send: drop CURL_UNCONST() from buffer argument on most platforms

Keep it on platforms requiring a non-const buffer. These are AmigaOS and
OS400.

Also:
- replace `SEND_QUAL_ARG2` with boolean macro `SEND_NONCONST_ARG2`.

Closes #20463

lib/config-mac.h

@@ -77,7 +77,6 @@
 
 #define HAVE_SEND 1
 #define SEND_TYPE_ARG1 int
-#define SEND_QUAL_ARG2 const
 #define SEND_TYPE_ARG2 void *
 #define SEND_TYPE_ARG3 size_t
 #define SEND_TYPE_ARG4 int

lib/config-os400.h

@@ -256,8 +256,8 @@
 /* Define to the type of arg 1 for send. */
 #define SEND_TYPE_ARG1 int
 
-/* Define to the type qualifier of arg 2 for send. */
-#define SEND_QUAL_ARG2
+/* Define if the type qualifier of arg 2 for send is not const. */
+#define SEND_NONCONST_ARG2
 
 /* Define to the type of arg 2 for send. */
 #define SEND_TYPE_ARG2 char *

lib/config-riscos.h

@@ -213,9 +213,6 @@
 /* Define to the type of arg 1 for send. */
 #define SEND_TYPE_ARG1 int
 
-/* Define to the type qualifier of arg 2 for send. */
-#define SEND_QUAL_ARG2 const
-
 /* Define to the type of arg 2 for send. */
 #define SEND_TYPE_ARG2 void *
 

lib/config-win32.h

@@ -156,9 +156,6 @@
 /* Define to the type of arg 1 for send. */
 #define SEND_TYPE_ARG1 SOCKET
 
-/* Define to the type qualifier of arg 2 for send. */
-#define SEND_QUAL_ARG2 const
-
 /* Define to the type of arg 2 for send. */
 #define SEND_TYPE_ARG2 char *
 

lib/curl_setup_once.h

@@ -144,9 +144,10 @@ struct timeval {
  * which is used to write outgoing data on a connected socket.
  * If yours has another name then do not define HAVE_SEND.
  *
- * If HAVE_SEND is defined then SEND_TYPE_ARG1, SEND_QUAL_ARG2,
- * SEND_TYPE_ARG2, SEND_TYPE_ARG3, SEND_TYPE_ARG4 and
- * SEND_TYPE_RETV must also be defined.
+ * If HAVE_SEND is defined then SEND_TYPE_ARG1, SEND_TYPE_ARG2,
+ * SEND_TYPE_ARG3, SEND_TYPE_ARG4 and SEND_TYPE_RETV must also
+ * be defined. SEND_NONCONST_ARG2 must also be defined if ARG2
+ * does not accept const.
  */
 
 #define sread(x, y, z) (ssize_t)recv((RECV_TYPE_ARG1)(x), \
@@ -165,10 +166,17 @@ struct timeval {
                                        (SEND_TYPE_ARG2)CURL_UNCONST(y), \
                                        (SEND_TYPE_ARG3)(z))
 #elif defined(HAVE_SEND)
+#ifdef SEND_NONCONST_ARG2
 #define swrite(x, y, z) (ssize_t)send((SEND_TYPE_ARG1)(x), \
-                              (SEND_QUAL_ARG2 SEND_TYPE_ARG2)CURL_UNCONST(y), \
+                                      (SEND_TYPE_ARG2)CURL_UNCONST(y), \
                                       (SEND_TYPE_ARG3)(z), \
                                       (SEND_TYPE_ARG4)(SEND_4TH_ARG))
+#else
+#define swrite(x, y, z) (ssize_t)send((SEND_TYPE_ARG1)(x), \
+                                      (const SEND_TYPE_ARG2)(y), \
+                                      (SEND_TYPE_ARG3)(z), \
+                                      (SEND_TYPE_ARG4)(SEND_4TH_ARG))
+#endif /* SEND_NONCONST_ARG2 */
 #else /* HAVE_SEND */
 #ifndef swrite
 #error "Missing definition of macro swrite!"

lib/functypes.h

@@ -59,9 +59,9 @@
 #define RECV_TYPE_ARG4 long
 #define RECV_TYPE_RETV long
 
-/* int send(int, const char *, int, int); */
+/* int send(int, char *, int, int); */
 #define SEND_TYPE_ARG1 int
-#define SEND_QUAL_ARG2
+#define SEND_NONCONST_ARG2
 #define SEND_TYPE_ARG2 char *
 #define SEND_TYPE_ARG3 int
 #define SEND_TYPE_RETV int
@@ -87,10 +87,6 @@
 #define RECV_TYPE_RETV ssize_t
 #endif
 
-#ifndef SEND_QUAL_ARG2
-#define SEND_QUAL_ARG2 const
-#endif
-
 #ifndef SEND_TYPE_ARG1
 #define SEND_TYPE_ARG1 int
 #endif

projects/vms/config_h.com

@@ -1582,13 +1582,6 @@ $!      Process SEND directives
 $!-------------------------------------
 $       if key2a .eqs. "SEND"
 $       then
-$           if key2 .eqs. "SEND_QUAL_ARG2"
-$           then
-$               write tf "#ifndef ''key2'"
-$               write tf "#define ''key2' const"
-$               write tf "#endif"
-$               goto cfgh_in_loop1
-$           endif
 $           if key2 .eqs. "SEND_TYPE_ARG1"
 $           then
 $               write tf "#ifndef ''key2'"