[binutils-gdb] gdb: error if 'thread' or 'task' keywords are overused

[binutils-gdb] gdb: error if 'thread' or 'task' keywords are overused

[Andrew Burgess]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=980dbf36225150bf2558e5eda5f8c374adfe1323

commit 980dbf36225150bf2558e5eda5f8c374adfe1323
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Wed Nov 9 12:54:55 2022 +0000

    gdb: error if 'thread' or 'task' keywords are overused
    
    When creating a breakpoint or watchpoint, the 'thread' and 'task'
    keywords can be used to create a thread or task specific breakpoint or
    watchpoint.
    
    Currently, a thread or task specific breakpoint can only apply for a
    single thread or task, if multiple threads or tasks are specified when
    creating the breakpoint (or watchpoint), then the last specified id
    will be used.
    
    The exception to the above is that when the 'thread' keyword is used
    during the creation of a watchpoint, GDB will give an error if
    'thread' is given more than once.
    
    In this commit I propose making this behaviour consistent, if the
    'thread' or 'task' keywords are used more than once when creating
    either a breakpoint or watchpoint, then GDB will give an error.
    
    I haven't updated the manual, we don't explicitly say that these
    keywords can be repeated, and (to me), given the keyword takes a
    single id, I don't think it makes much sense to repeat the keyword.
    As such, I see this more as adding a missing error to GDB, rather than
    making some big change.  However, I have added an entry to the NEWS
    file as I guess it is possible that some people might hit this new
    error with an existing (I claim, badly written) GDB script.
    
    I've added some new tests to check for the new error.
    
    Just one test needed updating, gdb.linespec/keywords.exp, this test
    did use the 'thread' keyword twice, and expected the breakpoint to be
    created.  Looking at what this test was for though, it was checking
    the use of '-force-condition', and I don't think that being able to
    repeat 'thread' was actually a critical part of this test.
    
    As such, I've updated this test to expect the error when 'thread' is
    repeated.

Diff:
---
 gdb/NEWS                                         | 14 ++++++++++++++
 gdb/breakpoint.c                                 |  9 +++++++++
 gdb/testsuite/gdb.ada/tasks.exp                  |  4 ++++
 gdb/testsuite/gdb.linespec/keywords.exp          | 10 ++++++++--
 gdb/testsuite/gdb.threads/thread-specific-bp.exp |  4 ++++
 gdb/testsuite/gdb.threads/watchthreads2.exp      |  3 +++
 6 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 882ea4cda36..1567cbea9bd 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -30,6 +30,20 @@
   This support requires that GDB be built with Python scripting
   enabled.
 
+* For the break command, multiple uses of the 'thread' or 'task'
+  keywords will now give an error instead of just using the thread or
+  task id from the last instance of the keyword.  E.g.:
+    break foo thread 1 thread 2
+  will now give an error rather than using 'thread 2'.
+
+* For the watch command, multiple uses of the 'task' keyword will now
+  give an error instead of just using the task id from the last
+  instance of the keyword.  E.g.:
+    watch my_var task 1 task 2
+  will now give an error rather than using 'task 2'.  The 'thread'
+  keyword already gave an error when used multiple times with the
+  watch command, this remains unchanged.
+
 * New commands
 
 maintenance print record-instruction [ N ]
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index e25c5889ec4..8bc62743bb5 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -8797,6 +8797,9 @@ find_condition_and_thread (const char *tok, CORE_ADDR pc,
 	  const char *tmptok;
 	  struct thread_info *thr;
 
+	  if (*thread != -1)
+	    error(_("You can specify only one thread."));
+
 	  tok = end_tok + 1;
 	  thr = parse_thread_id (tok, &tmptok);
 	  if (tok == tmptok)
@@ -8808,6 +8811,9 @@ find_condition_and_thread (const char *tok, CORE_ADDR pc,
 	{
 	  char *tmptok;
 
