getinmemory.nim

#**************************************************************************
#                                   _   _ ____  _
#   Project                     ___| | | |  _ \| |
#                              / __| | | | |_) | |
#                             | (__| |_| |  _ <| |___
#                              \___|\___/|_| \_\_____|
#
#  Copyright (C) 1998 - 2013, Daniel Stenberg, <[email protected]>, et al.
#
#  This software is licensed as described in the file COPYING, which
#  you should have received as part of this distribution. The terms
#  are also available at http://curl.haxx.se/docs/copyright.html.
#
#  You may opt to use, copy, modify, merge, publish, distribute and/or sell
#  copies of the Software, and permit persons to whom the Software is
#  furnished to do so, under the terms of the COPYING file.
#
#  This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
#  KIND, either express or implied.
#
# *************************************************************************
# Example source code to show how the callback function can be used to
#  download data into a chunk of memory instead of storing it in a file.
#

type
  MemoryStruct* = object
    memory*: cstring
    size*: csize


proc WriteMemoryCallback*(contents: pointer; size: csize; nmemb: csize;
                          userp: pointer): csize =
  var realsize: csize = size * nmemb
  var mem: ptr MemoryStruct = cast[ptr MemoryStruct](userp)
  mem.memory = realloc(mem.memory, mem.size + realsize + 1)
  if mem.memory == nil:
    # out of memory!
    printf("not enough memory (realloc returned NULL)\x0A")
    return 0
  memcpy(addr((mem.memory[mem.size])), contents, realsize)
  inc(mem.size, realsize)
  mem.memory[mem.size] = 0
  return realsize

proc main*(): cint =
  var curl_handle: ptr CURL
  var res: CURLcode
  var chunk: MemoryStruct
  chunk.memory = malloc(1)
  # will be grown as needed by the realloc above
  chunk.size = 0
  # no data at this point
  curl_global_init(CURL_GLOBAL_ALL)
  # init the curl session
  curl_handle = curl_easy_init()
  # specify URL to get
  curl_easy_setopt(curl_handle, CURLOPT_URL, "http://www.example.com/")
  # send all data to this function
  curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback)
  # we pass our 'chunk' struct to the callback function
  curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, cast[pointer](addr(chunk)))
  # some servers don't like requests that are made without a user-agent
  #     field, so we provide one
  curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0")
  # get it!
  res = curl_easy_perform(curl_handle)
  # check for errors
  if res != CURLE_OK:
    fprintf(stderr, "curl_easy_perform() failed: %s\x0A",
            curl_easy_strerror(res))
  else:
    #
    #      Now, our chunk.memory points to a memory block that is chunk.size
    #      bytes big and contains the remote file.
    #
    #      Do something nice with it!
    #
    printf("%lu bytes retrieved\x0A", cast[clong](chunk.size))
  # cleanup curl stuff
  curl_easy_cleanup(curl_handle)
  if chunk.memory:
    free(chunk.memory)
  curl_global_cleanup()
  return 0