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Groups > comp.lang.forth > #15294

Re: Function Points

From "Rod Pemberton" <do_not_have@notemailnot.cmm>
Newsgroups comp.lang.forth
Subject Re: Function Points
Date 2012-08-31 01:23 -0400
Organization Aioe.org NNTP Server
Message-ID <k1phj0$lr8$1@speranza.aioe.org> (permalink)
References (9 earlier) <2012Aug26.150931@mips.complang.tuwien.ac.at> <7xbohvy8pc.fsf@ruckus.brouhaha.com> <2012Aug30.160847@mips.complang.tuwien.ac.at> <7xmx1cmg1t.fsf@ruckus.brouhaha.com> <2250796.QNINORRiYk@sunwukong.fritz.box>

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"Bernd Paysan" <bernd.paysan@gmx.de> wrote in message
news:2250796.QNINORRiYk@sunwukong.fritz.box...

[...]

> But C's main problem is one fundamental mistake: buffers are passed
> around as pointers, without length.

If you knew anything about C, you'd know that the length of a buffer is
always known.  It's either in the declaration of the buffer, or was needed
to allocate the buffer dynamicly, or is available with sizeof() or strlen()
etc.  Whether or not the length is available when needed is a programmer
implementation issue.

> This is a direct invitation to buffer overflows.

That doesn't follow.

C's buffer overflows are the result of:

1) unlimited keyboard input functions
2) delimited buffers without the required delimiter
3) abuse of the single stack (common, not required) used for
control-flow, parameters, and data

How is Forth any different?

C doesn't require a stack, but most use one in order to:
a) implement recursion of procedures
b) reduce memory allocation requirements

> The problem of C is not just a lack of type information, it is
> the lack of a very vital information: the lack of knowing how
> big a buffer actually is.
>

Example 1) - static allocation

#define BSIZ  32
char buf[BSIZ];

len0=BSIZ;
len1=sizeof(buf);


Example 2) - dynamic allocation

#define BSIZ 32
char str[]="ABCDEF";

len0=BSIZ;
malloc(len0);

len1=80*sizeof(char);
malloc(len1);

len2=10*strlen(str);
malloc(len2);


The length is needed to allocate a buffer, staticly or dynamicly.  The
length is known from then on, or can be determined by using the
appropriate function or size operator.

> Forth doesn't know about types, but its buffer operations
> all know about the size of the buffer.

Which "buffer operations" in C don't?


The few memory functions in C operate on any data and are passed a length.
Their data is not delimited.  So, they require a length.

The many string functions in C operate on strings, which in C is an array of
characters delimited by C's definition of a byte, set to all bits cleared
(zero).  Other C string functions operate on strings delimited by other
characters.

> The other way to deal with that problem is to have a unique hash
> function, which the attacker can't create hash collisions for (for being
> "unique", something quite simple is completely sufficient: xor all
> strings with the same secret).

There is no guarantee that for two non-XOR'd strings which are hash
collisions that their two XOR'd strings won't be hash collisions also.  If
the hash function has low collisions, then it's unlikely the XOR'd strings
will collide, but that's also true for the non-XOR'd strings.  If the hash
function has high collisions (for simplicity, or speed etc.), then it's
likely the XOR'd strings will collide too, but that's also true for the
non-XOR'd strings.  Even with a low collision hash function, I think the
idea of XOR-ing is a bad idea.  For a set of non-XOR'd strings, collisions
will occur for certain strings.  With a set of XOR'd strings, collisions
will occur for certain strings too.  I.e., the probability or frequency of
collisions is the same.  The XOR has no effect on that probability.  The
hash function hasn't changed.  A certain percentage will collide.  So, all I
believe XOR-ing will do is change which inputs collide, but it won't reduce
the frequency of the collisions.  If this works for you, it's because the
strings are limited in the numeric range of their characters, and you've
shifted which hash collisions occur via the use of XOR-ing "secret" string.
The reason why I think this is a bad idea is because you've effectively
tuned the hash to produce low collisions for a _specific_ set of input
strings and a _specific_ "secret" string.  However, both that input set of
strings and "secret" string can be changed.  If they are changed, the hash
needs to be retuned.  What needs to be done instead of XOR-ing is to
increase the randomness of the string data.  String data has a narrow
numeric range of values.  An array of randomized data with a larger range
than the character range can be used to translate the the strings'
characters to the random data prior to the hash.


