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Re: how to figure out the size of buffer from malloc

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On 2012-02-17, pembed2012 <once@was.enough.invalid> wrote:
> It started off with the buffers being NULL-free strings. However now I 
> need to work with strings with embedded NULL characters. This means I 

So the requirements changed.

> can't find the length of the buffer with strlen. And it would be too much 
> change to add a new argument to pass the length of the buffer. 

That is the right thing to do.  Guess how long it will take you to do it
and then give the estimate to whoever changed the requirement.
Aren't you being paid?

> So the 
> only good solution is for myfunc to work out by it's self 1) if the 
> buffer is a dynamic pointer or stack array and 2) the size of the buffer.

This is not possible in any portable way. Some malloc implementations have a
function which can tell you how large the underlying block is (but not
necessarily with byte accuracy). As far as obtaining the size of an array in
automatic storage, forget it.

You can add a length field to string objects without introducing a new
parameter everywhere. Just change the type from "char *" to "string *",
where string is a struct type such as:

  typedef struct { int size; char *data; } string;

Or even:

  /* flexible array hack */
  typedef struct { int size; char [1]; } string;

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how to figure out the size of buffer from malloc pembed2012 <once@was.enough.invalid> - 2012-02-16 20:21 +0000
  Re: how to figure out the size of buffer from malloc James Kuyper <jameskuyper@verizon.net> - 2012-02-16 15:38 -0500
  Re: how to figure out the size of buffer from malloc John Gordon <gordon@panix.com> - 2012-02-16 20:48 +0000
    Re: how to figure out the size of buffer from malloc pembed2012 <once@was.enough.invalid> - 2012-02-16 22:42 +0000
      Re: how to figure out the size of buffer from malloc John Gordon <gordon@panix.com> - 2012-02-16 22:50 +0000
      Re: how to figure out the size of buffer from malloc Keith Thompson <kst-u@mib.org> - 2012-02-16 14:50 -0800
        Re: how to figure out the size of buffer from malloc pembed2012 <once@was.enough.invalid> - 2012-02-17 19:45 +0000
          Re: how to figure out the size of buffer from malloc China Blue Sea <chine.bleu@yahoo.com> - 2012-02-17 11:53 -0800
          Re: how to figure out the size of buffer from malloc Ike Naar <ike@sverige.freeshell.org> - 2012-02-17 20:23 +0000
          Re: how to figure out the size of buffer from malloc James Kuyper <jameskuyper@verizon.net> - 2012-02-17 15:33 -0500
            Re: how to figure out the size of buffer from malloc pembed2012 <once@was.enough.invalid> - 2012-02-17 22:13 +0000
              Re: how to figure out the size of buffer from malloc James Kuyper <jameskuyper@verizon.net> - 2012-02-17 17:25 -0500
              Re: how to figure out the size of buffer from malloc Shao Miller <sha0.miller@gmail.com> - 2012-02-17 17:54 -0500
              Re: how to figure out the size of buffer from malloc Keith Thompson <kst-u@mib.org> - 2012-02-17 15:01 -0800
                Re: how to figure out the size of buffer from malloc Shao Miller <sha0.miller@gmail.com> - 2012-02-17 18:10 -0500
              Re: how to figure out the size of buffer from malloc Ian Pilcher <arequipeno@gmail.com> - 2012-02-17 18:14 -0600
              Re: how to figure out the size of buffer from malloc "BartC" <bc@freeuk.com> - 2012-02-18 11:07 +0000
              Re: how to figure out the size of buffer from malloc ImpalerCore <jadill33@gmail.com> - 2012-02-18 04:40 -0800
              Re: how to figure out the size of buffer from malloc Kaz Kylheku <kaz@kylheku.com> - 2012-02-18 12:48 +0000
          Re: how to figure out the size of buffer from malloc Shao Miller <sha0.miller@gmail.com> - 2012-02-17 17:45 -0500
      Re: how to figure out the size of buffer from malloc Shao Miller <sha0.miller@gmail.com> - 2012-02-16 22:18 -0500
  Re: how to figure out the size of buffer from malloc Devil with the China Blue Dress <chine.bleu@yahoo.com> - 2012-02-16 13:20 -0800
  Re: how to figure out the size of buffer from malloc Lew Pitcher <lpitcher@teksavvy.com> - 2012-02-16 17:07 -0500
  Re: how to figure out the size of buffer from malloc Keith Thompson <kst-u@mib.org> - 2012-02-16 14:28 -0800
  Re: how to figure out the size of buffer from malloc Mark Adler <madler@alumni.caltech.edu> - 2012-02-16 23:49 -0800
  Re: how to figure out the size of buffer from malloc Michael Angelo Ravera <maravera@prodigy.net> - 2012-02-18 09:54 -0800
    Re: how to figure out the size of buffer from malloc gazelle@shell.xmission.com (Kenny McCormack) - 2012-02-18 18:21 +0000
      Re: how to figure out the size of buffer from malloc Shao Miller <sha0.miller@gmail.com> - 2012-02-18 13:56 -0500
      Re: how to figure out the size of buffer from malloc Stephen Sprunk <stephen@sprunk.org> - 2012-02-18 13:42 -0600

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