+#ifdef PNG_READ_SUPPORTED
+void /* PRIVATE */
+png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
+{
+ if (info_ptr == NULL) /* reduce code size; check here not in the caller */
+ return;
+
+ info_ptr->colorspace = png_ptr->colorspace;
+ png_colorspace_sync_info(png_ptr, info_ptr);
+}
+#endif
+#endif
+
+#ifdef PNG_COLORSPACE_SUPPORTED
+/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
+ * cHRM, as opposed to using chromaticities. These internal APIs return
+ * non-zero on a parameter error. The X, Y and Z values are required to be
+ * positive and less than 1.0.
+ */
+static int
+png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
+{
+ png_int_32 d, dwhite, whiteX, whiteY;
+
+ d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
+ if (!png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d)) return 1;
+ if (!png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d)) return 1;
+ dwhite = d;
+ whiteX = XYZ->red_X;
+ whiteY = XYZ->red_Y;
+
+ d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
+ if (!png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d)) return 1;
+ if (!png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d)) return 1;
+ dwhite += d;
+ whiteX += XYZ->green_X;
+ whiteY += XYZ->green_Y;
+
+ d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
+ if (!png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d)) return 1;
+ if (!png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d)) return 1;
+ dwhite += d;
+ whiteX += XYZ->blue_X;
+ whiteY += XYZ->blue_Y;
+
+ /* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
+ * thus:
+ */
+ if (!png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite)) return 1;
+ if (!png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite)) return 1;
+
+ return 0;
+}
+
+static int
+png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
+{
+ png_fixed_point red_inverse, green_inverse, blue_scale;
+ png_fixed_point left, right, denominator;
+
+ /* Check xy and, implicitly, z. Note that wide gamut color spaces typically
+ * have end points with 0 tristimulus values (these are impossible end
+ * points, but they are used to cover the possible colors.)
+ */
+ if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
+ if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
+ if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
+ if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
+ if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
+ if (xy->bluey < 0 || xy->bluey > PNG_FP_1-xy->bluex) return 1;
+ if (xy->whitex < 0 || xy->whitex > PNG_FP_1) return 1;
+ if (xy->whitey < 0 || xy->whitey > PNG_FP_1-xy->whitex) return 1;
+
+ /* The reverse calculation is more difficult because the original tristimulus
+ * value had 9 independent values (red,green,blue)x(X,Y,Z) however only 8
+ * derived values were recorded in the cHRM chunk;
+ * (red,green,blue,white)x(x,y). This loses one degree of freedom and
+ * therefore an arbitrary ninth value has to be introduced to undo the
+ * original transformations.
+ *
+ * Think of the original end-points as points in (X,Y,Z) space. The
+ * chromaticity values (c) have the property:
+ *
+ * C
+ * c = ---------
+ * X + Y + Z
+ *
+ * For each c (x,y,z) from the corresponding original C (X,Y,Z). Thus the
+ * three chromaticity values (x,y,z) for each end-point obey the
+ * relationship:
+ *
+ * x + y + z = 1
+ *
+ * This describes the plane in (X,Y,Z) space that intersects each axis at the
+ * value 1.0; call this the chromaticity plane. Thus the chromaticity
+ * calculation has scaled each end-point so that it is on the x+y+z=1 plane
+ * and chromaticity is the intersection of the vector from the origin to the
+ * (X,Y,Z) value with the chromaticity plane.
+ *
+ * To fully invert the chromaticity calculation we would need the three
+ * end-point scale factors, (red-scale, green-scale, blue-scale), but these
+ * were not recorded. Instead we calculated the reference white (X,Y,Z) and
+ * recorded the chromaticity of this. The reference white (X,Y,Z) would have
+ * given all three of the scale factors since:
+ *
+ * color-C = color-c * color-scale
+ * white-C = red-C + green-C + blue-C
+ * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
+ *
+ * But cHRM records only white-x and white-y, so we have lost the white scale
+ * factor:
+ *
+ * white-C = white-c*white-scale
+ *
+ * To handle this the inverse transformation makes an arbitrary assumption
+ * about white-scale:
+ *
+ * Assume: white-Y = 1.0
+ * Hence: white-scale = 1/white-y
+ * Or: red-Y + green-Y + blue-Y = 1.0
+ *
+ * Notice the last statement of the assumption gives an equation in three of
+ * the nine values we want to calculate. 8 more equations come from the
+ * above routine as summarised at the top above (the chromaticity
+ * calculation):
+ *
+ * Given: color-x = color-X / (color-X + color-Y + color-Z)
+ * Hence: (color-x - 1)*color-X + color.x*color-Y + color.x*color-Z = 0
+ *
+ * This is 9 simultaneous equations in the 9 variables "color-C" and can be
+ * solved by Cramer's rule. Cramer's rule requires calculating 10 9x9 matrix
+ * determinants, however this is not as bad as it seems because only 28 of
+ * the total of 90 terms in the various matrices are non-zero. Nevertheless
+ * Cramer's rule is notoriously numerically unstable because the determinant
+ * calculation involves the difference of large, but similar, numbers. It is
+ * difficult to be sure that the calculation is stable for real world values
+ * and it is certain that it becomes unstable where the end points are close
+ * together.