+	  if (*task != 0)
+	    error(_("You can specify only one task."));
+
 	  tok = end_tok + 1;
 	  *task = strtol (tok, &tmptok, 0);
 	  if (tok == tmptok)
@@ -10090,6 +10096,9 @@ watch_command_1 (const char *arg, int accessflag, int from_tty,
 	    {
 	      char *tmp;
 
+	      if (task != 0)
+		error(_("You can specify only one task."));
+
 	      task = strtol (value_start, &tmp, 0);
 	      if (tmp == value_start)
 		error (_("Junk after task keyword."));
diff --git a/gdb/testsuite/gdb.ada/tasks.exp b/gdb/testsuite/gdb.ada/tasks.exp
index a9b58f20cf6..3eea04b3911 100644
--- a/gdb/testsuite/gdb.ada/tasks.exp
+++ b/gdb/testsuite/gdb.ada/tasks.exp
@@ -39,6 +39,10 @@ gdb_test "info tasks" \
                "\r\n"] \
          "info tasks before inserting breakpoint"
 
+# Check that multiple uses of the 'task' keyword will give an error.
+gdb_test "break break_me task 1 task 3" "You can specify only one task\\."
+gdb_test "watch j task 1 task 3" "You can specify only one task\\."
+
 # Insert a breakpoint that should stop only if task 1 stops.  Since
 # task 1 never calls break_me, this shouldn't actually ever trigger.
 # The fact that this breakpoint is created _before_ the next one
diff --git a/gdb/testsuite/gdb.linespec/keywords.exp b/gdb/testsuite/gdb.linespec/keywords.exp
index bff64249542..dc66e32237c 100644
--- a/gdb/testsuite/gdb.linespec/keywords.exp
+++ b/gdb/testsuite/gdb.linespec/keywords.exp
@@ -80,8 +80,14 @@ foreach prefix {"" "thread 1 "} {
     foreach suffix {"" " " " thread 1"} {
 	foreach cond {"" " if 1"} {
 	    with_test_prefix "prefix: '$prefix', suffix: '$suffix', cond: '$cond'" {
-		gdb_breakpoint "main ${prefix}-force-condition${suffix}${cond}"\
-		    "message"
+
+		if { [regexp thread $prefix] && [regexp thread $suffix] } {
+		    gdb_test "break main ${prefix}-force-condition${suffix}${cond}" \
+			"You can specify only one thread\\."
+		} else {
+		    gdb_breakpoint "main ${prefix}-force-condition${suffix}${cond}"\
+			"message"
+		}
 	    }
 	}
     }
diff --git a/gdb/testsuite/gdb.threads/thread-specific-bp.exp b/gdb/testsuite/gdb.threads/thread-specific-bp.exp
index f440574d780..cecf946f5c4 100644
--- a/gdb/testsuite/gdb.threads/thread-specific-bp.exp
+++ b/gdb/testsuite/gdb.threads/thread-specific-bp.exp
@@ -63,6 +63,10 @@ proc check_thread_specific_breakpoint {non_stop} {
 	return -1
     }
 
+    # Check that multiple uses of 'thread' keyword give an error.
+    gdb_test "break main thread $start_thre thread $main_thre" \
+	"You can specify only one thread\\."
+
     # Set a thread-specific breakpoint at "main".  This can't ever
     # be hit, but that's OK.
     gdb_breakpoint "main thread $start_thre"
diff --git a/gdb/testsuite/gdb.threads/watchthreads2.exp b/gdb/testsuite/gdb.threads/watchthreads2.exp
index 09858aee486..a1398d668a4 100644
--- a/gdb/testsuite/gdb.threads/watchthreads2.exp
+++ b/gdb/testsuite/gdb.threads/watchthreads2.exp
@@ -71,6 +71,9 @@ if { $nr_started == $NR_THREADS } {
     return -1
 }
 
+# Check that multiple uses of the 'thread' keyword will give an error.
+gdb_test "watch x thread 1 thread 2" "You can specify only one thread\\."
+
 # Watch X, it will be modified by all threads.
 # We want this watchpoint to be set *after* all threads are running.
 gdb_test "watch x" "Hardware watchpoint 3: x"