; pngmem.asm - stub functions for memory allocation
; Last changed in libpng 1.6.24 [August 4, 2016%]
; Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
; (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
; (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
; This code is released under the libpng license.
; For conditions of distribution and use, see the disclaimer
; and license in png.inc
; This file provides a location for all memory allocation. Users who
; need special memory handling are expected to supply replacement
; functions for png_malloc() and png_free(), and to use
; png_create_read_struct_2() and png_create_write_struct_2() to
; identify the replacement functions.
; Free a png_struct
;void (png_structrp png_ptr)
align 4
proc png_destroy_png_struct uses eax ecx edi esi, png_ptr:dword
locals
dummy_struct png_struct
endl
mov edi,[png_ptr]
cmp edi,0
je @f ;if (..!=0)
; png_free might call png_error and may certainly call
; png_get_mem_ptr, so fake a temporary png_struct to support this.
mov ecx,sizeof.png_struct
mov esi,edi
mov edi,ebp
sub edi,ecx
rep movsb ;dummy_struct = *png_ptr
mov edi,[png_ptr]
xor eax,eax
mov ecx,sizeof.png_struct
rep stosb ;memset(png_ptr, 0, (sizeof *png_ptr))
mov esi,ebp
sub esi,sizeof.png_struct
stdcall png_free, esi, [png_ptr]
if PNG_SETJMP_SUPPORTED eq 1
; We may have a jmp_buf left to deallocate.
stdcall png_free_jmpbuf, esi
end if
@@:
ret
endp
; Allocate memory. For reasonable files, size should never exceed
; 64K. However, zlib may allocate more than 64K if you don't tell
; it not to. See zconf.h and png.h for more information. zlib does
; need to allocate exactly 64K, so whatever you call here must
; have the ability to do that.
;voidp (const_structrp png_ptr, png_alloc_size_t size)
align 4
proc png_calloc uses ebx ecx edi, png_ptr:dword, size:dword
stdcall png_malloc, [png_ptr], [size]
cmp eax,0
je @f ;if (..!=0)
mov ebx,eax
mov edi,eax
mov ecx,[size]
xor eax,eax
rep stosb ;memset(ret, 0, size)
mov eax,ebx
@@:
ret
endp
; png_malloc_base, an internal function added at libpng 1.6.0, does the work of
; allocating memory, taking into account limits and PNG_USER_MEM_SUPPORTED.
; Checking and error handling must happen outside this routine; it returns NULL
; if the allocation cannot be done (for any reason.)
;voidp (const_structrp png_ptr, png_alloc_size_t size)
align 4
proc png_malloc_base uses ebx ecx, png_ptr:dword, size:dword
; Moved to png_malloc_base from png_malloc_default in 1.6.0; the DOS
; allocators have also been removed in 1.6.0, so any 16-bit system now has
; to implement a user memory handler. This checks to be sure it isn't
; called with big numbers.
; Some compilers complain that this is always true. However, it
; can be false when integer overflow happens.
cmp dword[size],0
jle .end0
cmp dword[size],PNG_SIZE_MAX
jg .end0 ; if (..>.. && ..<=..)
if PNG_MAX_MALLOC_64K eq 1
cmp dword[size],65536
jg .end0
end if
if PNG_USER_MEM_SUPPORTED eq 1
mov ebx,[png_ptr]
cmp ebx,0
je @f
cmp dword[ebx+png_struct.malloc_fn],0
je @f ;if (..!=0 && ..!=0)
stdcall [ebx+png_struct.malloc_fn], ebx, [size]
jmp .end_f
@@: ;else
end if
;stdcall [mem.alloc], [size]
mcall SF_SYS_MISC, SSF_MEM_ALLOC, [size]
jmp .end_f ;checked for truncation above
.end0: ;else
xor eax,eax
.end_f:
ret
endp
; This is really here only to work round a spurious warning in GCC 4.6 and 4.7
; that arises because of the checks in png_realloc_array that are repeated in
; png_malloc_array.
;voidp (const_structrp png_ptr, int nelements, size_t element_size)
align 4
proc png_malloc_array_checked, png_ptr:dword, nelements:dword, element_size:dword
; png_alloc_size_t req = nelements; /* known to be > 0 */
; if (req <= PNG_SIZE_MAX/element_size)
; return png_malloc_base(png_ptr, req * element_size);
; The failure case when the request is too large
xor eax,eax
.end_f:
ret
endp
;voidp (const_structrp png_ptr, int nelements, size_t element_size)
align 4
proc png_malloc_array, png_ptr:dword, nelements:dword, element_size:dword
; if (nelements <= 0 || element_size == 0)
; png_error(png_ptr, "internal error: array alloc");
stdcall png_malloc_array_checked, [png_ptr], [nelements], [element_size]
ret
endp
;voidp (const_structrp png_ptr, const_voidp old_array,
; int old_elements, int add_elements, size_t element_size)
align 4
proc png_realloc_array, png_ptr:dword, old_array:dword, old_elements:dword, add_elements:dword, element_size:dword
; These are internal errors:
; if (add_elements <= 0 || element_size == 0 || old_elements < 0 ||
; (old_array == NULL && old_elements > 0))
; png_error(png_ptr, "internal error: array realloc");
; Check for overflow on the elements count (so the caller does not have to
; check.)