+ *
+ * So this code uses the perhaps slightly less optimal but more
+ * understandable and totally obvious approach of calculating color-scale.
+ *
+ * This algorithm depends on the precision in white-scale and that is
+ * (1/white-y), so we can immediately see that as white-y approaches 0 the
+ * accuracy inherent in the cHRM chunk drops off substantially.
+ *
+ * libpng arithmetic: a simple invertion of the above equations
+ * ------------------------------------------------------------
+ *
+ * white_scale = 1/white-y
+ * white-X = white-x * white-scale
+ * white-Y = 1.0
+ * white-Z = (1 - white-x - white-y) * white_scale
+ *
+ * white-C = red-C + green-C + blue-C
+ * = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
+ *
+ * This gives us three equations in (red-scale,green-scale,blue-scale) where
+ * all the coefficients are now known:
+ *
+ * red-x*red-scale + green-x*green-scale + blue-x*blue-scale
+ * = white-x/white-y
+ * red-y*red-scale + green-y*green-scale + blue-y*blue-scale = 1
+ * red-z*red-scale + green-z*green-scale + blue-z*blue-scale
+ * = (1 - white-x - white-y)/white-y
+ *
+ * In the last equation color-z is (1 - color-x - color-y) so we can add all
+ * three equations together to get an alternative third:
+ *
+ * red-scale + green-scale + blue-scale = 1/white-y = white-scale
+ *
+ * So now we have a Cramer's rule solution where the determinants are just
+ * 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
+ * multiplication of three coefficients so we can't guarantee to avoid
+ * overflow in the libpng fixed point representation. Using Cramer's rule in
+ * floating point is probably a good choice here, but it's not an option for
+ * fixed point. Instead proceed to simplify the first two equations by
+ * eliminating what is likely to be the largest value, blue-scale:
+ *
+ * blue-scale = white-scale - red-scale - green-scale
+ *
+ * Hence:
+ *
+ * (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
+ * (white-x - blue-x)*white-scale
+ *
+ * (red-y - blue-y)*red-scale + (green-y - blue-y)*green-scale =
+ * 1 - blue-y*white-scale
+ *
+ * And now we can trivially solve for (red-scale,green-scale):
+ *
+ * green-scale =
+ * (white-x - blue-x)*white-scale - (red-x - blue-x)*red-scale
+ * -----------------------------------------------------------
+ * green-x - blue-x
+ *
+ * red-scale =
+ * 1 - blue-y*white-scale - (green-y - blue-y) * green-scale
+ * ---------------------------------------------------------
+ * red-y - blue-y
+ *
+ * Hence:
+ *
+ * red-scale =
+ * ( (green-x - blue-x) * (white-y - blue-y) -
+ * (green-y - blue-y) * (white-x - blue-x) ) / white-y
+ * -------------------------------------------------------------------------
+ * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
+ *
+ * green-scale =
+ * ( (red-y - blue-y) * (white-x - blue-x) -
+ * (red-x - blue-x) * (white-y - blue-y) ) / white-y
+ * -------------------------------------------------------------------------
+ * (green-x - blue-x)*(red-y - blue-y)-(green-y - blue-y)*(red-x - blue-x)
+ *
+ * Accuracy:
+ * The input values have 5 decimal digits of accuracy. The values are all in
+ * the range 0 < value < 1, so simple products are in the same range but may
+ * need up to 10 decimal digits to preserve the original precision and avoid
+ * underflow. Because we are using a 32-bit signed representation we cannot
+ * match this; the best is a little over 9 decimal digits, less than 10.
+ *
+ * The approach used here is to preserve the maximum precision within the
+ * signed representation. Because the red-scale calculation above uses the
+ * difference between two products of values that must be in the range -1..+1
+ * it is sufficient to divide the product by 7; ceil(100,000/32767*2). The
+ * factor is irrelevant in the calculation because it is applied to both
+ * numerator and denominator.
+ *
+ * Note that the values of the differences of the products of the
+ * chromaticities in the above equations tend to be small, for example for
+ * the sRGB chromaticities they are:
+ *
+ * red numerator: -0.04751
+ * green numerator: -0.08788
+ * denominator: -0.2241 (without white-y multiplication)
+ *
+ * The resultant Y coefficients from the chromaticities of some widely used
+ * color space definitions are (to 15 decimal places):
+ *
+ * sRGB
+ * 0.212639005871510 0.715168678767756 0.072192315360734
+ * Kodak ProPhoto
+ * 0.288071128229293 0.711843217810102 0.000085653960605
+ * Adobe RGB
+ * 0.297344975250536 0.627363566255466 0.075291458493998
+ * Adobe Wide Gamut RGB
+ * 0.258728243040113 0.724682314948566 0.016589442011321
+ */
+ /* By the argument, above overflow should be impossible here. The return
+ * value of 2 indicates an internal error to the caller.
+ */
+ if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7))
+ return 2;
+ if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7))
+ return 2;
+ denominator = left - right;
+
+ /* Now find the red numerator. */
+ if (!png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7))
+ return 2;
+ if (!png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7))
+ return 2;
+
+ /* Overflow is possible here and it indicates an extreme set of PNG cHRM
+ * chunk values. This calculation actually returns the reciprocal of the
+ * scale value because this allows us to delay the multiplication of white-y
+ * into the denominator, which tends to produce a small number.
