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Re: relearning C: why does an in-place change to a char* segfault?

From Keith Thompson <Keith.S.Thompson+u@gmail.com>
Newsgroups comp.lang.c
Subject Re: relearning C: why does an in-place change to a char* segfault?
Date 2024-08-05 15:40 -0700
Organization None to speak of
Message-ID <875xsebnkl.fsf@nosuchdomain.example.com> (permalink)
References (5 earlier) <v8mkao$3n2rq$5@dont-email.me> <8734nldmea.fsf@nosuchdomain.example.com> <v8prni$hmng$1@dont-email.me> <871q33cw4p.fsf@nosuchdomain.example.com> <v8rg3j$13kvd$1@dont-email.me>

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Lawrence D'Oliveiro <ldo@nz.invalid> writes:
> On Sun, 04 Aug 2024 23:38:14 -0700, Keith Thompson wrote:
>> Lawrence D'Oliveiro <ldo@nz.invalid> writes:
>>> On Sat, 03 Aug 2024 19:58:37 -0700, Keith Thompson wrote:
>>>> Lawrence D'Oliveiro <ldo@nz.invalid> writes:
>>>>> On Sat, 03 Aug 2024 17:07:37 -0700, Keith Thompson wrote:
>>>>>> ... general compression isn't something I've seen ...
>>>>>
>>>>> I recall Apple had a patent on some aspects of the “PEF” executable
>>>>> format that they created for their PowerPC machines running old
>>>>> MacOS. This had to do with some clever instruction encodings for
>>>>> loading stuff into memory.
>>>> 
>>>> Is that relevant to what I asked about?
>>>
>>> “Compression”
>> 
>> Was that intended to be responsive?
>
> Hint: you have to know something about executable formats.

I am profoundly uninterested in hints.

Here's what you snipped from what I wrote upthread:

    What I had in mind is something that, given this:

        static int buf = { 1, 1, 1, ..., 1 }; // say, 1000 elements

    would store something less than 1000*sizeof(int) bytes in the executable
    file.  I wouldn't be hard to do, but I'm not convinced it would be
    worthwhile.

There's a lot I don't know about executable formats, and you seem
uninterested in doing more than showing off your presumed knowledge
without actually sharing it.  Others have already answered my direct
question (Richard Damon and David Brown mentioned implementations
that use simple run-length encoding, and David gave some reasons
why it could be useful), so you can stop wasting everyone's time.

-- 
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
void Void(void) { Void(); } /* The recursive call of the void */

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relearning C: why does an in-place change to a char* segfault? Mark Summerfield <mark@qtrac.eu> - 2024-08-01 08:06 +0000
  Re: relearning C: why does an in-place change to a char* segfault? Mark Summerfield <mark@qtrac.eu> - 2024-08-01 08:24 +0000
    Re: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-01 11:53 +0100
  Re: relearning C: why does an in-place change to a char* segfault? Richard Harnden <richard.nospam@gmail.invalid> - 2024-08-01 09:38 +0100
    Re: relearning C: why does an in-place change to a char* segfault? Mark Summerfield <mark@qtrac.eu> - 2024-08-01 08:54 +0000
    Re: relearning C: why does an in-place change to a char* segfault? Bart <bc@freeuk.com> - 2024-08-01 11:12 +0100
      Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-01 13:59 -0700
        Re: relearning C: why does an in-place change to a char* segfault? Bart <bc@freeuk.com> - 2024-08-01 22:07 +0100
          Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-01 14:28 -0700
          Re: relearning C: why does an in-place change to a char* segfault? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-01 20:20 -0400
          Re: relearning C: why does an in-place change to a char* segfault? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-08-02 01:06 +0000
            Re: relearning C: why does an in-place change to a char* segfault? Bart <bc@freeuk.com> - 2024-08-02 10:43 +0100
              Re: relearning C: why does an in-place change to a char* segfault? Richard Damon <richard@damon-family.org> - 2024-08-02 11:03 -0400
              Re: relearning C: why does an in-place change to a char* segfault? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-02 14:19 -0400
                Re: relearning C: why does an in-place change to a char* segfault? Bart <bc@freeuk.com> - 2024-08-02 19:33 +0100
                Re: relearning C: why does an in-place change to a char* segfault? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-03 01:31 +0000
                Re: relearning C: why does an in-place change to a char* segfault? Richard Damon <richard@damon-family.org> - 2024-08-02 22:01 -0400
                Re: relearning C: why does an in-place change to a char* segfault? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2024-08-03 08:32 -0600
                Re: relearning C: why does an in-place change to a char* segfault? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-04 01:05 +0000
                Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 02:52 -0700
                Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-13 17:46 -0700
                Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-13 18:44 -0700
                Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-15 16:00 -0700
                Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-15 16:27 -0700
                Re: relearning C: why does an in-place change to a char* segfault? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-14 10:33 -0400
                Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-15 16:05 -0700
          Re: relearning C: why does an in-place change to a char* segfault? Bonita Montero <Bonita.Montero@gmail.com> - 2024-08-04 15:52 +0200
        Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 14:11 -0700
          Re: relearning C: why does an in-place change to a char* segfault? Vir Campestris <vir.campestris@invalid.invalid> - 2024-08-13 15:34 +0100
            Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-13 13:08 -0700
              Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-13 17:41 -0700
              Re: relearning C: why does an in-place change to a char* segfault? David Brown <david.brown@hesbynett.no> - 2024-08-14 10:40 +0200
            Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-13 17:40 -0700
              Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-13 18:47 -0700
                Re: relearning C: why does an in-place change to a char* segfault? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-08-14 03:16 +0000
                Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-13 20:49 -0700
  Re: relearning C: why does an in-place change to a char* segfault? scott@slp53.sl.home (Scott Lurndal) - 2024-08-01 13:28 +0000
  No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Michael S <already5chosen@yahoo.com> - 2024-08-01 17:40 +0300
    Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? David Brown <david.brown@hesbynett.no> - 2024-08-01 19:56 +0200
      Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? candycanearter07 <candycanearter07@candycanearter07.nomail.afraid> - 2024-08-02 05:30 +0000
        Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 03:02 -0700
          Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Richard Harnden <richard.nospam@gmail.invalid> - 2024-08-02 13:04 +0100
            Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-02 09:59 -0400
            Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-02 11:24 -0700
              Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Richard Damon <richard@damon-family.org> - 2024-08-02 14:42 -0400
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-02 14:58 -0400
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Richard Damon <richard@damon-family.org> - 2024-08-02 15:11 -0400
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 08:32 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 08:27 -0700
              Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-02 12:27 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-02 23:29 +0100
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-02 16:11 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-05 02:06 +0100
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-04 19:37 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-04 19:38 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-05 12:03 +0100
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-05 13:35 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-05 21:54 +0100
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-05 15:39 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-06 12:29 +0100
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-06 12:48 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-06 23:59 +0100
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-12 16:18 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2024-08-05 15:44 -0700
              Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 14:38 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-12 14:55 -0700
            Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? dave_thompson_2@comcast.net - 2024-08-25 16:52 -0400
              Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-25 14:26 -0700
          Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 14:33 -0700
            Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-12 14:45 -0700
              Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 16:05 -0700
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? David Brown <david.brown@hesbynett.no> - 2024-08-13 13:08 +0200
                Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-13 13:00 -0700
        Re: No warning at implicit removal of const. Was: relearning C: why does an in-place change to a char* segfault? David Brown <david.brown@hesbynett.no> - 2024-08-03 19:54 +0200
  Re: relearning C: why does an in-place change to a char* segfault? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-08-01 12:02 -0400
  Re: relearning C: why does an in-place change to a char* segfault? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-08-01 19:39 +0000
    Re: relearning C: why does an in-place change to a char* segfault? Bart <bc@freeuk.com> - 2024-08-01 21:42 +0100
      Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-01 14:13 -0700
      Re: relearning C: why does an in-place change to a char* segfault? Ben Bacarisse <ben@bsb.me.uk> - 2024-08-01 22:40 +0100
      Re: relearning C: why does an in-place change to a char* segfault? Kaz Kylheku <643-408-1753@kylheku.com> - 2024-08-02 00:37 +0000
        Re: relearning C: why does an in-place change to a char* segfault? Bart <bc@freeuk.com> - 2024-08-02 11:36 +0100
        Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 13:47 -0700
      Re: relearning C: why does an in-place change to a char* segfault? David Brown <david.brown@hesbynett.no> - 2024-08-03 00:14 +0200
        Re: relearning C: why does an in-place change to a char* segfault? scott@slp53.sl.home (Scott Lurndal) - 2024-08-03 17:07 +0000
          Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-03 17:11 -0700
        Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-03 17:07 -0700
          Re: relearning C: why does an in-place change to a char* segfault? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-04 01:08 +0000
            Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-03 19:58 -0700
              Re: relearning C: why does an in-place change to a char* segfault? Richard Damon <richard@damon-family.org> - 2024-08-04 07:22 -0400
                Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-12 02:55 -0700
              Re: relearning C: why does an in-place change to a char* segfault? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-05 06:33 +0000
                Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-04 23:38 -0700
                Re: relearning C: why does an in-place change to a char* segfault? Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-08-05 21:27 +0000
                Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-05 15:40 -0700
                Re: relearning C: why does an in-place change to a char* segfault? Bart <bc@freeuk.com> - 2024-08-06 16:57 +0100
                Re: relearning C: why does an in-place change to a char* segfault? David Brown <david.brown@hesbynett.no> - 2024-08-06 20:40 +0200
          Re: relearning C: why does an in-place change to a char* segfault? David Brown <david.brown@hesbynett.no> - 2024-08-04 17:20 +0200
    Re: relearning C: why does an in-place change to a char* segfault? Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2024-08-01 14:06 -0700
    Re: relearning C: why does an in-place change to a char* segfault? Tim Rentsch <tr.17687@z991.linuxsc.com> - 2024-08-13 17:43 -0700

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