File: otfcmap.cc

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// -*- related-file-name: "../include/efont/otfcmap.hh" -*-

/* otfcmap.{cc,hh} -- OpenType cmap table
 *
 * Copyright (c) 2002-2012 Eddie Kohler
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version. This program is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
 * Public License for more details.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <efont/otfcmap.hh>
#include <lcdf/error.hh>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <efont/otfdata.hh>     // for ntohl()

#define USHORT_AT(d)            (Data::u16_aligned(d))
#define SHORT_AT(d)             (Data::s16_aligned(d))
#define ULONG_AT(d)             (Data::u32_aligned(d))

namespace Efont { namespace OpenType {

Cmap::Cmap(const String &s, ErrorHandler *errh)
    : _str(s)
{
    _str.align(4);
    _error = parse_header(errh ? errh : ErrorHandler::silent_handler());
}

int
Cmap::parse_header(ErrorHandler *errh)
{
    // HEADER FORMAT:
    // USHORT   version
    // USHORT   numTables
    int len = _str.length();
    const uint8_t *data = _str.udata();
    if (HEADER_SIZE > len)
        return errh->error("OTF cmap too small"), -EFAULT;
    if (!(data[0] == '\000' && data[1] == '\000'))
        return errh->error("bad cmap version number"), -ERANGE;
    _ntables = USHORT_AT(data + 2);
    if (_ntables == 0)
        return errh->error("OTF cmap contains no tables"), -EINVAL;
    if (HEADER_SIZE + ENCODING_SIZE * _ntables > len)
        return errh->error("cmap directory out of range"), -EFAULT;

    // ENCODING ENTRY FORMAT:
    // USHORT   platformID
    // USHORT   encodingID
    // ULONG    offset
    int last_platform = -1;
    int last_encoding = -1;
    int last_language = -1;
    _first_unicode_table = -1;
    for (int i = 0; i < _ntables; i++) {
        int loc = HEADER_SIZE + ENCODING_SIZE * i;
        int platform = USHORT_AT(data + loc);
        int encoding = USHORT_AT(data + loc + 2);
        uint32_t offset = ULONG_AT(data + loc + 4);
        if (offset + 8 > (uint32_t) len) {
          length_error:
            return errh->error("encoding data for entry %d out of range", i);
        }
        int format = USHORT_AT(data + offset);
        int language;
        if (format == F_BYTE || format == F_HIBYTE || format == F_SEGMENTED
            || format == F_TRIMMED) {
            if (USHORT_AT(data + offset + 2) < 6)
                goto length_error;
            language = USHORT_AT(data + offset + 4);
        } else if (format == F_HIBYTE32 || format == F_TRIMMED32
                   || format == F_SEGMENTED32) {
            if (offset + 12 > (uint32_t) len || ULONG_AT(data + offset + 4) < 12)
                goto length_error;
            language = ULONG_AT(data + offset + 8);
        } else
            continue;
        if (!(platform > last_platform
              || (platform == last_platform
                  && (encoding > last_encoding
                      || (encoding == last_encoding
                          && language > last_language)))))
            return errh->error("subtables out of order at entry %d", i);
        if ((platform == 0 || (platform == 3 && encoding == 1))
            && _first_unicode_table < 0)
            _first_unicode_table = i;
        last_platform = platform, last_encoding = encoding, last_language = language;
    }

    _table_error.assign(_ntables, -2);
    return 0;
}

int
Cmap::first_table(int platform, int encoding) const
{
    if (error() < 0)
        return -1;
    const uint8_t *data = _str.udata();
    data += HEADER_SIZE;
    for (int i = 0; i < _ntables; i++, data += ENCODING_SIZE) {
        int p = USHORT_AT(data), e = USHORT_AT(data + 2);
        if (platform == p && (encoding < 0 || encoding == e))
            return i;
    }
    return -1;
}

int
Cmap::check_table(int t, ErrorHandler *errh) const
{
    if (!errh)
        errh = ErrorHandler::silent_handler();
    if (t == USE_FIRST_UNICODE_TABLE && _first_unicode_table == -1) {
        errh->warning("font appears not to support Unicode");
        _first_unicode_table = 0;
    }
    if (t == USE_FIRST_UNICODE_TABLE)
        t = _first_unicode_table;
    if (_error < 0 || t < 0 || t >= _ntables)
        return errh->error("no such table");
    if (_table_error[t] != -2)
        return _table_error[t];
    _table_error[t] = -1;

