kc3-lang/libjpeg-turbo/jdmrgext.c

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• Hash : 9120a247
  Author :
  Date : 2020-07-23T21:24:38
  

  Fix jpeg_skip_scanlines() segfault w/merged upsamp
  
  The additional segfault mentioned in #244 was due to the fact that
  the merged upsamplers use a different private structure than the
  non-merged upsamplers.  jpeg_skip_scanlines() was assuming the latter, so
  when merged upsampling was enabled, jpeg_skip_scanlines() clobbered one
  of the IDCT method pointers in the merged upsampler's private structure.
  
  For reasons unknown, the test image in #441 did not encounter this
  segfault (too small?), but it encountered an issue similar to the one
  fixed in 5bc43c7821df982f65aa1c738f67fbf7cba8bd69, whereby it was
  necessary to set up a dummy postprocessing function in
  read_and_discard_scanlines() when merged upsampling was enabled.
  Failing to do so caused either a segfault in merged_2v_upsample() (due
  to a NULL pointer being passed to jcopy_sample_rows()) or an error
  ("Corrupt JPEG data: premature end of data segment"), depending on the
  number of scanlines skipped and whether the first scanline skipped was
  an odd- or even-numbered row.
  
  Fixes #441
  Fixes #244 (for real this time)
  

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• jdmrgext.c

• /*
   * jdmrgext.c
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1994-1996, Thomas G. Lane.
   * libjpeg-turbo Modifications:
   * Copyright (C) 2011, 2015, 2020, D. R. Commander.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   *
   * This file contains code for merged upsampling/color conversion.
   */
  
  
  /* This file is included by jdmerge.c */
  
  
  /*
   * Upsample and color convert for the case of 2:1 horizontal and 1:1 vertical.
   */
  
  INLINE
  LOCAL(void)
  h2v1_merged_upsample_internal(j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
                                JDIMENSION in_row_group_ctr,
                                JSAMPARRAY output_buf)
  {
    my_merged_upsample_ptr upsample = (my_merged_upsample_ptr)cinfo->upsample;
    register int y, cred, cgreen, cblue;
    int cb, cr;
    register JSAMPROW outptr;
    JSAMPROW inptr0, inptr1, inptr2;
    JDIMENSION col;
    /* copy these pointers into registers if possible */
    register JSAMPLE *range_limit = cinfo->sample_range_limit;
    int *Crrtab = upsample->Cr_r_tab;
    int *Cbbtab = upsample->Cb_b_tab;
    JLONG *Crgtab = upsample->Cr_g_tab;
    JLONG *Cbgtab = upsample->Cb_g_tab;
    SHIFT_TEMPS
  
    inptr0 = input_buf[0][in_row_group_ctr];
    inptr1 = input_buf[1][in_row_group_ctr];
    inptr2 = input_buf[2][in_row_group_ctr];
    outptr = output_buf[0];
    /* Loop for each pair of output pixels */
    for (col = cinfo->output_width >> 1; col > 0; col--) {
      /* Do the chroma part of the calculation */
      cb = GETJSAMPLE(*inptr1++);
      cr = GETJSAMPLE(*inptr2++);
      cred = Crrtab[cr];
      cgreen = (int)RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
      cblue = Cbbtab[cb];
      /* Fetch 2 Y values and emit 2 pixels */
      y  = GETJSAMPLE(*inptr0++);
      outptr[RGB_RED] =   range_limit[y + cred];
      outptr[RGB_GREEN] = range_limit[y + cgreen];
      outptr[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr[RGB_ALPHA] = 0xFF;
  #endif
      outptr += RGB_PIXELSIZE;
      y  = GETJSAMPLE(*inptr0++);
      outptr[RGB_RED] =   range_limit[y + cred];
      outptr[RGB_GREEN] = range_limit[y + cgreen];
      outptr[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr[RGB_ALPHA] = 0xFF;
  #endif
      outptr += RGB_PIXELSIZE;
    }
    /* If image width is odd, do the last output column separately */
    if (cinfo->output_width & 1) {
      cb = GETJSAMPLE(*inptr1);
      cr = GETJSAMPLE(*inptr2);
      cred = Crrtab[cr];
      cgreen = (int)RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
      cblue = Cbbtab[cb];
      y  = GETJSAMPLE(*inptr0);
      outptr[RGB_RED] =   range_limit[y + cred];
      outptr[RGB_GREEN] = range_limit[y + cgreen];
      outptr[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr[RGB_ALPHA] = 0xFF;
  #endif
    }
  }
  