+ */
+ if (!png_muldiv(&red_inverse, xy->whitey, denominator, left-right) ||
+ red_inverse <= xy->whitey /* r+g+b scales = white scale */)
+ return 1;
+
+ /* Similarly for green_inverse: */
+ if (!png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7))
+ return 2;
+ if (!png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7))
+ return 2;
+ if (!png_muldiv(&green_inverse, xy->whitey, denominator, left-right) ||
+ green_inverse <= xy->whitey)
+ return 1;
+
+ /* And the blue scale, the checks above guarantee this can't overflow but it
+ * can still produce 0 for extreme cHRM values.
+ */
+ blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
+ png_reciprocal(green_inverse);
+ if (blue_scale <= 0) return 1;
+
+
+ /* And fill in the png_XYZ: */
+ if (!png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse)) return 1;
+ if (!png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse)) return 1;
+ if (!png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
+ red_inverse))
+ return 1;
+
+ if (!png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse))
+ return 1;
+ if (!png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse))
+ return 1;
+ if (!png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
+ green_inverse))
+ return 1;
+
+ if (!png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1)) return 1;
+ if (!png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1)) return 1;
+ if (!png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
+ PNG_FP_1))
+ return 1;
+
+ return 0; /*success*/
+}
+
+static int
+png_XYZ_normalize(png_XYZ *XYZ)
+{
+ png_int_32 Y;
+
+ if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
+ XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
+ XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
+ return 1;
+
+ /* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
+ * IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
+ * relying on addition of two positive values producing a negative one is not
+ * safe.
+ */
+ Y = XYZ->red_Y;
+ if (0x7fffffff - Y < XYZ->green_X) return 1;
+ Y += XYZ->green_Y;
+ if (0x7fffffff - Y < XYZ->blue_X) return 1;
+ Y += XYZ->blue_Y;
+
+ if (Y != PNG_FP_1)
+ {
+ if (!png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y)) return 1;
+
+ if (!png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y)) return 1;
+
+ if (!png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y)) return 1;
+ if (!png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y)) return 1;
+ }
+
+ return 0;
+}
+
+static int
+png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
+{
+ /* Allow an error of +/-0.01 (absolute value) on each chromaticity */
+ return !(PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
+ PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
+ PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
+ PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
+ PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
+ PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
+ PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
+ PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta));
+}
+
+/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
+ * chunk chromaticities. Earlier checks used to simply look for the overflow
+ * condition (where the determinant of the matrix to solve for XYZ ends up zero
+ * because the chromaticity values are not all distinct.) Despite this it is
+ * theoretically possible to produce chromaticities that are apparently valid
+ * but that rapidly degrade to invalid, potentially crashing, sets because of
+ * arithmetic inaccuracies when calculations are performed on them. The new
+ * check is to round-trip xy -> XYZ -> xy and then check that the result is
+ * within a small percentage of the original.
+ */
+static int
+png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
+{
+ int result;
+ png_xy xy_test;
+
+ /* As a side-effect this routine also returns the XYZ endpoints. */
+ result = png_XYZ_from_xy(XYZ, xy);
+ if (result) return result;
+
+ result = png_xy_from_XYZ(&xy_test, XYZ);
+ if (result) return result;
+
+ if (png_colorspace_endpoints_match(xy, &xy_test,
+ 5/*actually, the math is pretty accurate*/))
+ return 0;
+
+ /* Too much slip */
+ return 1;
+}
+
+/* This is the check going the other way. The XYZ is modified to normalize it
+ * (another side-effect) and the xy chromaticities are returned.
+ */
+static int
+png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
+{
+ int result;
+ png_XYZ XYZtemp;
+
+ result = png_XYZ_normalize(XYZ);
+ if (result) return result;
+
+ result = png_xy_from_XYZ(xy, XYZ);
+ if (result) return result;
+
+ XYZtemp = *XYZ;
+ return png_colorspace_check_xy(&XYZtemp, xy);
+}
+
+/* Used to check for an endpoint match against sRGB */
+static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
+{
+ /* color x y */
+ /* red */ 64000, 33000,
+ /* green */ 30000, 60000,
+ /* blue */ 15000, 6000,
+ /* white */ 31270, 32900
+};
+
+static int
+png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
+ int preferred)
+{
+ if (colorspace->flags & PNG_COLORSPACE_INVALID)
+ return 0;
+
+ /* The consistency check is performed on the chromaticities; this factors out
+ * variations because of the normalization (or not) of the end point Y
+ * values.
+ */
+ if (preferred < 2 && (colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS))
+ {
+ /* The end points must be reasonably close to any we already have. The
+ * following allows an error of up to +/-.001
+ */
+ if (!png_colorspace_endpoints_match(xy, &colorspace->end_points_xy, 100))
+ {
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "inconsistent chromaticities");
+ return 0; /* failed */
+ }
+
+ /* Only overwrite with preferred values */
+ if (!preferred)
+ return 1; /* ok, but no change */
+ }
+
+ colorspace->end_points_xy = *xy;
+ colorspace->end_points_XYZ = *XYZ;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
+
+ /* The end points are normally quoted to two decimal digits, so allow +/-0.01
+ * on this test.
