From e909e6d6e9be0a25b4c48f0fa341c8ef8baf89bc Mon Sep 17 00:00:00 2001
From: nick black <dankamongmen@gmail.com>
Date: Tue, 22 Jun 2021 14:13:16 -0400
Subject: [PATCH] gimme that appsync support #1582

---
 src/lib/debug.c    |  5 +++--
 src/lib/input.c    | 26 ++++++++++++++++++++++++--
 src/lib/termdesc.c |  2 +-
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/src/lib/debug.c b/src/lib/debug.c
index 6eeb40f540..e55203ae6d 100644
--- a/src/lib/debug.c
+++ b/src/lib/debug.c
@@ -51,10 +51,11 @@ static void
 tinfo_debug_caps(const tinfo* ti, FILE* debugfp, int rows, int cols,
                  unsigned images, unsigned videos){
   const char indent[] = " ";
-  fprintf(debugfp, "%scolors: %u rgb: %c ccc: %c setaf: %c setab: %c\n",
+  fprintf(debugfp, "%scolors: %u rgb: %c ccc: %c setaf: %c setab: %c app-sync: %c\n",
           indent, ti->caps.colors, capbool(ti->caps.rgb), capbool(ti->caps.can_change_colors),
           capyn(get_escape(ti, ESCAPE_SETAF)),
-          capyn(get_escape(ti, ESCAPE_SETAB)));
+          capyn(get_escape(ti, ESCAPE_SETAB)),
+          capyn(get_escape(ti, ESCAPE_BSU)));
   fprintf(debugfp, "%ssgr: %c sgr0: %c op: %c fgop: %c bgop: %c\n",
           indent, capyn(get_escape(ti, ESCAPE_SGR)),
                   capyn(get_escape(ti, ESCAPE_SGR0)),
diff --git a/src/lib/input.c b/src/lib/input.c
index 2a49188754..b39a77d06d 100644
--- a/src/lib/input.c
+++ b/src/lib/input.c
@@ -646,6 +646,8 @@ typedef enum {
   STATE_SIXEL_HEIGHT,  // reading maximum sixel height until 'S'
   STATE_SIXEL_CREGS,   // reading max color registers until 'S'
   STATE_XTSMGRAPHICS_DRAIN, // drain out XTSMGRAPHICS to 'S'
+  STATE_APPSYNC_REPORT, // got DECRPT ?2026
+  STATE_APPSYNC_REPORT_DRAIN, // drain out decrpt to 'y'
 } initstates_e;
 
 typedef struct query_state {
@@ -817,7 +819,7 @@ stash_string(query_state* inits){
 // ought be fed to the machine, and -1 on an invalid state transition.
 static int
 pump_control_read(query_state* inits, unsigned char c){
-//fprintf(stderr, "state: %2d char: %1c %3d %02x\n", inits->state, isprint(c) ? c : ' ', c, c);
+fprintf(stderr, "state: %2d char: %1c %3d %02x\n", inits->state, isprint(c) ? c : ' ', c, c);
   if(c == NCKEY_ESC){
     inits->state = STATE_ESC;
     return 0;
@@ -1006,6 +1008,9 @@ pump_control_read(query_state* inits, unsigned char c){
       if(c == '1'){
         inits->state = STATE_DA_1;
       }else if(c == '2'){
+        if(ruts_numeric(&inits->numeric, c)){ // stash for DECRPT
+          return -1;
+        }
         inits->state = STATE_SIXEL;
       }else if(c == '4' || c == '7'){ // VT132, VT131
         inits->state = STATE_DA_DRAIN;
@@ -1065,7 +1070,13 @@ pump_control_read(query_state* inits, unsigned char c){
       break;
     case STATE_SIXEL:
       if(c == ';'){
-        inits->state = STATE_SIXEL_SEMI1;
+        if(inits->numeric == 2026){
+          inits->state = STATE_APPSYNC_REPORT;
+        }else{
+          inits->state = STATE_SIXEL_SEMI1;
+        }
+      }else if(ruts_numeric(&inits->numeric, c)){
+        return -1;
       }else{
         // FIXME error?
       }
@@ -1108,6 +1119,17 @@ pump_control_read(query_state* inits, unsigned char c){
         inits->state = STATE_NULL;
       }
       break;
+    case STATE_APPSYNC_REPORT:
+      if(c == '2'){
+        inits->appsync = 1;
+        inits->state = STATE_APPSYNC_REPORT_DRAIN;
+      }
+      break;
+    case STATE_APPSYNC_REPORT_DRAIN:
+      if(c == 'y'){
+        inits->state = STATE_NULL;
+      }
+      break;
     default:
       fprintf(stderr, "Reached invalid init state %d\n", inits->state);
       return -1;
diff --git a/src/lib/termdesc.c b/src/lib/termdesc.c
index 7df7cc1304..4cf8156962 100644
--- a/src/lib/termdesc.c
+++ b/src/lib/termdesc.c
@@ -288,7 +288,7 @@ apply_term_heuristics(tinfo* ti, const char* termname, int fd,
 static int
 send_initial_queries(int fd){
   const char queries[] = CSI_BGQ
-                         "\x1b[?2026$p"      // App-Sync Update support
+                         "\x1b[?2026$p"      // query for App-sync updates
                          "\x1b[=0c"          // Tertiary Device Attributes
                          "\x1b[>0q"          // XTVERSION
                          "\x1bP+q544e\x1b\\" // XTGETTCAP['TN']