MIME: Support RFC2231 for filenames. Bug 466

Patch originally from Alexander Shikoff, heavily reworked by JH.

doc/doc-docbook/spec.xfpt

@@ -31157,7 +31157,8 @@ containing the decoded data.
 This is perhaps the most important of the MIME variables. It contains a
 proposed filename for an attachment, if one was found in either the
 &'Content-Type:'& or &'Content-Disposition:'& headers. The filename will be
-RFC2047 decoded, but no additional sanity checks are done. If no filename was
+RFC2047 or RFC2231 decoded, but no additional sanity checks are done.
+ If no filename was
 found, this variable contains the empty string.
 
 .vitem &$mime_is_coverletter$&

doc/doc-txt/ChangeLog

@@ -86,6 +86,9 @@ JH/24 Verification callouts now attempt to use TLS by default.
 HS/01 DNSSEC options (dnssec_require_domains, dnssec_request_domains) 
       are generic router options now. The defaults didn't change.
 
+JH/25 Bug 466: Add RFC2322 support for MIME attachment filenames.
+      Original patch from Alexander Shikoff, worked over by JH.
+
 
 Exim version 4.85
 -----------------

src/src/macros.h

@@ -12,6 +12,9 @@ a string as a text string. This is sometimes useful for debugging output. */
 #define mac_string(s) # s
 #define mac_expanded_string(s) mac_string(s)
 
+/* Number of elements of an array */
+#define nelem(arr) (sizeof(arr) / sizeof(*arr))
+
 
 /* When running in the test harness, the load average is fudged. */
 
@@ -156,11 +159,11 @@ into big_buffer_size and in some circumstances increased. It should be at least
 as long as the maximum path length. */
 
 #if defined PATH_MAX && PATH_MAX > 16384
-#define BIG_BUFFER_SIZE PATH_MAX
+# define BIG_BUFFER_SIZE PATH_MAX
 #elif defined MAXPATHLEN && MAXPATHLEN > 16384
-#define BIG_BUFFER_SIZE MAXPATHLEN
+# define BIG_BUFFER_SIZE MAXPATHLEN
 #else
-#define BIG_BUFFER_SIZE 16384
+# define BIG_BUFFER_SIZE 16384
 #endif
 
 /* header size of pipe content