    const uint8_t *data = table_data(t);
    uint32_t left = _str.uend() - data;
    int format = USHORT_AT(data);
    uint32_t length = 0;        // value not used

    switch (format) {

      case F_BYTE:
        if (left < 4
            || (length = USHORT_AT(data + 2)) > left
            || length != 259)
            return errh->error("bad table %d length (format %d)", t, format);
        break;

      case F_HIBYTE:
        if (left < 4
            || (length = USHORT_AT(data + 2)) > left
            || length < 524)
            return errh->error("bad table %d length (format %d)", t, format);
        for (int hi_byte = 0; hi_byte < 256; hi_byte++)
            if (uint32_t subh_key = USHORT_AT(data + 6 + 2 * hi_byte)) {
                if ((subh_key & 7) || HIBYTE_SUBHEADERS + subh_key + 8 > length)
                    return errh->error("bad table %d subheader %d offset (format 2)", t, hi_byte);
                const uint8_t *subh = data + HIBYTE_SUBHEADERS + subh_key;
                int firstCode = USHORT_AT(subh);
                int entryCount = USHORT_AT(subh + 2);
                int idRangeOffset = USHORT_AT(subh + 6);
                if (firstCode + entryCount > 256 || entryCount == 0)
                    return errh->error("bad table %d subheader %d contents (format 2)", t, hi_byte);
                if ((HIBYTE_SUBHEADERS + subh_key + 6) // pos[idRangeOffset]
                    + idRangeOffset + entryCount * 2 > length)
                    return errh->error("bad table %d subheader %d length (format 2)", t, hi_byte);
            }
        break;

      case F_SEGMENTED: {
          if (left < 4
              || (length = USHORT_AT(data + 2)) > left
              || length < 16)
              return errh->error("bad table %d length (format %d)", t, format);
          int segCountX2 = USHORT_AT(data + 6);
          int searchRange = USHORT_AT(data + 8);
          int entrySelector = USHORT_AT(data + 10);
          int rangeShift = USHORT_AT(data + 12);
          if ((segCountX2 & 1)
              || segCountX2 == 0
              || (searchRange & (searchRange - 1)) /* not a power of 2? */
              || searchRange <= segCountX2/2
              || (searchRange>>1) > segCountX2/2
              || 1 << (entrySelector + 1) != searchRange
              || rangeShift != segCountX2 - searchRange)
              return errh->error("bad table %d segment counts (format 4)", t);
          uint32_t segCount = segCountX2 >> 1;
          if (length < 16 + 8 * segCount)
              return errh->error("bad table %d length (format %d)", t, format);
          const uint8_t *endCodes = data + 14;
          const uint8_t *startCodes = endCodes + 2 + segCountX2;
          const uint8_t *idDeltas = startCodes + segCountX2;
          const uint8_t *idRangeOffsets = idDeltas + segCountX2;
          int last_end = 0;
          for (int i = 0; i < segCountX2; i += 2) {
              int endCode = USHORT_AT(endCodes + i);
              int startCode = USHORT_AT(startCodes + i);
              /* int idDelta = SHORT_AT(idDeltas + i); // no need to check */
              int idRangeOffset = USHORT_AT(idRangeOffsets + i);
              if (endCode < startCode || startCode < last_end)
                  return errh->error("bad table %d overlapping range %d (format %d)", t, i/2, format);
              if (idRangeOffset
                  && idRangeOffsets + i + idRangeOffset + (endCode - startCode)*2 + 2 > data + length)
                  return errh->error("bad table %d range %d length (format 4)", t, i/2);
              last_end = endCode + 1;
          }
          if (USHORT_AT(endCodes + segCountX2 - 2) != 0xFFFF)
              return errh->error("bad table %d incorrect final endCode (format 4)", t);
          break;
      }

      case F_TRIMMED: {
          if (left < 4
              || (length = USHORT_AT(data + 2)) > left
              || length < 10)
              return errh->error("bad table %d length (format %d)", t, format);
          uint32_t entryCount = USHORT_AT(data + 8);
          if (10 + entryCount * 2 > length)
              return errh->error("bad table %d length (format %d)", t, format);
          break;
      }

