xplanet-giflib-4.2

giflib-4.2.x.patch

--- a/src/libimage/gif.c
+++ b/src/libimage/gif.c
@@ -20,222 +20,566 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include <gif_lib.h>
 
 /*
-  A lot of this is based on the gif2rgb and rgb2gif codes in the libungif 
-  distribution. 
+  Based on the gif2rgb and rgb2gif codes in the libgif distribution. 
 */
 
 int
 read_gif(const char *filename, int *width, int *height, unsigned char **rgb)
 {
-    int interlace_offset[] = { 0, 4, 2, 1 };
-    int interlace_jump[] = { 8, 8, 4, 2 };
-    GifColorType *colormap;
-    GifFileType *infile;
-    GifRecordType record_type;
-    GifRowType *buffer = NULL;
-
-    int i, j;
-    int color_index;
-    unsigned char *ptr = NULL;
-
-    infile = DGifOpenFileName(filename);
-
-    if (infile == NULL)
-    {
-        PrintGifError();
-        return(0);
-    }
-
-    do
-    {
-        if (DGifGetRecordType(infile, &record_type) == GIF_ERROR) 
-        {
-            PrintGifError();
-            return(0);
+    int	BackGround = 0;
+    /* The way Interlaced image should be read - offsets and
+       jumps... */
+    int InterlacedOffset[] = { 0, 4, 2, 1 }; 
+    int InterlacedJumps[] = { 8, 8, 4, 2 };
+    ColorMapObject *ColorMap;
+
+    int	i, j, Size, Row, Col, Width, Height, ExtCode, Count;
+    GifRecordType RecordType;
+    GifByteType *Extension;
+    GifRowType *ScreenBuffer;
+    GifFileType *GifFile;
+
+    GifRowType GifRow;
+    GifColorType *ColorMapEntry;
+    unsigned char *BufferP;
+
+    if ((GifFile = DGifOpenFileName(filename)) == NULL) {
+	fprintf(stderr, "Can't open GIF file %s\n", filename);
+	return(0);
+    }
+    /* (Following comment was probably written on a 286 running under DOS.)  */
+    /* Allocate the screen as vector of column of rows. We can't allocate the*/
+    /* whole screen at once, as this broken minded CPU can allocate up to    */
+    /* 64k at a time and our image can be bigger than that:		     */
+    /* Note this screen is device independent - it's the screen defined by   */
+    /* the GIF file parameters.						     */
+    if ((ScreenBuffer = (GifRowType *)
+	 malloc(GifFile->SHeight * sizeof(GifRowType))) == NULL)
+    {
+	fprintf(stderr, "Failed to allocate memory required, aborted.");
+	return(0);
+    }
+
+    Size = GifFile->SWidth * sizeof(GifPixelType);/* Size in bytes one row.*/
+    if ((ScreenBuffer[0] = (GifRowType) malloc(Size)) == NULL) /* First row. */
+    {
+	fprintf(stderr, "Failed to allocate memory required, aborted.");
+	return(0);
+    }
+
+    for (i = 0; i < GifFile->SWidth; i++)  /* Set its color to BackGround. */
+	ScreenBuffer[0][i] = GifFile->SBackGroundColor;
+    for (i = 1; i < GifFile->SHeight; i++) {
+	/* Allocate the other rows, and set their color to background too: */
+	if ((ScreenBuffer[i] = (GifRowType) malloc(Size)) == NULL)
+	{
+	    fprintf(stderr, "Failed to allocate memory required, aborted.\n");
+	    return(0);
+	}
+
+	memcpy(ScreenBuffer[i], ScreenBuffer[0], Size);
+    }
+
+    /* Scan the content of the GIF file and load the image(s) in: */
+    do {
+	if (DGifGetRecordType(GifFile, &RecordType) == GIF_ERROR) {
+	    fprintf(stderr, "Can't read GIF file\n");
+	    return(0);
+	}
+	switch (RecordType) {
+	case IMAGE_DESC_RECORD_TYPE:
+	    if (DGifGetImageDesc(GifFile) == GIF_ERROR) {
+		return(0);
+	    }
+	    Row = GifFile->Image.Top; /* Image Position relative to Screen. */
+	    Col = GifFile->Image.Left;
+	    Width = GifFile->Image.Width;
+	    Height = GifFile->Image.Height;
+	    if (GifFile->Image.Left + GifFile->Image.Width > GifFile->SWidth ||
+		GifFile->Image.Top + GifFile->Image.Height > GifFile->SHeight) {
+		return(0);
+	    }
+	    if (GifFile->Image.Interlace) {
+		/* Need to perform 4 passes on the images: */
+		for (Count = i = 0; i < 4; i++)
+		    for (j = Row + InterlacedOffset[i]; j < Row + Height;
+			 j += InterlacedJumps[i]) {
+			if (DGifGetLine(GifFile, &ScreenBuffer[j][Col],
+					Width) == GIF_ERROR) {
+			    return(0);
+			}
+		    }
+	    }
+	    else {
+		for (i = 0; i < Height; i++) {
+		    if (DGifGetLine(GifFile, &ScreenBuffer[Row++][Col],
+				    Width) == GIF_ERROR) {
+			return(0);
+		    }
+		}
+	    }
+	    break;
+	case EXTENSION_RECORD_TYPE:
+	    /* Skip any extension blocks in file: */
+	    if (DGifGetExtension(GifFile, &ExtCode, &Extension) == GIF_ERROR) {
+		return(0);
+	    }
+	    while (Extension != NULL) {
+		if (DGifGetExtensionNext(GifFile, &Extension) == GIF_ERROR) {
+		    return(0);
+		}
+	    }
+	    break;
+	case TERMINATE_RECORD_TYPE:
+	    break;
+	default:		    /* Should be traps by DGifGetRecordType. */
+	    break;
+	}
+    } while (RecordType != TERMINATE_RECORD_TYPE);
+
+    /* Lets dump it - set the global variables required and do it: */
+    BackGround = GifFile->SBackGroundColor;
+    ColorMap = (GifFile->Image.ColorMap
+		? GifFile->Image.ColorMap
+		: GifFile->SColorMap);
+    if (ColorMap == NULL) {
+	fprintf(stderr, "Gif Image does not have a colormap\n");
+	return(0);
+    }
+
+    *width = GifFile->SWidth;
+    *height = GifFile->SHeight;
+
+    rgb[0] = malloc(3 * *width * *height);
+    if (rgb[0] == NULL)
+    {
+	fprintf(stderr, "Can't allocate memory for GIF file.\n");
+	return(0);
+    }
+
+    BufferP = rgb[0];
+    
+    for (i = 0; i < *height; i++) {
+	GifRow = ScreenBuffer[i];
+	for (j = 0; j < *width; j++) {
+	    ColorMapEntry = &ColorMap->Colors[GifRow[j]];
+	    *BufferP++ = ColorMapEntry->Red;
+	    *BufferP++ = ColorMapEntry->Green;
+	    *BufferP++ = ColorMapEntry->Blue;
+	}
+    }
+    
+    if (DGifCloseFile(GifFile) == GIF_ERROR) {
+	return(0);
+    }
+
+    return(1);
+}
+
+/* Make some variables global, so we could access them faster: */
+static int
+    ExpNumOfColors = 8,
+    ColorMapSize = 256;
+
+/******************************************************************************
+ * Code to quantize high resolution image into lower one. You may want to
+ * peek into the following article this code is based on:
+ * "Color Image Quantization for frame buffer Display", by Paul Heckbert
+ * SIGGRAPH 1982 page 297-307.
+ ******************************************************************************
+ * History:
+ * 5 Jan 90 - Version 1.0 by Gershon Elber.
+ *****************************************************************************/
+
+#define ABS(x)    ((x) > 0 ? (x) : (-(x)))
+
+#define COLOR_ARRAY_SIZE 32768
+#define BITS_PER_PRIM_COLOR 5
+#define MAX_PRIM_COLOR      0x1f
+
+static int SortRGBAxis;
+
+typedef struct QuantizedColorType {
+    GifByteType RGB[3];
+    GifByteType NewColorIndex;
+    long Count;
+    struct QuantizedColorType *Pnext;
+} QuantizedColorType;
+
+typedef struct NewColorMapType {
+    GifByteType RGBMin[3], RGBWidth[3];
+    unsigned int NumEntries; /* # of QuantizedColorType in linked list below */
+    unsigned long Count; /* Total number of pixels in all the entries */
+    QuantizedColorType *QuantizedColors;
+} NewColorMapType;
+
+static int SubdivColorMap(NewColorMapType * NewColorSubdiv,
+                          unsigned int ColorMapSize,
+                          unsigned int *NewColorMapSize);
+static int SortCmpRtn(const void *Entry1, const void *Entry2);
+
+/******************************************************************************
+ * Quantize high resolution image into lower one. Input image consists of a
+ * 2D array for each of the RGB colors with size Width by Height. There is no
+ * Color map for the input. Output is a quantized image with 2D array of
+ * indexes into the output color map.
+ *   Note input image can be 24 bits at the most (8 for red/green/blue) and
+ * the output has 256 colors at the most (256 entries in the color map.).
+ * ColorMapSize specifies size of color map up to 256 and will be updated to
+ * real size before returning.
+ *   Also non of the parameter are allocated by this routine.
+ *   This function returns GIF_OK if succesfull, GIF_ERROR otherwise.
+ ******************************************************************************/
+static int
+QuantizeBuffer(unsigned int Width,
+               unsigned int Height,
+               int *ColorMapSize,
+               GifByteType * RedInput,
+               GifByteType * GreenInput,
+               GifByteType * BlueInput,
+               GifByteType * OutputBuffer,
+               GifColorType * OutputColorMap) {
+
+    unsigned int Index, NumOfEntries;
+    int i, j, MaxRGBError[3];
+    unsigned int NewColorMapSize;
+    long Red, Green, Blue;
+    NewColorMapType NewColorSubdiv[256];
+    QuantizedColorType *ColorArrayEntries, *QuantizedColor;
+
+    ColorArrayEntries = (QuantizedColorType *)malloc(
+                           sizeof(QuantizedColorType) * COLOR_ARRAY_SIZE);
+    if (ColorArrayEntries == NULL) {
+        return GIF_ERROR;
+    }
+
+    for (i = 0; i < COLOR_ARRAY_SIZE; i++) {
+        ColorArrayEntries[i].RGB[0] = i >> (2 * BITS_PER_PRIM_COLOR);
+        ColorArrayEntries[i].RGB[1] = (i >> BITS_PER_PRIM_COLOR) &
+           MAX_PRIM_COLOR;
+        ColorArrayEntries[i].RGB[2] = i & MAX_PRIM_COLOR;
+        ColorArrayEntries[i].Count = 0;
+    }
+
+    /* Sample the colors and their distribution: */
+    for (i = 0; i < (int)(Width * Height); i++) {
+        Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
+                  (2 * BITS_PER_PRIM_COLOR)) +
+                ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
+                  BITS_PER_PRIM_COLOR) +
+                (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR));
+        ColorArrayEntries[Index].Count++;
+    }
+
+    /* Put all the colors in the first entry of the color map, and call the
+     * recursive subdivision process.  */
+    for (i = 0; i < 256; i++) {
+        NewColorSubdiv[i].QuantizedColors = NULL;
+        NewColorSubdiv[i].Count = NewColorSubdiv[i].NumEntries = 0;
+        for (j = 0; j < 3; j++) {
+            NewColorSubdiv[i].RGBMin[j] = 0;
+            NewColorSubdiv[i].RGBWidth[j] = 255;
         }
-
-        switch (record_type)
-        {
-        case IMAGE_DESC_RECORD_TYPE:
-            if (DGifGetImageDesc(infile) == GIF_ERROR)
-            {
-                PrintGifError();
-                return(0);
+    }
+
+    /* Find the non empty entries in the color table and chain them: */
+    for (i = 0; i < COLOR_ARRAY_SIZE; i++)
+        if (ColorArrayEntries[i].Count > 0)
+            break;
+    QuantizedColor = NewColorSubdiv[0].QuantizedColors = &ColorArrayEntries[i];
+    NumOfEntries = 1;
+    while (++i < COLOR_ARRAY_SIZE)
+        if (ColorArrayEntries[i].Count > 0) {
+            QuantizedColor->Pnext = &ColorArrayEntries[i];
+            QuantizedColor = &ColorArrayEntries[i];
+            NumOfEntries++;
+        }
+    QuantizedColor->Pnext = NULL;
+
+    NewColorSubdiv[0].NumEntries = NumOfEntries; /* Different sampled colors */
+    NewColorSubdiv[0].Count = ((long)Width) * Height; /* Pixels */
+    NewColorMapSize = 1;
+    if (SubdivColorMap(NewColorSubdiv, *ColorMapSize, &NewColorMapSize) !=
+       GIF_OK) {
+        free((char *)ColorArrayEntries);
+        return GIF_ERROR;
+    }
+    if (NewColorMapSize < *ColorMapSize) {
+        /* And clear rest of color map: */
+        for (i = NewColorMapSize; i < *ColorMapSize; i++)
+            OutputColorMap[i].Red = OutputColorMap[i].Green =
+                OutputColorMap[i].Blue = 0;
+    }
+
+    /* Average the colors in each entry to be the color to be used in the
+     * output color map, and plug it into the output color map itself. */
+    for (i = 0; i < NewColorMapSize; i++) {
+        if ((j = NewColorSubdiv[i].NumEntries) > 0) {
+            QuantizedColor = NewColorSubdiv[i].QuantizedColors;
+            Red = Green = Blue = 0;
+            while (QuantizedColor) {
+                QuantizedColor->NewColorIndex = i;
+                Red += QuantizedColor->RGB[0];
+                Green += QuantizedColor->RGB[1];
+                Blue += QuantizedColor->RGB[2];
+                QuantizedColor = QuantizedColor->Pnext;
             }
-
-            *width = infile->Image.Width;
-            *height = infile->Image.Height;
-
-            buffer = malloc(*height * sizeof(GifRowType *));
-            if (buffer == NULL)
-            {
-                fprintf(stderr, "Can't allocate memory for GIF file.\n");
-                return(0);
-            }
-            
-            for (i = 0; i < *height; i++) 
-            {
-                buffer[i] = malloc(*width * sizeof(GifPixelType));
-                if (buffer[i] == NULL)
-                {
-                    fprintf(stderr, "Can't allocate memory for GIF line.\n");
-                    return(0);
-                }
-            }
-            
-            if (infile->Image.Interlace)
-            {
-                for (i = 0; i < 4; i++)
-                    for (j = interlace_offset[i]; j < *height; 
-                         j += interlace_jump[i])
-                        DGifGetLine(infile, buffer[j], *width);
-            }
-            else
-            {