  
  /*
   * Upsample and color convert for the case of 2:1 horizontal and 2:1 vertical.
   */
  
  INLINE
  LOCAL(void)
  h2v2_merged_upsample_internal(j_decompress_ptr cinfo, JSAMPIMAGE input_buf,
                                JDIMENSION in_row_group_ctr,
                                JSAMPARRAY output_buf)
  {
    my_merged_upsample_ptr upsample = (my_merged_upsample_ptr)cinfo->upsample;
    register int y, cred, cgreen, cblue;
    int cb, cr;
    register JSAMPROW outptr0, outptr1;
    JSAMPROW inptr00, inptr01, inptr1, inptr2;
    JDIMENSION col;
    /* copy these pointers into registers if possible */
    register JSAMPLE *range_limit = cinfo->sample_range_limit;
    int *Crrtab = upsample->Cr_r_tab;
    int *Cbbtab = upsample->Cb_b_tab;
    JLONG *Crgtab = upsample->Cr_g_tab;
    JLONG *Cbgtab = upsample->Cb_g_tab;
    SHIFT_TEMPS
  
    inptr00 = input_buf[0][in_row_group_ctr * 2];
    inptr01 = input_buf[0][in_row_group_ctr * 2 + 1];
    inptr1 = input_buf[1][in_row_group_ctr];
    inptr2 = input_buf[2][in_row_group_ctr];
    outptr0 = output_buf[0];
    outptr1 = output_buf[1];
    /* Loop for each group of output pixels */
    for (col = cinfo->output_width >> 1; col > 0; col--) {
      /* Do the chroma part of the calculation */
      cb = GETJSAMPLE(*inptr1++);
      cr = GETJSAMPLE(*inptr2++);
      cred = Crrtab[cr];
      cgreen = (int)RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
      cblue = Cbbtab[cb];
      /* Fetch 4 Y values and emit 4 pixels */
      y  = GETJSAMPLE(*inptr00++);
      outptr0[RGB_RED] =   range_limit[y + cred];
      outptr0[RGB_GREEN] = range_limit[y + cgreen];
      outptr0[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr0[RGB_ALPHA] = 0xFF;
  #endif
      outptr0 += RGB_PIXELSIZE;
      y  = GETJSAMPLE(*inptr00++);
      outptr0[RGB_RED] =   range_limit[y + cred];
      outptr0[RGB_GREEN] = range_limit[y + cgreen];
      outptr0[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr0[RGB_ALPHA] = 0xFF;
  #endif
      outptr0 += RGB_PIXELSIZE;
      y  = GETJSAMPLE(*inptr01++);
      outptr1[RGB_RED] =   range_limit[y + cred];
      outptr1[RGB_GREEN] = range_limit[y + cgreen];
      outptr1[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr1[RGB_ALPHA] = 0xFF;
  #endif
      outptr1 += RGB_PIXELSIZE;
      y  = GETJSAMPLE(*inptr01++);
      outptr1[RGB_RED] =   range_limit[y + cred];
      outptr1[RGB_GREEN] = range_limit[y + cgreen];
      outptr1[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr1[RGB_ALPHA] = 0xFF;
  #endif
      outptr1 += RGB_PIXELSIZE;
    }
    /* If image width is odd, do the last output column separately */
    if (cinfo->output_width & 1) {
      cb = GETJSAMPLE(*inptr1);
      cr = GETJSAMPLE(*inptr2);
      cred = Crrtab[cr];
      cgreen = (int)RIGHT_SHIFT(Cbgtab[cb] + Crgtab[cr], SCALEBITS);
      cblue = Cbbtab[cb];
      y  = GETJSAMPLE(*inptr00);
      outptr0[RGB_RED] =   range_limit[y + cred];
      outptr0[RGB_GREEN] = range_limit[y + cgreen];
      outptr0[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr0[RGB_ALPHA] = 0xFF;
  #endif
      y  = GETJSAMPLE(*inptr01);
      outptr1[RGB_RED] =   range_limit[y + cred];
      outptr1[RGB_GREEN] = range_limit[y + cgreen];
      outptr1[RGB_BLUE] =  range_limit[y + cblue];
  #ifdef RGB_ALPHA
      outptr1[RGB_ALPHA] = 0xFF;
  #endif
    }
  }
  

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