+ */
+ if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000))
+ colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
+
+ else
+ colorspace->flags &= PNG_COLORSPACE_CANCEL(
+ PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+ return 2; /* ok and changed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_chromaticities(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_xy *xy, int preferred)
+{
+ /* We must check the end points to ensure they are reasonable - in the past
+ * color management systems have crashed as a result of getting bogus
+ * colorant values, while this isn't the fault of libpng it is the
+ * responsibility of libpng because PNG carries the bomb and libpng is in a
+ * position to protect against it.
+ */
+ png_XYZ XYZ;
+
+ switch (png_colorspace_check_xy(&XYZ, xy))
+ {
+ case 0: /* success */
+ return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
+ preferred);
+
+ case 1:
+ /* We can't invert the chromaticities so we can't produce value XYZ
+ * values. Likely as not a color management system will fail too.
+ */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "invalid chromaticities");
+ break;
+
+ default:
+ /* libpng is broken; this should be a warning but if it happens we
+ * want error reports so for the moment it is an error.
+ */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_error(png_ptr, "internal error checking chromaticities");
+ break;
+ }
+
+ return 0; /* failed */
+}
+
+int /* PRIVATE */
+png_colorspace_set_endpoints(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
+{
+ png_XYZ XYZ = *XYZ_in;
+ png_xy xy;
+
+ switch (png_colorspace_check_XYZ(&xy, &XYZ))
+ {
+ case 0:
+ return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
+ preferred);
+
+ case 1:
+ /* End points are invalid. */
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_benign_error(png_ptr, "invalid end points");
+ break;
+
+ default:
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+ png_error(png_ptr, "internal error checking chromaticities");
+ break;
+ }
+
+ return 0; /* failed */
+}
+
+#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
+/* Error message generation */
+static char
+png_icc_tag_char(png_uint_32 byte)
+{
+ byte &= 0xff;
+ if (byte >= 32 && byte <= 126)
+ return (char)byte;
+ else
+ return '?';
+}
+
+static void
+png_icc_tag_name(char *name, png_uint_32 tag)
+{
+ name[0] = '\'';
+ name[1] = png_icc_tag_char(tag >> 24);
+ name[2] = png_icc_tag_char(tag >> 16);
+ name[3] = png_icc_tag_char(tag >> 8);
+ name[4] = png_icc_tag_char(tag );
+ name[5] = '\'';
+}
+
+static int
+is_ICC_signature_char(png_alloc_size_t it)
+{
+ return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
+ (it >= 97 && it <= 122);
+}
+
+static int is_ICC_signature(png_alloc_size_t it)
+{
+ return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
+ is_ICC_signature_char((it >> 16) & 0xff) &&
+ is_ICC_signature_char((it >> 8) & 0xff) &&
+ is_ICC_signature_char(it & 0xff);
+}
+
+static int
+png_icc_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[196]; /* see below for calculation */
+
+ if (colorspace != NULL)
+ colorspace->flags |= PNG_COLORSPACE_INVALID;
+
+ 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 */
+ if (is_ICC_signature(value))
+ {
+ /* So 'value' is at most 4 bytes and the following cast is safe */
+ png_icc_tag_name(message+pos, (png_uint_32)value);
+ pos += 6; /* total +8; less than the else clause */
+ message[pos++] = ':';
+ message[pos++] = ' ';
+ }
+# ifdef PNG_WARNINGS_SUPPORTED
+ else
+ {
+ 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, "h: "); /*+2 = 116*/
+ }
+# endif
+ /* The 'reason' is an arbitrary message, allow +79 maximum 195 */
+ pos = png_safecat(message, (sizeof message), pos, reason);
+
+ /* This is recoverable, but make it unconditionally an app_error on write to
+ * avoid writing invalid ICC profiles into PNG files. (I.e. we handle them
+ * on read, with a warning, but on write unless the app turns off
+ * application errors the PNG won't be written.)
+ */
+ png_chunk_report(png_ptr, message,
+ (colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
+
+ return 0;
+}
+#endif /* sRGB || iCCP */
+
+#ifdef PNG_sRGB_SUPPORTED
+int /* PRIVATE */
+png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ int intent)
+{
+ /* sRGB sets known gamma, end points and (from the chunk) intent. */
+ /* IMPORTANT: these are not necessarily the values found in an ICC profile
+ * because ICC profiles store values adapted to a D50 environment; it is
+ * expected that the ICC profile mediaWhitePointTag will be D50, see the
+ * checks and code elsewhere to understand this better.
+ *
+ * These XYZ values, which are accurate to 5dp, produce rgb to gray
+ * coefficients of (6968,23435,2366), which are reduced (because they add up
+ * to 32769 not 32768) to (6968,23434,2366). These are the values that
+ * libpng has traditionally used (and are the best values given the 15bit
+ * algorithm used by the rgb to gray code.)