-                for (i = 0; i < *height; i++)
-                    DGifGetLine(infile, buffer[i], *width);
-            }
-            break;
-        case EXTENSION_RECORD_TYPE:
-        {
-            /* Skip extension blocks */
-            int ext_code;
-            GifByteType *ext;
-            if (DGifGetExtension(infile, &ext_code, &ext) == GIF_ERROR) 
-            {
-                PrintGifError();
-                return(0);
-            }
-            while (ext != NULL) 
-            {
-                if (DGifGetExtensionNext(infile, &ext) == GIF_ERROR) 
-                {
-                    PrintGifError();
-                    return(0);
+            OutputColorMap[i].Red = (Red << (8 - BITS_PER_PRIM_COLOR)) / j;
+            OutputColorMap[i].Green = (Green << (8 - BITS_PER_PRIM_COLOR)) / j;
+            OutputColorMap[i].Blue = (Blue << (8 - BITS_PER_PRIM_COLOR)) / j;
+        } else
+            fprintf(stderr,
+                    "Null entry in quantized color map - that's weird.\n");
+    }
+
+    /* Finally scan the input buffer again and put the mapped index in the
+     * output buffer.  */
+    MaxRGBError[0] = MaxRGBError[1] = MaxRGBError[2] = 0;
+    for (i = 0; i < (int)(Width * Height); i++) {
+        Index = ((RedInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
+                 (2 * BITS_PER_PRIM_COLOR)) +
+                ((GreenInput[i] >> (8 - BITS_PER_PRIM_COLOR)) <<
+                 BITS_PER_PRIM_COLOR) +
+                (BlueInput[i] >> (8 - BITS_PER_PRIM_COLOR));
+        Index = ColorArrayEntries[Index].NewColorIndex;
+        OutputBuffer[i] = Index;
+        if (MaxRGBError[0] < ABS(OutputColorMap[Index].Red - RedInput[i]))
+            MaxRGBError[0] = ABS(OutputColorMap[Index].Red - RedInput[i]);
+        if (MaxRGBError[1] < ABS(OutputColorMap[Index].Green - GreenInput[i]))
+            MaxRGBError[1] = ABS(OutputColorMap[Index].Green - GreenInput[i]);
+        if (MaxRGBError[2] < ABS(OutputColorMap[Index].Blue - BlueInput[i]))
+            MaxRGBError[2] = ABS(OutputColorMap[Index].Blue - BlueInput[i]);
+    }
+
+    free((char *)ColorArrayEntries);
+
+    *ColorMapSize = NewColorMapSize;
+
+    return GIF_OK;
+}
+
+/******************************************************************************
+ * Routine to subdivide the RGB space recursively using median cut in each
+ * axes alternatingly until ColorMapSize different cubes exists.
+ * The biggest cube in one dimension is subdivide unless it has only one entry.
+ * Returns GIF_ERROR if failed, otherwise GIF_OK.
+ ******************************************************************************/
+static int
+SubdivColorMap(NewColorMapType * NewColorSubdiv,
+               unsigned int ColorMapSize,
+               unsigned int *NewColorMapSize) {
+
+    int MaxSize;
+    unsigned int i, j, Index = 0, NumEntries, MinColor, MaxColor;
+    long Sum, Count;
+    QuantizedColorType *QuantizedColor, **SortArray;
+
+    while (ColorMapSize > *NewColorMapSize) {
+        /* Find candidate for subdivision: */
+        MaxSize = -1;
+        for (i = 0; i < *NewColorMapSize; i++) {
+            for (j = 0; j < 3; j++) {
+                if ((((int)NewColorSubdiv[i].RGBWidth[j]) > MaxSize) &&
+                      (NewColorSubdiv[i].NumEntries > 1)) {
+                    MaxSize = NewColorSubdiv[i].RGBWidth[j];
+                    Index = i;
+                    SortRGBAxis = j;
                 }
             }
         }
-        break;
-        case TERMINATE_RECORD_TYPE:
-            break;
-        default:
-            fprintf(stderr, "unknown record type in GIF file\n");
-            break;
+
+        if (MaxSize == -1)
+            return GIF_OK;
+
+        /* Split the entry Index into two along the axis SortRGBAxis: */
+
+        /* Sort all elements in that entry along the given axis and split at
+         * the median.  */
+        SortArray = (QuantizedColorType **)malloc(
+                      sizeof(QuantizedColorType *) * 
+                      NewColorSubdiv[Index].NumEntries);
+        if (SortArray == NULL)
+            return GIF_ERROR;
+        for (j = 0, QuantizedColor = NewColorSubdiv[Index].QuantizedColors;
+             j < NewColorSubdiv[Index].NumEntries && QuantizedColor != NULL;
+             j++, QuantizedColor = QuantizedColor->Pnext)
