Re: [patch] Forbid run with a core file loaded

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

On Fri, 21 May 2010 17:31:06 +0200, Mark Kettenis wrote:
> In general these "Are you sure?" type questions are un-Unixy and
> rather annoying in my opinion.  They make sense if the user is about
> to take an action that is going to lose state (such as loading a core
> file while a program is running), but I think we shouldn't add them in
> this case.

That makes sense, removed the question.


On Fri, 21 May 2010 17:02:31 +0200, Joel Brobecker wrote:
> > +set test "start with core"
> > +gdb_test_multiple "start" $test {
> > +    -re {Core file is already loaded.  Unload it[?] [(]y or n[)] } {
> > +	pass $test
> > +    }
> > +}
> 
> We should not use the "start" command in testcases, as it does not
> work with remote targets. I'm afraid we're going to have to rely on
> the run command instead.

OK, used runto_main now.  Attach test does not run with gdbserver the same way
gdb.base/attach.exp does not.  Tested this testfile with runtest-gdbserver
(only on localhost).


On Fri, 21 May 2010 17:06:07 +0200, Pedro Alves wrote:
> I don't think it makes that much sense nowadays to have a
> distinct core_stratum vs process_stratum.

OK, removed core_stratum.


> It core_ops was a process_stratum, pushing linux-nat.c would auto discard
> the core, as you can't have two targets of the same stratum on the stack.

Followed it although some ordering adjustments were required.


> The only main use for that stratum nowadays is for find_core_target,
> I think.

Replaced.  Unaware if some 3rd patches were using secondary core_stratum, it
probably could not work anyway.


> > 	Forbid run with a core file loaded.
> > 	* infcmd.c (run_command_1) <core_bfd>: New.
> 
> What about "attach"?

Forgot, implemented/fixed.


No regressions on {x86_64,x86_64-m32,i686}-fedora12-linux-gnu.


Thanks,
Jan


gdb/
2010-05-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Make core files the process_stratum.
	* corefile.c (core_target): New variable.
	(core_file_command): Remove variable t, use core_target.
	* corelow.c (core_ops): Make it static.
	(init_core_ops): Change to process_stratum.  Initialize CORE_TARGET.
	* gdbarch.sh (core_pid_to_str): Remove core_stratum from its comment.
	* gdbarch.h: Regenerate.
	* gdbcore.h (core_target): New declaration.
	* inf-ptrace.c (inf_ptrace_create_inferior): Move push_target before
	fork_inferior, comment it.
	(inf_ptrace_attach): Call pop_all_targets_above.
	* record.c (record_open): Replace core_stratum by a core_bfd check.
	* target.c (find_core_target): Remove.
	* target.h (enum strata) <core_stratum>: Remove.
	(find_core_target): Remove declaration.
	* tracepoint.c (init_tfile_ops) <to_stratum>: Remove comment.

gdb/doc/
2010-05-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Make core files the process_stratum.
	* gdb.texinfo (Active Targets): Remove core_stratum.  Include
	record_stratum example.

gdb/testsuite/
2010-05-23  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Make core files the process_stratum.
	* gdb.base/corefile.exp (run: load core again)
	(run: sanity check we see the core file, run: with core)
	(run: core file is cleared, attach: load core again)
	(attach: sanity check we see the core file, attach: with core)
	(attach: core file is cleared): New tests.
	* gdb.base/coremaker.c (main): New parameters.  Implement "sleep" argv.