      case F_SEGMENTED32: {
          if (left < 8
              || (length = ULONG_AT(data + 4)) > left
              || length < 16)
              return errh->error("bad table %d length (format %d)", t, format);
          uint32_t nGroups = ULONG_AT(data + 16);
          if ((length - 16) / 12 < nGroups)
              return errh->error("bad table %d length (format %d)", t, format);
          uint32_t last_post_end = 0;
          data += 16;
          for (uint32_t i = 0; i < nGroups; i++, data += 12) {
              uint32_t startCharCode = ULONG_AT(data);
              uint32_t endCharCode = ULONG_AT(data + 4);
              if (startCharCode < last_post_end || endCharCode < startCharCode)
                  return errh->error("bad table %d overlapping range %d (format %d)", t, i, format);
              last_post_end = endCharCode + 1;
          }
          break;
      }

      case F_HIBYTE32:
      case F_TRIMMED32:
      default:
        return errh->error("bad table %d unsupported format %d", t, format);

    }

    _table_error[t] = t;
    return t;
}

Glyph
Cmap::map_table(int t, uint32_t uni, ErrorHandler *errh) const
{
    if ((t = check_table(t, errh)) < 0)
        return 0;

    const uint8_t *data = table_data(t);
    switch (USHORT_AT(data)) {

    case F_BYTE:
        if (uni < 256)
            return data[6 + uni];
        else
            return 0;

    case F_HIBYTE: {
        if (uni >= 65536)
            return 0;
        int hi_byte = (uni >> 8) & 255;
        int subh = USHORT_AT(data + 6 + hi_byte * 2);
        if (subh == 0 && hi_byte) // XXX?
            return 0;
        data += 524 + subh;
        int firstCode = USHORT_AT(data);
        int entryCount = USHORT_AT(data + 2);
        int idDelta = SHORT_AT(data + 4);
        int idRangeOffset = USHORT_AT(data + 6);
        int lo_byte = uni & 255;
        if (lo_byte < firstCode || lo_byte >= firstCode + entryCount)
            return 0;
        int answer = USHORT_AT(data + 6 + idRangeOffset + (lo_byte - firstCode) * 2);
        if (answer == 0)
            return 0;
        return (answer + idDelta) & 65535;
    }

    case F_SEGMENTED: {
        if (uni >= 65536)
            return 0;
        int segCount = USHORT_AT(data + 6) >> 1;
        const uint8_t *endCounts = data + 14;
        const uint8_t *startCounts = endCounts + (segCount << 1) + 2;
        const uint8_t *idDeltas = startCounts + (segCount << 1);
        const uint8_t *idRangeOffsets = idDeltas + (segCount << 1);
        int l = 0, r = segCount;
        while (l < r) {
            int m = l + (r - l) / 2;
            uint32_t endCount = USHORT_AT(endCounts + (m << 1));
            uint32_t startCount = USHORT_AT(startCounts + (m << 1));
            if (uni < startCount)
                r = m;
            else if (uni <= endCount) {
                int idDelta = SHORT_AT(idDeltas + (m << 1));
                int idRangeOffset = USHORT_AT(idRangeOffsets + (m << 1));
                if (idRangeOffset == 0)
                    return (idDelta + uni) & 65535;
                int g = USHORT_AT(idRangeOffsets + (m << 1) + idRangeOffset + ((uni - startCount) << 1));
                if (g == 0)
                    return 0;
                return (idDelta + g) & 65535;
            } else
                l = m + 1;
        }
        return 0;
    }

    case F_TRIMMED: {
        uint32_t firstCode = USHORT_AT(data + 6);
        uint32_t entryCount = USHORT_AT(data + 8);
        if (uni < firstCode || uni >= firstCode + entryCount)
            return 0;
        return USHORT_AT(data + 10 + ((uni - firstCode) << 1));
    }

    case F_SEGMENTED32: {
        uint32_t nGroups = ULONG_AT(data + 12);
        uint32_t l = 0, r = nGroups;
        const uint8_t *groups = data + 16;
        while (l < r) {
            uint32_t m = l + (r - l) / 2;
            uint32_t startCharCode = ULONG_AT(groups + m * 12);
            uint32_t endCharCode = ULONG_AT(groups + m * 12 + 4);
            if (uni < startCharCode)
                r = m;
            else if (uni <= endCharCode)
                return ULONG_AT(groups + m * 12 + 8) + uni - startCharCode;
            else
                l = m + 1;
        }
        return 0;
    }

    default:
        return 0;

