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Re: recovering from std::bad_alloc in std::string reserve

From Lynn McGuire <lynnmcguire5@gmail.com>
Newsgroups comp.lang.c++
Subject Re: recovering from std::bad_alloc in std::string reserve
Date 2021-05-27 18:17 -0500
Organization A noiseless patient Spider
Message-ID <s8p9ak$gun$1@dont-email.me> (permalink)
References (3 earlier) <s8nbvd$5ah$1@dont-email.me> <s8oqn6$fbj$1@dont-email.me> <_CUrI.452334$ST2.205157@fx47.iad> <87sg27zu0i.fsf@nosuchdomain.example.com> <87o8cvzsux.fsf@nosuchdomain.example.com>

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On 5/27/2021 5:58 PM, Keith Thompson wrote:
> Keith Thompson <Keith.S.Thompson+u@gmail.com> writes:
>> scott@slp53.sl.home (Scott Lurndal) writes:
>>> Lynn McGuire <lynnmcguire5@gmail.com> writes:
>>>> On 5/27/2021 12:50 AM, Christian Gollwitzer wrote:
>>>>> Am 26.05.21 um 20:32 schrieb Lynn McGuire: - Alf
>>>>>>
>>>>>> I have already replaced the fell code with _ftelli64.
>>>>>>
>>>>>> //  get the size of the output file
>>>>>> fseek (pOutputFile, 0, SEEK_END);
>>>>>> __int64 outputFileLength = _ftelli64 (pOutputFile) + 42;  // give it
>>>>>> some slop
>>>>>> int outputFileLengthInt = (int) outputFileLength;
>>>>>
>>>>> ...and here you restrict it to 2GB again, or worse, retrieve a negative
>>>>> file size for sizes between 2GB and 4GB.
>>>>>
>>>>>
>>>>> To prepare for a 64bit move, you should replace all size variables with
>>>>> size_t for unsigned or ptrdiff_t for signed. That will correspond to a
>>>>> 32bit integer in 32 bit and a 64 bit integer in 64 bit.
>>>>>
>>>>>       Christian
>>>>
>>>> Done.  With checking against SIZE_MAX before casting the variable to size_t.
>>>
>>> Why?   size_t is guaranteed to hold the size of any object, which implies that
>>> it must be large enough to accomodate an object the size of the virtual address
>>> space.   Generally it's minimum size in bits is the same as long.
>>
>> That's likely to be true, but it's not absolutely guaranteed.
> 
> My apologies, I was wrong.
> 
>> size_t is intended to hold the size of any single object, but it may
>> not be able to hold the sum of sizes of all objects or the size of
>> the virtual address space.  An implementation might restrict the
>> size of any single object to something smaller than the size of
>> the entire virtual address space.  (Think segments.)
> 
> I believe this is still correct.
> 
>> Also, I haven't found anything in the standard that says you
>> can't at least try to create an object bigger than SIZE_MAX bytes.
>> calloc(SIZE_MAX, 2) attempts to allocate such an object, and I don't
>> see a requirement that it must fail.  If an implementation lets you
>> define a named object bigger than SIZE_MAX bytes, then presumably
>> applying sizeof to it would result in an overflow, and therefore
>> undefined behavior.
>>
>> Any reasonable implementation will simply make size_t big enough
>> to hold the size of any object it can create, but I don't see a
>> requirement for it.
> 
> The above is correct in C, but not in C++, which makes an additional
> guarantee that C doesn't.  C++17 21.2.4 [support.types.layout] says:
> 
>      The type size_t is an implementation-defined unsigned integer type
>      that is large enough to contain the size in bytes of any object
>      (8.3.3).

Except the actual size of a FILE * object in the filesystem.  Size_t can 
hold the size of the FILE * structure but if the actual file size is 
greater than 4 GB in a Win32 program, size_t will be wrong.

Now if the program is Win64, size_t can hold the actual size of any file 
in the filesystem.

