mewin/libpng
1
0
Fork 0
mirror of https://git.code.sf.net/p/libpng/code.git synced 2025-07-10 18:04:09 +02:00
Code Issues Projects Releases Wiki Activity

[libpng16] Cleaned up and corrected ICC profile handling.

Browse Source 
contrib/libtests/makepng: corrected 'rgb' and 'gray' cases.  profile_error
    messages could be truncated; made a correct buffer size calculation and
    adjusted pngerror.c appropriately. png_icc_check_* checking improved;
    changed the functions to receive the correct color type of the PNG on read
    or write and check that it matches the color space of the profile (despite
    what the comments said before, there is danger in assuming the app will
    cope correctly with an RGB profile on a grayscale image and, since it
    violates the PNG spec, allowing it is certain to produce inconsistent
    app behavior and might even cause app crashes.) Check that profiles
    contain the tags needed to process the PNG (tags all required by the ICC
    spec). Removed unused PNG_STATIC from pngpriv.h.
This commit is contained in:
John Bowler
2012-08-25 16:21:46 -05:00
committed by Glenn Randers-Pehrson
parent 8010217201
commit 14d0ca620e
8 changed files with 185 additions and 45 deletions
Download Patch File Download Diff File Expand all files Collapse all files

165
png.c
View File

@@ -749,13 +749,13 @@ png_get_copyright(png_const_structrp png_ptr)
#else
# ifdef __STDC__
return PNG_STRING_NEWLINE \
"libpng version 1.6.0beta28 - August 22, 2012" PNG_STRING_NEWLINE \
"libpng version 1.6.0beta28 - August 25, 2012" PNG_STRING_NEWLINE \
"Copyright (c) 1998-2012 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
PNG_STRING_NEWLINE;
# else
return "libpng version 1.6.0beta28 - August 22, 2012\
return "libpng version 1.6.0beta28 - August 25, 2012\
Copyright (c) 1998-2012 Glenn Randers-Pehrson\
Copyright (c) 1996-1997 Andreas Dilger\
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -1693,24 +1693,25 @@ profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_alloc_size_t value, png_const_charp reason)
{
size_t pos;
char message[256];
char message[196]; /* see below for calculation */
if (colorspace != NULL)
colorspace->flags |= PNG_COLORSPACE_INVALID;
pos = png_safecat(message, (sizeof message), 0, "profile '");
pos = png_safecat(message, pos+79, pos, name);
pos = png_safecat(message, (sizeof message), pos, "': ");
pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
# ifdef PNG_WARNINGS_SUPPORTED
{
char number[PNG_NUMBER_BUFFER_SIZE];
char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
pos = png_safecat(message, (sizeof message), pos,
png_format_number(number, number+(sizeof number),
PNG_NUMBER_FORMAT_x, value));
}
pos = png_safecat(message, (sizeof message), pos, ": ");
pos = png_safecat(message, (sizeof message), pos, "h: "); /* +2 = 116 */
# endif
/* The 'reason' is an arbitrary message, allow +79 maximum 195 */
pos = png_safecat(message, (sizeof message), pos, reason);
if (colorspace != NULL)
@@ -1874,7 +1875,7 @@ png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
int /* PRIVATE */
png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_uint_32 profile_length,
png_const_bytep profile/* first 132 bytes only */)
png_const_bytep profile/* first 132 bytes only */, int color_type)
{
png_uint_32 temp;
@@ -1930,16 +1931,37 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
* 6), or a greyscale colour space for greyscale images (PNG colour types 0
* and 4)."
*
* This code does not check the color type because png_set_iCCP may be called
* before png_set_IHDR on write and because, anyway, the PNG spec is
* fundamentally flawed: RGB profiles can be used quite meaningfully for
* grayscale images and both RGB and palette images might only have gray
* colors in them, so gray profiles may be appropriate.
* This checking code ensures the embedded profile (on either read or write)
* conforms to the specification requirements. Notice that an ICC 'gray'
* color-space profile contains the information to transform the monochrome
* data to XYZ or L*a*b (according to which PCS the profile uses) and this
* should be used in preference to the standard libpng K channel replication
* into R, G and B channels.
*
* Previously it was suggested that an RGB profile on grayscale data could be
* handled. However it it is clear that using an RGB profile in this context
* must be an error - there is no specification of what it means. Thus it is
* almost certainly more correct to ignore the profile.
*/
temp = png_get_uint_32(profile+16); /* data colour space field */
if (temp != 0x52474220 /* 'RGB ' */ && temp != 0x47524159 /* 'GRAY' */)
return profile_error(png_ptr, colorspace, name, temp,
"invalid color space");
switch (temp)
{
case 0x52474220: /* 'RGB ' */