Rod Pemberton

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Thread

Comparative Productivity of Programming Languages visualforth@rocketmail.com - 2012-08-21 21:43 -0700
  Re: Comparative Productivity of Programming Languages "A. K." <akk@nospam.org> - 2012-08-22 07:07 +0200
  Re: Comparative Productivity of Programming Languages Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-08-22 03:35 -0500
    Re: Comparative Productivity of Programming Languages John Passaniti <john.passaniti@gmail.com> - 2012-08-22 14:06 -0700
      Function Points (was: Comparative Productivity of Programming Languages) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-23 14:50 +0000
        Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-23 11:43 -0700
          Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-25 14:13 +0000
            Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-25 10:12 -0700
              Re: Function Points Doug Hoffman <glidedog@gmail.com> - 2012-08-25 15:39 -0400
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-25 15:09 -0700
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-08-25 12:34 -1000
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-25 16:43 -0700
                Re: Function Points jacko <jackokring@gmail.com> - 2012-08-25 18:05 -0700
                Re: Function Points jacko <jackokring@gmail.com> - 2012-08-25 20:34 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-26 03:24 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-25 22:44 -0700
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-08-25 21:19 -1000
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-26 00:36 -0700
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-08-25 21:50 -1000
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-26 01:08 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-26 23:20 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-26 19:33 -0700
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-08-27 13:34 -0500
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-27 22:38 +0200
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-08-28 02:45 -0500
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-27 18:14 -0700
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-27 18:24 -0700
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-30 14:22 +0000
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-08-28 03:07 -0500
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-28 08:18 -0700
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-08-28 12:15 -0500
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-28 23:05 -0700
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-08-29 03:55 -0500
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-27 22:28 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-27 20:26 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-28 23:17 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-29 01:13 -0700
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-29 02:23 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-30 02:59 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-29 22:18 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-30 20:44 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-31 01:29 -0700
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-31 09:33 +0000
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-30 02:58 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-29 19:39 -0700
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-30 14:10 +0000
                Re: Function Points gavino_himself <visploveslisp@gmail.com> - 2012-08-30 20:08 -0700
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-08-30 17:47 -1000
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-08-27 13:43 -1000
                Re: Function Points "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2012-08-27 12:14 +0100
                Re: Function Points Mark Wills <markrobertwills@yahoo.co.uk> - 2012-08-27 05:12 -0700
                Re: Function Points "Paul E. Bennett" <Paul_E.Bennett@topmail.co.uk> - 2012-08-27 15:52 +0100
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-26 13:09 +0000
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-27 20:52 -0700
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-30 14:08 +0000
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-30 10:43 -0700
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-08-30 08:25 -1000
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-08-30 22:42 +0200
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-08-31 01:23 -0400
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-08-31 03:08 -0500
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-08-31 18:56 -0400
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-01 02:35 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-31 23:52 -0700
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-01 14:27 +0000
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-01 14:18 +0000
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-01 17:45 +0200
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-01 16:14 +0000
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-01 19:13 +0200
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-09-02 03:19 -0500
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-01 16:18 -0400
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-02 03:04 +0200
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-02 04:02 -0400
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-02 17:40 +0200
                Re: Function Points jim@rainbarrel.com - 2012-09-02 10:32 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-02 20:49 +0200
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-02 16:33 -0400
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-02 17:03 -0400
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-09-02 09:02 -1000
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-02 16:35 -0400
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-09-02 13:42 -1000
                Re: Function Points jim@rainbarrel.com - 2012-09-02 16:54 -0700
                Re: Function Points Mark Wills <markrobertwills@yahoo.co.uk> - 2012-09-03 00:29 -0700
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-03 01:30 -0400
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-09-02 21:21 -1000
                Re: Function Points jim@rainbarrel.com - 2012-09-03 10:37 -0700
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-04 07:14 +0000
