// Copyright (C) 2004-2021 Artifex Software, Inc.

//

// This file is part of MuPDF.

//

// MuPDF is free software: you can redistribute it and/or modify it under the

// terms of the GNU Affero General Public License as published by the Free

// Software Foundation, either version 3 of the License, or (at your option)

// any later version.

//

// MuPDF 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 Affero General Public License for more

// details.

//

// You should have received a copy of the GNU Affero General Public License

// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>

//

// Alternative licensing terms are available from the licensor.

// For commercial licensing, see <https://www.artifex.com/> or contact

// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,

// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include "mupdf/pdf.h"

#include <string.h>

#define IS_NUMBER \

  '+':case'-':case'.':case'0':case'1':case'2':case'3':\

  case'4':case'5':case'6':case'7':case'8':case'9'

#define IS_WHITE \

  '\x00':case'\x09':case'\x0a':case'\x0c':case'\x0d':case'\x20'

#define IS_HEX \

  '0':case'1':case'2':case'3':case'4':case'5':case'6':\

  case'7':case'8':case'9':case'A':case'B':case'C':\

  case'D':case'E':case'F':case'a':case'b':case'c':\

  case'd':case'e':case'f'

#define IS_DELIM \

  '(':case')':case'<':case'>':case'[':case']':case'{':\

  case'}':case'/':case'%'

#define RANGE_0_9 \

  '0':case'1':case'2':case'3':case'4':case'5':\

  case'6':case'7':case'8':case'9'

#define RANGE_a_f \

  'a':case'b':case'c':case'd':case'e':case'f'

#define RANGE_A_F \

  'A':case'B':case'C':case'D':case'E':case'F'

#define RANGE_0_7 \

  '0':case'1':case'2':case'3':case'4':case'5':case'6':case'7'

/* #define DUMP_LEXER_STREAM */

#ifdef DUMP_LEXER_STREAM

static inline int lex_byte(fz_context *ctx, fz_stream *stm)

{

  int c = fz_read_byte(ctx, stm);

  if (c == EOF)

    fz_write_printf(ctx, fz_stdout(ctx), "<EOF>");

  else if (c >= 32 && c < 128)

    fz_write_printf(ctx, fz_stdout(ctx), "%c", c);

  else

    fz_write_printf(ctx, fz_stdout(ctx), "<%02x>", c);

  return c;

}

#else

#define lex_byte(C,S) fz_read_byte(C,S)

#endif

static inline int iswhite(int ch)

{

  return

    ch == '\000' ||

    ch == '\011' ||

    ch == '\012' ||

    ch == '\014' ||

    ch == '\015' ||

    ch == '\040';

}

static inline int fz_isprint(int ch)

{

  return ch >= ' ' && ch <= '~';

}

static inline int unhex(int ch)

{

  if (ch >= '0' && ch <= '9') return ch - '0';

  if (ch >= 'A' && ch <= 'F') return ch - 'A' + 0xA;

  if (ch >= 'a' && ch <= 'f') return ch - 'a' + 0xA;

  return 0;

}

static void

lex_white(fz_context *ctx, fz_stream *f)

{

  int c;

  do {

    c = lex_byte(ctx, f);

  } while ((c <= 32) && (iswhite(c)));

  if (c != EOF)

    fz_unread_byte(ctx, f);

}

static void

lex_comment(fz_context *ctx, fz_stream *f)

{

  int c;

  do {

    c = lex_byte(ctx, f);

  } while ((c != '\012') && (c != '\015') && (c != EOF));

}

/* Fast(ish) but inaccurate strtof, with Adobe overflow handling. */

static float acrobat_compatible_atof(char *s)

{

  int neg = 0;

  int i = 0;

  while (*s == '-')

  {

    neg = 1;

    ++s;

  }

  while (*s == '+')

  {

    ++s;

  }

  while (*s >= '0' && *s <= '9')

  {

    /* We deliberately ignore overflow here.

     * Tests show that Acrobat handles * overflows in exactly the same way we do:

     * 123450000000000000000678 is read as 678.

     */

    i = i * 10 + (*s - '0');

    ++s;

  }

  if (*s == '.')

  {

    float v = i;

    float n = 0;

    float d = 1;

    ++s;

    while (*s >= '0' && *s <= '9')

    {

      n = 10 * n + (*s - '0');

      d = 10 * d;

      ++s;

    }

    v += n / d;

    return neg ? -v : v;

  }

  else

  {

    return neg ? -i : i;

  }

}

/* Fast but inaccurate atoi. */

static int fast_atoi(char *s)

{

  int neg = 0;

  int i = 0;

  while (*s == '-')

  {

    neg = 1;

    ++s;

  }

  while (*s == '+')

  {

    ++s;

  }

  while (*s >= '0' && *s <= '9')

  {

    /* We deliberately ignore overflow here. */

    i = i * 10 + (*s - '0');

    ++s;

  }

  return neg ? -i : i;

}

static int

lex_number(fz_context *ctx, fz_stream *f, pdf_lexbuf *buf, int c)

{

  char *s = buf->scratch;

  char *e = buf->scratch + buf->size - 1; /* leave space for zero terminator */

  char *isreal = (c == '.' ? s : NULL);

  int neg = (c == '-');

  int isbad = 0;

  *s++ = c;

  c = lex_byte(ctx, f);

  /* skip extra '-' signs at start of number */

  if (neg)

  {

    while (c == '-')

      c = lex_byte(ctx, f);

  }

  while (s < e)

  {

    switch (c)

    {

    case IS_WHITE:

    case IS_DELIM:

      fz_unread_byte(ctx, f);

      goto end;

    case EOF:

      goto end;

    case '.':

      if (isreal)

        isbad = 1;

      isreal = s;

      *s++ = c;

      break;

    case '-':

      /* Bug 703248: Some PDFs (particularly those

       * generated by google docs) apparently have

       * numbers like 0.000000000000-5684342 in them.

       * We'll stop our interpretation at the -, but

       * keep reading to skip over the trailing

       * digits so they aren't parsed later. */

      *s++ = '\0';

      break;

    case RANGE_0_9:

      *s++ = c;

      break;

    default:

      isbad = 1;

      *s++ = c;

      break;

    }

    c = lex_byte(ctx, f);

  }

end:

  *s = '\0';

  if (isbad)

    return PDF_TOK_KEYWORD;

  if (isreal)

  {

    /* We'd like to use the fastest possible atof

     * routine, but we'd rather match acrobats

     * handling of broken numbers. As such, we

     * spot common broken cases and call an

     * acrobat compatible routine where required. */

    if (neg > 1 || isreal - buf->scratch >= 10)

      buf->f = acrobat_compatible_atof(buf->scratch);

    else

      buf->f = fz_atof(buf->scratch);

    return PDF_TOK_REAL;

  }

  else

  {

    buf->i = fast_atoi(buf->scratch);

    return PDF_TOK_INT;

  }

}

static void

lex_name(fz_context *ctx, fz_stream *f, pdf_lexbuf *lb)

{

  char *s = lb->scratch;

  char *e = s + fz_minz(127, lb->size);

  int c;

  while (1)

  {

    if (s == e)

    {

      if (e - lb->scratch < 127)

      {

        s += pdf_lexbuf_grow(ctx, lb);

        e = lb->scratch + fz_minz(127, lb->size);

      }

      else

      {

        /* truncate names that are too long */

        fz_warn(ctx, "name is too long");

        *s = 0;

        lb->len = s - lb->scratch;

        s = NULL;

      }

    }

    c = lex_byte(ctx, f);

    switch (c)

    {

    case IS_WHITE:

    case IS_DELIM:

      fz_unread_byte(ctx, f);

      goto end;

    case EOF:

      goto end;

    case '#':

    {

      int hex[2];

      int i;

      for (i = 0; i < 2; i++)

      {

        c = fz_peek_byte(ctx, f);

        switch (c)

        {

        case RANGE_0_9:

          if (i == 1 && c == '0' && hex[0] == 0)

            goto illegal;

          hex[i] = lex_byte(ctx, f) - '0';

          break;

        case RANGE_a_f:

          hex[i] = lex_byte(ctx, f) - 'a' + 10;

          break;

        case RANGE_A_F:

          hex[i] = lex_byte(ctx, f) - 'A' + 10;

          break;

        default:

        case EOF:

          goto illegal;

        }

      }

      if (s) *s++ = (hex[0] << 4) + hex[1];

      break;

illegal:

      if (i == 1)

        fz_unread_byte(ctx, f);

      if (s) *s++ = '#';

      continue;

    }

    default:

      if (s) *s++ = c;

      break;

    }

  }

end:

  if (s)

  {

    *s = '\0';

    lb->len = s - lb->scratch;

  }

}

static int

lex_string(fz_context *ctx, fz_stream *f, pdf_lexbuf *lb)

{

  char *s = lb->scratch;

  char *e = s + lb->size;

  int bal = 1;

  int oct;

  int c;

  while (1)

  {

    if (s == e)

    {

      s += pdf_lexbuf_grow(ctx, lb);

      e = lb->scratch + lb->size;

    }

    c = lex_byte(ctx, f);

    switch (c)

    {

    case EOF:

      return PDF_TOK_ERROR;

    case '(':

      bal++;

      *s++ = c;

      break;

    case ')':

      bal --;

      if (bal == 0)

        goto end;

      *s++ = c;

      break;

    case '\\':

      c = lex_byte(ctx, f);

      switch (c)

      {

      case EOF:

        return PDF_TOK_ERROR;

      case 'n':

        *s++ = '\n';

        break;

      case 'r':

        *s++ = '\r';

        break;

      case 't':

        *s++ = '\t';

        break;

      case 'b':

        *s++ = '\b';

        break;

      case 'f':

        *s++ = '\f';

        break;

      case '(':

        *s++ = '(';

        break;

      case ')':

        *s++ = ')';

        break;

      case '\\':

        *s++ = '\\';

        break;

      case RANGE_0_7:

        oct = c - '0';

        c = lex_byte(ctx, f);

        if (c >= '0' && c <= '7')

        {

          oct = oct * 8 + (c - '0');

          c = lex_byte(ctx, f);

          if (c >= '0' && c <= '7')

            oct = oct * 8 + (c - '0');

          else if (c != EOF)

            fz_unread_byte(ctx, f);

        }

        else if (c != EOF)

          fz_unread_byte(ctx, f);

        *s++ = oct;

        break;

      case '\n':

        break;

      case '\r':

        c = lex_byte(ctx, f);

        if ((c != '\n') && (c != EOF))

          fz_unread_byte(ctx, f);

        break;

      default:

        *s++ = c;

      }

      break;

    default:

      *s++ = c;

      break;

    }

  }

end:

  lb->len = s - lb->scratch;

  return PDF_TOK_STRING;

}

static int

lex_hex_string(fz_context *ctx, fz_stream *f, pdf_lexbuf *lb)

{

  char *s = lb->scratch;

  char *e = s + lb->size;

  int a = 0, x = 0;

  int c;

  while (1)

  {

    if (s == e)

    {

      s += pdf_lexbuf_grow(ctx, lb);

      e = lb->scratch + lb->size;

    }

    c = lex_byte(ctx, f);

    switch (c)

    {

    case IS_WHITE:

      break;

    default:

      fz_warn(ctx, "invalid character in hex string");

      /* fall through */

    case IS_HEX:

      if (x)

      {

        *s++ = a * 16 + unhex(c);

        x = !x;

      }

      else

      {

        a = unhex(c);

        x = !x;