if (!(color_type & PNG_COLOR_MASK_COLOR))
return profile_error(png_ptr, colorspace, name, temp,
"RGB color space not permitted on grayscale PNG");
break;
case 0x47524159: /* 'GRAY' */
if (color_type & PNG_COLOR_MASK_COLOR)
return profile_error(png_ptr, colorspace, name, temp,
"Gray color space not permitted on RGB PNG");
break;
default:
return profile_error(png_ptr, colorspace, name, temp,
"invalid color space");
}
/* It is up to the application to check that the profile class matches the
* application requirements; the spec provides no guidance, but it's pretty
@@ -1956,13 +1978,16 @@ png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
{
if (temp == 0x6C696E6B /* 'link' */ || temp == 0x61627374 /* 'abst' */)
return profile_error(png_ptr, colorspace, name, temp,
"invalid class");
"invalid ICC profile class");
/* This can only be 0x6E6D636C: a 'nmcl' profile. This is a device
* specific profile.
* specific profile. The checks on the tags below will ensure that it can
* actually be used, but it certainly is not expected and is probably an
* error.
*/
else
(void)profile_error(png_ptr, NULL, name, temp, "unexpected ICC class");
(void)profile_error(png_ptr, NULL, name, temp,
"unexpected ICC profile class");
}
return 1;
@@ -1976,6 +2001,16 @@ png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_uint_32 tag_count = png_get_uint_32(profile+128);
png_uint_32 itag;
png_const_bytep tag = profile+132; /* The first tag */
int have_AToB0Tag = 0; /* Whether the profile has an AToB0Tag */
int have_grayTRCTag = 0; /* Whether the profile has a grayTRCTag */
unsigned int matrix_TRC_tags = 0; /* Which matrix/TRC tags are present */
# define HAVE_redMatrixColumnTag 0x01
# define HAVE_greenMatrixColumnTag 0x02
# define HAVE_blueMatrixColumnTag 0x04
# define HAVE_redTRCTag 0x10
# define HAVE_greenTRCTag 0x20
# define HAVE_blueTRCTag 0x40
# define HAVE_all_tags 0x77
for (itag=0; itag < tag_count; ++itag, tag += 12)
{
@@ -1992,9 +2027,90 @@ png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
tag_length > profile_length - tag_start)
return profile_error(png_ptr, colorspace, name, tag_id,
"tag data outside profile");
/* Check the tag_id for the specific profiles which must be present for
* the profile to be valid.
*/
switch (tag_id)
{
case 0x41324230: /* 'A2B0' - AToB0Tag */
have_AToB0Tag = 1;
break;
case 0x6B545243: /* 'kTRC' - grayTRCTag */
have_grayTRCTag = 1;
break;
case 0x7258595A: /* 'rXYZ' - redMatrixColumnTag */
matrix_TRC_tags |= HAVE_redMatrixColumnTag;
break;
case 0x72545243: /* 'rTRC' - redTRCTag */
matrix_TRC_tags |= HAVE_redTRCTag;
break;
case 0x6758595A: /* 'gXYZ' - greenMatrixColumnTag */
matrix_TRC_tags |= HAVE_greenMatrixColumnTag;
break;
case 0x67545243: /* 'gTRC' - greenTRCTag */
matrix_TRC_tags |= HAVE_greenTRCTag;
break;
case 0x6258595A: /* 'bXYZ' - blueMatrixColumnTag */
matrix_TRC_tags |= HAVE_blueMatrixColumnTag;
break;
case 0x62545243: /* 'bTRC' - blueTRCTag */
matrix_TRC_tags |= HAVE_blueTRCTag;
break;
default:
break;
}
}
return 1;
/* An AToB0Tag works in all valid profiles, but if it is absent then
* something matching the profile class and color space must be present.
*/
if (!have_AToB0Tag)
{
png_uint_32 profile_class = png_get_uint_32(profile+12);
switch (profile_class)
{
case 0x73636E72: /* 'scnr' - an input profile */
case 0x6D6E7472: /* 'mntr' - a display device profile */
case 0x70727472: /* 'prtr' - an output device profile */
if (png_get_uint_32(profile+16) /* color space */ ==
0x47524159 /* gray */)
{
if (!have_grayTRCTag)
return profile_error(png_ptr, colorspace, name, profile_class,
"missing grayTRCTag for monochrome profile");
}
else
{
if (matrix_TRC_tags != HAVE_all_tags)
return profile_error(png_ptr, colorspace, name, profile_class,
"missing Matrix/TRC tags for RGB profile");
}
return 1;
case 0x73706163: /* 'spac' */
return profile_error(png_ptr, colorspace, name, profile_class,
"missing AToB0Tag for colorspace profile");
default: /* should have been checked before */
png_error(png_ptr, "invalid ICC class");
return 0; /* NOT REACHED */
}
}
else
return 1;
}
#ifdef PNG_sRGB_SUPPORTED
@@ -2192,14 +2308,15 @@ png_icc_set_gAMA_and_cHRM(png_const_structrp png_ptr,
int /* PRIVATE */
png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_uint_32 profile_length,
png_const_bytep profile, int preferred)
png_const_bytep profile, int preferred, int color_type)
{
if (colorspace->flags & PNG_COLORSPACE_INVALID)
return 0;
if (png_icc_check_length(png_ptr, colorspace, name, profile_length) &&
png_icc_check_header(png_ptr, colorspace, name, profile_length, profile)
&& png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
color_type) &&
png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
profile))
{
png_icc_set_gAMA_and_cHRM(png_ptr, colorspace, name, profile, 0,