Make stripctrl_string take an existing StripCtrlChars.

Now instead of making a StripCtrlChars just for that function call, it
uses an existing one, pointing it at the output strbuf via
stripctrl_retarget.

This adds flexibility (now you can use the same convenient string-
sanitising function with a StripCtrl configured in any way you like)
and also saves pointless setting-up and tearing-down of identical sccs
all the time.

The existing call sites in PSCP and PSFTP now use a static
StripCtrlChars instance that was made at program startup.

misc.h

@@ -387,10 +387,10 @@ StripCtrlChars *stripctrl_new_term_fn(
 void stripctrl_retarget(StripCtrlChars *sccpub, BinarySink *new_bs_out);
 void stripctrl_reset(StripCtrlChars *sccpub);
 void stripctrl_free(StripCtrlChars *sanpub);
-char *stripctrl_string_ptrlen(ptrlen str);
+char *stripctrl_string_ptrlen(StripCtrlChars *sccpub, ptrlen str);
-static inline char *stripctrl_string(const char *str)
+static inline char *stripctrl_string(StripCtrlChars *sccpub, const char *str)
 {
-    return stripctrl_string_ptrlen(ptrlen_from_asciz(str));
+    return stripctrl_string_ptrlen(sccpub, ptrlen_from_asciz(str));
 }
 
 #endif

pscp.c

@@ -256,8 +256,9 @@ static NORETURN void bump(const char *fmt, ...)
  * version of a string for display, and free it automatically
  * afterwards.
  */
+static StripCtrlChars *string_scc;
 #define with_stripctrl(varname, input)                                  \
-    for (char *varname = stripctrl_string(input); varname;      \
+    for (char *varname = stripctrl_string(string_scc, input); varname;  \
          sfree(varname), varname = NULL)
 
 /*
@@ -1889,7 +1890,8 @@ static void sink(const char *targ, const char *src)
 	stat_bytes = 0;
 	stat_starttime = time(NULL);
 	stat_lasttime = 0;
-        stat_name = stripctrl_string(stripslashes(destfname, true));
+        stat_name = stripctrl_string(
+            string_scc, stripslashes(destfname, true));
 
 	received = 0;
 	while (received < act.size) {
@@ -2319,6 +2321,8 @@ int psftp_main(int argc, char *argv[])
         stderr_bs = BinarySink_UPCAST(stderr_scc);
     }
 
+    string_scc = stripctrl_new(NULL, false, L'\0');
+
     if (list) {
 	if (argc != 1)
 	    usage();

psftp.c

@@ -70,8 +70,9 @@ static Seat psftp_seat[1] = {{ &psftp_seat_vt }};
  * version of a string for display, and free it automatically
  * afterwards.
  */
+static StripCtrlChars *string_scc;
 #define with_stripctrl(varname, input)                                  \
-    for (char *varname = stripctrl_string(input); varname;      \
+    for (char *varname = stripctrl_string(string_scc, input); varname;  \
          sfree(varname), varname = NULL)
 
 /* ----------------------------------------------------------------------
@@ -2863,6 +2864,8 @@ int psftp_main(int argc, char *argv[])
         stderr_bs = BinarySink_UPCAST(stderr_scc);
     }
 
+    string_scc = stripctrl_new(NULL, false, L'\0');
+
     /*
      * If the loaded session provides a hostname, and a hostname has not
      * otherwise been specified, pop it in `userhost' so that

stripctrl.c

@@ -95,7 +95,7 @@ void stripctrl_reset(StripCtrlChars *sccpub)
      * start converting a fresh piece of data to send to a channel
      * that hasn't seen the previous output.
      */
-    memset(&scc->term_utf8_decode, 0, sizeof(scc->term_utf8_decode));
+    memset(&scc->utf8, 0, sizeof(scc->utf8));
     memset(&scc->mbs_in, 0, sizeof(scc->mbs_in));
     memset(&scc->mbs_out, 0, sizeof(scc->mbs_out));
 }
@@ -358,12 +358,12 @@ static void stripctrl_term_BinarySink_write(
     }
 }
 
-char *stripctrl_string_ptrlen(ptrlen str)
+char *stripctrl_string_ptrlen(StripCtrlChars *sccpub, ptrlen str)
 {
     strbuf *out = strbuf_new();
-    StripCtrlChars *scc = stripctrl_new(BinarySink_UPCAST(out), false, L'?');
+    stripctrl_retarget(sccpub, BinarySink_UPCAST(out));
-    put_datapl(scc, str);
+    put_datapl(sccpub, str);
-    stripctrl_free(scc);
+    stripctrl_retarget(sccpub, NULL);
     return strbuf_to_str(out);
 }