                Re: Function Points Coos Haak <chforth@hccnet.nl> - 2012-09-03 21:12 +0200
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-03 17:32 -0400
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-03 17:51 -0400
                Re: Function Points John Passaniti <john.passaniti@gmail.com> - 2012-09-03 22:37 -0700
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-04 04:25 -0400
                Re: Function Points John Passaniti <john.passaniti@gmail.com> - 2012-09-04 07:35 -0700
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-05 02:13 -0400
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-09-04 20:18 -1000
                Re: Function Points John Passaniti <john.passaniti@gmail.com> - 2012-09-05 10:56 -0700
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-05 16:11 -0400
                Re: Function Points John Passaniti <john.passaniti@gmail.com> - 2012-09-05 14:07 -0700
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-02 16:27 -0400
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-03 00:52 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-02 16:28 -0700
                Re: Function Points jim@rainbarrel.com - 2012-09-02 16:48 -0700
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-02 20:21 -0400
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-09-02 14:45 -1000
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-03 01:12 -0400
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-09-02 21:26 -1000
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-03 01:06 -0400
                Re: Function Points Mark Wills <markrobertwills@yahoo.co.uk> - 2012-08-31 03:29 -0700
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-31 10:35 +0000
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-08-31 18:49 -0400
                Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-01 14:49 +0000
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-09-01 08:36 -1000
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-01 16:11 -0400
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-03 01:58 +0200
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-01 17:54 +0200
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-01 16:19 -0400
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-02 03:05 +0200
                Re: Function Points Coos Haak <chforth@hccnet.nl> - 2012-08-31 23:10 +0200
                Re: Function Points "Elizabeth D. Rather" <erather@forth.com> - 2012-08-31 15:50 -1000
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-01 10:31 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-01 21:52 +0200
                Re: Function Points "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-09-01 16:36 -0400
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-01 14:36 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-02 03:30 +0200
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-02 23:15 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-02 15:02 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-03 01:50 +0200
                Re: Function Points jim@rainbarrel.com - 2012-09-02 16:57 -0700
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-03 23:11 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-04 14:30 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-04 10:14 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-04 22:10 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-06 00:19 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-06 17:48 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-06 12:01 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-06 22:02 +0200
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-09-06 14:19 -0700
                Heap (was: Function Points) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-07 11:30 +0000
                Re: Heap (was: Function Points) Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-07 18:12 +0200
                Re: Heap (was: Function Points) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-07 16:48 +0000
                Re: Heap (was: Function Points) Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-07 21:34 +0200
                Re: Heap Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2012-09-07 22:04 +0100
                Re: Heap anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-08 11:52 +0000
                Re: Heap Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-08 22:48 +0200
                Re: Heap (was: Function Points) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-08 12:11 +0000
                priority queue (was: Function Points) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-09-03 11:46 +0000
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-03 15:03 +0200
                Re: Function Points mhx@iae.nl (Marcel Hendrix) - 2012-09-03 22:36 +0200
                Re: Function Points mhx@iae.nl (Marcel Hendrix) - 2012-09-06 20:27 +0200
                Re: Function Points Andrew Haley <andrew29@littlepinkcloud.invalid> - 2012-09-02 04:00 -0500
                Re: Function Points visualforth@rocketmail.com - 2012-09-03 10:40 -0700
                Re: Function Points Bernd Paysan <bernd.paysan@gmx.de> - 2012-09-03 20:26 +0200
                Re: Function Points Doug Hoffman <glidedog@gmail.com> - 2012-08-27 11:49 -0400
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-27 09:16 -0700
                Re: Function Points Josh Grams <josh@qualdan.com> - 2012-08-28 22:46 +0000
                Re: Function Points jacko <jackokring@gmail.com> - 2012-08-28 16:06 -0700
                Re: Function Points Doug Hoffman <glidedog@gmail.com> - 2012-08-28 20:50 -0400
              Re: Function Points anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-26 12:59 +0000
                Re: Function Points Paul Rubin <no.email@nospam.invalid> - 2012-08-26 22:24 -0700
        Re: Function Points (was: Comparative Productivity of Programming Languages) John Passaniti <john.passaniti@gmail.com> - 2012-08-23 15:02 -0700
          Re: Function Points (was: Comparative Productivity of Programming Languages) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2012-08-25 14:57 +0000
  Re: Comparative Productivity of Programming Languages "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-08-22 08:07 -0400
    Re: Comparative Productivity of Programming Languages visualforth@rocketmail.com - 2012-08-22 08:12 -0700
  Re: Comparative Productivity of Programming Languages visualforth@rocketmail.com - 2012-08-22 07:37 -0700

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