183 lines
5.6 KiB
C
183 lines
5.6 KiB
C
/*
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* Copyright (c) 2011, 2012, 2013, 2014, 2015, 2022 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* stdlib/realloc.c
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* Reallocates a chunk of memory from the dynamic memory heap.
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*/
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#include <assert.h>
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#include <errno.h>
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#include <malloc.h>
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#include <stdlib.h>
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#include <string.h>
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#if defined(HEAP_NO_ASSERT)
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#define __heap_verify() ((void) 0)
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#undef assert
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#define assert(x) do { ((void) 0); } while ( 0 )
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#endif
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#if !defined(HEAP_GUARD_DEBUG)
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#ifdef __TRACE_ALLOCATION_SITES
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void* realloc_trace(struct __allocation_site* new_allocation_site,
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void* ptr,
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size_t requested_size)
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#else
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void* realloc(void* ptr, size_t requested_size)
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#endif
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{
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if ( !ptr )
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#ifdef __TRACE_ALLOCATION_SITES
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return malloc_trace(new_allocation_site, requested_size);
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#else
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return malloc(requested_size);
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#endif
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if ( !heap_size_has_bin(requested_size) )
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return errno = ENOMEM, (void*) NULL;
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// Decide how big an allocation we would like to make.
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size_t requested_chunk_outer_size = sizeof(struct heap_chunk) +
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sizeof(struct heap_chunk_post);
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size_t requested_chunk_inner_size = heap_align(requested_size);
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size_t requested_chunk_size = requested_chunk_outer_size +
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requested_chunk_inner_size;
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if ( !heap_size_has_bin(requested_chunk_size) )
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return errno = ENOMEM, (void*) NULL;
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__heap_lock();
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__heap_verify();
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// Retrieve the chunk that contains this allocation.
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struct heap_chunk* chunk = heap_data_to_chunk((uint8_t*) ptr);
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#ifdef __TRACE_ALLOCATION_SITES
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assert(MAGIC_IS_ALLOCATION_SITE(chunk->chunk_magic));
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struct __allocation_site* allocation_site =
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ALLOCATION_SITE_OF_MAGIC(chunk->chunk_magic);
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#endif
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assert(chunk->chunk_magic == HEAP_CHUNK_MAGIC ||
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MAGIC_IS_ALLOCATION_SITE(chunk->chunk_magic));
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assert(heap_chunk_to_post(chunk)->chunk_magic == HEAP_CHUNK_MAGIC);
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assert(heap_chunk_to_post(chunk)->chunk_size == chunk->chunk_size);
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// Do nothing if the chunk already has the ideal size.
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if ( chunk->chunk_size == requested_chunk_size )
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{
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__heap_verify();
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__heap_unlock();
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return heap_chunk_to_data(chunk);
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}
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// If the ideal size is smaller than the current, attempt the shrink the
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// allocation if a new chunk can be created.
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if ( requested_chunk_size < chunk->chunk_size )
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{
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assert(requested_chunk_size <= chunk->chunk_size);
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#ifdef __TRACE_ALLOCATION_SITES
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allocation_site->current_size -= chunk->chunk_size;
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allocation_site->allocations--;
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#endif
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if ( heap_can_split_chunk(chunk, requested_chunk_size) )
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heap_split_chunk(chunk, requested_chunk_size);
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#ifdef __TRACE_ALLOCATION_SITES
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allocation_site->current_size += chunk->chunk_size;
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allocation_site->allocations++;
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chunk->chunk_magic = MAGIC_OF_ALLOCATION_SITE(allocation_site);
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#endif
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__heap_verify();
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__heap_unlock();
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return heap_chunk_to_data(chunk);
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}
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// TODO: What if the right neighbor is the part edge?
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// If we need to expand the chunk, attempt to combine it with its right
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// neighbor if it is large enough.
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struct heap_chunk* right;
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if ( (right = heap_chunk_right(chunk)) &&
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!heap_chunk_is_used(right) &&
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requested_chunk_size <= chunk->chunk_size + right->chunk_size )
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{
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#ifdef __TRACE_ALLOCATION_SITES
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allocation_site->current_size -= chunk->chunk_size;
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allocation_site->allocations--;
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#endif
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heap_remove_chunk(right);
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heap_chunk_format((uint8_t*) chunk, chunk->chunk_size + right->chunk_size);
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assert(requested_chunk_size <= chunk->chunk_size);
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if ( heap_can_split_chunk(chunk, requested_chunk_size) )
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heap_split_chunk(chunk, requested_chunk_size);
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#ifdef __TRACE_ALLOCATION_SITES
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allocation_site->current_size += chunk->chunk_size;
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allocation_site->allocations++;
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chunk->chunk_magic = MAGIC_OF_ALLOCATION_SITE(allocation_site);
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#endif
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__heap_verify();
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__heap_unlock();
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return heap_chunk_to_data(chunk);
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}
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// It appears that we cannot retain the orignal allocation location and we
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// will have to relocate the allocation elsewhere to expand it.
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size_t orignal_ptr_size = heap_chunk_data_size(chunk);
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__heap_verify();
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__heap_unlock();
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assert(orignal_ptr_size < requested_size);
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#ifdef __TRACE_ALLOCATION_SITES
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void* result = malloc_trace(allocation_site, requested_size);
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#else
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void* result = malloc(requested_size);
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#endif
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if ( !result )
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return (void*) NULL;
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memcpy(result, ptr, orignal_ptr_size);
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free(ptr);
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return result;
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}
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#else
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void* realloc(void* ptr, size_t requested_size)
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{
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if ( !ptr )
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return malloc(requested_size);
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struct heap_alloc* alloc_ptr =
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(struct heap_alloc*) HEAP_ALIGN_PAGEDOWN((uintptr_t) ptr - 16);
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assert(alloc_ptr->from == (uintptr_t) alloc_ptr);
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struct heap_alloc alloc = *alloc_ptr;
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size_t size = (alloc.from + alloc.size - HEAP_PAGE_SIZE) - (uintptr_t) ptr;
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if ( requested_size <= size )
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return ptr;
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void* replacement = malloc(requested_size);
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if ( !replacement )
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return NULL;
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memcpy(replacement, ptr, size);
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free(ptr);
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return replacement;
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}
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#endif
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