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 --git a/gdb/NEWS b/gdb/NEWS
index 882ea4cda367eaf796a3c6c8aaadacef93655a51..1567cbea9bda4768a938f82a1e04927df7f2ad64 100644 (file)
--- 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 e25c5889ec4fb450d0b5331a79864e004ba7e517..8bc62743bb58620558b70ded12623bafdca310b7 100644 (file)
--- 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 a9b58f20cf60005d17240e56bc846a579944f13b..3eea04b39117cf53c098e7857e1245bad3ad5bf2 100644 (file)
--- 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 bff6424954252e748409151e0cb589677a4f97c4..dc66e32237cd1825025d21f90c565941f84a377b 100644 (file)
--- 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 f440574d780fea5b51e5d942afdc4d5ae8200ca7..cecf946f5c4988d97e9f9b8691d4bd56d8f36fea 100644 (file)
--- 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 09858aee486ba9bbe37b1a76754af2e8eb97c29e..a1398d668a4ca11364b1617faa078edb347b24a8 100644 (file)
--- 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"