[libpng16] Start-up code size improvements, error handler flexibility.
These changes alter how the tricky allocation of the initial png_struct and
png_info structures are handled. png_info is now handled in pretty much the
same way as everything else, except that the allocations handle NULL return
silently. png_struct is changed in a similar way on allocation and on
deallocation a 'safety' error handler is put in place (which should never
be required). The error handler itself is changed to permit mismatches
in the application and libpng error buffer size; however, this means a
silent change to the API to return the jmp_buf if the size doesn't match
the size from the libpng compilation; libpng now allocates the memory and
this may fail. Overall these changes result in slight code size
reductions; however, this is a reduction in code that is always executed
so is particularly valuable. Overall on a 64-bit system the libpng DLL
decreases in code size by 1733 bytes. pngerror.o increases in size by
about 465 bytes because of the new functionality.
diff --git a/pngmem.c b/pngmem.c
index 4c14764..daed745 100644
--- a/pngmem.c
+++ b/pngmem.c
@@ -20,106 +20,23 @@
#include "pngpriv.h"
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
-/* Allocate memory for a png_struct or a png_info. The malloc and
- memset can be replaced by a single call to calloc() if this is thought
- to improve performance noticably. */
-PNG_FUNCTION(png_voidp /* PRIVATE */,
-png_create_struct,(int type),PNG_ALLOCATED)
-{
-# ifdef PNG_USER_MEM_SUPPORTED
- return (png_create_struct_2(type, NULL, NULL));
-}
-
-/* Allocate memory for a png_struct or a png_info. The malloc and
- memset can be replaced by a single call to calloc() if this is thought
- to improve performance noticably. */
-PNG_FUNCTION(png_voidp /* PRIVATE */,
-png_create_struct_2,(int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr),
- PNG_ALLOCATED)
-{
-# endif /* PNG_USER_MEM_SUPPORTED */
- png_size_t size;
- png_voidp struct_ptr;
-
- if (type == PNG_STRUCT_INFO)
- size = png_sizeof(png_info);
-
- else if (type == PNG_STRUCT_PNG)
- size = png_sizeof(png_struct);
-
- else
- return (NULL);
-
-# ifdef PNG_USER_MEM_SUPPORTED
- if (malloc_fn != NULL)
- {
- png_struct dummy_struct;
- png_structp png_ptr = &dummy_struct;
- png_ptr->mem_ptr=mem_ptr;
- struct_ptr = (*(malloc_fn))(png_ptr, size);
-
- if (struct_ptr != NULL)
- png_memset(struct_ptr, 0, size);
-
- return (struct_ptr);
- }
-# endif /* PNG_USER_MEM_SUPPORTED */
-
-# if defined(__TURBOC__) && !defined(__FLAT__)
- struct_ptr = (png_voidp)farmalloc(size);
-# else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
- struct_ptr = (png_voidp)halloc(size, 1);
-# else
- struct_ptr = (png_voidp)malloc(size);
-# endif
-# endif
-
- if (struct_ptr != NULL)
- png_memset(struct_ptr, 0, size);
-
- return (struct_ptr);
-}
-
-
-/* Free memory allocated by a png_create_struct() call */
+/* Free a png_struct */
void /* PRIVATE */
-png_destroy_struct(png_voidp struct_ptr)
+png_destroy_png_struct(png_structp png_ptr)
{
-# ifdef PNG_USER_MEM_SUPPORTED
- png_destroy_struct_2(struct_ptr, NULL, NULL);
-}
-
-/* Free memory allocated by a png_create_struct() call */
-void /* PRIVATE */
-png_destroy_struct_2(png_voidp struct_ptr, png_free_ptr free_fn,
- png_voidp mem_ptr)
-{
-# endif /* PNG_USER_MEM_SUPPORTED */
- if (struct_ptr != NULL)
+ if (png_ptr != NULL)
{
-# ifdef PNG_USER_MEM_SUPPORTED
- if (free_fn != NULL)
- {
- png_struct dummy_struct;
- png_structp png_ptr = &dummy_struct;
- png_ptr->mem_ptr=mem_ptr;
- (*(free_fn))(png_ptr, struct_ptr);
- return;
- }
-# endif /* PNG_USER_MEM_SUPPORTED */
-# if defined(__TURBOC__) && !defined(__FLAT__)
- farfree(struct_ptr);
+ /* png_free might call png_error and may certainly call
+ * png_get_mem_ptr, so fake a temporary png_struct to support this.
