tiff: Make the TIFF_LONG and TIFF_SHORT types unsigned.

TIFF v6.0 (unimplemented) adds signed equivalents.
(cherry picked from commit e32548d133)

Signed-off-by: Reinhard Tartler <siretart@tauware.de>

libavcodec/tiff.c

@@ -58,24 +58,24 @@ typedef struct TiffContext {
     LZWState *lzw;
 } TiffContext;
 
-static int tget_short(const uint8_t **p, int le){
-    int v = le ? AV_RL16(*p) : AV_RB16(*p);
+static unsigned tget_short(const uint8_t **p, int le) {
+    unsigned v = le ? AV_RL16(*p) : AV_RB16(*p);
     *p += 2;
     return v;
 }
 
-static int tget_long(const uint8_t **p, int le){
-    int v = le ? AV_RL32(*p) : AV_RB32(*p);
+static unsigned tget_long(const uint8_t **p, int le) {
+    unsigned v = le ? AV_RL32(*p) : AV_RB32(*p);
     *p += 4;
     return v;
 }
 
-static int tget(const uint8_t **p, int type, int le){
+static unsigned tget(const uint8_t **p, int type, int le) {
     switch(type){
     case TIFF_BYTE : return *(*p)++;
     case TIFF_SHORT: return tget_short(p, le);
     case TIFF_LONG : return tget_long (p, le);
-    default        : return -1;
+    default        : return UINT_MAX;
     }
 }
 
@@ -276,7 +276,7 @@ static int init_image(TiffContext *s)
 
 static int tiff_decode_tag(TiffContext *s, const uint8_t *start, const uint8_t *buf, const uint8_t *end_buf)
 {
-    int tag, type, count, off, value = 0;
+    unsigned tag, type, count, off, value = 0;
     int i, j;
     uint32_t *pal;
     const uint8_t *rp, *gp, *bp;
@@ -311,7 +311,7 @@ static int tiff_decode_tag(TiffContext *s, const uint8_t *start, const uint8_t *
                 break;
             }
         default:
-            value = -1;
+            value = UINT_MAX;
             buf = start + off;
         }
     } else {
@@ -397,7 +397,7 @@ static int tiff_decode_tag(TiffContext *s, const uint8_t *start, const uint8_t *
         }
         break;
     case TIFF_ROWSPERSTRIP:
-        if(type == TIFF_LONG && value == -1)
+        if (type == TIFF_LONG && value == UINT_MAX)
             value = s->avctx->height;
         if(value < 1){
             av_log(s->avctx, AV_LOG_ERROR, "Incorrect value of rows per strip\n");