[PATCH 1/4] Implement 'set honor-dontdump-flag' command

[Sergio Lopez <slp@redhat.com>]

Commit df8411da087dc05481926f4c4a82deabc5bc3859 implemented support for
checking /proc/PID/coredump_filter, and also changed gcore behavior to
unconditionally honor the VM_DONTDUMP flag, preventing sections marked
as such for being dumped into the core file.

This patch adds support for the 'set honor-dontdump-flag' command for
instructing gdb to ignore the VM_DONTDUMP flag. Combined with 'set
use-coredump-filter', this allows the user to restore the old behavior,
dumping all sections (except the ones marked as IO) unconditionally.

ChangeLog
2017-11-28  Sergio Lopez  <slp@redhat.com>

        * linux-tdep.c (honor_dontdump_flag): New variable.
        (dump_mapping_p): Use honor_dontdump_flag variable.
        (_initialize_linux_tdep): New command 'set honor-dontdump-flag'.
---
 gdb/ChangeLog    |  6 ++++++
 gdb/linux-tdep.c | 19 ++++++++++++++++++-
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ebb969998c..ce68fee776 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2017-11-28  Sergio Lopez  <slp@redhat.com>
+
+	* linux-tdep.c (honor_dontdump_flag): New variable.
+	(dump_mapping_p): Use honor_dontdump_flag variable.
+	(_initialize_linux_tdep): New command 'set honor-dontdump-flag'.
+
 2017-11-27  Tom Tromey  <tom@tromey.com>
 
 	* Makefile.in (REMOTE_OBS): Remove.
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index 24237b8d39..5f4a1cdad1 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -93,6 +93,11 @@ struct smaps_vmflags
 
 static int use_coredump_filter = 1;
 
+/* Whether to honor the VM_DONTDUMP flag in /proc/PID/smaps when
+   generating a corefile.  */
+
+static int honor_dontdump_flag = 1;
+
 /* This enum represents the signals' numbers on a generic architecture
    running the Linux kernel.  The definition of "generic" comes from
    the file <include/uapi/asm-generic/signal.h>, from the Linux kernel
@@ -655,7 +660,7 @@ dump_mapping_p (filter_flags filterflags, const struct smaps_vmflags *v,
 	return 0;
 
       /* Check if we should exclude this mapping.  */
-      if (v->exclude_coredump)
+      if (honor_dontdump_flag && v->exclude_coredump)
 	return 0;
 
       /* Update our notion of whether this mapping is shared or
@@ -2517,4 +2522,16 @@ of /proc/PID/coredump_filter when generating the corefile.  For more information
 about this file, refer to the manpage of core(5)."),
 			   NULL, show_use_coredump_filter,
 			   &setlist, &showlist);
+
+  add_setshow_boolean_cmd ("honor-dontdump-flag", class_files,
+			   &honor_dontdump_flag, _("\
+Set whether gcore should honor the VM_DONTDUMP flag."),
+			   _("\
+Show whether gcore should honor the VM_DONTDUMP flag."),
+			   _("\
+Use this command to set whether gcore should honor the VM_DONTDUMP\n\
+flag from /proc/PID/smaps when generating the corefile.  For more information\n\
+about this file, refer to the manpage of proc(5) and core(5)."),
+			   NULL, show_use_coredump_filter,
+			   &setlist, &showlist);
 }
-- 
2.14.3