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Remove top-level const from function-scope variables

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As per the const correctness rules, top-level const-ness of data
in automatic scopes does not propagate outside of these scopes
(unlike const-ness at lower levels, such as pointers to const data).

Previously, const was used liberally, but inconsistently across the
libpng codebase. Using const wherever applicable is not incorrect.
However, _consistent_ use of const is difficult to maintain in such
conditions.

In conclusion, we shall continue to use const only where doing so is
strictly necessary:

1. If a function guarantees that it will not modify an argument
   passed by pointer, the corresponding function parameter should be
   a pointer-to-const (const T *).

2. Static data should not be modified, therefore it should be const.

Reference:
Google C++ Style Guide
https://google.github.io/styleguide/cppguide.html#Use_of_const
This commit is contained in:
Cosmin Truta
2018-08-18 22:47:16 -04:00
parent 1ef8882814
commit ceb327789b
22 changed files with 196 additions and 205 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
pngwrite.c
View File

@@ -1536,7 +1536,7 @@ png_write_image_16bit(png_voidp argument)
display->first_row);
png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
png_uint_16p row_end;
const unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
3 : 1;
int aindex = 0;
png_uint_32 y = image->height;
@@ -1573,7 +1573,7 @@ png_write_image_16bit(png_voidp argument)
while (out_ptr < row_end)
{
const png_uint_16 alpha = in_ptr[aindex];
png_uint_16 alpha = in_ptr[aindex];
png_uint_32 reciprocal = 0;
int c;
@@ -1695,7 +1695,7 @@ png_write_image_8bit(png_voidp argument)
display->first_row);
png_bytep output_row = png_voidcast(png_bytep, display->local_row);
png_uint_32 y = image->height;
const unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
3 : 1;
if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
@@ -1783,25 +1783,25 @@ png_write_image_8bit(png_voidp argument)
static void
png_image_set_PLTE(png_image_write_control *display)
{
const png_imagep image = display->image;
png_imagep image = display->image;
const void *cmap = display->colormap;
const int entries = image->colormap_entries > 256 ? 256 :
int entries = image->colormap_entries > 256 ? 256 :
(int)image->colormap_entries;
/* NOTE: the caller must check for cmap != NULL and entries != 0 */
const png_uint_32 format = image->format;
const unsigned int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
png_uint_32 format = image->format;
unsigned int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
# if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
const int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
int afirst = (format & PNG_FORMAT_FLAG_AFIRST) != 0 &&
(format & PNG_FORMAT_FLAG_ALPHA) != 0;
# else
# define afirst 0
# endif
# ifdef PNG_FORMAT_BGR_SUPPORTED
const int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
int bgr = (format & PNG_FORMAT_FLAG_BGR) != 0 ? 2 : 0;
# else
# define bgr 0
# endif
@@ -1951,12 +1951,12 @@ png_image_write_main(png_voidp argument)
* and total image size to ensure that they are within the system limits.
*/
{
const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
if (image->width <= 0x7fffffffU/channels) /* no overflow */
{
png_uint_32 check;
const png_uint_32 png_row_stride = image->width * channels;
png_uint_32 png_row_stride = image->width * channels;
if (display->row_stride == 0)
display->row_stride = (png_int_32)/*SAFE*/png_row_stride;
@@ -2052,7 +2052,7 @@ png_image_write_main(png_voidp argument)
*/
if (write_16bit != 0)
{
const png_uint_16 le = 0x0001;
png_uint_16 le = 0x0001;
if ((*(png_const_bytep) & le) != 0)
png_set_swap(png_ptr);
@@ -2166,7 +2166,7 @@ image_memory_write)(png_structp png_ptr, png_bytep/*const*/ data, size_t size)
{
png_image_write_control *display = png_voidcast(png_image_write_control*,
png_ptr->io_ptr/*backdoor: png_get_io_ptr(png_ptr)*/);
const png_alloc_size_t ob = display->output_bytes;
png_alloc_size_t ob = display->output_bytes;
/* Check for overflow; this should never happen: */
if (size <= ((png_alloc_size_t)-1) - ob)