19

    No line 19 in the current file.

    Make breakpoint pending on future shared library load? (y or [n])

    The problem here is that when create_sals_line_offset sets the default

    symtab, it immediately calls symtab_to_fullname, passing that fullname

    to collect_symtabs_from_filename to find all matching symtabs.  This

    fails because we end up looking for a symtab with the name of the

    actual file on disk (which is different in this case because of the

    symlink) instead of the one stored in the debug info.

    Since we already have the lookup name of the default symtab, use it

    instead of the fullname. [This fullname thing was originally added

    in 2007 in a series dealing with *displaying* absolute file names.

    Clearly, this instance has nothing to do with the display of file names.]

    gdb/ChangeLog

            PR symtab/23853

            * linespec.c (create_sals_line_offset): Search for the default

            symtab's filename instead of its fullname.

    gdb/testsuite/ChangeLog

            PR symtab/23853

            * gdb.base/symlink-sourcefile.c: New file.

            * gdb.base/symlink-sourcefile.exp: New file.

Index: gdb-7.6.1/gdb/linespec.c

===================================================================

--- gdb-7.6.1.orig/gdb/linespec.c

+++ gdb-7.6.1/gdb/linespec.c

@@ -1844,17 +1844,15 @@ create_sals_line_offset (struct linespec

   if (VEC_length (symtab_p, ls->file_symtabs) == 1

       && VEC_index (symtab_p, ls->file_symtabs, 0) == NULL)

     {

-      const char *fullname;

-

       set_current_program_space (self->program_space);

       /* Make sure we have at least a default source line.  */

       set_default_source_symtab_and_line ();

       initialize_defaults (&self->default_symtab, &self->default_line);

-      fullname = symtab_to_fullname (self->default_symtab);

       VEC_pop (symtab_p, ls->file_symtabs);

       VEC_free (symtab_p, ls->file_symtabs);

-      ls->file_symtabs = collect_symtabs_from_filename (fullname);

+      ls->file_symtabs

+	= collect_symtabs_from_filename (self->default_symtab->filename);

       use_default = 1;

     }

Index: gdb-7.6.1/gdb/testsuite/gdb.base/symlink-sourcefile.c

===================================================================

--- /dev/null

+++ gdb-7.6.1/gdb/testsuite/gdb.base/symlink-sourcefile.c

@@ -0,0 +1,26 @@

+/* Copyright 2019 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/>.  */

+

+static int

+foo (void)

+{

+  return 0; /* break here  */

+}

+

+int

+main (void)

+{

+  return foo ();

+}

Index: gdb-7.6.1/gdb/testsuite/gdb.base/symlink-sourcefile.exp

===================================================================

--- /dev/null

+++ gdb-7.6.1/gdb/testsuite/gdb.base/symlink-sourcefile.exp

@@ -0,0 +1,46 @@

+# Copyright 2019 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/>.

+

+# Test that GDB can find the default symtab when it is a symbolic link.

+standard_testfile

+

+set test "file symbolic link name"

+set srcdirabs [file join [pwd] $srcdir]

+set linksrc "link-${srcfile}"

+set srcfilelink [standard_output_file $linksrc]

+

+

+# Remove any existing symlink and build executable using a

+# symbolic link to the actual source file.

+remote_file host delete $srcfilelink

+set status [remote_exec host \

+		"ln -sf $srcdirabs/$subdir/$srcfile $srcfilelink"]

+if {[lindex $status 0] != 0} {

+    unsupported "$test (host does not support symbolic links)"

+    return 0

+}

+

+if {[prepare_for_testing $testfile $testfile $srcfilelink]} {

+    return -1

+}

+

+if {![runto_main]} {

+    untested "could not run to main"

+    return -1

+}

+

+# Using a line number ensures that the default symtab is used.

+gdb_breakpoint [gdb_get_line_number "break here" $srcfile] message

+gdb_continue_to_breakpoint "run to breakpoint marker"

Index: gdb-7.6.1/gdb/testsuite/lib/gdb.exp

===================================================================

--- gdb-7.6.1.orig/gdb/testsuite/lib/gdb.exp

+++ gdb-7.6.1/gdb/testsuite/lib/gdb.exp

@@ -4062,7 +4062,10 @@ proc build_executable_from_specs {testna

 	set objects {}

 	set i 0

 	foreach {s local_options} $args {

-	    if  { [gdb_compile "${srcdir}/${subdir}/${s}" "${binfile}${i}.o" object $local_options] != "" } {

+	    if {! [regexp "^/" "$s"] } then {

+		set s "$srcdir/$subdir/$s"

+	    }

+	    if  { [gdb_compile "${s}" "${binfile}${i}.o" object $local_options] != "" } {

 		untested $testname

 		return -1

 	    }