cURL: make possible to send file from buffer string

Add CURLStringFile class which works similarly to CURLFile, but
uploads a file from a string rather than a file. This avoids the
need to create a temporary file, or use of a data:// stream.

Basic usage:

    $file = new CURLStringFile($data, 'filename.txt', 'text/plain');
    curl_setopt($curl, CURLOPT_POSTFIELDS, ['file' => $file]);

Closes GH-6456.

1 files changed, 5 insertions, 0 deletions

diff --git a/UPGRADING b/UPGRADING
index 2e4700c1c9..5d72233e90 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -100,6 +100,11 @@ PHP 8.1 UPGRADE NOTES
 
 - Curl:
   . Added CURLOPT_DOH_URL option.
+  . Added CURLStringFile, which can be used to post a file from a string rather
+    than a file:
+
+        $file = new CURLStringFile($data, 'filename.txt', 'text/plain');
+        curl_setopt($curl, CURLOPT_POSTFIELDS, ['file' => $file]);
 
 - hash:
   . The following functions have changed signatures: