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pytime.c:184 and pytime.c:218: runtime error, outside the range of representable values of type 'long' #65140

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pytime.c:184 and pytime.c:218: runtime error, outside the range of representable values of type 'long'#65140
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testsTests in the Lib/test dir

Description

@JeffreyWalton
JeffreyWalton
mannequin
opened on Mar 15, 2014
BPO 20941
Nosy @vstinner, @gareth-rees, @vadmium
Superseder
  • bpo-31373: demoting floating float values to unrepresentable types is undefined behavior
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
closed_at = <Date 2018-05-22.13:33:25.714>
created_at = <Date 2014-03-15.21:48:45.694>
labels = ['tests']
title = "pytime.c:184 and pytime.c:218: runtime error, outside the range of representable values of type 'long'"
updated_at = <Date 2018-05-22.13:33:25.713>
user = 'https://bugs.python.org/JeffreyWalton'

    bugs.python.org fields:

    activity = <Date 2018-05-22.13:33:25.713>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2018-05-22.13:33:25.714>
closer = 'vstinner'
components = ['Tests']
creation = <Date 2014-03-15.21:48:45.694>
creator = 'Jeffrey.Walton'
dependencies = []
files = []
hgrepos = ['223']
issue_num = 20941
keywords = []
message_count = 8.0
messages = ['213686', '213756', '213760', '213910', '317089', '317090', '317091', '317278']
nosy_count = 4.0
nosy_names = ['vstinner', 'gdr@garethrees.org', 'martin.panter', 'Jeffrey.Walton']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '31373'
type = None
url = 'https://bugs.python.org/issue20941'
versions = ['Python 3.5']

    Activity

    1. JeffreyWalton commented on Mar 15, 2014

      @JeffreyWalton
      JeffreyWaltonmannequin
      on Mar 15, 2014
      MannequinAuthor

      pytime.c:184: runtime error: value -1e+200 is outside the range of representable values of type 'long'

      and

      pytime.c:218: runtime error: value -1e+200 is outside the range of representable values of type 'long'

      It appears the cast on 'intpart' is generating the finding. 'intpart' is a double.

          *sec = (time_t)intpart;
    err = intpart - (double)*sec;
    if (err <= -1.0 || err >= 1.0) {
        error_time_t_overflow();
        return -1;
    }

      Shouldn't a range test based on TIME_T_MAX with an epsilon occur first?

    2. JeffreyWalton
      added
      testsTests in the Lib/test dir
      on Mar 15, 2014

    3. vstinner commented on Mar 16, 2014

      @vstinner
      vstinner
      on Mar 16, 2014
      Member

      Hi,

      pytime.c:184: runtime error: value -1e+200 is outside the range of representable values of type 'long'

      How did you get this warning?

      Shouldn't a range test based on TIME_T_MAX with an epsilon occur first?

      Two lines after, the integer overflow is checked:

              *sec = (time_t)intpart;
        err = intpart - (double)*sec;
        if (err <= -1.0 || err >= 1.0) {
            error_time_t_overflow();
            return -1;
        }

      And it works, example:

      >>> import _testcapi
>>> _testcapi.pytime_object_to_time_t(-1e+200, 0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: timestamp out of range for platform time_t

      (where 0 means _PyTime_ROUND_DOWN)

    4. gareth-rees commented on Mar 16, 2014

      @gareth-rees
      gareth-reesmannequin
      on Mar 16, 2014
      Mannequin

      How did you get this warning?

      This looks like runtime output from a program built using Clang/LLVM with -fsanitize=undefined. See here: http://clang.llvm.org/docs/UsersManual.html#controlling-code-generation

      Signed integer overflow is undefined behaviour, so by the time *sec = (time_t)intpart has been evaluated, the undefined behaviour has already happened. It is too late to check for it afterwards.

    5. vstinner commented on Mar 17, 2014

      @vstinner
      vstinner
      on Mar 17, 2014
      Member

      Shouldn't a range test based on TIME_T_MAX with an epsilon occur first?

      What is this constant? I don't see it in Python source code.

    6. vadmium commented on May 19, 2018

      @vadmium
      vadmium
      on May 19, 2018
      Member

      Maybe worth checking if this is fixed due to the changes in bpo-31373 for 3.6+.

    7. vstinner commented on May 19, 2018

      @vstinner
      vstinner
      on May 19, 2018
      Member

      "resolution: out of date"

      Is this issue fixed or not? It's still open.

    8. vadmium commented on May 19, 2018

      @vadmium
      vadmium
      on May 19, 2018
      Member

      I don’t know; I haven’t tested it. I was anticipating that it is fixed, but perhaps I should leave the resolution alone instead?

    9. vstinner commented on May 22, 2018

      @vstinner
      vstinner
      on May 22, 2018
      Member

      I close the issue as a duplicate of bpo-31373. Reopen/comment bpo-31373 if the issue is not completely fixed.

    10. vstinner
      closed this as completedon May 22, 2018
    11. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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