+ */
+ static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
+ {
+ /* color X Y Z */
+ /* red */ 41239, 21264, 1933,
+ /* green */ 35758, 71517, 11919,
+ /* blue */ 18048, 7219, 95053
+ };
+
+ /* Do nothing if the colorspace is already invalidated. */
+ if (colorspace->flags & PNG_COLORSPACE_INVALID)
+ return 0;
+
+ /* Check the intent, then check for existing settings. It is valid for the
+ * PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
+ * be consistent with the correct values. If, however, this function is
+ * called below because an iCCP chunk matches sRGB then it is quite
+ * conceivable that an older app recorded incorrect gAMA and cHRM because of
+ * an incorrect calculation based on the values in the profile - this does
+ * *not* invalidate the profile (though it still produces an error, which can
+ * be ignored.)
+ */
+ if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
+ return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+ (unsigned)intent, "invalid sRGB rendering intent");
+
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
+ colorspace->rendering_intent != intent)
+ return png_icc_profile_error(png_ptr, colorspace, "sRGB",
+ (unsigned)intent, "inconsistent rendering intents");
+
+ if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
+ {
+ png_benign_error(png_ptr, "duplicate sRGB information ignored");
+ return 0;
+ }
+
+ /* If the standard sRGB cHRM chunk does not match the one from the PNG file
+ * warn but overwrite the value with the correct one.
+ */
+ if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
+ !png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
+ 100))
+ png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
+ PNG_CHUNK_ERROR);
+
+ /* This check is just done for the error reporting - the routine always
+ * returns true when the 'from' argument corresponds to sRGB (2).
+ */
+ (void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
+ 2/*from sRGB*/);
+
+ /* intent: bugs in GCC force 'int' to be used as the parameter type. */
+ colorspace->rendering_intent = (png_uint_16)intent;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
+
+ /* endpoints */
+ colorspace->end_points_xy = sRGB_xy;
+ colorspace->end_points_XYZ = sRGB_XYZ;
+ colorspace->flags |=
+ (PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
+
+ /* gamma */
+ colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
+ colorspace->flags |= PNG_COLORSPACE_HAVE_GAMMA;
+
+ /* Finally record that we have an sRGB profile */
+ colorspace->flags |=
+ (PNG_COLORSPACE_MATCHES_sRGB|PNG_COLORSPACE_FROM_sRGB);
+
+ return 1; /* set */
+}
+#endif /* sRGB */
+
+#ifdef PNG_iCCP_SUPPORTED
+/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
+ * is XYZ(0.9642,1.0,0.8249), which scales to:
+ *
+ * (63189.8112, 65536, 54060.6464)
+ */
+static const png_byte D50_nCIEXYZ[12] =
+ { 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
+
+int /* PRIVATE */
+png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length)
+{
+ if (profile_length < 132)
+ return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+ "too short");
+
+ if (profile_length & 3)
+ return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
+ "invalid length");
+
+ return 1;
+}
+
+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 */, int color_type)
+{
+ png_uint_32 temp;
+
+ /* Length check; this cannot be ignored in this code because profile_length
+ * is used later to check the tag table, so even if the profile seems over
+ * long profile_length from the caller must be correct. The caller can fix
+ * this up on read or write by just passing in the profile header length.
+ */
+ temp = png_get_uint_32(profile);
+ if (temp != profile_length)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "length does not match profile");
+
+ temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
+ if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
+ profile_length < 132+12*temp) /* truncated tag table */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "tag count too large");
+
+ /* The 'intent' must be valid or we can't store it, ICC limits the intent to
+ * 16 bits.
+ */
+ temp = png_get_uint_32(profile+64);
+ if (temp >= 0xffff) /* The ICC limit */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid rendering intent");
+
+ /* This is just a warning because the profile may be valid in future
+ * versions.
+ */
+ if (temp >= PNG_sRGB_INTENT_LAST)
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "intent outside defined range");
+
+ /* At this point the tag table can't be checked because it hasn't necessarily
+ * been loaded; however, various header fields can be checked. These checks
+ * are for values permitted by the PNG spec in an ICC profile; the PNG spec
+ * restricts the profiles that can be passed in an iCCP chunk (they must be
+ * appropriate to processing PNG data!)
+ */
+
+ /* Data checks (could be skipped). These checks must be independent of the
+ * version number; however, the version number doesn't accomodate changes in
+ * the header fields (just the known tags and the interpretation of the
+ * data.)
+ */
+ temp = png_get_uint_32(profile+36); /* signature 'ascp' */
+ if (temp != 0x61637370)
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid signature");
+
+ /* Currently the PCS illuminant/adopted white point (the computational
+ * white point) are required to be D50,
+ * however the profile contains a record of the illuminant so perhaps ICC
+ * expects to be able to change this in the future (despite the rationale in
+ * the introduction for using a fixed PCS adopted white.) Consequently the
+ * following is just a warning.
+ */
+ if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
+ (void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
+ "PCS illuminant is not D50");
+
+ /* The PNG spec requires this:
+ * "If the iCCP chunk is present, the image samples conform to the colour
+ * space represented by the embedded ICC profile as defined by the
+ * International Color Consortium [ICC]. The colour space of the ICC profile
+ * shall be an RGB colour space for colour images (PNG colour types 2, 3, and
+ * 6), or a greyscale colour space for greyscale images (PNG colour types 0
+ * and 4)."
+ *
+ * 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 */
+ switch (temp)
+ {
+ case 0x52474220: /* 'RGB ' */
+ if (!(color_type & PNG_COLOR_MASK_COLOR))
+ return png_icc_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 png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "Gray color space not permitted on RGB PNG");
+ break;
+
+ default:
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid ICC profile 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
+ * weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
+ * ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
+ * cases. Issue an error for device link or abstract profiles - these don't
+ * contain the records necessary to transform the color-space to anything
+ * other than the target device (and not even that for an abstract profile).
+ * Profiles of these classes may not be embedded in images.
+ */
+ temp = png_get_uint_32(profile+12); /* profile/device class */
+ switch (temp)
+ {
+ case 0x73636E72: /* 'scnr' */
+ case 0x6D6E7472: /* 'mntr' */
+ case 0x70727472: /* 'prtr' */
+ case 0x73706163: /* 'spac' */
+ /* All supported */
+ break;
+
+ case 0x61627374: /* 'abst' */
+ /* May not be embedded in an image */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "invalid embedded Abstract ICC profile");
+
+ case 0x6C696E6B: /* 'link' */
+ /* DeviceLink profiles cannnot be interpreted in a non-device specific
+ * fashion, if an app uses the AToB0Tag in the profile the results are
+ * undefined unless the result is sent to the intended device,
+ * therefore a DeviceLink profile should not be found embedded in a
+ * PNG.
+ */
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "unexpected DeviceLink ICC profile class");
+
+ case 0x6E6D636C: /* 'nmcl' */
+ /* A NamedColor profile is also device specific, however it doesn't
+ * contain an AToB0 tag that is open to misintrepretation. Almost
+ * certainly it will fail the tests below.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "unexpected NamedColor ICC profile class");
+ break;
+
+ default:
+ /* To allow for future enhancements to the profile accept unrecognized
+ * profile classes with a warning, these then hit the test below on the
+ * tag content to ensure they are backward compatible with one of the
+ * understood profiles.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, temp,
+ "unrecognized ICC profile class");
+ break;
+ }
+
+ /* For any profile other than a device link one the PCS must be encoded
+ * either in XYZ or Lab.
+ */
+ temp = png_get_uint_32(profile+20);
+ switch (temp)
+ {
+ case 0x58595A20: /* 'XYZ ' */
+ case 0x4C616220: /* 'Lab ' */
+ break;
+
+ default:
+ return png_icc_profile_error(png_ptr, colorspace, name, temp,
+ "unexpected ICC PCS encoding");
+ }
+
+ return 1;
+}
+
+int /* PRIVATE */
+png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
+ png_const_charp name, png_uint_32 profile_length,
+ png_const_bytep profile /* header plus whole tag table */)
+{
+ png_uint_32 tag_count = png_get_uint_32(profile+128);
+ png_uint_32 itag;
+ png_const_bytep tag = profile+132; /* The first tag */
+
+ /* First scan all the tags in the table and add bits to the icc_info value
+ * (temporarily in 'tags').
+ */
+ for (itag=0; itag < tag_count; ++itag, tag += 12)
+ {
+ png_uint_32 tag_id = png_get_uint_32(tag+0);
+ png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
+ png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
+
+ /* The ICC specification does not exclude zero length tags, therefore the
+ * start might actually be anywhere if there is no data, but this would be
+ * a clear abuse of the intent of the standard so the start is checked for
+ * being in range. All defined tag types have an 8 byte header - a 4 byte
+ * type signature then 0.
+ */
+ if ((tag_start & 3) != 0)
+ {
+ /* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
+ * only a warning here because libpng does not care about the
+ * alignment.
+ */
+ (void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
+ "ICC profile tag start not a multiple of 4");
+ }
+
+ /* This is a hard error; potentially it can cause read outside the
+ * profile.
+ */
+ if (tag_start > profile_length || tag_length > profile_length - tag_start)
+ return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
+ "ICC profile tag outside profile");
+ }
+
+ return 1; /* success, maybe with warnings */
+}
+
+#ifdef PNG_sRGB_SUPPORTED
+/* Information about the known ICC sRGB profiles */
+static const struct
+{
+ png_uint_32 adler, crc, length;
+ png_uint_32 md5[4];
+ png_byte have_md5;
+ png_byte is_broken;
+ png_uint_16 intent;
+
+# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
+# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
+ { adler, crc, length, md5, broke, intent },
+
+} png_sRGB_checks[] =
+{
+ /* This data comes from contrib/tools/checksum-icc run on downloads of
+ * all four ICC sRGB profiles from www.color.org.
+ */
+ /* adler32, crc32, MD5[4], intent, date, length, file-name */
+ PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
+ PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
+ "2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
+
+ /* ICC sRGB v2 perceptual no black-compensation: */
+ PNG_ICC_CHECKSUM(0x4909e5e1, 0x427ebb21,
+ PNG_MD5(0xc95bd637, 0xe95d8a3b, 0x0df38f99, 0xc1320389), 1, 0,
+ "2009/03/27 21:37:45", 3052, "sRGB_IEC61966-2-1_no_black_scaling.icc")
+
+ PNG_ICC_CHECKSUM(0xfd2144a1, 0x306fd8ae,
+ PNG_MD5(0xfc663378, 0x37e2886b, 0xfd72e983, 0x8228f1b8), 0, 0,
+ "2009/08/10 17:28:01", 60988, "sRGB_v4_ICC_preference_displayclass.icc")
+
+ /* ICC sRGB v4 perceptual */
+ PNG_ICC_CHECKSUM(0x209c35d2, 0xbbef7812,
+ PNG_MD5(0x34562abf, 0x994ccd06, 0x6d2c5721, 0xd0d68c5d), 0, 0,
+ "2007/07/25 00:05:37", 60960, "sRGB_v4_ICC_preference.icc")
+
+ /* The following profiles have no known MD5 checksum. If there is a match
+ * on the (empty) MD5 the other fields are used to attempt a match and
+ * a warning is produced. The first two of these profiles have a 'cprt' tag
+ * which suggests that they were also made by Hewlett Packard.
+ */
+ PNG_ICC_CHECKSUM(0xa054d762, 0x5d5129ce,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 0,
+ "2004/07/21 18:57:42", 3024, "sRGB_IEC61966-2-1_noBPC.icc")
+
+ /* This is a 'mntr' (display) profile with a mediaWhitePointTag that does not
+ * match the D50 PCS illuminant in the header (it is in fact the D65 values,
+ * so the white point is recorded as the un-adapted value.) The profiles
+ * below only differ in one byte - the intent - and are basically the same as
+ * the previous profile except for the mediaWhitePointTag error and a missing
+ * chromaticAdaptationTag.
+ */
+ PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
+ "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
+
+ PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
+ PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
+ "1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
+};
+
+static int
+png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
+ png_const_bytep profile, uLong adler)
+{
+ /* The quick check is to verify just the MD5 signature and trust the
+ * rest of the data. Because the profile has already been verified for
+ * correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
+ * field too, so if the profile has been edited with an intent not defined
+ * by sRGB (but maybe defined by a later ICC specification) the read of
+ * the profile will fail at that point.
+ */
+ png_uint_32 length = 0;
+ png_uint_32 intent = 0x10000; /* invalid */
+#if PNG_sRGB_PROFILE_CHECKS > 1
+ uLong crc = 0; /* the value for 0 length data */
+#endif
+ unsigned int i;
+
+ for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
+ {
+ if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
+ png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
+ png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
+ png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
+ {
+ /* This may be one of the old HP profiles without an MD5, in that
+ * case we can only use the length and Adler32 (note that these
+ * are not used by default if there is an MD5!)
+ */
+# if PNG_sRGB_PROFILE_CHECKS == 0
+ if (png_sRGB_checks[i].have_md5)
+ return 1+png_sRGB_checks[i].is_broken;
+# endif
+
+ /* Profile is unsigned or more checks have been configured in. */
+ if (length == 0)
+ {
+ length = png_get_uint_32(profile);
+ intent = png_get_uint_32(profile+64);
+ }
+
+ /* Length *and* intent must match */
+ if (length == png_sRGB_checks[i].length &&
+ intent == png_sRGB_checks[i].intent)
+ {
+ /* Now calculate the adler32 if not done already. */
+ if (adler == 0)
+ {
+ adler = adler32(0, NULL, 0);
+ adler = adler32(adler, profile, length);
+ }
+
+ if (adler == png_sRGB_checks[i].adler)
+ {
+ /* These basic checks suggest that the data has not been
+ * modified, but if the check level is more than 1 perform
+ * our own crc32 checksum on the data.
+ */
+# if PNG_sRGB_PROFILE_CHECKS > 1
+ if (crc == 0)
+ {
+ crc = crc32(0, NULL, 0);
+ crc = crc32(crc, profile, length);
+ }
+
+ /* So this check must pass for the 'return' below to happen.
+ */
+ if (crc == png_sRGB_checks[i].crc)
+# endif
+ {
+ if (png_sRGB_checks[i].is_broken)
+ {
+ /* These profiles are known to have bad data that may cause
+ * problems if they are used, therefore attempt to
+ * discourage their use, skip the 'have_md5' warning below,
+ * which is made irrelevant by this error.
+ */
+ png_chunk_report(png_ptr, "known incorrect sRGB profile",
+ PNG_CHUNK_ERROR);
+ }
+
+ /* Warn that this being done; this isn't even an error since
+ * the profile is perfectly valid, but it would be nice if
+ * people used the up-to-date ones.
+ */
+ else if (!png_sRGB_checks[i].have_md5)
+ {
+ png_chunk_report(png_ptr,
+ "out-of-date sRGB profile with no signature",
+ PNG_CHUNK_WARNING);
+ }
+
+ return 1+png_sRGB_checks[i].is_broken;
+ }
+ }
+ }
+
+# if PNG_sRGB_PROFILE_CHECKS > 0
+ /* The signature matched, but the profile had been changed in some
+ * way. This is an apparent violation of the ICC terms of use and,
+ * anyway, probably indicates a data error or uninformed hacking.
