tiff: refactor deflate support in a separate function

Report when zlib support is missing.

libavcodec/tiff.c

@@ -111,23 +111,14 @@ static int tiff_uncompress(uint8_t *dst, unsigned long *len, const uint8_t *src,
     *len = zstream.total_out;
     return zret == Z_STREAM_END ? Z_OK : zret;
 }
-#endif
 
-static int tiff_unpack_strip(TiffContext *s, uint8_t *dst, int stride,
-                             const uint8_t *src, int size, int lines)
+static int tiff_unpack_zlib(TiffContext *s, uint8_t *dst, int stride,
+                            const uint8_t *src, int size,
+                            int width, int lines)
 {
-    int c, line, pixels, code, ret;
-    const uint8_t *ssrc = src;
-    int width           = ((s->width * s->bpp) + 7) >> 3;
-
-    if (size <= 0)
-        return AVERROR_INVALIDDATA;
-
-#if CONFIG_ZLIB
-    if (s->compr == TIFF_DEFLATE || s->compr == TIFF_ADOBE_DEFLATE) {
     uint8_t *zbuf;
     unsigned long outlen;
-        int ret;
+    int ret, line;
     outlen = width * lines;
     zbuf   = av_malloc(outlen);
     if (!zbuf)
@@ -148,8 +139,29 @@ static int tiff_unpack_strip(TiffContext *s, uint8_t *dst, int stride,
     }
     av_free(zbuf);
     return 0;
-    }
+}
+#endif
+
+static int tiff_unpack_strip(TiffContext *s, uint8_t *dst, int stride,
+                             const uint8_t *src, int size, int lines)
+{
+    int c, line, pixels, code, ret;
+    const uint8_t *ssrc = src;
+    int width           = ((s->width * s->bpp) + 7) >> 3;
+
+    if (size <= 0)
+        return AVERROR_INVALIDDATA;
+
+    if (s->compr == TIFF_DEFLATE || s->compr == TIFF_ADOBE_DEFLATE) {
+#if CONFIG_ZLIB
+        return tiff_unpack_zlib(s, dst, stride, src, size, width, lines);
+#else
+        av_log(s->avctx, AV_LOG_ERROR,
+               "zlib support not enabled, "
+               "deflate compression not supported\n");
+        return AVERROR(ENOSYS);
 #endif
+    }
     if (s->compr == TIFF_LZW) {
         if ((ret = ff_lzw_decode_init(s->lzw, 8, src, size, FF_LZW_TIFF)) < 0) {
             av_log(s->avctx, AV_LOG_ERROR, "Error initializing LZW decoder\n");