simplify url_fseek()

Originally committed as revision 6316 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/aviobuf.c

@@ -106,56 +106,41 @@ void put_flush_packet(ByteIOContext *s)
 offset_t url_fseek(ByteIOContext *s, offset_t offset, int whence)
 {
     offset_t offset1;
+    offset_t pos= s->pos - (s->write_flag ? 0 : (s->buf_end - s->buffer));
 
     if (whence != SEEK_CUR && whence != SEEK_SET)
         return -EINVAL;
 
+    if (whence == SEEK_CUR) {
+        offset1 = pos + (s->buf_ptr - s->buffer);
+        if (offset == 0)
+            return offset1;
+        offset += offset1;
+    }
+    offset1 = offset - pos;
+    if (!s->must_flush &&
+        offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
+        /* can do the seek inside the buffer */
+        s->buf_ptr = s->buffer + offset1;
+    } else {
+        if (!s->seek)
+            return -EPIPE;
+
 #ifdef CONFIG_MUXERS
-    if (s->write_flag) {
-        if (whence == SEEK_CUR) {
-            offset1 = s->pos + (s->buf_ptr - s->buffer);
-            if (offset == 0)
-                return offset1;
-            offset += offset1;
-        }
-        offset1 = offset - s->pos;
-        if (!s->must_flush &&
-            offset1 >= 0 && offset1 < (s->buf_end - s->buffer)) {
-            /* can do the seek inside the buffer */
-            s->buf_ptr = s->buffer + offset1;
-        } else {
-            if (!s->seek)
-                return -EPIPE;
+        if (s->write_flag) {
             flush_buffer(s);
             s->must_flush = 1;
-            s->buf_ptr = s->buffer;
-            s->seek(s->opaque, offset, SEEK_SET);
-            s->pos = offset;
-        }
-    } else
+        } else
 #endif //CONFIG_MUXERS
-    {
-        if (whence == SEEK_CUR) {
-            offset1 = s->pos - (s->buf_end - s->buffer) + (s->buf_ptr - s->buffer);
-            if (offset == 0)
-                return offset1;
-            offset += offset1;
-        }
-        offset1 = offset - (s->pos - (s->buf_end - s->buffer));
-        if (offset1 >= 0 && offset1 <= (s->buf_end - s->buffer)) {
-            /* can do the seek inside the buffer */
-            s->buf_ptr = s->buffer + offset1;
-        } else {
-            if (!s->seek)
-                return -EPIPE;
-            s->buf_ptr = s->buffer;
+        {
             s->buf_end = s->buffer;
-            if (s->seek(s->opaque, offset, SEEK_SET) == (offset_t)-EPIPE)
-                return -EPIPE;
-            s->pos = offset;
         }
-        s->eof_reached = 0;
+        s->buf_ptr = s->buffer;
+        if (s->seek(s->opaque, offset, SEEK_SET) == (offset_t)-EPIPE)
+            return -EPIPE;
+        s->pos = offset;
     }
+    s->eof_reached = 0;
     return offset;
 }