binutils-gdb/gdb/testsuite/gdb.python/py-completion.py

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# Copyright (C) 2014-2018 Free Software Foundation, Inc.
PR python/16699: GDB Python command completion with overriden complete vs. completer class This PR came from a Red Hat bug that was filed recently. I checked and it still exists on HEAD, so here's a proposed fix. Although this is marked as a Python backend bug, this is really about the completion mechanism used by GDB. Since this code reminds me of my first attempt to make a good noodle, it took me quite some time to fix it in a non-intrusive way. The problem is triggered when one registers a completion method inside a class in a Python script, rather than registering the command using a completer class directly. For example, consider the following script: class MyFirstCommand(gdb.Command): def __init__(self): gdb.Command.__init__(self,'myfirstcommand',gdb.COMMAND_USER,gdb.COMPLETE_FILENAME) def invoke(self,argument,from_tty): raise gdb.GdbError('not implemented') class MySecondCommand(gdb.Command): def __init__(self): gdb.Command.__init__(self,'mysecondcommand',gdb.COMMAND_USER) def invoke(self,argument,from_tty): raise gdb.GdbError('not implemented') def complete(self,text,word): return gdb.COMPLETE_FILENAME MyFirstCommand () MySecondCommand () When one loads this into GDB and tries to complete filenames for both myfirstcommand and mysecondcommand, she gets: (gdb) myfirstcommand /hom<TAB> (gdb) myfirstcommand /home/ ^ ... (gdb) mysecondcommand /hom<TAB> (gdb) mysecondcommand /home ^ (The "^" marks the final position of the cursor after the TAB). So we see that myfirstcommand honors the COMPLETE_FILENAME class (as specified in the command creation), but mysecondcommand does not. After some investigation, I found that the problem lies with the set of word break characters that is used for each case. The set should be the same for both commands, but it is not. During the process of deciding which type of completion should be used, the code in gdb/completer.c:complete_line_internal analyses the command that requested the completion and tries to determine the type of completion wanted by checking which completion function will be called (e.g., filename_completer for filenames, location_completer for locations, etc.). This all works fine for myfirstcommand, because immediately after the command registration the Python backend already sets its completion function to filename_completer (which then causes the complete_line_internal function to choose the right set of word break chars). However, for mysecondcommand, this decision is postponed to when the completer function is evaluated, and the Python backend uses an internal completer (called cmdpy_completer). complete_line_internal doesn't know about this internal completer, and can't choose the right set of word break chars in time, which then leads to a bad decision when completing the "/hom" word. So, after a few attempts, I decided to create another callback in "struct cmd_list_element" that will be responsible for handling the case when there is an unknown completer function for complete_line_internal to work with. So far, only the Python backend uses this callback, and only when the user provides a completer method instead of registering the command directly with a completer class. I think this is the best option because it not very intrusive (all the other commands will still work normally), but especially because the whole completion code is so messy that it would be hard to fix this without having to redesign things. I have regtested this on Fedora 18 x86_64, without regressions. I also included a testcase. gdb/ChangeLog: 2014-09-03 Sergio Durigan Junior <sergiodj@redhat.com> PR python/16699 * cli/cli-decode.c (set_cmd_completer_handle_brkchars): New function. (add_cmd): Set "completer_handle_brkchars" to NULL. * cli/cli-decode.h (struct cmd_list_element) <completer_handle_brkchars>: New field. * command.h (completer_ftype_void): New typedef. (set_cmd_completer_handle_brkchars): New prototype. * completer.c (set_gdb_completion_word_break_characters): New function. (complete_line_internal): Call "completer_handle_brkchars" callback from command. * completer.h: Include "command.h". (set_gdb_completion_word_break_characters): New prototype. * python/py-cmd.c (cmdpy_completer_helper): New function. (cmdpy_completer_handle_brkchars): New function. (cmdpy_completer): Adjust to use cmdpy_completer_helper. (cmdpy_init): Set completer_handle_brkchars to cmdpy_completer_handle_brkchars. gdb/testsuite/ChangeLog: 2014-09-03 Sergio Durigan Junior <sergiodj@redhat.com> PR python/16699 * gdb.python/py-completion.exp: New file. * gdb.python/py-completion.py: Likewise.
