Workarounds for GDB MI’s issues
Workaround for inaccuracy while adding a multiple location breakpoint bug.
This bug makes an incorrect output when multiple breakpoints are in the same location: each breakpoint’s data is glued together in a non-conforming MI syntax.
This issue affects the result (synchronous), the asynchronous records and it even affects the results of a Breakpoint Table
=breakpoint-modified,bkpt={...
^done,bkpt={...
BreakpointTable={...
The proposed solution is to replace that by a simple list.
Notice how we also changed the expected keyword bkpt by bkpts:
>>> text = '=breakpoint-modified,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="<MULTIPLE>",times="1",original-location="roll"},{number="1.1",enabled="y",addr="0x08048563",func="roll",file="two_pthreads.c",fullname="/threads/two_pthreads.c",line="5",thread-groups=["i1"]},{number="1.2",enabled="y",addr="0x08048563",func="roll",file="two_pthreads.c",fullname="/threads/two_pthreads.c",line="5",thread-groups=["i2"]}\n'
>>> import pprint
>>> from gdb_mi import Output
>>> o = Output()
>>> record = o.parse_line(text)
>>> record.async_class, record.type
('breakpoints-modified', 'Notify')
>>> record
{'bkpts': [{'addr': '<MULTIPLE>',
'disp': 'keep',
'enabled': 'y',
'number': '1',
'original-location': 'roll',
'times': '1',
'type': 'breakpoint'},
{'addr': '0x08048563',
'enabled': 'y',
'file': 'two_pthreads.c',
'fullname': '/threads/two_pthreads.c',
'func': 'roll',
'line': '5',
'number': '1.1',
'thread-groups': ['i1']},
{'addr': '0x08048563',
'enabled': 'y',
'file': 'two_pthreads.c',
'fullname': '/threads/two_pthreads.c',
'func': 'roll',
'line': '5',
'number': '1.2',
'thread-groups': ['i2']}],
'class': 'breakpoints-modified',
'token': None,
'type': 'Notify'}
To make this behavior uniform we apply the same change even if there is only one breakpoint:
>>> text = '^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x08048564",func="main",file="myprog.c",fullname="/home/nickrob/myprog.c",line="68",thread-groups=["i1"],times="0"}\n'
>>> record = o.parse_line(text)
>>> record.result_class, record.type
('done', 'Result')
>>> record
{'bkpts': [{'addr': '0x08048564',
'disp': 'keep',
'enabled': 'y',
'file': 'myprog.c',
'fullname': '/home/nickrob/myprog.c',
'func': 'main',
'line': '68',
'number': '1',
'thread-groups': ['i1'],
'times': '0',
'type': 'breakpoint'}],
'class': 'done',
'token': None,
'type': 'Result'}
Due the same bug, we need to modify the event BreakpointTable which lists
the breakpoints and if some of them are in the same address, this will
trigger the same bug.
