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util/bit_array.h: remove use of memset and memcpy 

This makes the code less dependent on functions considered unsafe.

Fixes #3748
This commit is contained in:
Norman Feske 2020-05-05 12:44:34 +02:00
parent f722aa3325
commit bbc21cf063
3 changed files with 39 additions and 24 deletions
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2
repos/base/include/util/bit_allocator.h
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@ -55,7 +55,7 @@ class Genode::Bit_allocator
class Range_conflict : Exception {};
Bit_allocator() { _reserve(BITS, BITS_ALIGNED - BITS); }
Bit_allocator(const Bit_allocator & o) : _array(o._array) { }
Bit_allocator(Bit_allocator const &other) : _array(other._array) { }
/**
* Allocate block of bits

48
repos/base/include/util/bit_array.h
View File

@ -20,7 +20,7 @@
#include <base/stdint.h>
namespace Genode {
class Bit_array_base;
template <unsigned> class Bit_array;
}
@ -44,9 +44,9 @@ class Genode::Bit_array_base
private:
unsigned _bit_cnt;
unsigned _word_cnt;
addr_t *_words;
unsigned const _bit_cnt;
unsigned const _word_cnt = _bit_cnt / BITS_PER_WORD;
addr_t * const _words;
addr_t _word(addr_t index) const {
return index / BITS_PER_WORD; }
@ -76,10 +76,10 @@ class Genode::Bit_array_base
{
_check_range(index, width);
addr_t rest, word, mask;
addr_t rest;
do {
word = _word(index);
mask = _mask(index, width, rest);
addr_t const word = _word(index);
addr_t const mask = _mask(index, width, rest);
if (free) {
if ((_words[word] & mask) != mask)
@ -96,16 +96,27 @@ class Genode::Bit_array_base
} while (rest);
}
/*
* Noncopyable
*/
Bit_array_base(Bit_array_base const &);
Bit_array_base &operator = (Bit_array_base const &);
public:
Bit_array_base(unsigned bits, addr_t *addr, bool clear)
: _bit_cnt(bits),
_word_cnt(_bit_cnt / BITS_PER_WORD),
_words(addr)
/**
* Constructor
*
* \param ptr pointer to array used as backing store for the bits.
* The array must be initialized with zeros.
*
* \throw Invalid_bit_count
*/
Bit_array_base(unsigned bits, addr_t *ptr)
:
_bit_cnt(bits), _words(ptr)
{
if (!bits || bits % BITS_PER_WORD) throw Invalid_bit_count();
if (clear) memset(_words, 0, sizeof(addr_t)*_word_cnt);
}
/**
@ -146,13 +157,16 @@ class Genode::Bit_array : public Bit_array_base
static_assert(BITS % BITS_PER_WORD == 0,
"Count of bits need to be word aligned!");
addr_t _array[_WORDS];
struct Array { addr_t values[_WORDS]; } _array { };
public:
Bit_array() : Bit_array_base(BITS, _array, true) { }
Bit_array(const Bit_array & o) : Bit_array_base(BITS, _array, false) {
memcpy(&_array, &o._array, sizeof(_array)); }
Bit_array() : Bit_array_base(BITS, _array.values) { }
Bit_array(Bit_array const &other)
:
Bit_array_base(BITS, _array.values), _array(other._array)
{ }
};
#endif /* _INCLUDE__UTIL__BIT_ARRAY_H_ */

13
repos/os/include/os/packet_allocator.h
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@ -39,7 +39,7 @@ class Genode::Packet_allocator : public Genode::Range_allocator
Allocator *_md_alloc; /* meta-data allocator */
size_t _block_size; /* granularity of packet allocations */
void *_bits = nullptr; /* memory chunk containing the bits */
addr_t *_bits = nullptr; /* memory chunk containing the bits */
Bit_array_base *_array = nullptr; /* bit array managing available blocks */
addr_t _base = 0; /* allocation base */
addr_t _next = 0; /* next free bit index */
@ -76,11 +76,12 @@ class Genode::Packet_allocator : public Genode::Range_allocator
{
if (_base || _array) return -1;
_base = base;
_bits = _md_alloc->alloc(_block_cnt(size)/8);
_array = new (_md_alloc) Bit_array_base(_block_cnt(size),
(addr_t*)_bits,
true);
size_t const number_of_bytes = _block_cnt(size)/8;
_base = base;
_bits = (addr_t *)_md_alloc->alloc(number_of_bytes);
memset(_bits, 0, number_of_bytes);
_array = new (_md_alloc) Bit_array_base(_block_cnt(size), _bits);
return 0;
}