mirror of
https://github.com/openharmony/third_party_libpng.git
synced 2026-07-01 09:25:04 -04:00
zhwang0
112 lines
3.5 KiB
Diff
112 lines
3.5 KiB
Diff
diff --git a/pngread.c b/pngread.c
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index a7a644e..7f9c5de 100644
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--- a/pngread.c
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+++ b/pngread.c
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@@ -3521,6 +3521,54 @@ png_image_read_colormapped(png_voidp argument)
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}
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}
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+/* Row reading for interlaced 16-to-8 bit depth conversion with local buffer. */
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+static int
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+png_image_read_direct_scaled(png_voidp argument)
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+{
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+ png_image_read_control *display = png_voidcast(png_image_read_control*,
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+ argument);
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+ png_imagep image = display->image;
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+ png_structrp png_ptr = image->opaque->png_ptr;
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+ png_bytep local_row = png_voidcast(png_bytep, display->local_row);
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+ png_bytep first_row = png_voidcast(png_bytep, display->first_row);
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+ ptrdiff_t row_bytes = display->row_bytes;
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+ int passes;
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+
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+ /* Handle interlacing. */
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+ switch (png_ptr->interlaced)
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+ {
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+ case PNG_INTERLACE_NONE:
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+ passes = 1;
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+ break;
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+
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+ case PNG_INTERLACE_ADAM7:
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+ passes = PNG_INTERLACE_ADAM7_PASSES;
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+ break;
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+
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+ default:
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+ png_error(png_ptr, "unknown interlace type");
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+ }
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+
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+ /* Read each pass using local_row as intermediate buffer. */
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+ while (--passes >= 0)
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+ {
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+ png_uint_32 y = image->height;
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+ png_bytep output_row = first_row;
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+
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+ for (; y > 0; --y)
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+ {
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+ /* Read into local_row (gets transformed 8-bit data). */
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+ png_read_row(png_ptr, local_row, NULL);
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+
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+ /* Copy from local_row to user buffer. */
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+ memcpy(output_row, local_row, (size_t)row_bytes);
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+ output_row += row_bytes;
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+ }
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+ }
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+
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+ return 1;
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+}
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+
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/* Just the row reading part of png_image_read. */
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static int
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png_image_read_composite(png_voidp argument)
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@@ -3942,6 +3990,7 @@ png_image_read_direct(png_voidp argument)
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int linear = (format & PNG_FORMAT_FLAG_LINEAR) != 0;
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int do_local_compose = 0;
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int do_local_background = 0; /* to avoid double gamma correction bug */
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+ int do_local_scale = 0; /* for interlaced 16-to-8 bit conversion */
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int passes = 0;
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/* Add transforms to ensure the correct output format is produced then check
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@@ -4068,8 +4117,16 @@ png_image_read_direct(png_voidp argument)
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png_set_expand_16(png_ptr);
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else /* 8-bit output */
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+ {
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png_set_scale_16(png_ptr);
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+ /* For interlaced images, use local_row buffer to avoid overflow
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+ * in png_combine_row() which writes using IHDR bit-depth.
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+ */
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+ if (png_ptr->interlaced != 0)
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+ do_local_scale = 1;
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+ }
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+
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change &= ~PNG_FORMAT_FLAG_LINEAR;
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}
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@@ -4345,6 +4402,24 @@ png_image_read_direct(png_voidp argument)
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return result;
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}
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+ else if (do_local_scale != 0)
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+ {
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+ /* For interlaced 16-to-8 conversion, use an intermediate row buffer
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+ * to avoid buffer overflows in png_combine_row. The local_row is sized
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+ * for the transformed (8-bit) output, preventing the overflow that would
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+ * occur if png_combine_row wrote 16-bit data directly to the user buffer.
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+ */
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+ int result;
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+ png_voidp row = png_malloc(png_ptr, png_get_rowbytes(png_ptr, info_ptr));
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+
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+ display->local_row = row;
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+ result = png_safe_execute(image, png_image_read_direct_scaled, display);
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+ display->local_row = NULL;
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+ png_free(png_ptr, row);
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+
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+ return result;
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+ }
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+
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else
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{
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png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
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--
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