--- a/gdb/corefile.c
+++ b/gdb/corefile.c
@@ -59,6 +59,10 @@ static int exec_file_hook_count = 0;	/* size of array */
 /* Binary file diddling handle for the core file.  */
 
 bfd *core_bfd = NULL;
+
+/* corelow.c target (if included for this gdb target).  */
+
+struct target_ops *core_target;
 
 
 /* Backward compatability with old way of specifying core files.  */
@@ -66,18 +70,15 @@ bfd *core_bfd = NULL;
 void
 core_file_command (char *filename, int from_tty)
 {
-  struct target_ops *t;
-
   dont_repeat ();		/* Either way, seems bogus. */
 
-  t = find_core_target ();
-  if (t == NULL)
+  if (core_target == NULL)
     error (_("GDB can't read core files on this machine."));
 
   if (!filename)
-    (t->to_detach) (t, filename, from_tty);
+    (core_target->to_detach) (core_target, filename, from_tty);
   else
-    (t->to_open) (filename, from_tty);
+    (core_target->to_open) (filename, from_tty);
 }
 
 
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -100,7 +100,7 @@ static void init_core_ops (void);
 
 void _initialize_corelow (void);
 
-struct target_ops core_ops;
+static struct target_ops core_ops;
 
 /* An arbitrary identifier for the core inferior.  */
 #define CORELOW_PID 1
@@ -911,11 +911,17 @@ init_core_ops (void)
   core_ops.to_thread_alive = core_thread_alive;
   core_ops.to_read_description = core_read_description;
   core_ops.to_pid_to_str = core_pid_to_str;
-  core_ops.to_stratum = core_stratum;
+  core_ops.to_stratum = process_stratum;
   core_ops.to_has_memory = core_has_memory;
   core_ops.to_has_stack = core_has_stack;
   core_ops.to_has_registers = core_has_registers;
   core_ops.to_magic = OPS_MAGIC;
+
+  if (core_target)
+    internal_error (__FILE__, __LINE__, 
+		    _("init_core_ops: core target already exists (\"%s\")."),
+		    core_target->to_longname);
+  core_target = &core_ops;
 }
 
 void
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -609,8 +609,7 @@ v:struct core_regset_section *:core_regset_sections:const char *name, int len:::
 # core file into buffer READBUF with length LEN.
 M:LONGEST:core_xfer_shared_libraries:gdb_byte *readbuf, ULONGEST offset, LONGEST len:readbuf, offset, len
 
-# How the core_stratum layer converts a PTID from a core file to a
-# string.
+# How the core target converts a PTID from a core file to a string.
 M:char *:core_pid_to_str:ptid_t ptid:ptid
 
 # BFD target to use when generating a core file.
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -666,8 +666,7 @@ typedef LONGEST (gdbarch_core_xfer_shared_libraries_ftype) (struct gdbarch *gdba
 extern LONGEST gdbarch_core_xfer_shared_libraries (struct gdbarch *gdbarch, gdb_byte *readbuf, ULONGEST offset, LONGEST len);
 extern void set_gdbarch_core_xfer_shared_libraries (struct gdbarch *gdbarch, gdbarch_core_xfer_shared_libraries_ftype *core_xfer_shared_libraries);
 
-/* How the core_stratum layer converts a PTID from a core file to a
-   string. */
+/* How the core target converts a PTID from a core file to a string. */
 
 extern int gdbarch_core_pid_to_str_p (struct gdbarch *gdbarch);
 
--- a/gdb/gdbcore.h
+++ b/gdb/gdbcore.h
@@ -108,6 +108,8 @@ extern void specify_exec_file_hook (void (*hook) (char *filename));
 
 extern bfd *core_bfd;
 
+extern struct target_ops *core_target;
+
 /* Whether to open exec and core files read-only or read-write.  */
 
 extern int write_files;
--- a/gdb/inf-ptrace.c
+++ b/gdb/inf-ptrace.c
@@ -121,11 +121,12 @@ inf_ptrace_create_inferior (struct target_ops *ops,
 {
   int pid;
 
+  /* Clear possible core file with its process_stratum.  */
+  push_target (ops);
+
   pid = fork_inferior (exec_file, allargs, env, inf_ptrace_me, NULL,
 		       NULL, NULL);
 
-  push_target (ops);
-
   /* On some targets, there must be some explicit synchronization
      between the parent and child processes after the debugger
      forks, and before the child execs the debuggee program.  This
@@ -194,6 +195,10 @@ inf_ptrace_attach (struct target_ops *ops, char *args, int from_tty)
   if (pid == getpid ())		/* Trying to masturbate?  */
     error (_("I refuse to debug myself!"));
 
+  /* target_pid_to_str already uses the target.  Clear possible core file with
+     its process_stratum.  */
+  pop_all_targets_above (ops->to_stratum - 1, 0);
+
   if (from_tty)
     {
       exec_file = get_exec_file (0);
--- a/gdb/record.c
+++ b/gdb/record.c
@@ -958,7 +958,7 @@ record_open (char *name, int from_tty)
   record_beneath_to_stopped_by_watchpoint = tmp_to_stopped_by_watchpoint;
   record_beneath_to_stopped_data_address = tmp_to_stopped_data_address;
 
-  if (current_target.to_stratum == core_stratum)
+  if (core_bfd)
     record_core_open_1 (name, from_tty);
   else
     record_open_1 (name, from_tty);
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -2699,31 +2699,6 @@ find_run_target (void)
   return (count == 1 ? runable : NULL);
 }
 
-/* Find a single core_stratum target in the list of targets and return it.
-   If for some reason there is more than one, return NULL.  */
-
-struct target_ops *
-find_core_target (void)
-{
-  struct target_ops **t;
-  struct target_ops *runable = NULL;
-  int count;
-
-  count = 0;
-
-  for (t = target_structs; t < target_structs + target_struct_size;
-       ++t)
-    {
-      if ((*t)->to_stratum == core_stratum)
-	{
-	  runable = *t;
-	  ++count;
-	}
-    }
-
-  return (count == 1 ? runable : NULL);
-}
-
 /*
  * Find the next target down the stack from the specified target.
  */
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -65,8 +65,7 @@ enum strata
   {
     dummy_stratum,		/* The lowest of the low */
     file_stratum,		/* Executable files, etc */
-    core_stratum,		/* Core dump files */
-    process_stratum,		/* Executing processes */
+    process_stratum,		/* Executing processes or core dump files */
     thread_stratum,		/* Executing threads */
     record_stratum,		/* Support record debugging */
     arch_stratum		/* Architecture overrides */
@@ -1496,8 +1495,6 @@ extern void find_default_create_inferior (struct target_ops *,
 
 extern struct target_ops *find_run_target (void);
 
-extern struct target_ops *find_core_target (void);
-
 extern struct target_ops *find_target_beneath (struct target_ops *);
 
 /* Read OS data object of type TYPE from the target, and return it in
--- a/gdb/tracepoint.c
+++ b/gdb/tracepoint.c
@@ -4050,8 +4050,6 @@ init_tfile_ops (void)
   tfile_ops.to_get_trace_status = tfile_get_trace_status;
   tfile_ops.to_trace_find = tfile_trace_find;
   tfile_ops.to_get_trace_state_variable_value = tfile_get_trace_state_variable_value;
-  /* core_stratum might seem more logical, but GDB doesn't like having
-     more than one core_stratum vector.  */
   tfile_ops.to_stratum = process_stratum;
   tfile_ops.to_has_all_memory = tfile_has_all_memory;
   tfile_ops.to_has_memory = tfile_has_memory;
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -15024,33 +15024,21 @@ and @code{show architecture}.
 @cindex active targets
 @cindex multiple targets
 
-There are three classes of targets: processes, core files, and
-executable files.  @value{GDBN} can work concurrently on up to three
-active targets, one in each class.  This allows you to (for example)
-start a process and inspect its activity without abandoning your work on
-a core file.
-
-For example, if you execute @samp{gdb a.out}, then the executable file
-@code{a.out} is the only active target.  If you designate a core file as
-well---presumably from a prior run that crashed and coredumped---then
-@value{GDBN} has two active targets and uses them in tandem, looking
-first in the corefile target, then in the executable file, to satisfy
-requests for memory addresses.  (Typically, these two classes of target
-are complementary, since core files contain only a program's
-read-write memory---variables and so on---plus machine status, while
-executable files contain only the program text and initialized data.)
-
-When you type @code{run}, your executable file becomes an active process
-target as well.  When a process target is active, all @value{GDBN}
-commands requesting memory addresses refer to that target; addresses in
-an active core file or executable file target are obscured while the
-process target is active.
-
-Use the @code{core-file} and @code{exec-file} commands to select a new
-core file or executable target (@pxref{Files, ,Commands to Specify
-Files}).  To specify as a target a process that is already running, use
-the @code{attach} command (@pxref{Attach, ,Debugging an Already-running
-Process}).
+There are multiple classes of targets such as: processes, executable files or
+recording sessions.  Core files belong to the process class, there can be
+active only one of a core or a running process.  Otherwise @value{GDBN} can
+work concurrently on multiple active targets, one in each class.  This allows
+you to (for example) start a process and inspect its activity while still
+having access to the executable file after the process finishes.  Or if you
+start process recording (@pxref{Reverse Execution}) and @code{reverse-step}
+there you are presented a virtual layer of the recording target while the
+process target remains stopped at the chronologically last point of the process
+execution.
+
+Use the @code{core-file} and @code{exec-file} commands to select a new core
+file or executable target (@pxref{Files, ,Commands to Specify Files}).  To
+specify as a target a process that is already running, use the @code{attach}
+command (@pxref{Attach, ,Debugging an Already-running Process}).
 
 @node Target Commands
 @section Commands for Managing Targets
--- a/gdb/testsuite/gdb.base/corefile.exp
+++ b/gdb/testsuite/gdb.base/corefile.exp
@@ -180,3 +180,62 @@ gdb_load ${binfile}
 gdb_test "up" "#\[0-9\]* *\[0-9xa-fH'\]* in .* \\(.*\\).*" "up in corefile.exp (reinit)"
 
 gdb_test "core" "No core file now."
+
+
+# Test a run (start) command will clear any loaded core file.
+
+gdb_test "core-file $corefile" "Core was generated by .*" "run: load core again"
+gdb_test "info files" "\r\nLocal core dump file:\r\n.*" "run: sanity check we see the core file"
+
+set test "run: with core"
+if [runto_main] {
+    pass $test
+} else {
+    fail $test
+}
+
+set test "run: core file is cleared"
+gdb_test_multiple "info files" $test {
+    "\r\nLocal core dump file:\r\n.*\r\n$gdb_prompt $" {
+	fail $test
+    }
+    "\r\n$gdb_prompt $" {
+	pass $test
+    }
+}
+
+gdb_exit
+
+
+# Test an attach command will clear any loaded core file.
+
+if ![is_remote target] {
+    set test "attach: spawn sleep"
+    set res [remote_spawn host "$binfile sleep"];
+    if { $res < 0 || $res == "" } {
+	perror "$test failed."
+	fail $test
+	return
+    }
+    set pid [exp_pid -i $res]
+    # We do not care of the startup phase where it will be caught.
+
+    gdb_start
+
+    gdb_test "core-file $corefile" "Core was generated by .*" "attach: load core again"
+    gdb_test "info files" "\r\nLocal core dump file:\r\n.*" "attach: sanity check we see the core file"
+
+    gdb_test "attach $pid" "Attaching to process $pid\r\n.*" "attach: with core"
+
+    set test "attach: core file is cleared"
+    gdb_test_multiple "info files" $test {
+	"\r\nLocal core dump file:\r\n.*\r\n$gdb_prompt $" {
+	    fail $test
+	}
+	"\r\n$gdb_prompt $" {
+	    pass $test
+	}
+    }
+
+    gdb_exit
+}
--- a/gdb/testsuite/gdb.base/coremaker.c
+++ b/gdb/testsuite/gdb.base/coremaker.c
@@ -133,8 +133,14 @@ func1 ()
   func2 ();
 }
 
-int main ()
+int
+main (int argc, char **argv)
 {
+  if (argc == 2 && strcmp (argv[1], "sleep") == 0)
+    {
+      sleep (60);
+      return 0;
+    }
   mmapdata ();
   func1 ();
   return 0;