+            SortArray[j] = QuantizedColor;
+
+        qsort(SortArray, NewColorSubdiv[Index].NumEntries,
+              sizeof(QuantizedColorType *), SortCmpRtn);
+
+        /* Relink the sorted list into one: */
+        for (j = 0; j < NewColorSubdiv[Index].NumEntries - 1; j++)
+            SortArray[j]->Pnext = SortArray[j + 1];
+        SortArray[NewColorSubdiv[Index].NumEntries - 1]->Pnext = NULL;
+        NewColorSubdiv[Index].QuantizedColors = QuantizedColor = SortArray[0];
+        free((char *)SortArray);
+
+        /* Now simply add the Counts until we have half of the Count: */
+        Sum = NewColorSubdiv[Index].Count / 2 - QuantizedColor->Count;
+        NumEntries = 1;
+        Count = QuantizedColor->Count;
+        while (QuantizedColor->Pnext != NULL &&
+	       (Sum -= QuantizedColor->Pnext->Count) >= 0 &&
+               QuantizedColor->Pnext->Pnext != NULL) {
+            QuantizedColor = QuantizedColor->Pnext;
+            NumEntries++;
+            Count += QuantizedColor->Count;
         }
-    } while (record_type != TERMINATE_RECORD_TYPE);
-
-    colormap = (infile->Image.ColorMap ? infile->Image.ColorMap->Colors
-                : infile->SColorMap->Colors);
-
-    rgb[0] = malloc(3 * *width * *height);
-    if (rgb[0] == NULL)
-    {
-        fprintf(stderr, "Can't allocate memory for GIF file.\n");
-        return(0);
-    }
-
-    ptr = rgb[0];
-
-    for (j = 0; j < *height; j++)
-    {
-        for (i = 0; i < *width; i++)
-        {
-            color_index = (int) buffer[j][i];
-            *ptr++ = (unsigned char) colormap[color_index].Red;
-            *ptr++ = (unsigned char) colormap[color_index].Green;
-            *ptr++ = (unsigned char) colormap[color_index].Blue;
+        /* Save the values of the last color of the first half, and first
+         * of the second half so we can update the Bounding Boxes later.
+         * Also as the colors are quantized and the BBoxes are full 0..255,
+         * they need to be rescaled.
+         */
+        MaxColor = QuantizedColor->RGB[SortRGBAxis]; /* Max. of first half */
+	/* coverity[var_deref_op] */
+        MinColor = QuantizedColor->Pnext->RGB[SortRGBAxis]; /* of second */
+        MaxColor <<= (8 - BITS_PER_PRIM_COLOR);
+        MinColor <<= (8 - BITS_PER_PRIM_COLOR);
+
+        /* Partition right here: */
+        NewColorSubdiv[*NewColorMapSize].QuantizedColors =
+           QuantizedColor->Pnext;
+        QuantizedColor->Pnext = NULL;
+        NewColorSubdiv[*NewColorMapSize].Count = Count;
+        NewColorSubdiv[Index].Count -= Count;
+        NewColorSubdiv[*NewColorMapSize].NumEntries =
+           NewColorSubdiv[Index].NumEntries - NumEntries;
+        NewColorSubdiv[Index].NumEntries = NumEntries;
+        for (j = 0; j < 3; j++) {
+            NewColorSubdiv[*NewColorMapSize].RGBMin[j] =
+               NewColorSubdiv[Index].RGBMin[j];
+            NewColorSubdiv[*NewColorMapSize].RGBWidth[j] =
+               NewColorSubdiv[Index].RGBWidth[j];
         }
-        free(buffer[j]);
-    }
-    
-    free(buffer);
-
-    DGifCloseFile(infile);
-    return(1);
+        NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] =
+           NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] +
+           NewColorSubdiv[*NewColorMapSize].RGBWidth[SortRGBAxis] - MinColor;
+        NewColorSubdiv[*NewColorMapSize].RGBMin[SortRGBAxis] = MinColor;
+
+        NewColorSubdiv[Index].RGBWidth[SortRGBAxis] =
+           MaxColor - NewColorSubdiv[Index].RGBMin[SortRGBAxis];
+
+        (*NewColorMapSize)++;
+    }
+
+    return GIF_OK;
+}
+
+/****************************************************************************
+ * Routine called by qsort to compare two entries.
+ ****************************************************************************/
+static int
+SortCmpRtn(const void *Entry1,
+           const void *Entry2) {
+
+    return (*((QuantizedColorType **) Entry1))->RGB[SortRGBAxis] -
+       (*((QuantizedColorType **) Entry2))->RGB[SortRGBAxis];
+}
+
+/******************************************************************************
+* Close output file (if open), and exit.
+******************************************************************************/
+static void QuitGifError(GifFileType *GifFile)
+{
+    fprintf(stderr, "Error writing GIF file\n");
+    if (GifFile != NULL) EGifCloseFile(GifFile);
 }
 