+ */
+ png_struct dummy_struct = *png_ptr;
+ memset(png_ptr, 0, sizeof *png_ptr);
+ png_free(&dummy_struct, png_ptr);
-# else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
- hfree(struct_ptr);
-
-# else
- free(struct_ptr);
-
-# endif
-# endif
+# ifdef PNG_SETJMP_SUPPORTED
+ /* We may have a jmp_buf left to deallocate. */
+ png_free_jmpbuf(&dummy_struct);
+# endif
}
}
@@ -129,95 +46,107 @@
* need to allocate exactly 64K, so whatever you call here must
* have the ability to do that.
*/
-
PNG_FUNCTION(png_voidp,PNGAPI
png_calloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
{
png_voidp ret;
- ret = (png_malloc(png_ptr, size));
+ ret = png_malloc(png_ptr, size);
if (ret != NULL)
- png_memset(ret,0,(png_size_t)size);
+ png_memset(ret, 0, size);
- return (ret);
+ return ret;
}
+/* 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.)
+ */
+PNG_FUNCTION(png_voidp /* PRIVATE */,
+png_malloc_base,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+{
+ /* 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.
+ */
+ if (size > 0 && size <= ~(size_t)0
+# ifdef PNG_MAX_MALLOC_64K
+ && size <= 65536U
+# endif
+ )
+ {
+ if (png_ptr != NULL && png_ptr->malloc_fn != NULL)
+ return png_ptr->malloc_fn(png_ptr, size);
+
+ else
+ return malloc((size_t)size); /* checked for truncation above */
+ }
+
+ else
+ return NULL;
+}
+
+/* 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.
+ */
PNG_FUNCTION(png_voidp,PNGAPI
png_malloc,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
{
png_voidp ret;
-# ifdef PNG_USER_MEM_SUPPORTED
- if (png_ptr == NULL || size == 0)
- return (NULL);
+ if (png_ptr == NULL)
+ return NULL;
- if (png_ptr->malloc_fn != NULL)
- ret = ((png_voidp)(*(png_ptr->malloc_fn))(png_ptr, (png_size_t)size));
+ ret = png_malloc_base(png_ptr, size);
- else
- ret = (png_malloc_default(png_ptr, size));
+ if (ret == NULL)
+ png_error(png_ptr, "Out of memory"); /* 'm' means png_malloc */
- if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
- png_error(png_ptr, "Out of Memory");
-
- return (ret);
+ return ret;
}
+#ifdef PNG_USER_MEM_SUPPORTED
PNG_FUNCTION(png_voidp,PNGAPI
-png_malloc_default,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+png_malloc_default,(png_structp png_ptr, png_alloc_size_t size),
+ PNG_ALLOCATED PNG_DEPRECATED)
{
png_voidp ret;
-# endif /* PNG_USER_MEM_SUPPORTED */
- if (png_ptr == NULL || size == 0)
- return (NULL);
+ if (png_ptr == NULL)
+ return NULL;
-# ifdef PNG_MAX_MALLOC_64K
- if (size > (png_uint_32)65536L)
+ /* Passing 'NULL' here bypasses the application provided memory handler. */
+ ret = png_malloc_base(NULL/*use malloc*/, size);
+
+ if (ret == NULL)
+ png_error(png_ptr, "Out of Memory"); /* 'M' means png_malloc_default */
+
+ return ret;
+}
+#endif /* PNG_USER_MEM_SUPPORTED */
+
+/* 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.