#ifdef _WIN64
     typedef unsigned __int64 size_t;
     typedef __int64          ptrdiff_t;
     typedef __int64          intptr_t;
#else
     typedef unsigned int     size_t;
     typedef int              ptrdiff_t;
     typedef int              intptr_t;
#endif

Lynn

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recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-24 20:46 -0500
  Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-24 20:50 -0500
    Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-24 20:52 -0500
      Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-25 07:47 +0300
        Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-25 12:20 -0500
          Re: recovering from std::bad_alloc in std::string reserve Christian Gollwitzer <auriocus@gmx.de> - 2021-05-26 08:36 +0200
            Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-26 13:28 -0500
      Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-25 12:56 +0200
        Re: recovering from std::bad_alloc in std::string reserve scott@slp53.sl.home (Scott Lurndal) - 2021-05-25 14:55 +0000
          Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-25 18:42 +0300
            Re: recovering from std::bad_alloc in std::string reserve MrSpook_Ann1u@d0v_5eh1bqgd.com - 2021-05-25 16:10 +0000
              Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-25 18:23 +0200
              Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-25 19:57 +0300
                Re: recovering from std::bad_alloc in std::string reserve MrSpook_ddZgr4t4@okc9_pd48oig5.info - 2021-05-26 07:15 +0000
                Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-26 09:22 +0200
                Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-26 10:54 +0300
                Re: recovering from std::bad_alloc in std::string reserve MrSpook_dw5lvA4g@kak0_42x.edu - 2021-05-26 08:29 +0000
            Re: recovering from std::bad_alloc in std::string reserve Nikolaj Lazic <nlazicBEZ_OVOGA@mudrac.ffzg.hr> - 2021-05-25 16:21 +0000
              Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-25 20:04 +0300
                Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-25 12:46 -0500
                Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-25 20:58 +0300
                Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-25 13:48 -0500
                Re: recovering from std::bad_alloc in std::string reserve Nikolaj Lazic <nlazicBEZ_OVOGA@mudrac.ffzg.hr> - 2021-05-25 18:23 +0000
                Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-25 13:49 -0500
                Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-26 21:07 -0500
          Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-25 18:23 +0200
  Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-24 22:33 -0500
    Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-24 22:35 -0500
      Re: recovering from std::bad_alloc in std::string reserve Juha Nieminen <nospam@thanks.invalid> - 2021-05-25 05:16 +0000
        Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-25 13:00 +0200
        Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-25 12:49 -0500
  Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-27 14:08 -0500
    Re: recovering from std::bad_alloc in std::string reserve scott@slp53.sl.home (Scott Lurndal) - 2021-05-27 21:59 +0000
      Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-05-27 15:33 -0700
        Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-05-27 15:58 -0700
          Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-27 18:17 -0500
            Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-05-27 16:58 -0700
              Re: recovering from std::bad_alloc in std::string reserve Öö Tiib <ootiib@hot.ee> - 2021-05-27 18:36 -0700
                Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-27 21:38 -0500
                Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-28 08:53 +0300
                Re: recovering from std::bad_alloc in std::string reserve Bo Persson <bo@bo-persson.se> - 2021-05-28 09:47 +0200
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-05-27 19:54 -0700
                Re: recovering from std::bad_alloc in std::string reserve Öö Tiib <ootiib@hot.ee> - 2021-05-27 21:02 -0700
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-05-28 12:09 -0700
                Re: recovering from std::bad_alloc in std::string reserve scott@slp53.sl.home (Scott Lurndal) - 2021-05-28 20:26 +0000
                Re: recovering from std::bad_alloc in std::string reserve Öö Tiib <ootiib@hot.ee> - 2021-05-28 17:10 -0700
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-05-29 11:47 +0200
                Re: recovering from std::bad_alloc in std::string reserve "daniel...@gmail.com" <danielaparker@gmail.com> - 2021-05-30 15:15 -0700
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-05-31 08:33 +0200
                Re: recovering from std::bad_alloc in std::string reserve "daniel...@gmail.com" <danielaparker@gmail.com> - 2021-05-31 08:21 -0700
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-05-31 18:13 +0200
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-05-31 14:43 -0700
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-05-31 14:44 -0700
                Re: recovering from std::bad_alloc in std::string reserve "daniel...@gmail.com" <danielaparker@gmail.com> - 2021-05-31 15:20 -0700
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-01 11:17 -0700
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-01 20:25 +0200
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-01 16:55 -0700
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-02 09:06 +0200
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-05 17:50 -0700
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-06 11:10 +0200
                Re: recovering from std::bad_alloc in std::string reserve Öö Tiib <ootiib@hot.ee> - 2021-06-06 04:07 -0700
                Re: recovering from std::bad_alloc in std::string reserve Richard Damon <Richard@Damon-Family.org> - 2021-06-06 07:49 -0400
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-01 20:21 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-02 09:29 +0200
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-02 18:43 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-02 23:32 +0200
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-03 00:49 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-03 09:08 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-03 10:53 +0200
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-03 16:20 +0200
                Re: recovering from std::bad_alloc in std::string reserve James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-06-03 11:20 -0400
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-03 19:04 +0200
                Re: recovering from std::bad_alloc in std::string reserve scott@slp53.sl.home (Scott Lurndal) - 2021-06-03 22:24 +0000
                Re: recovering from std::bad_alloc in std::string reserve Öö Tiib <ootiib@hot.ee> - 2021-06-03 16:27 -0700
                Re: recovering from std::bad_alloc in std::string reserve scott@slp53.sl.home (Scott Lurndal) - 2021-06-04 00:36 +0000
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-04 08:46 +0200
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-05 22:02 -0700
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-06 11:17 +0200
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-06 18:39 +0200
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 16:33 -0700
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-07 08:41 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-06 17:46 +0200
                Re: recovering from std::bad_alloc in std::string reserve MrSpook_Qfmtjdmi@nc6.com - 2021-06-06 14:11 +0000
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-03 16:43 +0200
                Re: recovering from std::bad_alloc in std::string reserve Manfred <noname@add.invalid> - 2021-06-01 18:00 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-01 19:15 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-01 15:55 +0200
                Re: recovering from std::bad_alloc in std::string reserve Bo Persson <bo@bo-persson.se> - 2021-06-01 13:59 +0200
                Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-06-01 13:26 -0500
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-01 08:29 +0200
                Re: recovering from std::bad_alloc in std::string reserve Bo Persson <bo@bo-persson.se> - 2021-06-01 14:05 +0200
                Re: recovering from std::bad_alloc in std::string reserve David Brown <david.brown@hesbynett.no> - 2021-06-01 15:58 +0200
                Re: recovering from std::bad_alloc in std::string reserve James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-06-01 11:33 -0400
                Re: recovering from std::bad_alloc in std::string reserve Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-01 10:52 -0700
            Re: recovering from std::bad_alloc in std::string reserve James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-05-27 23:16 -0400
            Re: recovering from std::bad_alloc in std::string reserve scott@slp53.sl.home (Scott Lurndal) - 2021-05-28 14:34 +0000
          Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-27 18:19 -0500
        Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-28 03:47 +0200
      Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-27 17:45 -0500
        Re: recovering from std::bad_alloc in std::string reserve scott@slp53.sl.home (Scott Lurndal) - 2021-05-28 14:38 +0000
          Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-28 16:44 +0200
          Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-28 16:42 +0200
          Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-28 18:22 +0300
      Re: recovering from std::bad_alloc in std::string reserve Paavo Helde <myfirstname@osa.pri.ee> - 2021-05-28 08:47 +0300
  Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-26 06:16 +0200
    Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-26 13:30 -0500
      Re: recovering from std::bad_alloc in std::string reserve Bonita Montero <Bonita.Montero@gmail.com> - 2021-05-26 20:37 +0200
        Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-26 14:09 -0500
  Re: recovering from std::bad_alloc in std::string reserve "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-05-26 18:33 +0200
    Re: recovering from std::bad_alloc in std::string reserve Lynn McGuire <lynnmcguire5@gmail.com> - 2021-05-26 13:32 -0500
      Re: recovering from std::bad_alloc in std::string reserve Christian Gollwitzer <auriocus@gmx.de> - 2021-05-27 07:50 +0200
  Re: recovering from std::bad_alloc in std::string reserve "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-06-01 17:35 -0700

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