 int 
 write_gif(const char *filename, int width, int height, char *rgb)
 {
     int i;
-    int colormap_size = 256;
-    GifByteType *red, *green, *blue, *buffer, *ptr;
-    GifFileType *outfile;
-    ColorMapObject *colormap;
+    GifByteType *red, *green, *blue;
+
+    GifByteType *OutputBuffer = NULL;
+    ColorMapObject *OutputColorMap = NULL;
+
+    GifFileType *GifFile;
+    GifByteType *Ptr;
+
+    bool GifTestExistance = false;
+
+    ColorMapSize = 1 << ExpNumOfColors;
+
+    if ((OutputColorMap = MakeMapObject(ColorMapSize, NULL)) == NULL ||
+	(OutputBuffer = (GifByteType *) malloc(width * height *
+					    sizeof(GifByteType))) == NULL)
+    {
+	fprintf(stderr,"Failed to allocate memory required, aborted.");
+	return(0);
+    }
 
     red = malloc(width * height * sizeof(GifByteType));
     green = malloc(width * height * sizeof(GifByteType));
     blue = malloc(width * height * sizeof(GifByteType));
-    buffer = malloc(width * height * sizeof(GifByteType));
-
-    if (red == NULL || green == NULL || blue == NULL || buffer == NULL)
-    {
-        fprintf(stderr, "Can't allocate memory for GIF file.\n");
-        return(0);
-    }
-
-    colormap = MakeMapObject(colormap_size, NULL);
-
+    if (red == NULL || green == NULL || blue == NULL)
+    {
+	fprintf(stderr, "Can't allocate memory for GIF file.\n");
+	return(0);
+    }
     for (i = 0; i < width * height; i++)
     {
-        red[i]   = (GifByteType) rgb[3*i  ];
-        green[i] = (GifByteType) rgb[3*i+1];
-        blue[i]  = (GifByteType) rgb[3*i+2];
-    }
-  
-    if (QuantizeBuffer(width, height, &colormap_size, red, green, blue,   
-                       buffer, colormap->Colors) == GIF_ERROR)
-    {
-        PrintGifError();
-        return(0);
+	red[i]   = (GifByteType) rgb[3*i  ];
+	green[i] = (GifByteType) rgb[3*i+1];
+	blue[i]  = (GifByteType) rgb[3*i+2];
+    }
+
+    if (QuantizeBuffer(width, height, &ColorMapSize,
+		       red, green, blue,
+		       OutputBuffer, OutputColorMap->Colors) == GIF_ERROR)
+
+    {
+	QuitGifError(NULL);
+	return(0);
     }
 