      }

      break;

    case '>':

      if (x)

      {

        *s++ = a * 16; /* pad truncated string with '0' */

      }

      goto end;

    case EOF:

      return PDF_TOK_ERROR;

    }

  }

end:

  lb->len = s - lb->scratch;

  return PDF_TOK_STRING;

}

static pdf_token

pdf_token_from_keyword(char *key)

{

  switch (*key)

  {

  case 'R':

    if (!strcmp(key, "R")) return PDF_TOK_R;

    break;

  case 't':

    if (!strcmp(key, "true")) return PDF_TOK_TRUE;

    if (!strcmp(key, "trailer")) return PDF_TOK_TRAILER;

    break;

  case 'f':

    if (!strcmp(key, "false")) return PDF_TOK_FALSE;

    break;

  case 'n':

    if (!strcmp(key, "null")) return PDF_TOK_NULL;

    if (!strcmp(key, "newobj")) return PDF_TOK_NEWOBJ;

    break;

  case 'o':

    if (!strcmp(key, "obj")) return PDF_TOK_OBJ;

    break;

  case 'e':

    if (!strcmp(key, "endobj")) return PDF_TOK_ENDOBJ;

    if (!strcmp(key, "endstream")) return PDF_TOK_ENDSTREAM;

    break;

  case 's':

    if (!strcmp(key, "stream")) return PDF_TOK_STREAM;

    if (!strcmp(key, "startxref")) return PDF_TOK_STARTXREF;

    break;

  case 'x':

    if (!strcmp(key, "xref")) return PDF_TOK_XREF;

    break;

  }

  while (*key)

  {

    if (!fz_isprint(*key))

      return PDF_TOK_ERROR;

    ++key;

  }

  return PDF_TOK_KEYWORD;

}

void pdf_lexbuf_init(fz_context *ctx, pdf_lexbuf *lb, int size)

{

  lb->size = lb->base_size = size;

  lb->len = 0;

  lb->scratch = &lb->buffer[0];

}

void pdf_lexbuf_fin(fz_context *ctx, pdf_lexbuf *lb)

{

  if (lb && lb->size != lb->base_size)

    fz_free(ctx, lb->scratch);

}

ptrdiff_t pdf_lexbuf_grow(fz_context *ctx, pdf_lexbuf *lb)

{

  char *old = lb->scratch;

  size_t newsize = lb->size * 2;

  if (lb->size == lb->base_size)

  {

    lb->scratch = Memento_label(fz_malloc(ctx, newsize), "pdf_lexbuf");

    memcpy(lb->scratch, lb->buffer, lb->size);

  }

  else

  {

    lb->scratch = fz_realloc(ctx, lb->scratch, newsize);

  }

  lb->size = newsize;

  return lb->scratch - old;

}

pdf_token

pdf_lex(fz_context *ctx, fz_stream *f, pdf_lexbuf *buf)

{

  while (1)

  {

    int c = lex_byte(ctx, f);

    switch (c)

    {

    case EOF:

      return PDF_TOK_EOF;

    case IS_WHITE:

      lex_white(ctx, f);

      break;

    case '%':

      lex_comment(ctx, f);

      break;

    case '/':

      lex_name(ctx, f, buf);

      return PDF_TOK_NAME;

    case '(':

      return lex_string(ctx, f, buf);

    case ')':

      return PDF_TOK_ERROR;

    case '<':

      c = lex_byte(ctx, f);

      if (c == '<')

        return PDF_TOK_OPEN_DICT;

      if (c != EOF)

        fz_unread_byte(ctx, f);

      return lex_hex_string(ctx, f, buf);

    case '>':

      c = lex_byte(ctx, f);

      if (c == '>')

        return PDF_TOK_CLOSE_DICT;

      if (c != EOF)

        fz_unread_byte(ctx, f);

      return PDF_TOK_ERROR;

    case '[':

      return PDF_TOK_OPEN_ARRAY;

    case ']':

      return PDF_TOK_CLOSE_ARRAY;

    case '{':

      return PDF_TOK_OPEN_BRACE;

    case '}':

      return PDF_TOK_CLOSE_BRACE;

    case IS_NUMBER:

      return lex_number(ctx, f, buf, c);

    default: /* isregular: !isdelim && !iswhite && c != EOF */

      fz_unread_byte(ctx, f);

      lex_name(ctx, f, buf);

      return pdf_token_from_keyword(buf->scratch);

    }

  }

}

pdf_token

pdf_lex_no_string(fz_context *ctx, fz_stream *f, pdf_lexbuf *buf)

{

  while (1)

  {

    int c = lex_byte(ctx, f);

    switch (c)

    {

    case EOF:

      return PDF_TOK_EOF;

    case IS_WHITE:

      lex_white(ctx, f);

      break;

    case '%':

      lex_comment(ctx, f);

      break;

    case '/':

      lex_name(ctx, f, buf);

      return PDF_TOK_NAME;

    case '(':

      return PDF_TOK_ERROR; /* no strings allowed */

    case ')':

      return PDF_TOK_ERROR; /* no strings allowed */

    case '<':

      c = lex_byte(ctx, f);

      if (c == '<')

        return PDF_TOK_OPEN_DICT;

      if (c != EOF)

        fz_unread_byte(ctx, f);

      return PDF_TOK_ERROR; /* no strings allowed */

    case '>':

      c = lex_byte(ctx, f);

      if (c == '>')

        return PDF_TOK_CLOSE_DICT;

      if (c != EOF)

        fz_unread_byte(ctx, f);

      return PDF_TOK_ERROR;

    case '[':

      return PDF_TOK_OPEN_ARRAY;

    case ']':

      return PDF_TOK_CLOSE_ARRAY;

    case '{':

      return PDF_TOK_OPEN_BRACE;

    case '}':

      return PDF_TOK_CLOSE_BRACE;

    case IS_NUMBER:

      return lex_number(ctx, f, buf, c);

    default: /* isregular: !isdelim && !iswhite && c != EOF */

      fz_unread_byte(ctx, f);

      lex_name(ctx, f, buf);

      return pdf_token_from_keyword(buf->scratch);

    }

  }

}

void pdf_append_token(fz_context *ctx, fz_buffer *fzbuf, int tok, pdf_lexbuf *buf)

{

  switch (tok)

  {

  case PDF_TOK_NAME:

    fz_append_printf(ctx, fzbuf, "/%s", buf->scratch);

    break;

  case PDF_TOK_STRING:

    if (buf->len >= buf->size)

      pdf_lexbuf_grow(ctx, buf);

    buf->scratch[buf->len] = 0;

    fz_append_pdf_string(ctx, fzbuf, buf->scratch);

    break;

  case PDF_TOK_OPEN_DICT:

    fz_append_string(ctx, fzbuf, "<<");

    break;

  case PDF_TOK_CLOSE_DICT:

    fz_append_string(ctx, fzbuf, ">>");

    break;

  case PDF_TOK_OPEN_ARRAY:

    fz_append_byte(ctx, fzbuf, '[');

    break;

  case PDF_TOK_CLOSE_ARRAY:

    fz_append_byte(ctx, fzbuf, ']');

    break;

  case PDF_TOK_OPEN_BRACE:

    fz_append_byte(ctx, fzbuf, '{');

    break;

  case PDF_TOK_CLOSE_BRACE:

    fz_append_byte(ctx, fzbuf, '}');

    break;

  case PDF_TOK_INT:

    fz_append_printf(ctx, fzbuf, "%ld", buf->i);

    break;

  case PDF_TOK_REAL:

    fz_append_printf(ctx, fzbuf, "%g", buf->f);

    break;

  default:

    fz_append_data(ctx, fzbuf, buf->scratch, buf->len);

    break;

  }

}