2014-09-03 22:30:28 +02:00
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
# This testcase tests PR python/16699
import gdb
class CompleteFileInit(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completefileinit',gdb.COMMAND_USER,gdb.COMPLETE_FILENAME)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
class CompleteFileMethod(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completefilemethod',gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return gdb.COMPLETE_FILENAME
class CompleteFileCommandCond(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completefilecommandcond',gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
# This is a test made to know if the command
# completion still works fine. When the user asks to
# complete something like "completefilecommandcond
# /path/to/py-completion-t", it should not complete to
# "/path/to/py-completion-test/", but instead just
# wait for input.
if "py-completion-t" in text:
return gdb.COMPLETE_COMMAND
else:
return gdb.COMPLETE_FILENAME
Fix Python completion when using the "complete" command This patch is related to PR python/16699, and is an improvement over the patch posted here: <https://sourceware.org/ml/gdb-patches/2014-03/msg00301.html> Keith noticed that, when using the "complete" command on GDB to complete a Python command, some strange things could happen. In order to understand what can go wrong, I need to explain how the Python completion mechanism works. When the user requests a completion of a Python command by using TAB, GDB will first try to determine the right set of "brkchars" that will be used when doing the completion. This is done by actually calling the "complete" method of the Python class. Then, when we already know the "brkchars" that will be used, we call the "complete" method again, for the same values. If you read the thread mentioned above, you will see that one of the design decisions was to make the "cmdpy_completer_helper" (which is the function the does the actual calling of the "complete" method) cache the first result of the completion, since this result will be used in the second call, to do the actual completion. The problem is that the "complete" command does not process the brkchars, and the current Python completion mechanism (improved by the patch mentioned above) relies on GDB trying to determine the brkchars, and then doing the completion itself. Therefore, when we use the "complete" command instead of doing a TAB-completion on GDB, there is a scenario where we can use the invalid cache of a previous Python command that was completed before. For example: (gdb) A <TAB> (gdb) complete B B value1 B value10 B value2 B value3 B value4 B value5 B value6 B value7 B value8 B value9 (gdb) B <TAB> comp1 comp2 comp4 comp6 comp8 comp10 comp3 comp5 comp7 comp9 Here, we see that "complete B " gave a different result than "B <TAB>". The reason for that is because "A <TAB>" was called before, and its completion results were "value*", so when GDB tried to "complete B " it wrongly answered with the results for A. The problem here is using a wrong cache (A's cache) for completing B. We tried to come up with a solution that would preserve the caching mechanism, but it wasn't really possible. So I decided to completely remove the cache, and doing the method calling twice for every completion. This is not optimal, but I do not think it will impact users noticeably. It is worth mentioning another small issue that I found. The code was doing: wordobj = PyUnicode_Decode (word, sizeof (word), host_charset (), NULL); which is totally wrong, because using "sizeof" here will lead to always the same result. So I changed this to use "strlen". The testcase also catches this problem. Keith kindly expanded the existing testcase to cover the problem described above, and everything is passing. gdb/ChangeLog: 2015-04-08 Sergio Durigan Junior <sergiodj@redhat.com> PR python/16699 * python/py-cmd.c (cmdpy_completer_helper): Adjust function to not use a caching mechanism. Adjust comments and code to reflect that. Replace 'sizeof' by 'strlen' when fetching 'wordobj'. (cmdpy_completer_handle_brkchars): Adjust call to cmdpy_completer_helper. Call Py_XDECREF for 'resultobj'. (cmdpy_completer): Likewise. gdb/testsuite/ChangeLog: 2015-04-08 Keith Seitz <keiths@redhat.com> PR python/16699 * gdb.python/py-completion.exp: New tests for completion. * gdb.python/py-completion.py (CompleteLimit1): New class. (CompleteLimit2): Likewise. (CompleteLimit3): Likewise. (CompleteLimit4): Likewise. (CompleteLimit5): Likewise. (CompleteLimit6): Likewise. (CompleteLimit7): Likewise.
2015-04-09 00:27:10 +02:00
class CompleteLimit1(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completelimit1',gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return ["cl11", "cl12", "cl13"]
class CompleteLimit2(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completelimit2',
gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return ["cl21", "cl23", "cl25", "cl27", "cl29",
"cl22", "cl24", "cl26", "cl28", "cl210"]
class CompleteLimit3(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completelimit3',
gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return ["cl31", "cl33", "cl35", "cl37", "cl39",
"cl32", "cl34", "cl36", "cl38", "cl310"]
class CompleteLimit4(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completelimit4',
gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return ["cl41", "cl43", "cl45", "cl47", "cl49",
"cl42", "cl44", "cl46", "cl48", "cl410"]
class CompleteLimit5(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completelimit5',
gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return ["cl51", "cl53", "cl55", "cl57", "cl59",
"cl52", "cl54", "cl56", "cl58", "cl510"]
class CompleteLimit6(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completelimit6',
gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return ["cl61", "cl63", "cl65", "cl67", "cl69",
"cl62", "cl64", "cl66", "cl68", "cl610"]
class CompleteLimit7(gdb.Command):
def __init__(self):
gdb.Command.__init__(self,'completelimit7',
gdb.COMMAND_USER)
def invoke(self,argument,from_tty):
raise gdb.GdbError('not implemented')
def complete(self,text,word):
return ["cl71", "cl73", "cl75", "cl77", "cl79",
"cl72", "cl74", "cl76", "cl78", "cl710"]
PR python/16699: GDB Python command completion with overriden complete vs. completer class This PR came from a Red Hat bug that was filed recently. I checked and it still exists on HEAD, so here's a proposed fix. Although this is marked as a Python backend bug, this is really about the completion mechanism used by GDB. Since this code reminds me of my first attempt to make a good noodle, it took me quite some time to fix it in a non-intrusive way. The problem is triggered when one registers a completion method inside a class in a Python script, rather than registering the command using a completer class directly. For example, consider the following script: class MyFirstCommand(gdb.Command): def __init__(self): gdb.Command.__init__(self,'myfirstcommand',gdb.COMMAND_USER,gdb.COMPLETE_FILENAME) def invoke(self,argument,from_tty): raise gdb.GdbError('not implemented') class MySecondCommand(gdb.Command): def __init__(self): gdb.Command.__init__(self,'mysecondcommand',gdb.COMMAND_USER) def invoke(self,argument,from_tty): raise gdb.GdbError('not implemented') def complete(self,text,word): return gdb.COMPLETE_FILENAME MyFirstCommand () MySecondCommand () When one loads this into GDB and tries to complete filenames for both myfirstcommand and mysecondcommand, she gets: (gdb) myfirstcommand /hom<TAB> (gdb) myfirstcommand /home/ ^ ... (gdb) mysecondcommand /hom<TAB> (gdb) mysecondcommand /home ^ (The "^" marks the final position of the cursor after the TAB). So we see that myfirstcommand honors the COMPLETE_FILENAME class (as specified in the command creation), but mysecondcommand does not. After some investigation, I found that the problem lies with the set of word break characters that is used for each case. The set should be the same for both commands, but it is not. During the process of deciding which type of completion should be used, the code in gdb/completer.c:complete_line_internal analyses the command that requested the completion and tries to determine the type of completion wanted by checking which completion function will be called (e.g., filename_completer for filenames, location_completer for locations, etc.). This all works fine for myfirstcommand, because immediately after the command registration the Python backend already sets its completion function to filename_completer (which then causes the complete_line_internal function to choose the right set of word break chars). However, for mysecondcommand, this decision is postponed to when the completer function is evaluated, and the Python backend uses an internal completer (called cmdpy_completer). complete_line_internal doesn't know about this internal completer, and can't choose the right set of word break chars in time, which then leads to a bad decision when completing the "/hom" word. So, after a few attempts, I decided to create another callback in "struct cmd_list_element" that will be responsible for handling the case when there is an unknown completer function for complete_line_internal to work with. So far, only the Python backend uses this callback, and only when the user provides a completer method instead of registering the command directly with a completer class. I think this is the best option because it not very intrusive (all the other commands will still work normally), but especially because the whole completion code is so messy that it would be hard to fix this without having to redesign things. I have regtested this on Fedora 18 x86_64, without regressions. I also included a testcase. gdb/ChangeLog: 2014-09-03 Sergio Durigan Junior <sergiodj@redhat.com> PR python/16699 * cli/cli-decode.c (set_cmd_completer_handle_brkchars): New function. (add_cmd): Set "completer_handle_brkchars" to NULL. * cli/cli-decode.h (struct cmd_list_element) <completer_handle_brkchars>: New field. * command.h (completer_ftype_void): New typedef. (set_cmd_completer_handle_brkchars): New prototype. * completer.c (set_gdb_completion_word_break_characters): New function. (complete_line_internal): Call "completer_handle_brkchars" callback from command. * completer.h: Include "command.h". (set_gdb_completion_word_break_characters): New prototype. * python/py-cmd.c (cmdpy_completer_helper): New function. (cmdpy_completer_handle_brkchars): New function. (cmdpy_completer): Adjust to use cmdpy_completer_helper. (cmdpy_init): Set completer_handle_brkchars to cmdpy_completer_handle_brkchars. gdb/testsuite/ChangeLog: 2014-09-03 Sergio Durigan Junior <sergiodj@redhat.com> PR python/16699 * gdb.python/py-completion.exp: New file. * gdb.python/py-completion.py: Likewise.
