notcurses_options: allow outfd to be specified

include/notcurses.h

@@ -17,6 +17,10 @@ typedef struct notcurses_options {
   // the environment variable TERM is used. Failure to open the terminal
   // definition will result in failure to initialize notcurses.
   const char* termtype;
+  // A file descriptor for this terminal on which we will generate output.
+  // Must be a valid file descriptor attached to a terminal, or notcurses will
+  // refuse to start. You'll usually want STDOUT_FILENO.
+  int outfd;
   // If smcup/rmcup capabilities are indicated, notcurses defaults to making
   // use of the "alternate screen." This flag inhibits use of smcup/rmcup.
   bool inhibit_alternate_screen;

src/bin/demo.c

@@ -5,7 +5,12 @@
 
 int main(void){
   struct notcurses* nc;
-  if((nc = notcurses_init(NULL)) == NULL){
+  notcurses_options nopts = {
+    .inhibit_alternate_screen = false,
+    .outfd = STDOUT_FILENO,
+    .termtype = NULL,
+  };
+  if((nc = notcurses_init(&nopts)) == NULL){
     return EXIT_FAILURE;
   }
   if(notcurses_fg_rgb8(nc, 200, 0, 200)){

src/lib/notcurses.c

@@ -145,12 +145,15 @@ alloc_plane(notcurses* nc, cell* oldplane, int* rows, int* cols){
 // FIXME should probably register a SIGWINCH handler here
 // FIXME install other sighandlers to clean things up
 notcurses* notcurses_init(const notcurses_options* opts){
+if(!ttyname(opts->outfd)){
+  exit(EXIT_FAILURE);
+}
   struct termios modtermios;
   notcurses* ret = malloc(sizeof(*ret));
   if(ret == NULL){
     return ret;
   }
-  ret->ttyfd = STDOUT_FILENO; // FIXME use others if stdout is redirected?
+  ret->ttyfd = opts->outfd;
   if(tcgetattr(ret->ttyfd, &ret->tpreserved)){
     fprintf(stderr, "Couldn't preserve terminal state for %d (%s)\n",
             ret->ttyfd, strerror(errno));
@@ -193,6 +196,8 @@ notcurses* notcurses_init(const notcurses_options* opts){
   if(!opts->inhibit_alternate_screen){
     term_verify_seq(&ret->smcup, "smcup");
     term_verify_seq(&ret->rmcup, "rmcup");
+  }else{
+    ret->smcup = ret->rmcup = NULL;
   }
   if((ret->plane = alloc_plane(ret, NULL, &ret->rows, &ret->cols)) == NULL){
     goto err;
@@ -224,6 +229,7 @@ int notcurses_stop(notcurses* nc){
   return ret;
 }
 
+// FIXME don't go using STDOUT_FILENO here, we want nc->outfd!
 // only works with string literals!
 #define strout(x) write(STDOUT_FILENO, (x), sizeof(x))
 

tests/notcurses.cpp

@@ -9,7 +9,9 @@ class NotcursesTest : public :: testing::Test {
     if(getenv("TERM") == nullptr){
       GTEST_SKIP();
     }
-    nc_ = notcurses_init(nullptr);
+    notcurses_options nopts{};
+    nopts.outfd = STDIN_FILENO;
+    nc_ = notcurses_init(&nopts);
     ASSERT_NE(nullptr, nc_);
   }
 
@@ -21,7 +23,6 @@ TEST_F(NotcursesTest, BasicLifetime) {
 }
 
 TEST_F(NotcursesTest, TermDimensions) {
-  ASSERT_NE(nullptr, nc_);
   int x, y;
   EXPECT_EQ(0, notcurses_term_dimensions(nc_, &y, &x));
   auto stry = getenv("LINES");