Here is the fix:
>>> text = '^done,BreakpointTable={nr_rows="3",nr_cols="6",hdr=[{width="7",alignment="-1",col_name="number",colhdr="Num"},{width="14",alignment="-1",col_name="type",colhdr="Type"},{width="4",alignment="-1",col_name="disp",colhdr="Disp"},{width="3",alignment="-1",col_name="enabled",colhdr="Enb"},{width="18",alignment="-1",col_name="addr",colhdr="Address"},{width="40",alignment="2",col_name="what",colhdr="What"}],body=[bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="<MULTIPLE>",times="0",original-location="roll"},{number="1.1",enabled="y",addr="0x00000000004006a9",func="roll",file="three_pthreads.c",fullname="/threads/three_pthreads.c",line="5",thread-groups=["i1"]},{number="1.2",enabled="y",addr="0x00000000004006a9",func="roll",file="three_pthreads.c",fullname="/threads/three_pthreads.c",line="5",thread-groups=["i2"]},bkpt={number="2",type="breakpoint",disp="keep",enabled="y",addr="<MULTIPLE>",times="0",original-location="roll"},{number="2.1",enabled="y",addr="0x00000000004006a9",func="roll",file="three_pthreads.c",fullname="/threads/three_pthreads.c",line="5",thread-groups=["i1"]},{number="2.2",enabled="y",addr="0x00000000004006a9",func="roll",file="three_pthreads.c",fullname="/threads/three_pthreads.c",line="5",thread-groups=["i2"]},bkpt={number="3",type="breakpoint",disp="keep",enabled="y",addr="<MULTIPLE>",times="0",original-location="roll"},{number="3.1",enabled="y",addr="0x00000000004006a9",func="roll",file="three_pthreads.c",fullname="/threads/three_pthreads.c",line="5",thread-groups=["i1"]},{number="3.2",enabled="y",addr="0x00000000004006a9",func="roll",file="three_pthreads.c",fullname="/threads/three_pthreads.c",line="5",thread-groups=["i2"]}]}\n'
>>> record = o.parse_line(text)
>>> record # byexample: -tags
{'BreakpointTable': {'body': [{'addr': '<MULTIPLE>',
'disp': 'keep',
'enabled': 'y',
'number': '1',
'original-location': 'roll',
'times': '0',
'type': 'breakpoint'},
{'addr': '0x00000000004006a9',
'enabled': 'y',
'file': 'three_pthreads.c',
'fullname': '/threads/three_pthreads.c',
'func': 'roll',
'line': '5',
'number': '1.1',
'thread-groups': ['i1']},
{'addr': '0x00000000004006a9',
'enabled': 'y',
'file': 'three_pthreads.c',
'fullname': '/threads/three_pthreads.c',
'func': 'roll',
'line': '5',
'number': '1.2',
'thread-groups': ['i2']},
{'addr': '<MULTIPLE>',
'disp': 'keep',
'enabled': 'y',
'number': '2',
'original-location': 'roll',
'times': '0',
'type': 'breakpoint'},
{'addr': '0x00000000004006a9',
'enabled': 'y',
'file': 'three_pthreads.c',
'fullname': '/threads/three_pthreads.c',
'func': 'roll',
'line': '5',
'number': '2.1',
'thread-groups': ['i1']},
{'addr': '0x00000000004006a9',
'enabled': 'y',
'file': 'three_pthreads.c',
'fullname': '/threads/three_pthreads.c',
'func': 'roll',
'line': '5',
'number': '2.2',
'thread-groups': ['i2']},
{'addr': '<MULTIPLE>',
'disp': 'keep',
'enabled': 'y',
'number': '3',
'original-location': 'roll',
'times': '0',
'type': 'breakpoint'},
{'addr': '0x00000000004006a9',
'enabled': 'y',
'file': 'three_pthreads.c',
'fullname': '/threads/three_pthreads.c',
'func': 'roll',
'line': '5',
'number': '3.1',
'thread-groups': ['i1']},
{'addr': '0x00000000004006a9',
'enabled': 'y',
'file': 'three_pthreads.c',
'fullname': '/threads/three_pthreads.c',
'func': 'roll',
'line': '5',
'number': '3.2',
'thread-groups': ['i2']}],
'hdr': [{'alignment': '-1',
'col_name': 'number',
'colhdr': 'Num',
'width': '7'},
{'alignment': '-1',
'col_name': 'type',
'colhdr': 'Type',
'width': '14'},
{'alignment': '-1',
'col_name': 'disp',
'colhdr': 'Disp',
'width': '4'},
{'alignment': '-1',
'col_name': 'enabled',
'colhdr': 'Enb',
'width': '3'},
{'alignment': '-1',
'col_name': 'addr',
'colhdr': 'Address',
'width': '18'},
{'alignment': '2',
'col_name': 'what',
'colhdr': 'What',
'width': '40'}],
'nr_cols': '6',
'nr_rows': '3'},
'class': 'done',
'token': None,
'type': 'Result'}