2014-09-03 22:30:28 +02:00
CompleteFileInit()
CompleteFileMethod()
CompleteFileCommandCond()
Fix Python completion when using the "complete" command This patch is related to PR python/16699, and is an improvement over the patch posted here: <https://sourceware.org/ml/gdb-patches/2014-03/msg00301.html> Keith noticed that, when using the "complete" command on GDB to complete a Python command, some strange things could happen. In order to understand what can go wrong, I need to explain how the Python completion mechanism works. When the user requests a completion of a Python command by using TAB, GDB will first try to determine the right set of "brkchars" that will be used when doing the completion. This is done by actually calling the "complete" method of the Python class. Then, when we already know the "brkchars" that will be used, we call the "complete" method again, for the same values. If you read the thread mentioned above, you will see that one of the design decisions was to make the "cmdpy_completer_helper" (which is the function the does the actual calling of the "complete" method) cache the first result of the completion, since this result will be used in the second call, to do the actual completion. The problem is that the "complete" command does not process the brkchars, and the current Python completion mechanism (improved by the patch mentioned above) relies on GDB trying to determine the brkchars, and then doing the completion itself. Therefore, when we use the "complete" command instead of doing a TAB-completion on GDB, there is a scenario where we can use the invalid cache of a previous Python command that was completed before. For example: (gdb) A <TAB> (gdb) complete B B value1 B value10 B value2 B value3 B value4 B value5 B value6 B value7 B value8 B value9 (gdb) B <TAB> comp1 comp2 comp4 comp6 comp8 comp10 comp3 comp5 comp7 comp9 Here, we see that "complete B " gave a different result than "B <TAB>". The reason for that is because "A <TAB>" was called before, and its completion results were "value*", so when GDB tried to "complete B " it wrongly answered with the results for A. The problem here is using a wrong cache (A's cache) for completing B. We tried to come up with a solution that would preserve the caching mechanism, but it wasn't really possible. So I decided to completely remove the cache, and doing the method calling twice for every completion. This is not optimal, but I do not think it will impact users noticeably. It is worth mentioning another small issue that I found. The code was doing: wordobj = PyUnicode_Decode (word, sizeof (word), host_charset (), NULL); which is totally wrong, because using "sizeof" here will lead to always the same result. So I changed this to use "strlen". The testcase also catches this problem. Keith kindly expanded the existing testcase to cover the problem described above, and everything is passing. gdb/ChangeLog: 2015-04-08 Sergio Durigan Junior <sergiodj@redhat.com> PR python/16699 * python/py-cmd.c (cmdpy_completer_helper): Adjust function to not use a caching mechanism. Adjust comments and code to reflect that. Replace 'sizeof' by 'strlen' when fetching 'wordobj'. (cmdpy_completer_handle_brkchars): Adjust call to cmdpy_completer_helper. Call Py_XDECREF for 'resultobj'. (cmdpy_completer): Likewise. gdb/testsuite/ChangeLog: 2015-04-08 Keith Seitz <keiths@redhat.com> PR python/16699 * gdb.python/py-completion.exp: New tests for completion. * gdb.python/py-completion.py (CompleteLimit1): New class. (CompleteLimit2): Likewise. (CompleteLimit3): Likewise. (CompleteLimit4): Likewise. (CompleteLimit5): Likewise. (CompleteLimit6): Likewise. (CompleteLimit7): Likewise.
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CompleteLimit1()
CompleteLimit2()
CompleteLimit3()
CompleteLimit4()
CompleteLimit5()
CompleteLimit6()
CompleteLimit7()