add CURLINFO_SCHEME, CURLINFO_PROTOCOL, and %{scheme}

Adds access to the effectively used protocol/scheme to both libcurl and
curl, both in string and numeric (CURLPROTO_*) form.

Note that the string form will be uppercase, as it is just the internal
string.

As these strings are declared internally as const, and all other strings
returned by curl_easy_getinfo() are de-facto const as well, string
handling in getinfo.c got const-ified.

Closes #1137

1 files changed, 59 insertions, 0 deletions

diff --git a/docs/libcurl/opts/CURLINFO_SCHEME.3 b/docs/libcurl/opts/CURLINFO_SCHEME.3
new file mode 100644
index 000000000..78c3d6886
--- /dev/null
+++ b/docs/libcurl/opts/CURLINFO_SCHEME.3
@@ -0,0 +1,59 @@
+.\" **************************************************************************
+.\" *                                  _   _ ____  _
+.\" *  Project                     ___| | | |  _ \| |
+.\" *                             / __| | | | |_) | |
+.\" *                            | (__| |_| |  _ <| |___
+.\" *                             \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2016, 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.
+.\" *
+.\" **************************************************************************
+.\"
+.TH CURLINFO_SCHEME 3 "23 November 2016" "libcurl 7.52.0" "curl_easy_getinfo options"
+.SH NAME
+CURLINFO_SCHEME \- get the URL scheme (sometimes called protocol) used in the connection
+.SH SYNOPSIS
+#include <curl/curl.h>
+
+CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_SCHEME, long *p);
+.SH DESCRIPTION
+Pass a pointer to a char pointer to receive the pointer to a zero-terminated
+string holding the URL scheme used for the most recent connection done with this
+\fBcurl\fP handle.
+
+The \fBid\fP pointer will be NULL or pointing to private read-only memory you
+MUST NOT free or modify.
+.SH PROTOCOLS
+All
+.SH EXAMPLE
+.nf
+CURL *curl = curl_easy_init();
+if(curl) {
+  CURLcode res;
+  curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
+  res = curl_easy_perform(curl);
+  if(res == CURLE_OK) {
+    char * scheme;
+    curl_easy_getinfo(curl, CURLINFO_SCHEME, &scheme);
+  }
+  curl_easy_cleanup(curl);
+}
+.fi
+.SH AVAILABILITY
+Added in 7.52.0
+.SH RETURN VALUE
+Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
+.SH "SEE ALSO"
+.BR CURLINFO_RESPONSE_CODE "(3), "
+.BR curl_easy_getinfo "(3), " curl_easy_setopt "(3), "