+ */
+PNG_FUNCTION(png_voidp,PNGAPI
+png_malloc_warn,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
+{
+ if (png_ptr != NULL)
{
-# ifndef PNG_USER_MEM_SUPPORTED
- if ((png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
- png_error(png_ptr, "Cannot Allocate > 64K");
+ png_voidp ret = png_malloc_base(png_ptr, size);
- else
-# endif
- return NULL;
+ if (ret != NULL)
+ return ret;
+
+ png_warning(png_ptr, "Out of memory");
}
-# endif
- /* Check for overflow */
-# if defined(__TURBOC__) && !defined(__FLAT__)
-
- if (size != (unsigned long)size)
- ret = NULL;
-
- else
- ret = farmalloc(size);
-
-# else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
- if (size != (unsigned long)size)
- ret = NULL;
-
- else
- ret = halloc(size, 1);
-
-# else
- if (size != (size_t)size)
- ret = NULL;
-
- else
- ret = malloc((size_t)size);
-# endif
-# endif
-
-# ifndef PNG_USER_MEM_SUPPORTED
- if (ret == NULL && (png_ptr->flags&PNG_FLAG_MALLOC_NULL_MEM_OK) == 0)
- png_error(png_ptr, "Out of Memory");
-# endif
-
- return (ret);
+ return NULL;
}
/* Free a pointer allocated by png_malloc(). If ptr is NULL, return
@@ -229,60 +158,24 @@
if (png_ptr == NULL || ptr == NULL)
return;
-# ifdef PNG_USER_MEM_SUPPORTED
+#ifdef PNG_USER_MEM_SUPPORTED
if (png_ptr->free_fn != NULL)
- {
- (*(png_ptr->free_fn))(png_ptr, ptr);
- return;
- }
+ png_ptr->free_fn(png_ptr, ptr);
else
png_free_default(png_ptr, ptr);
}
-void PNGAPI
-png_free_default(png_structp png_ptr, png_voidp ptr)
+PNG_FUNCTION(void,PNGAPI
+png_free_default,(png_structp png_ptr, png_voidp ptr),PNG_DEPRECATED)
{
if (png_ptr == NULL || ptr == NULL)
return;
+#endif /* PNG_USER_MEM_SUPPORTED */
-# endif /* PNG_USER_MEM_SUPPORTED */
-
-# if defined(__TURBOC__) && !defined(__FLAT__)
- farfree(ptr);
-
-# else
-# if defined(_MSC_VER) && defined(MAXSEG_64K)
- hfree(ptr);
-
-# else
free(ptr);
-
-# endif
-# endif
}
-/* This function was added at libpng version 1.2.3. The png_malloc_warn()
- * function will set up png_malloc() to issue a png_warning and return NULL
- * instead of issuing a png_error, if it fails to allocate the requested
- * memory.
- */
-PNG_FUNCTION(png_voidp,PNGAPI
-png_malloc_warn,(png_structp png_ptr, png_alloc_size_t size),PNG_ALLOCATED)
-{
- png_voidp ptr;
- png_uint_32 save_flags;
- if (png_ptr == NULL)
- return (NULL);
-
- save_flags = png_ptr->flags;
- png_ptr->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK;
- ptr = (png_voidp)png_malloc((png_structp)png_ptr, size);
- png_ptr->flags=save_flags;
- return(ptr);
-}
-
-
#ifdef PNG_USER_MEM_SUPPORTED
/* This function is called when the application wants to use another method
* of allocating and freeing memory.
@@ -307,9 +200,9 @@
png_get_mem_ptr(png_const_structp png_ptr)
{
if (png_ptr == NULL)
- return (NULL);
+ return NULL;
- return ((png_voidp)png_ptr->mem_ptr);
+ return png_ptr->mem_ptr;
}
#endif /* PNG_USER_MEM_SUPPORTED */
#endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */