func()

in font/sfnt/sfnt.go [759:866]

• 90 lines of code
• 35 McCabe index (conditional complexity)

func (f *Font) initializeTables(offset int, isDfont bool) (buf1 []byte, finalTableOffset int32, isPostScript bool, err error) {
	f.initialOffset = int32(offset)
	if int(f.initialOffset) != offset {
		return nil, 0, false, errUnsupportedTableOffsetLength
	}
	// https://www.microsoft.com/typography/otspec/otff.htm "Organization of an
	// OpenType Font" says that "The OpenType font starts with the Offset
	// Table", which is 12 bytes.
	buf, err := f.src.view(nil, offset, 12)
	if err != nil {
		return nil, 0, false, err
	}
	// When updating the cases in this switch statement, also update the
	// Collection.initialize method.
	switch u32(buf) {
	default:
		return nil, 0, false, errInvalidFont
	case dfontResourceDataOffset:
		return nil, 0, false, errInvalidSingleFont
	case 0x00010000:
		// No-op.
	case 0x4f54544f: // "OTTO".
		isPostScript = true
	case 0x74727565: // "true"
		// No-op.
	case 0x74746366: // "ttcf".
		return nil, 0, false, errInvalidSingleFont
	}
	numTables := int(u16(buf[4:]))
	if numTables > maxNumTables {
		return nil, 0, false, errUnsupportedNumberOfTables
	}

	// "The Offset Table is followed immediately by the Table Record entries...
	// sorted in ascending order by tag", 16 bytes each.
	buf, err = f.src.view(buf, offset+12, 16*numTables)
	if err != nil {
		return nil, 0, false, err
	}
	for b, first, prevTag := buf, true, uint32(0); len(b) > 0; b = b[16:] {
		tag := u32(b)
		if first {
			first = false
		} else if tag <= prevTag {
			return nil, 0, false, errInvalidTableTagOrder
		}
		prevTag = tag

		o, n := u32(b[8:12]), u32(b[12:16])
		// For dfont files, the offset is relative to the resource, not the
		// file.
		if isDfont {
			origO := o
			o += uint32(offset)
			if o < origO {
				return nil, 0, false, errUnsupportedTableOffsetLength
			}
		}
		if o > maxTableOffset || n > maxTableLength {
			return nil, 0, false, errUnsupportedTableOffsetLength
		}
		// We ignore the checksums, but "all tables must begin on four byte
		// boundries [sic]".
		if o&3 != 0 {
			return nil, 0, false, errInvalidTableOffset
		}
		if finalTableOffset < int32(o+n) {
			finalTableOffset = int32(o + n)
		}

		// Match the 4-byte tag as a uint32. For example, "OS/2" is 0x4f532f32.
		switch tag {
		case 0x43424c43:
			f.cblc = table{o, n}
		case 0x43464620:
			f.cff = table{o, n}
		case 0x4f532f32:
			f.os2 = table{o, n}
		case 0x636d6170:
			f.cmap = table{o, n}
		case 0x676c7966:
			f.glyf = table{o, n}
		case 0x47504f53:
			f.gpos = table{o, n}
		case 0x68656164:
			f.head = table{o, n}
		case 0x68686561:
			f.hhea = table{o, n}
		case 0x686d7478:
			f.hmtx = table{o, n}
		case 0x6b65726e:
			f.kern = table{o, n}
		case 0x6c6f6361:
			f.loca = table{o, n}
		case 0x6d617870:
			f.maxp = table{o, n}
		case 0x6e616d65:
			f.name = table{o, n}
		case 0x706f7374:
			f.post = table{o, n}
		}
	}

	if (f.src.b != nil) && (int(finalTableOffset) > len(f.src.b)) {
		return nil, 0, false, errInvalidSourceData
	}
	return buf, finalTableOffset, isPostScript, nil
}