+ */
+ if (png_sRGB_checks[i].have_md5)
+ png_benign_error(png_ptr,
+ "copyright violation: edited ICC profile ignored");
+# endif
+ }
+ }
+
+ return 0; /* no match */
+}
+#endif
+
+#ifdef PNG_sRGB_SUPPORTED
+void /* PRIVATE */
+png_icc_set_sRGB(png_const_structrp png_ptr,
+ png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
+{
+ /* Is this profile one of the known ICC sRGB profiles? If it is, just set
+ * the sRGB information.
+ */
+ if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler))
+ (void)png_colorspace_set_sRGB(png_ptr, colorspace,
+ (int)/*already checked*/png_get_uint_32(profile+64));
+}
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
+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 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,
+ color_type) &&
+ png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
+ profile))
+ {
+# ifdef PNG_sRGB_SUPPORTED
+ /* If no sRGB support, don't try storing sRGB information */
+ png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
+# endif
+ return 1;
+ }
+
+ /* Failure case */
+ return 0;
+}
+#endif /* iCCP */
+
+#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
+void /* PRIVATE */
+png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
+{
+ /* Set the rgb_to_gray coefficients from the colorspace. */
+ if (!png_ptr->rgb_to_gray_coefficients_set &&
+ (png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
+ {
+ /* png_set_background has not been called, get the coefficients from the Y
+ * values of the colorspace colorants.
+ */
+ png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
+ png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
+ png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
+ png_fixed_point total = r+g+b;
+
+ if (total > 0 &&
+ r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
+ g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
+ b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
+ r+g+b <= 32769)
+ {
+ /* We allow 0 coefficients here. r+g+b may be 32769 if two or
+ * all of the coefficients were rounded up. Handle this by
+ * reducing the *largest* coefficient by 1; this matches the
+ * approach used for the default coefficients in pngrtran.c
+ */
+ int add = 0;
+
+ if (r+g+b > 32768)
+ add = -1;
+ else if (r+g+b < 32768)
+ add = 1;
+
+ if (add != 0)
+ {
+ if (g >= r && g >= b)
+ g += add;
+ else if (r >= g && r >= b)
+ r += add;
+ else
+ b += add;
+ }
+
+ /* Check for an internal error. */
+ if (r+g+b != 32768)
+ png_error(png_ptr,
+ "internal error handling cHRM coefficients");
+
+ else
+ {
+ png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
+ png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
+ }
+ }
+
+ /* This is a png_error at present even though it could be ignored -
+ * it should never happen, but it is important that if it does, the
+ * bug is fixed.
+ */
+ else
+ png_error(png_ptr, "internal error handling cHRM->XYZ");
+ }
+}
+#endif
+
+#endif /* COLORSPACE */
+
+void /* PRIVATE */
+png_check_IHDR(png_const_structrp png_ptr,
+ png_uint_32 width, png_uint_32 height, int bit_depth,
+ int color_type, int interlace_type, int compression_type,
+ int filter_type)
+{
+ int error = 0;
+
+ /* Check for width and height valid values */
+ if (width == 0)
+ {
+ png_warning(png_ptr, "Image width is zero in IHDR");
+ error = 1;
+ }
+
+ if (height == 0)
+ {
+ png_warning(png_ptr, "Image height is zero in IHDR");
+ error = 1;
+ }
+
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ if (width > png_ptr->user_width_max)
+
+# else
+ if (width > PNG_USER_WIDTH_MAX)
+# endif
+ {
+ png_warning(png_ptr, "Image width exceeds user limit in IHDR");
+ error = 1;
+ }
+
+# ifdef PNG_SET_USER_LIMITS_SUPPORTED
+ if (height > png_ptr->user_height_max)
+# else
+ if (height > PNG_USER_HEIGHT_MAX)
+# endif
+ {
+ png_warning(png_ptr, "Image height exceeds user limit in IHDR");
+ error = 1;
+ }
+
+ if (width > PNG_UINT_31_MAX)
+ {
+ png_warning(png_ptr, "Invalid image width in IHDR");
+ error = 1;
+ }
+
+ if (height > PNG_UINT_31_MAX)
+ {
+ png_warning(png_ptr, "Invalid image height in IHDR");
+ error = 1;
+ }
+
+ if (width > (PNG_UINT_32_MAX
+ >> 3) /* 8-byte RGBA pixels */
+ - 48 /* bigrowbuf hack */
+ - 1 /* filter byte */
+ - 7*8 /* rounding of width to multiple of 8 pixels */
+ - 8) /* extra max_pixel_depth pad */
+ png_warning(png_ptr, "Width is too large for libpng to process pixels");
+
+ /* Check other values */
+ if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
+ bit_depth != 8 && bit_depth != 16)
+ {
+ png_warning(png_ptr, "Invalid bit depth in IHDR");
+ error = 1;
+ }
+
+ if (color_type < 0 || color_type == 1 ||
+ color_type == 5 || color_type > 6)
+ {
+ png_warning(png_ptr, "Invalid color type in IHDR");
+ error = 1;
+ }
+
+ if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
+ ((color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
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