examples: bring back curl_formadd-using examples

... now with a -formadd suffix. While the new mime API is introduced in
7.56.0 we must acknowledge that lots of users can't upgrade their curl
versions immediately.

docs/examples/Makefile.inc

@@ -33,7 +33,7 @@ check_PROGRAMS = 10-at-a-time anyauthput cookie_interface debug fileupload \
   imap-search imap-create imap-delete imap-copy imap-noop imap-ssl         \
   imap-tls imap-multi url2file sftpget ftpsget postinmemory http2-download \
   http2-upload http2-serverpush getredirect ftpuploadfrommem               \
-  ftpuploadresume sslbackend
+  ftpuploadresume sslbackend postit2-formadd multi-formadd
 
 # These examples require external dependencies that may not be commonly
 # available on POSIX systems, so don't bother attempting to compile them here.

docs/examples/multi-formadd.c

@@ -0,0 +1,171 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, 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 https://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.
+ *
+ ***************************************************************************/
+/* <DESC>
+ * using the multi interface to do a multipart formpost without blocking
+ * </DESC>
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/time.h>
+
+#include <curl/curl.h>
+
+int main(void)
+{
+  CURL *curl;
+
+  CURLM *multi_handle;
+  int still_running;
+
+  struct curl_httppost *formpost = NULL;
+  struct curl_httppost *lastptr = NULL;
+  struct curl_slist *headerlist = NULL;
+  static const char buf[] = "Expect:";
+
+  /* Fill in the file upload field. This makes libcurl load data from
+     the given file name when curl_easy_perform() is called. */
+  curl_formadd(&formpost,
+               &lastptr,
+               CURLFORM_COPYNAME, "sendfile",
+               CURLFORM_FILE, "postit2.c",
+               CURLFORM_END);
+
+  /* Fill in the filename field */
+  curl_formadd(&formpost,
+               &lastptr,
+               CURLFORM_COPYNAME, "filename",
+               CURLFORM_COPYCONTENTS, "postit2.c",
+               CURLFORM_END);
+
+  /* Fill in the submit field too, even if this is rarely needed */
+  curl_formadd(&formpost,
+               &lastptr,
+               CURLFORM_COPYNAME, "submit",
+               CURLFORM_COPYCONTENTS, "send",
+               CURLFORM_END);
+
+  curl = curl_easy_init();
+  multi_handle = curl_multi_init();
+
+  /* initialize custom header list (stating that Expect: 100-continue is not
+     wanted */
+  headerlist = curl_slist_append(headerlist, buf);
+  if(curl && multi_handle) {
+
+    /* what URL that receives this POST */
+    curl_easy_setopt(curl, CURLOPT_URL, "http://www.example.com/upload.cgi");
+    curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+
+    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist);
+    curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
+
+    curl_multi_add_handle(multi_handle, curl);
+
+    curl_multi_perform(multi_handle, &still_running);
+
+    do {
+      struct timeval timeout;
+      int rc; /* select() return code */
+      CURLMcode mc; /* curl_multi_fdset() return code */
+
+      fd_set fdread;
+      fd_set fdwrite;
+      fd_set fdexcep;
+      int maxfd = -1;
+
+      long curl_timeo = -1;
+
+      FD_ZERO(&fdread);
+      FD_ZERO(&fdwrite);
+      FD_ZERO(&fdexcep);
+
+      /* set a suitable timeout to play around with */
+      timeout.tv_sec = 1;
+      timeout.tv_usec = 0;
+
+      curl_multi_timeout(multi_handle, &curl_timeo);
+      if(curl_timeo >= 0) {
+        timeout.tv_sec = curl_timeo / 1000;
+        if(timeout.tv_sec > 1)
+          timeout.tv_sec = 1;
+        else
+          timeout.tv_usec = (curl_timeo % 1000) * 1000;
+      }
+
+      /* get file descriptors from the transfers */
+      mc = curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);
+
+      if(mc != CURLM_OK) {
+        fprintf(stderr, "curl_multi_fdset() failed, code %d.\n", mc);
+        break;
+      }
+
+      /* On success the value of maxfd is guaranteed to be >= -1. We call
+         select(maxfd + 1, ...); specially in case of (maxfd == -1) there are
+         no fds ready yet so we call select(0, ...) --or Sleep() on Windows--
+         to sleep 100ms, which is the minimum suggested value in the
+         curl_multi_fdset() doc. */
+
+      if(maxfd == -1) {
+#ifdef _WIN32
+        Sleep(100);
+        rc = 0;
+#else
+        /* Portable sleep for platforms other than Windows. */
+        struct timeval wait = { 0, 100 * 1000 }; /* 100ms */
+        rc = select(0, NULL, NULL, NULL, &wait);
+#endif
+      }
+      else {
+        /* Note that on some platforms 'timeout' may be modified by select().
+           If you need access to the original value save a copy beforehand. */
+        rc = select(maxfd + 1, &fdread, &fdwrite, &fdexcep, &timeout);
+      }
+
+      switch(rc) {
+      case -1:
+        /* select error */
+        break;
+      case 0:
+      default:
+        /* timeout or readable/writable sockets */
+        printf("perform!\n");
+        curl_multi_perform(multi_handle, &still_running);
+        printf("running: %d!\n", still_running);
+        break;
+      }
+    } while(still_running);
+
+    curl_multi_cleanup(multi_handle);
+
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+
+    /* then cleanup the formpost chain */
+    curl_formfree(formpost);
+
+    /* free slist */
+    curl_slist_free_all(headerlist);
+  }
+  return 0;
+}

