--- OLD/pnm/giftopnm.c	Thu Jan  1 00:00:00 1970
+++ NEW/pnm/giftopnm.c	Thu Jan  1 00:00:00 1970
@@ -267,7 +267,7 @@
                foreground = buf[10];
                background = buf[11];
 
-               while (GetDataBlock(fd, (unsigned char*) buf) != 0) {
+               while (GetDataBlock(fd, (unsigned char*) buf) > 0) {
                        PPM_ASSIGN(image[ypos][xpos],
                                        cmap[CM_RED][v],
                                        cmap[CM_GREEN][v],
@@ -284,7 +284,7 @@
                break;
        case 0xfe:              /* Comment Extension */
                str = "Comment Extension";
-               while (GetDataBlock(fd, (unsigned char*) buf) != 0) {
+               while (GetDataBlock(fd, (unsigned char*) buf) > 0) {
                        if (showComment)
                                pm_message("gif comment: %s", buf );
                }
@@ -298,7 +298,7 @@
                if ((buf[0] & 0x1) != 0)
                        Gif89.transparent = buf[3];
 
-               while (GetDataBlock(fd, (unsigned char*) buf) != 0)
+               while (GetDataBlock(fd, (unsigned char*) buf) > 0)
                        ;
                return FALSE;
        default:
@@ -309,7 +309,7 @@
 
        pm_message("got a '%s' extension", str );
 
-       while (GetDataBlock(fd, (unsigned char*) buf) != 0)
+       while (GetDataBlock(fd, (unsigned char*) buf) > 0)
                ;
 
        return FALSE;
@@ -348,7 +348,7 @@
        static unsigned char    buf[280];
        static int              curbit, lastbit, done, last_byte;
        int                     i, j, ret;
-       unsigned char           count;
+ int count;
 
        if (flag) {
                curbit = 0;
@@ -368,6 +368,7 @@
 
                if ((count = GetDataBlock(fd, &buf[2])) == 0)
                        done = TRUE;
+		if (count < 0) return(-1);
 
                last_byte = 2 + count;
                curbit = (curbit - lastbit) + 16;