mirror of
https://github.com/sheumann/hush.git
synced 2024-11-09 02:09:01 +00:00
46 lines
1.5 KiB
C
46 lines
1.5 KiB
C
/* vi: set sw=4 ts=4: */
|
|
/*
|
|
* Utility routines.
|
|
*
|
|
* Copyright (C) 2008 Denys Vlasenko
|
|
*
|
|
* Licensed under GPLv2, see file LICENSE in this tarball for details.
|
|
*/
|
|
|
|
#include "libbb.h"
|
|
|
|
/* Resize (grow) malloced vector.
|
|
*
|
|
* #define magic packed two parameters into one:
|
|
* sizeof = sizeof_and_shift >> 8
|
|
* shift = (sizeof_and_shift) & 0xff
|
|
*
|
|
* Lets say shift = 4. 1 << 4 == 0x10.
|
|
* If idx == 0, 0x10, 0x20 etc, vector[] is resized to next higher
|
|
* idx step, plus one: if idx == 0x20, vector[] is resized to 0x31,
|
|
* thus last usable element is vector[0x30].
|
|
*
|
|
* In other words: after xrealloc_vector(v, 4, idx) it's ok to use
|
|
* at least v[idx] and v[idx+1], for all idx values.
|
|
*
|
|
* New elements are zeroed out, but only if realloc was done
|
|
* (not on every call). You can depend on v[idx] and v[idx+1] being
|
|
* zeroed out if you use it like this:
|
|
* v = xrealloc_vector(v, 4, idx);
|
|
* v[idx].some_fields = ...; - the rest stays 0/NULL
|
|
* idx++;
|
|
* If you do not advance idx like above, you should be more careful.
|
|
* Next call to xrealloc_vector(v, 4, idx) may or may not zero out v[idx].
|
|
*/
|
|
void* FAST_FUNC xrealloc_vector_helper(void *vector, unsigned sizeof_and_shift, int idx)
|
|
{
|
|
int mask = 1 << (uint8_t)sizeof_and_shift;
|
|
|
|
if (!(idx & (mask - 1))) {
|
|
sizeof_and_shift >>= 8; /* sizeof(vector[0]) */
|
|
vector = xrealloc(vector, sizeof_and_shift * (idx + mask + 1));
|
|
memset((char*)vector + (sizeof_and_shift * idx), 0, sizeof_and_shift * (mask + 1));
|
|
}
|
|
return vector;
|
|
}
|