docs/examples/postit2-formadd.c

@@ -0,0 +1,107 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, 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 https://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.
+ *
+ ***************************************************************************/
+/* <DESC>
+ * HTTP Multipart formpost with file upload and two additional parts.
+ * </DESC>
+ */
+/* Example code that uploads a file name 'foo' to a remote script that accepts
+ * "HTML form based" (as described in RFC1738) uploads using HTTP POST.
+ *
+ * The imaginary form we'll fill in looks like:
+ *
+ * <form method="post" enctype="multipart/form-data" action="examplepost.cgi">
+ * Enter file: <input type="file" name="sendfile" size="40">
+ * Enter file name: <input type="text" name="filename" size="30">
+ * <input type="submit" value="send" name="submit">
+ * </form>
+ *
+ * This exact source code has not been verified to work.
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include <curl/curl.h>
+
+int main(int argc, char *argv[])
+{
+  CURL *curl;
+  CURLcode res;
+
+  struct curl_httppost *formpost = NULL;
+  struct curl_httppost *lastptr = NULL;
+  struct curl_slist *headerlist = NULL;
+  static const char buf[] = "Expect:";
+
+  curl_global_init(CURL_GLOBAL_ALL);
+
+  /* Fill in the file upload field */
+  curl_formadd(&formpost,
+               &lastptr,
+               CURLFORM_COPYNAME, "sendfile",
+               CURLFORM_FILE, "postit2.c",
+               CURLFORM_END);
+
+  /* Fill in the filename field */
+  curl_formadd(&formpost,
+               &lastptr,
+               CURLFORM_COPYNAME, "filename",
+               CURLFORM_COPYCONTENTS, "postit2.c",
+               CURLFORM_END);
+
+
+  /* Fill in the submit field too, even if this is rarely needed */
+  curl_formadd(&formpost,
+               &lastptr,
+               CURLFORM_COPYNAME, "submit",
+               CURLFORM_COPYCONTENTS, "send",
+               CURLFORM_END);
+
+  curl = curl_easy_init();
+  /* initialize custom header list (stating that Expect: 100-continue is not
+     wanted */
+  headerlist = curl_slist_append(headerlist, buf);
+  if(curl) {
+    /* what URL that receives this POST */
+    curl_easy_setopt(curl, CURLOPT_URL, "http://example.com/examplepost.cgi");
+    if((argc == 2) && (!strcmp(argv[1], "noexpectheader")))
+      /* only disable 100-continue header if explicitly requested */
+      curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headerlist);
+    curl_easy_setopt(curl, CURLOPT_HTTPPOST, formpost);
+
+    /* Perform the request, res will get the return code */
+    res = curl_easy_perform(curl);
+    /* Check for errors */
+    if(res != CURLE_OK)
+      fprintf(stderr, "curl_easy_perform() failed: %s\n",
+              curl_easy_strerror(res));
+
+    /* always cleanup */
+    curl_easy_cleanup(curl);
+
+    /* then cleanup the formpost chain */
+    curl_formfree(formpost);
+    /* free slist */
+    curl_slist_free_all(headerlist);
+  }
+  return 0;
+}