    }
}

void
Cmap::dump_table(int t, Vector<std::pair<uint32_t, Glyph> > &ugp, ErrorHandler *errh) const
{
    if ((t = check_table(t, errh)) < 0)
        return;

    const uint8_t *data = table_data(t);
    switch (USHORT_AT(data)) {

    case F_BYTE:
        for (uint32_t u = 0; u < 256; ++u)
            if (int g = data[6 + u])
                ugp.push_back(std::make_pair(u, g));
        break;

    case F_HIBYTE:
        assert(USHORT_AT(data + 6) == 0);
        for (int hi_byte = 0; hi_byte < 256; hi_byte++) {
            int subh = USHORT_AT(data + 6 + hi_byte * 4);
            if (subh == 0 && hi_byte > 0)
                continue;
            const uint8_t *tdata = data + 524 + subh;
            int firstCode = USHORT_AT(tdata);
            int entryCount = USHORT_AT(tdata + 2);
            int idDelta = SHORT_AT(tdata + 4);
            int idRangeOffset = USHORT_AT(tdata + 6);
            const uint8_t *gdata = tdata + 6 + idRangeOffset;
            for (int i = 0; i < entryCount; i++)
                if (Glyph g = USHORT_AT(gdata + (i << 1))) {
                    g = (idDelta + g) & 65535;
                    uint32_t u = (hi_byte << 8) + firstCode + i;
                    ugp.push_back(std::make_pair(u, g));
                }
        }
        break;

    case F_SEGMENTED: {
        int segCountX2 = USHORT_AT(data + 6);
        const uint8_t *endCounts = data + 14;
        const uint8_t *startCounts = endCounts + segCountX2 + 2;
        const uint8_t *idDeltas = startCounts + segCountX2;
        const uint8_t *idRangeOffsets = idDeltas + segCountX2;
        for (int i = 0; i < segCountX2; i += 2) {
            uint32_t endCount = USHORT_AT(endCounts + i);
            uint32_t startCount = USHORT_AT(startCounts + i);
            int idDelta = SHORT_AT(idDeltas + i);
            int idRangeOffset = USHORT_AT(idRangeOffsets + i);
            if (idRangeOffset == 0) {
                for (uint32_t u = startCount; u <= endCount; ++u) {
                    Glyph g = (u + idDelta) & 65535;
                    ugp.push_back(std::make_pair(u, g));
                }
            } else {
                const uint8_t *gdata = idRangeOffsets + i + idRangeOffset;
                for (uint32_t u = startCount; u <= endCount; ++u, gdata += 2)
                    if (Glyph g = USHORT_AT(gdata)) {
                        g = (g + idDelta) & 65535;
                        ugp.push_back(std::make_pair(u, g));
                    }
            }
        }
        break;
    }

    case F_TRIMMED: {
        uint32_t firstCode = USHORT_AT(data + 6);
        int entryCount = USHORT_AT(data + 8);
        for (int i = 0; i < entryCount; i++)
            if (Glyph g = USHORT_AT(data + 10 + (i << 1)))
                ugp.push_back(std::make_pair(firstCode + i, g));
        break;
    }

    case F_SEGMENTED32: {
        uint32_t nGroups = ULONG_AT(data + 12);
        const uint8_t *groups = data + 16;
        for (uint32_t i = 0; i < nGroups; i++, groups += 12) {
            uint32_t startCharCode = ULONG_AT(groups);
            uint32_t nCharCodes = ULONG_AT(groups + 4) - startCharCode;
            Glyph startGlyphID = ULONG_AT(groups + 8);
            for (uint32_t i = 0; i <= nCharCodes; i++)
                ugp.push_back(std::make_pair(startCharCode + i, startGlyphID + i));
        }
        break;
    }

    default:
        break;

    }
}

int
Cmap::map_uni(const Vector<uint32_t> &vin, Vector<Glyph> &vout) const
{
    int t;
    if ((t = check_table(USE_FIRST_UNICODE_TABLE)) < 0)
        return -1;
    vout.resize(vin.size(), 0);
    for (int i = 0; i < vin.size(); i++)
        vout[i] = map_table(t, vin[i]);
    return 0;
}

}}