; if (add_elements <= INT_MAX - old_elements)
; {
; voidp new_array = png_malloc_array_checked(png_ptr,
; old_elements+add_elements, element_size);
;
; if (new_array != NULL)
; {
; Because png_malloc_array worked the size calculations below cannot
; overflow.
; if (old_elements > 0)
; memcpy(new_array, old_array, element_size*(unsigned)old_elements);
;
; memset((char*)new_array + element_size*(unsigned)old_elements, 0,
; element_size*(unsigned)add_elements);
;
; return new_array;
; }
; }
xor eax,eax ;error
.end_f:
ret
endp
; Various functions that have different error handling are derived from this.
; png_malloc always exists, but if PNG_USER_MEM_SUPPORTED is defined a separate
; function png_malloc_default is also provided.
;voidp (const_structrp png_ptr, png_alloc_size_t size)
align 4
proc png_malloc uses edi, png_ptr:dword, size:dword
xor eax,eax
mov edi,[png_ptr]
cmp edi,0
je @f ;if (..==0) return 0
stdcall png_malloc_base, edi, [size]
cmp eax,0
jne @f ;if (..==0)
png_error edi, 'Out of memory' ;'m' means png_malloc
@@:
ret
endp
;voidp (const_structrp png_ptr, png_alloc_size_t size)
align 4
proc png_malloc_default uses edi, png_ptr:dword, size:dword
xor eax,eax
mov edi,[png_ptr]
cmp edi,0
je @f ;if (..==0) return 0
; Passing 'NULL' here bypasses the application provided memory handler.
stdcall png_malloc_base, 0, [size] ;0 - use malloc
cmp eax,0
jne @f ;if (..==0)
png_error edi, 'Out of Memory' ;'M' means png_malloc_default
@@:
ret
endp
; This function was added at libpng version 1.2.3. The png_malloc_warn()
; function will issue a png_warning and return NULL instead of issuing a
; png_error, if it fails to allocate the requested memory.
;voidp (const_structrp png_ptr, png_alloc_size_t size)
align 4
proc png_malloc_warn uses edi, png_ptr:dword, size:dword
mov edi,[png_ptr]
cmp edi,0
je .end0 ;if (..!=0)
stdcall png_malloc_base, edi, [size]
cmp eax,0
jne .end_f ;if (..!=0) return ret
png_warning edi, 'Out of memory'
.end0:
xor eax,eax
.end_f:
ret
endp
; Free a pointer allocated by png_malloc(). If ptr is NULL, return
; without taking any action.
;void (const_structrp png_ptr, voidp ptr)
align 4
proc png_free uses eax ebx ecx, png_ptr:dword, p2ptr:dword
mov ebx,[png_ptr]
cmp ebx,0
je .end_f
mov ecx,[p2ptr]
cmp ecx,0
je .end_f ;if (..==0 || ..==0) return
if PNG_USER_MEM_SUPPORTED eq 1
cmp dword[ebx+png_struct.free_fn],0
je @f ;if (..!=0)
stdcall dword[ebx+png_struct.free_fn], ebx, [p2ptr]
jmp .end_f
@@: ;else
end if
mcall SF_SYS_MISC, SSF_MEM_FREE, [p2ptr]
.end_f:
ret
endp
; This function is called when the application wants to use another method
; of allocating and freeing memory.
;void (png_structrp png_ptr, voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn)
align 4
proc png_set_mem_fn uses eax edi, png_ptr:dword, mem_ptr:dword, malloc_fn:dword, free_fn:dword
mov edi,[png_ptr]
cmp edi,0
je @f ;if (..!=0)
mov eax,[mem_ptr]
mov [edi+png_struct.mem_ptr],eax
mov eax,[malloc_fn]
mov [edi+png_struct.malloc_fn],eax
mov eax,[free_fn]
mov [edi+png_struct.free_fn],eax
@@:
ret
endp
; This function returns a pointer to the mem_ptr associated with the user
; functions. The application should free any memory associated with this
; pointer before png_write_destroy and png_read_destroy are called.
;voidp (const_structrp png_ptr)
align 4
proc png_get_mem_ptr uses edi, png_ptr:dword
xor eax,eax
mov edi,[png_ptr]
cmp edi,0
je @f ;if (..==0) return 0
mov eax,[edi+png_struct.mem_ptr]
@@:
ret
endp