[RFA] patch for argz_insert()

[Charles Wilson]

2007-03-16  Charles Wilson  <cygwin@...>

	* libc/argz/argz_insert.c: before pointer is
	invalid after *argz realloc.  Compute offset
	between before and *argz, and use it after
	reallocation instead.

A little algebra should demonstrate the correctness of this patch.

given:
     delta = before - *argz

then:
     before = *argz + delta

therefore:
     memmove(before + len,              -> *argz + delta + len,
             before,                    -> *argz + delta,
             *argz + *argz_len - before ->
                  *argz + *argz_len - *argz - delta ->
                  *argz_len - delta
             );
     memcpy(before,   -> *argz + delta
            entry,
            len
           );

For a more thorough description, see:
http://cygwin.com/ml/cygwin/2007-03/msg00533.html

--
Chuck



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