     free(red);
     free(green);
     free(blue);
 
-    outfile = EGifOpenFileName((char *) filename, FALSE);
-    if (outfile == NULL)
-    {
-        PrintGifError();
-        return(0);
-    }
-
-    if (EGifPutScreenDesc(outfile, width, height, colormap_size, 0, colormap)
-        == GIF_ERROR)
-    {
-        PrintGifError();
-        return(0);
-    }
-
-    if (EGifPutImageDesc(outfile, 0, 0, width, height, FALSE, NULL)
-        == GIF_ERROR)
-    {
-        PrintGifError();
-        return(0);
-    }
-
-    ptr = buffer;
-    for (i = 0; i < height; i++)
-    {
-        if (EGifPutLine(outfile, ptr, width) == GIF_ERROR)
-        {
-            PrintGifError();
-            return(0);
-        }
-        ptr += width;
-    }
-
-    EGifSpew(outfile);
-
-    if (EGifCloseFile(outfile) == GIF_ERROR) 
-        PrintGifError();
-
-    free(buffer);
+    Ptr = OutputBuffer;
+
+    /* Open stdout for the output file: */
+    if ((GifFile = EGifOpenFileName(filename, GifTestExistance)) == NULL)
+
+    {
+	QuitGifError(GifFile);
+	return(0);
+    }
+
+    if (EGifPutScreenDesc(GifFile,
+			  width, height, ExpNumOfColors, 0,
+			  OutputColorMap) == GIF_ERROR ||
+	EGifPutImageDesc(GifFile,
+			 0, 0, width, height, false, NULL) == GIF_ERROR)
+
+    {
+	QuitGifError(GifFile);
+	return(0);
+    }
+
+    for (i = 0; i < height; i++) {
+	if (EGifPutLine(GifFile, Ptr, width) == GIF_ERROR)
+
+	{
+	    QuitGifError(GifFile);
+	    return(0);
+	}
+	Ptr += width;
+    }
+
+    if (EGifCloseFile(GifFile) == GIF_ERROR)
+
+    {
+	QuitGifError(GifFile);
+	return(0);
+    }
 
