From 0f10eaf9fcfdfd75cf2363582e241f262e2641ba Mon Sep 17 00:00:00 2001
From: nick black <dankamongmen@gmail.com>
Date: Wed, 26 May 2021 02:34:50 -0400
Subject: [PATCH] termdesc: move smcup/rmcup lookup into interrogate_terminfo()
 #1525

---
 src/lib/direct.c    |  2 +-
 src/lib/internal.h  |  6 ++++--
 src/lib/notcurses.c |  8 ++------
 src/lib/terminfo.c  | 24 +++++++++++++++---------
 4 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/src/lib/direct.c b/src/lib/direct.c
index 7daa51f91..be6c33a99 100644
--- a/src/lib/direct.c
+++ b/src/lib/direct.c
@@ -767,7 +767,7 @@ ncdirect* ncdirect_core_init(const char* termtype, FILE* outfp, uint64_t flags){
   if(ncvisual_init(NCLOGLEVEL_SILENT)){
     goto err;
   }
-  if(interrogate_terminfo(&ret->tcache, ret->ctermfd, shortname_term, utf8)){
+  if(interrogate_terminfo(&ret->tcache, ret->ctermfd, shortname_term, utf8, 1)){
     goto err;
   }
   update_term_dimensions(ret->ctermfd, NULL, NULL, &ret->tcache);
diff --git a/src/lib/internal.h b/src/lib/internal.h
index 9cd6a5ea0..cf0462ab0 100644
--- a/src/lib/internal.h
+++ b/src/lib/internal.h
@@ -605,11 +605,13 @@ void update_write_stats(const struct timespec* time1, const struct timespec* tim
 void sigwinch_handler(int signo);
 
 void init_lang(notcurses* nc); // nc may be NULL, only used for logging
-int terminfostr(char** gseq, const char* name);
 
 // load |ti| from the terminfo database, which must already have been
 // initialized. set |utf8| if we've verified UTF8 output encoding.
-int interrogate_terminfo(tinfo* ti, int fd, const char* termname, unsigned utf8);
+// set |noaltscreen| to inhibit alternate screen detection. |fd| ought
+// be connected to a terminal device, or -1 if no terminal is available.
+int interrogate_terminfo(tinfo* ti, int fd, const char* termname,
+                         unsigned utf8, unsigned noaltscreen);
 
 void free_terminfo_cache(tinfo* ti);
 
diff --git a/src/lib/notcurses.c b/src/lib/notcurses.c
index f5929cf07..8f75d91b0 100644
--- a/src/lib/notcurses.c
+++ b/src/lib/notcurses.c
@@ -1056,7 +1056,8 @@ notcurses* notcurses_core_init(const notcurses_options* opts, FILE* outfp){
   }
   const char* shortname_term = termname();
 // const char* longname_term = longname();
-  if(interrogate_terminfo(&ret->tcache, ret->ttyfd, shortname_term, utf8)){
+  if(interrogate_terminfo(&ret->tcache, ret->ttyfd, shortname_term, utf8,
+                          opts->flags & NCOPTION_NO_ALTERNATE_SCREEN)){
     goto err;
   }
   int dimy, dimx;
@@ -1070,11 +1071,6 @@ notcurses* notcurses_core_init(const notcurses_options* opts, FILE* outfp){
   if(set_fd_nonblocking(ret->input.ttyinfd, 1, &ret->stdio_blocking_save)){
     goto err;
   }
-  // Neither of these is supported on e.g. the "linux" virtual console.
-  if(!(opts->flags & NCOPTION_NO_ALTERNATE_SCREEN)){
-    terminfostr(&ret->tcache.smcup, "smcup");
-    terminfostr(&ret->tcache.rmcup, "rmcup");
-  }
   if(ncvisual_init(ret->loglevel)){
     goto err;
   }
diff --git a/src/lib/terminfo.c b/src/lib/terminfo.c
index 0a200ac86..ac46570f5 100644
--- a/src/lib/terminfo.c
+++ b/src/lib/terminfo.c
@@ -54,11 +54,8 @@ query_rgb(void){
   return rgb;
 }
 
-int terminfostr(char** gseq, const char* name){
-  char* seq;
-  if(gseq == NULL){
-    gseq = &seq;
-  }
+static int
+terminfostr(char** gseq, const char* name){
   *gseq = tigetstr(name);
   if(*gseq == NULL || *gseq == (char*)-1){
     *gseq = NULL;
@@ -66,10 +63,13 @@ int terminfostr(char** gseq, const char* name){
   }
   // terminfo syntax allows a number N of milliseconds worth of pause to be
   // specified using $<N> syntax. this is then honored by tputs(). but we don't
-  // use tputs(), instead preferring the much faster stdio+tiparm(). to avoid
-  // dumping "$<N>" sequences all over stdio, we chop them out.
+  // use tputs(), instead preferring the much faster stdio+tiparm() (at the
+  // expense of terminals which do require these delays). to avoid dumping
+  // "$<N>" sequences all over stdio, we chop them out.
   char* pause;
   if( (pause = strchr(*gseq, '$')) ){
+    // FIXME can there ever be further content following a pause?
+    // tighten this up to match the precise spec in terminfo(5)!
     *pause = '\0';
   }
   return 0;
@@ -140,7 +140,8 @@ void free_terminfo_cache(tinfo* ti){
 // termname is just the TERM environment variable. some details are not
 // exposed via terminfo, and we must make heuristic decisions based on
 // the detected terminal type, yuck :/.
-int interrogate_terminfo(tinfo* ti, int fd, const char* termname, unsigned utf8){
+int interrogate_terminfo(tinfo* ti, int fd, const char* termname,
+                         unsigned utf8, unsigned noaltscreen){
   memset(ti, 0, sizeof(*ti));
   ti->utf8 = utf8;
   // allow the "rgb" boolean terminfo capability, a COLORTERM environment
@@ -162,12 +163,17 @@ int interrogate_terminfo(tinfo* ti, int fd, const char* termname, unsigned utf8)
       ti->CCCflag = false;
     }
   }
-  // check that the terminal provides cursor addressing (absolute movement)
+  // verify that the terminal provides cursor addressing (absolute movement)
   terminfostr(&ti->cup, "cup");
   if(ti->cup == NULL){
     fprintf(stderr, "Required terminfo capability 'cup' not defined\n");
     return -1;
   }
+  // neither of these is supported on e.g. the "linux" virtual console.
+  if(!noaltscreen){
+    terminfostr(&ti->smcup, "smcup");
+    terminfostr(&ti->rmcup, "rmcup");
+  }
   // check that the terminal provides automatic margins
   ti->AMflag = tigetflag("am") == 1;
   if(!ti->AMflag){