http_chunked_compression: fixed errors

src/examples/http_chunked_compression.c

@@ -1,6 +1,7 @@
 /*
      This file is part of libmicrohttpd
      Copyright (C) 2019 Christian Grothoff (and other contributing authors)
+     Copyright (C) 2019-2022 Evgeny Grin (Karlson2k)
 
      This library is free software; you can redistribute it and/or
      modify it under the terms of the GNU Lesser General Public
@@ -20,15 +21,21 @@
  * @file http_chunked_compression.c
  * @brief example for how to compress a chunked HTTP response
  * @author Silvio Clecio (silvioprog)
+ * @author Karlson2k (Evgeny Grin)
  */
 
 #include "platform.h"
+#ifndef ZLIB_CONST
+/* Correct API with const pointer for input data is required */
+#define ZLIB_CONST 1
+#endif /* ! ZLIB_CONST */
 #include <zlib.h>
 #include <microhttpd.h>
 #ifdef HAVE_LIMITS_H
 #include <limits.h>
 #endif /* HAVE_LIMITS_H */
 #include <stddef.h>
+#include <stdint.h>
 
 #ifndef SSIZE_MAX
 #ifdef __SSIZE_MAX__
@@ -76,7 +83,7 @@ compress_buf (z_stream *strm, const void *src, size_t src_size, size_t *offset,
       flush = Z_SYNC_FLUSH;
     }
     *offset += strm->avail_in;
-    strm->next_in = (Bytef *) src;
+    strm->next_in = (const Bytef *) src;
     do
     {
       strm->avail_out = CHUNK;
@@ -92,7 +99,7 @@ compress_buf (z_stream *strm, const void *src, size_t src_size, size_t *offset,
         return MHD_NO;
       }
       *dest = tmp_dest;
-      memcpy ((*dest) + ((*dest_size) - have), tmp, have);
+      memcpy (((uint8_t *) (*dest)) + ((*dest_size) - have), tmp, have);
     }
     while (0 == strm->avail_out);
   }
@@ -109,6 +116,7 @@ read_cb (void *cls, uint64_t pos, char *mem, size_t size)
   void *buf;
   ssize_t ret;
   size_t offset;
+  size_t r_size;
 
   if (pos > SSIZE_MAX)
     return MHD_CONTENT_READER_END_WITH_ERROR;
@@ -116,24 +124,20 @@ read_cb (void *cls, uint64_t pos, char *mem, size_t size)
   src = malloc (size);
   if (NULL == src)
     return MHD_CONTENT_READER_END_WITH_ERROR;
-  ret = fread (src, 1, size, holder->file);
-  if (ret < 0)
+  r_size = fread (src, 1, size, holder->file);
+  if (0 == r_size)
   {
-    ret = MHD_CONTENT_READER_END_WITH_ERROR;
-    goto done;
-  }
-  if (0 == ret)
-  {
-    ret = MHD_CONTENT_READER_END_OF_STREAM;
+    ret = (0 != ferror (holder->file)) ?
+          MHD_CONTENT_READER_END_WITH_ERROR : MHD_CONTENT_READER_END_OF_STREAM;
     goto done;
   }
-  if (MHD_YES != compress_buf (&holder->stream, src, ret, &offset, &buf, &size,
-                               holder->buf))
+  if (MHD_YES != compress_buf (&holder->stream, src, r_size, &offset, &buf,
+                               &size, holder->buf))
     ret = MHD_CONTENT_READER_END_WITH_ERROR;
   else
   {
     memcpy (mem, buf, size);
-    ret = size;
+    ret = (ssize_t) size;
   }
   free (buf); /* Buf may be set even on error return. */
 done: