Update networking layer w/ CURL and emscripten impl

External/curl-8.17.0/docs/libcurl/opts/CURLOPT_CHUNK_DATA.md

@@ -0,0 +1,104 @@
+---
+c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+SPDX-License-Identifier: curl
+Title: CURLOPT_CHUNK_DATA
+Section: 3
+Source: libcurl
+See-also:
+  - CURLOPT_CHUNK_BGN_FUNCTION (3)
+  - CURLOPT_WILDCARDMATCH (3)
+Protocol:
+  - FTP
+Added-in: 7.21.0
+---
+
+# NAME
+
+CURLOPT_CHUNK_DATA - pointer passed to the FTP chunk callbacks
+
+# SYNOPSIS
+
+~~~c
+#include <curl/curl.h>
+
+CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CHUNK_DATA, void *pointer);
+~~~
+
+# DESCRIPTION
+
+Pass a *pointer* that is untouched by libcurl and passed as the ptr
+argument to the CURLOPT_CHUNK_BGN_FUNCTION(3) and
+CURLOPT_CHUNK_END_FUNCTION(3).
+
+# DEFAULT
+
+NULL
+
+# %PROTOCOLS%
+
+# EXAMPLE
+
+~~~c
+#include <stdio.h>
+
+struct callback_data {
+   FILE *output;
+};
+
+static long file_is_coming(struct curl_fileinfo *finfo,
+                           void *ptr,
+                           int remains)
+{
+  struct callback_data *data = ptr;
+  printf("%3d %40s %10luB ", remains, finfo->filename,
+         (unsigned long)finfo->size);
+
+  switch(finfo->filetype) {
+  case CURLFILETYPE_DIRECTORY:
+    printf(" DIR\n");
+    break;
+  case CURLFILETYPE_FILE:
+    printf("FILE ");
+    break;
+  default:
+    printf("OTHER\n");
+    break;
+  }
+
+  if(finfo->filetype == CURLFILETYPE_FILE) {
+    /* do not transfer files >= 50B */
+    if(finfo->size > 50) {
+      printf("SKIPPED\n");
+      return CURL_CHUNK_BGN_FUNC_SKIP;
+    }
+
+    data->output = fopen(finfo->filename, "wb");
+    if(!data->output) {
+      return CURL_CHUNK_BGN_FUNC_FAIL;
+    }
+  }
+
+  return CURL_CHUNK_BGN_FUNC_OK;
+}
+
+int main()
+{
+  /* data for callback */
+  struct callback_data callback_info;
+
+  CURL *curl = curl_easy_init();
+
+  /* callback is called before download of concrete file started */
+  curl_easy_setopt(curl, CURLOPT_CHUNK_BGN_FUNCTION, file_is_coming);
+  curl_easy_setopt(curl, CURLOPT_CHUNK_DATA, &callback_info);
+}
+~~~
+
+# %AVAILABILITY%
+
+# RETURN VALUE
+
+curl_easy_setopt(3) returns a CURLcode indicating success or error.
+
+CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
+libcurl-errors(3).