[RFA v2 7/8] Allow breakpoint commands to be set from Python

Tom Tromey
2018-04-25T15:41:44Z

This changes the Python API so that breakpoint commands can be set by
writing to the "commands" attribute.

gdb/ChangeLog
2018-04-25 Tom Tromey <tom@tromey.com>

PR python/22731:
* NEWS: Mention that breakpoint commands are writable.
* python/py-breakpoint.c (bppy_set_commands): New function.
(breakpoint_object_getset) <"commands">: Use it.

gdb/doc/ChangeLog
2018-04-25 Tom Tromey <tom@tromey.com>

PR python/22731:
* python.texi (Breakpoints In Python): Mention that "commands" is
writable.

gdb/testsuite/ChangeLog
2018-04-25 Tom Tromey <tom@tromey.com>

PR python/22731:
* gdb.python/py-breakpoint.exp: Test setting breakpoint commands.
---
gdb/ChangeLog | 7 +++++
gdb/NEWS | 5 ++++
gdb/doc/ChangeLog | 6 ++++
gdb/doc/python.texi | 2 +-
gdb/python/py-breakpoint.c | 45 +++++++++++++++++++++++++++++-
gdb/testsuite/ChangeLog | 5 ++++
gdb/testsuite/gdb.python/py-breakpoint.exp | 10 ++++++-
7 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/gdb/NEWS b/gdb/NEWS
index 63fe30d175..14d5fbb7c0 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -24,6 +24,11 @@ set|show record btrace cpu
Controls the processor to be used for enabling errata workarounds for
branch trace decode.

+* Python Scripting
+
+ ** The commands attached to a breakpoint can be set by assigning to
+ the breakpoint's "commands" field.
+
* New targets

RiscV ELF riscv*-*-elf
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index ebd48fffe7..a2b948a4ca 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -5116,7 +5116,7 @@ value is @code{None}. This attribute is writable.
This attribute holds the commands attached to the breakpoint. If
there are commands, this attribute's value is a string holding all the
commands, separated by newlines. If there are no commands, this
-attribute is @code{None}. This attribute is not writable.
+attribute is @code{None}. This attribute is writable.
@end defvar

@node Finish Breakpoints in Python
diff --git a/gdb/python/py-breakpoint.c b/gdb/python/py-breakpoint.c
index d654b92a8c..a66e553cf8 100644
--- a/gdb/python/py-breakpoint.c
+++ b/gdb/python/py-breakpoint.c
@@ -510,6 +510,49 @@ bppy_get_commands (PyObject *self, void *closure)
return host_string_to_python_string (stb.c_str ());
}

+/* Set the commands attached to a breakpoint. Returns 0 on success.
+ Returns -1 on error, with a python exception set. */
+static int
+bppy_set_commands (PyObject *self, PyObject *newvalue, void *closure)
+{
+ gdbpy_breakpoint_object *self_bp = (gdbpy_breakpoint_object *) self;
+ struct breakpoint *bp = self_bp->bp;
+ struct gdb_exception except = exception_none;
+
+ BPPY_SET_REQUIRE_VALID (self_bp);
+
+ gdb::unique_xmalloc_ptr<char> commands
+ (python_string_to_host_string (newvalue));
+ if (commands == nullptr)
+ return -1;
+
+ TRY
+ {
+ bool first = true;
+ char *save_ptr = nullptr;
+ auto reader
+ = [&] ()
+ {
+ const char *result = strtok_r (first ? commands.get () : nullptr,
+ "\n", &save_ptr);
+ first = false;
+ return result;
+ };
+
+ counted_command_line lines = read_command_lines_1 (reader, 1, nullptr);
+ breakpoint_set_commands (self_bp->bp, std::move (lines));
+ }
+ CATCH (ex, RETURN_MASK_ALL)
+ {
+ except = ex;
+ }
+ END_CATCH
+
+ GDB_PY_SET_HANDLE_EXCEPTION (except);
+
+ return 0;
+}
+
/* Python function to get the breakpoint type. */
static PyObject *
bppy_get_type (PyObject *self, void *closure)
@@ -1185,7 +1228,7 @@ when setting this property.", NULL },
{ "condition", bppy_get_condition, bppy_set_condition,
"Condition of the breakpoint, as specified by the user,\
or None if no condition set."},
- { "commands", bppy_get_commands, NULL,
+ { "commands", bppy_get_commands, bppy_set_commands,
"Commands of the breakpoint, as specified by the user."},
{ "type", bppy_get_type, NULL,
"Type of breakpoint."},
diff --git a/gdb/testsuite/gdb.python/py-breakpoint.exp b/gdb/testsuite/gdb.python/py-breakpoint.exp
index 6e0ff88f87..3ce0ea11de 100644
--- a/gdb/testsuite/gdb.python/py-breakpoint.exp
+++ b/gdb/testsuite/gdb.python/py-breakpoint.exp
@@ -197,8 +197,16 @@ proc_with_prefix test_bkpt_cond_and_cmds { } {

gdb_py_test_silent_cmd "python blist = gdb.breakpoints()" \
"Get Breakpoint List" 0
- gdb_test "python print (blist\[len(blist)-1\].commands)" \
+ gdb_py_test_silent_cmd "python last_bp = blist\[len(blist)-1\]" \
+ "Find last breakpoint" 0
+ gdb_test "python print (last_bp.commands)" \
"print \"Command for breakpoint has been executed.\".*print result"
+
+ gdb_test_no_output "python last_bp.commands = 'echo hi\\necho there'" \
+ "set commands"
+ # Note the length is 3 because the string ends in a \n.
+ gdb_test "python print (len(last_bp.commands.split('\\n')))" "3" \
+ "check number of lines in commands"
}

proc_with_prefix test_bkpt_invisible { } {
--
2.13.6