     return(1);
 }

giflib-5.x.patch

--- a/src/libimage/gif.c
+++ b/src/libimage/gif.c
@@ -42,13 +42,18 @@
     GifRecordType RecordType;
     GifByteType *Extension;
     GifRowType *ScreenBuffer;
-    GifFileType *GifFile;
 
     GifRowType GifRow;
     GifColorType *ColorMapEntry;
     unsigned char *BufferP;
 
-    if ((GifFile = DGifOpenFileName(filename)) == NULL) {
+    GifFileType *GifFile;
+#if GIFLIB_MAJOR >= 5
+    GifFile = DGifOpenFileName(filename, NULL);
+#else
+    GifFile = DGifOpenFileName(filename);
+#endif
+    if (GifFile == NULL) {
 	fprintf(stderr, "Can't open GIF file %s\n", filename);
 	return(0);
     }
@@ -507,9 +512,15 @@
 
     ColorMapSize = 1 << ExpNumOfColors;
 
-    if ((OutputColorMap = MakeMapObject(ColorMapSize, NULL)) == NULL ||
+#if GIFLIB_MAJOR >= 5
+    OutputColorMap = GifMakeMapObject(ColorMapSize, NULL);
+#else
+    OutputColorMap = MakeMapObject(ColorMapSize, NULL);
+#endif
+    
+    if (OutputColorMap == NULL ||
 	(OutputBuffer = (GifByteType *) malloc(width * height *
-					    sizeof(GifByteType))) == NULL)
+					       sizeof(GifByteType))) == NULL)
     {
 	fprintf(stderr,"Failed to allocate memory required, aborted.");
 	return(0);
@@ -545,9 +556,13 @@
 
     Ptr = OutputBuffer;
 
+#if GIFLIB_MAJOR >= 5
+    GifFile = EGifOpenFileName(filename, GifTestExistance, NULL);
+#else
+    GifFile = EGifOpenFileName(filename, GifTestExistance);
+#endif
     /* Open stdout for the output file: */
-    if ((GifFile = EGifOpenFileName(filename, GifTestExistance)) == NULL)
-
+    if (GifFile == NULL)
     {
 	QuitGifError(GifFile);
 	return(0);

These do not apply properly; "patch unexpectedly ends in middle of line". Could you please fix?